B33101 - Boiler Code - ATHRAathra.asn.au/library/B33101_Boiler_Code.pdf · BOILER CODE Issue...

FRONZ / ONTRACKAPPROVED CODE OF PRACTISE

FORHERITAGE NETWORK OPERATORS

Mechanical CodeB3.3.1.01

BOILER CODE

Issue Prepared (P),Reviewed (R),Amended (A)

Approved by Effective Date

1 T Pointon (P) LTSA 20022 S Pointon (A) LTSA 20063 P McCallum (A) Heritage Technical Committee 12 Dec 2006

Reference MaterialSource Description DateMarine Department Boiler Code 1975British Standard 2790 Part 1 - 1969 Metric Boiler Code 1969

The holder of printed or duplicated copies of this document isresponsible for ensuring they are using the latest version.

FRONZ / ONTRACK B3..3.1.01Issue 3

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Amendment History

Version Section Amendment2 Amended to include new inspection regulations3 Reformatted to FRONZ standard and minor errors corrected.

Sections headers added.


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CONTENTS

INTRODUCTION................................................................................................. 2

1. SCOPE: ................................................................................................... 2

Inspections.............................................................................................. 2

Boiler Certificate to be Exhibited. ......................................................... 2

Standards of Design and Construction................................................... 2

DESIGN RULES................................................................................................... 3

2. SPECIFICATION OF MATERIALS..................................................... 3

3. GENERAL CONSTRUCTION. ............................................................. 3

4. MINIMUM THICKNESS OF PLATES. ............................................... 4

5. PREPARATION OF PLATES. .............................................................. 4

6. BUTT STRAPS: ..................................................................................... 4

7. TUBE PLATES, THROAT PLATES, BACK PLATES........................ 4

8. COLD FLANGING OF PLATES. ......................................................... 4

9. GIRDER STAYS FOR FIREBOX CROWNS OF LOCOMOTIVEBOILERS................................................................................................ 5

10. BAR STAYS........................................................................................... 5

11. SCREW STAYS. .................................................................................... 6

12. CROWN STAYS. ................................................................................... 6

13. STAY TUBES. ....................................................................................... 6

14. STAYS ATTACHED BY WELDING................................................... 7

15. SEATING FOR MOUNTINGS.............................................................. 7

16. RIVET HOLES. ...................................................................................... 9

17. RIVETS AND RIVETING..................................................................... 9

18. CAULKING OF RIVETED JOINTS AND CONNECTIONS. ........... 10

19. RULES FOR SCANTLINGS. .............................................................. 10

20. DESIGN OF CYLINDRICAL SHELLS. ............................................. 10

21. DESIGN OF RIVETED JOINT. .......................................................... 11


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22. RIVET DIMENSIONS. ........................................................................ 11

23. DIAMETER OF RIVET HOLES. ........................................................ 12

24. MAXIMUM LONGITUDINAL PITCH. ............................................. 12

25. MINIMUM LONGITUDINAL PITCH. .............................................. 13

26. END AND CIRCUMFERENTIAL JOINTS........................................ 18

27. THICKNESS OF BUTT STRAPS. ...................................................... 18

28. DESIGN OF PLATES HAVING FLAT SURFACES. ........................ 19

29. PITCH OF TUBES. .............................................................................. 30

30. FLAT PLATE MARGINS.................................................................... 31

31. Design of Bar Stays, Screw Stays and Girder Stays. Longitudinal BarStays, Nuts and Washers - .................................................................... 32

32. FIREBOX CROWN STAYS................................................................ 32

33. GIRDER STAYS FOR FIREBOX CROWNS..................................... 33

34. TABLE 6. WELD ATTACHMENTS. ................................................. 33

35. GIRDER SLING STAYS. .................................................................... 34

36. SLING STAYS. .................................................................................... 34

37. DOUBLING PLATE FOR DIRECT CROWN STAYS. ..................... 34

38. LOADS ON STAY TUBES AND SOLID STAYS. ............................ 34

39. TABLE 8 GROSS LOADS SUPPORTED BY STAY TUBES (LB.), 9threads per inch or welded.................................................................... 35

40. COMPENSATION FOR OPENINGS IN SHELLS. ........................... 35

INSPECTIONS ................................................................................................... 38

41. BOILER INSPECTORS. ...................................................................... 38

42. INSPECTION REQUIREMENTS FOR LOCOMOTIVE BOILERS. 38

43. Inspection Frequency............................................................................ 38

44. Periodic Inspection Requirements. ....................................................... 39

45. Annual Periodic Inspections................................................................. 40

46. Five Yearly Periodic Inspection........................................................... 41

47. Ten Yearly Periodic Inspection ............................................................ 41

48. Hydraulic Tests. .................................................................................... 42


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49. Crack Detection Grooves. .................................................................... 42

50. Fusible Plugs......................................................................................... 44

51. General. ................................................................................................. 44

BOILER MANAGEMENT & MAINTENANCE.............................................. 45

52. GENERAL GUIDANCE ON LOCOMOTIVE BOILERMANAGEMENT.................................................................................. 45

53. Fittings and Attachments. ..................................................................... 46

54. Boiler Inspection and Testing By the Railway. ................................... 47

55. OPERATION ........................................................................................ 49

56. USING THE BOILER .......................................................................... 49

57. MAINTENANCE AND REPAIRS. ..................................................... 50

58. WATER TREATMENT. ...................................................................... 51

59. Blow-down............................................................................................ 52

60. Boiler Tubing........................................................................................ 53

61. Firebox stays. ........................................................................................ 54

62. Patches. ................................................................................................. 54

63. Welding................................................................................................. 54

64. Steam pipes and joints. ......................................................................... 54

65. Boiler lay-up. ........................................................................................ 55

66. Hydraulic pressure testing. ................................................................... 55

67. Safety valves. ........................................................................................ 56

HANDY HINTS.................................................................................................. 57

68. WASHOUT PLUGS. ............................................................................ 57

69. PAD WELDING. .................................................................................. 57

70. SUPER HEATER ELEMENTS. .......................................................... 57

71. PRESSURE GAUGES. ........................................................................ 57

72. FIREBOX PATCHING. ....................................................................... 58

73. INSIDE INSPECTION OF BOILER. .................................................. 58


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DRAWINGS ....................................................................................................... 59

74. Safety Valves ........................................................................................ 59

75. Standard Mud Plugs.............................................................................. 61

76. Fusible Plugs......................................................................................... 62

78. Seal Welding of Tubes ......................................................................... 65

79. Locomotive Firebox ............................................................................. 66


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FEDERATION OF RAILORGANISATIONS

OF NEW ZEALAND

BOILER CODE

FOR LOCOMOTIVE BOILERS

Dedicated to the memory of Ted Pointon,author of this code, who gave so generously of

his time and knowledge that we all might benefit.


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BOILER CODEINTRODUCTION

NOTE: This front section will be of help to those who have Boilers withoutpapers on their design. From these equations etc. the design pressure of theboiler can be worked out. It is not intended that new boilers will be built to thiscode. It will be of use for repair work to riveted boilers. All new boilers will bebuilt to British standard 2790 Part 1 -1969.

This standard has been withdrawn but are none the less still valid for locomotiveboilers. Any one requiring a copy of this standard should apply to the Federationof Rail Organisations of New Zealand.

1. SCOPE:

The rules of this code relate to the design, construction, inspection testing andmaintenance of locomotive boilers. The design equations are taken from the1975 Marine Department Boiler Code and the British Standard 2790 Part 1 -1969 Metric Boiler Code.

Inspections

Every boiler, subject to these rules must be inspected once in each year, (unlessapproved for 2 yearly inspection) by a Boiler Inspector who, when he hascompleted the Inspection and is satisfied that the boiler is in good repair and maybe safely used, shall issue a certificate.

Boiler Certificate to be Exhibited.

The certificate is to be exhibited in the cab of the Locomotive.

Standards of Design and Construction.

The standard of strength and safety of any boiler fitting, or auxiliary shall beprovided by a factor of safety of not less than five.


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DESIGN RULES

2. SPECIFICATION OF MATERIALS.Boiler Quality Steel.

Plates BS 1501BS 1502Section and Bars and

Stays Ministry of Transport Marine Division. File No:41/1/13 Binder: Boilers. 20 February 1975.“Round steel bar to BS 4360 grade 43 A. may beused for boiler stays. Manufacturers testcertificate required or material can be tested at aAuthorised testing Laboratory.”

Steel boiler tubes andsuperheater flues

BS 3059.

Brass tubes solid drawseamless brass

BSS 24/14 or equivalent.

Copper fire box plate British standard 24/11.Steel pipes and tubes forpressure purposes.

Carbon steel: ordinary duty BS 3601.

Steel pipes and tubes forpressure purposes

Carbon steel: High duties BS 3602

3. GENERAL CONSTRUCTION.

BOILERS OF RIVETED, WELDED OR SEAMLESS STEELCONSTRUCTION.

(a) Longitudinal joints of boiler shell. The riveted longitudinal joint of theshell shall be of butt and double strap construction. This rule does notapply to the portion of a shell which is stayed to the firebox by screwedstays or stays attached by welding.

(b) Crack Detection Grooves. When lap riveted construction has been usedin longitudinal joints, grooves shall be cut in the outside plate to givepositive indication of cracking or grooving of the plate adjacent to theinside of the joint.


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4. MINIMUM THICKNESS OF PLATES.

The thickness of mild steel plates subject to pressure shall not be less than 3/8thsof an inch. (10mm).

5. PREPARATION OF PLATES.

The edge of all plates and butt straps should be machined or flame cut bymachine, and the caulking edges should be at an angle of approximately 80deg.with the surface of the plate. Plates which are to be flame cut by machine withoutsubsequent heat treatment, grinding, or machining shall not have a higher carboncontent than 0.26 per cent. When the carbon content exceeds 0.26 per cent, heattreatment, grinding or machining shall be carried out. The edges of all platesshall have a smooth finish.

6. BUTT STRAPS:

Butt straps should be cut from the shell plates, or alternatively, all of the buttstraps of each required thickness shall be cut from one plate. The lengths of thestraps shall be transverse to the direction of rolling of the plate. Straps should bepressed or bent in rolls to the shell curvature. Where the ends of the butt strapsbutt against the shell rings or end plate they may be welded thereto.

7. TUBE PLATES, THROAT PLATES, BACK PLATES.

Wherever possible flanging shall be done by machine. Such flanging shallpreferably be done in one operation, but where this is impracticable, creepmachine flanging may be permitted, provided that the plate is worked at asuitable temperature and the plate is heated to an adequate distance beyond theportion under immediate treatment.

8. COLD FLANGING OF PLATES.

As a general rule cold flanging shall comply with the following fourrequirements;

(a) The material of the flanged plates shall be of approved flanging qualitysteel.


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(b) The plates being flanged shall be heat treated from time to time toremove the effects of work hardening of the material and shall be finallyheat treated at the conclusion of all cold working.

(c) The plate after flanging shall be machined or otherwise treated toremove all unevenness or crinkles and the faying and caulking surfacesshall be fair and smooth.

(d) The processes of flanging, heat treatment, machining, and theoperations generally shall be carried out to the satisfaction of anEngineer surveyor.

9. GIRDER STAYS FOR FIREBOX CROWNS OFLOCOMOTIVE BOILERS.

(a) Each girder, when of the normal type and fitted with stay bolts and nuts,shall be of the double-plate interconnected type, of sufficient strength tosupport its proportion of the load on the crown plate independently ofthe crown plate.

(b) The clear waterway between the crown plate and the underside of thegirder bars shall be as large practicable but not less than 1 ½ inch deep.The ends of the girders shall not rest on the landing of the flat crownplate, but shall be carefully fitted to bed directly on the bends of thecorners of the vertical end of side plates. The toes of the girders shall besolid with the girder plates and not separate pieces attached thereto.

(c) Where an all-welded firebox is fitted the attachment of girder stayswelded directly to the crown plates shall be by means of full penetrationwelds. Such girders shall be welded to the crown plate prior to stressrelieving of the firebox

(d) The girder stays shall be recessed for waterways (see Rule (b) above)unless attached by continuous full penetration welds. The welding shallbe carried out by an approved operator to the satisfaction of an EngineerSurveyor.

10. BAR STAYS

Where plus threads are used, the ends of the stays may be upset or the middle


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portions of the stays reduced for this purpose. Bar Stays which have been workedin the fire shall be subsequently annealed. The axis of each stay shall preferablebe normal to the plate surface it supports, but where it is not normal the stay shallbe fitted with tapered washers under the nuts. The stay may be either screwedinto the end plates or fitted into clearing holes. Where the bar stay passesthrough clearing holes in the end plates, an internal nut shall be fitted. Where thebar stay is screwed into end plates, the stay and holes shall have continuousthreads. The screw threads on the stays shall be of British Standard Whitworthform and pitch, of full depth and correct profile, and shall be clean and free fromchecks or imperfections. Nuts shall be a good fit to the threaded portion of thestays. Where bar stays are screwed through the plate and fitted with externalnuts, a finer screw thread not exceeding twelve threads per inch may be used.Copper washers may be used to ensure steam tight joints.

11. SCREW STAYS.

Screw stays, and the holes for these, shall be screwed with a continuous thread.The middle portion shall preferably be turned to the bottom of the threads. In nocase shall a pitch finer than twelve threads per inch or coarser than nine threadsper inch be used. After being fitted in position the ends, if not fitted with nutsshall be riveted over to form substantial heads or fillet welded.

12. CROWN STAYS.

Shall be screwed through both plates and be fitted with nuts or solid forgedheads on the fireside. The outer ends of crown stays shall be riveted over to formsubstantial heads. Alternatively both ends of the stays may be fillet welded.

The diameter of each screwed firebox stay shall be such that the stress calculatedon the net area at the bottom of the thread or at the least diameter of the stay,whichever is the smaller, shall not exceed 9,000lb.Per square inch. The minimumdiameter of screwed stays measured over the threads shall be 7/8" or twice thethickness of the plate, whichever is greater.

13. STAY TUBES.

Stay tubes shall be of such a thickness that the stress on the net sectional area atthe bottom of the thread or in the middle part of the tube, whichever is thesmaller, shall not exceed 7,500lb. Per square inch. The minimum thickness of


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stay tubes at any part shall be 3/16 inch. Where stay tubes have their thicknessincreased at the screwed ends to provide for plus threads, the thickening shall beattained by upsetting or by any approved welding process. Subsequent to anyprocessing of the ends, the tubes shall be annealed. Stay tubes may be attached tothe tube plates either by screwing or metal arc welding.

Where stay tubes are attached by welding the shear stress on the weld shall notexceed 5,600lb. per square inch. Stay tubes shall be expanded into the tube plateby a roller expander and if desired, seal welded. On completion of the weldingthe stay tube be lightly re-expanded.

14. STAYS ATTACHED BY WELDING.

Stays attached by welding will be accepted provided the welding is carried outby an approved operator. The diameter of each stay attached by welding shall besuch that the stress calculated on the net area at the least diameter of the stayshall not exceed 9,000lb. Per square inch, unless stress relieved. The minimumdiameter of stays attached by welding shall be ¾ inch (19mm) or twice thethickness of the plate whichever is the greater.

All stays attached by welding less than 14 inches long should be drilled with atell-tale hole, not less than 3/16 inch in diameter, drilled to a depth of ½ inchbeyond the inner face of each plate in the water space.

15. SEATING FOR MOUNTINGS.

Mountings over 1 inch bore, except flanged mountings up to and including 3inch bore, shall not be attached direct to any boiler plate, but shall be carried onsuitable forged cast or fabricated steel seatings.

These seatings shall take the form of short standpipes, saddles, forged pads, orpads cut from round bar as may be most convenient, and shall be attached to theboiler by rivets or welding, provided that cast-steel seatings shall not be attachedby welding.

Flanges and pads in contact with the boiler shall be formed to bed closely to theplate to which they are to be attached. In all cases where the boiler is lagged thejoint of the mounting shall be clear of the lagging surface.

(a) Standpipes: Where standpipes are used. The flanges shall be machined


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or flame-cut by machine on the edges. The bolting flanges shall bemachined on the jointing and bolting surfaces.

(b) Saddles: Where saddles are used the edges of the flanges shall bemachined or flame-cut by machine. The jointing surfaces shall bemachined. The studs for attachment of the mountings, if screwedthrough the saddle shall be fitted on the inside with nuts of fullthickness. Where the stud holes do not penetrate through the saddle thelength of the screwed portion of the stud in the plate shall be not lessthan the diameter of the stud.

(c) Pads: Where pads are used, the jointing surfaces shall be machined.The pads shall have sufficient thickness to allow the drilling of the studholes for mountings without the inner surface being pierced and thelength of the screwed portion of the stud in the pad shall be not lessthan the diameter of the stud.

(d) Methods of Attachment. The seating shall be attached to the shell orend plates shall be one of the following methods.

(i) Where the internal diameter of the standpipe does not exceed 1 inchthe standpipe may be screwed through the plate. And seal welded.

The Mountings may be screwed:

a) Directly into the plate or

b) Into steel distance pieces the length of the thread engagedbeing in no case, less than the bore of the mountings plus ¼inch.

The distance pieces shall be made of solid mild steel. Theyshall be screwed into the plate and seal welded. The walls ofthe distance pieces shall be not less than ¼ inch thick at thebottom of the thread.

(ii) Where the bore of the seating does not exceed 5 inches or in the caseof a pad or saddle, the diameter of the opening in the shell does notexceed 5 inches plus twice the thickness of the plate to which it isattached, The seating may be welded to the plate without subsequentheat treatment. If these limits are exceeded the whole plate to whichthe seating is attached shall be stress-relieved by heat treatment oncompletion of welding. Seatings welded to the shell or end plateshall be welded internally and externally.


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(e) Bolts and Nuts. All bolts and stud holes shall be drilled, and bolts andnuts shall be machined where in contact with the flange.

(f) Inspection and Cleaning Arrangements. General. Sufficientmudholes shall be provided to permit the inside of the boiler beingthoroughly cleaned and examined.

Screw plugs shall have at least four threads of engagement.

16. RIVET HOLES.

Rivet holes shall be drilled full size in the plate, they shall not be punched.Wherever possible, rivet holes shall be drilled in place, with straps, and endsbolted in position. After drilling the plates shall be separated, the burrs and sharpedges of the holes shall be removed, and the contact surfaces of the plate shall becleaned. All tacking holes shall be drilled to a size which will allow the holes tobe enlarged to the required rivet size by drilling or reaming. All rivet holes shallbe slightly countersunk under each head. The diameter of the rivet hole shall benot more than 1/16 inch larger than the standard diameter of the cold rivet asmanufactured.

17. RIVETS AND RIVETING.

Rivets shall comply with BS.425 or its equivalent.

Rivets shall be closed by hydraulic machinery wherever the design of the boilerpermits, but rivets may be closed by hand or pneumatic hammer in positionswhere hydraulic riveting or mechanical riveting is impracticable. Rivets shall beof sufficient length to fill the rivet holes and form sound substantial heads. Theheads shall be finished concentrically with rivet shanks. Rivets shall be heateduniformly throughout the full length. Drift pins shall not be used with such forceas to distort the rivet holes. If the rivet holes are not fair when the plates arebolted up for riveting, the holes shall be reamed fair before the riveting iscommenced. For hydraulic riveting the pressure shall be the least necessary toensure a tight joint, and only sufficient pressure shall be used to close the rivetproperly and securely without indenting, buckling or otherwise damaging theplate. The rivets shall be allowed to cool while under pressure from the rivetingmachine.


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18. CAULKING OF RIVETED JOINTS AND CONNECTIONS.

Caulking, when required, shall be done with a tool of such form that there is nodanger of scoring or damaging the plate which is under the caulking edge or ofspringing the caulked plate.

19. RULES FOR SCANTLINGS.

General; The formulae in this section give in all cases the minimum scantlingsand apply to boilers intended to work under average conditions, good feed water,and adequate maintenance. Where working conditions are adverse it isrecommended that for compensation the minimum scantlings found bycalculation from the formulae given should be increased by designing for anincreased working pressure.

20. DESIGN OF CYLINDRICAL SHELLS.

Riveted and Seamless Shells for Boilers.

The working pressure of cylindrical shells shall be determined by the followingformula:

W.P. ( t - 2 ) S J Equation 1C D

Where W.P = working pressure in pounds per square incht = thickness of plate in thirty-seconds of an inch.

S = minimum tensile breaking strength of plate in tons per squareinch.

J = percentage of strength of shell through longitudinal of a lineof holes for rivets, or an opening in shell not fullycompensated, whichever is least. Where shells are rolledfrom solid J shall be taken as 95 per cent and for weldedboilers J shall be taken as 88 per cent.

D = diameter of shell in inches measured inside the outer ring ofplates.

C = a coefficient = 2 .75 when the longitudinal joints are doublebutt straps or where shells are formed from solid rolledsections or butt welded.


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C = 2.83 when the longitudinal joints are lap joints and are treble-riveted.

C = 2.9 when the longitudinal joints are lap joints and are double-riveted.

C = 3.3 when the longitudinal joints are lap joints and are single-riveted.

The minimum thickness of shell or end plates are to be as follows:

Welded or seamless construction ¼ inch.

Riveted construction.

Under 3 feet outside diameter 5/16 inch.

Three feet outside diameter andover.

3/8 inch

Note. An addition of 10 percent shall be made to the above values of thecoefficient C where any one or more of the following unfavourable factorsoccurs.

(a) When the shell plates are not bent to cylindrical form by machine to theextreme ends of the plate, or when the edges of shell plates or buttstraps are not planed or machined.

(b) When lap jointed longitudinal joints are not accessible for close visualinspection in service.

(c) When the shell plates of externally fired boilers are exposed to directimpact of flame.

21. DESIGN OF RIVETED JOINT.

General riveted joints may be designed in accordance with the rules givenhereunder. These rules shall be used for joints in plates which have a tensilestrength exceeding 25 tons per square inch.

22. RIVET DIMENSIONS.

Rivets used in boiler in those parts subject to pressure should conform toB.S.425


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23. DIAMETER OF RIVET HOLES.

The diameter of the rivet hole in a joint shall be determined according to thethickness of the plates to be riveted. The diameter of the holes in longitudinaland circumferential seams shall in no case be less than thickness of the shellplates.

TABLE 2. RIVET-HOLE DIAMETERS

Thickness of plate Diameter of Rivet-holes¼ ½

5/165/8

3/8 ¾

½ 13/16

5/87/8

¾ 15/16

7/8 1

TABLE 3. RIVET PITCH CO-EFFICIENTS

Number of rivetsper Pitch

Coefficients forLap joints (C)

Coefficients for Double-strapped Joints (C)

1 1.31 1.75

2 2.62 3.50

3 3.47 4.63

4 4.14 5.52

5 6.00

24. MAXIMUM LONGITUDINAL PITCH.

The maximum pitch of the rivets in longitudinal joints shall be :-

P = (C x T) + 1 5/8 in.

Where P = maximum pitch in inches.

T = thickness of plate in inches.


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C = a coefficient given in table 3.

25. MINIMUM LONGITUDINAL PITCH.

The Longitudinal pitch should not be less than 2.4 times the rivet-hole diameterin single-riveted joints or 2.8 times the rivet-hole diameter in double-rivetedjoints.

Distance between rows of rivets and between rivets and the edges of the plate.The clear space between a rivet hole and the edges of a plate shall be not lessthan the diameter of the rivet hole. ie. the centre of the rivet hole shall be at adistance not less than one and a half diameters from the outer edge of the plate.

The distance between the rows of rivets of joints, whether lapped or fitted withbutt straps, shall be not less than that given by the following formulae

(a) Zigzag riveting;

(i) Where there is an equal number of rivets in each row, the distancebetween each row shall be not less than 0.33+ 0.67d

(see Table 4 Figs. B, D, and F.)

(ii) Where the number of rivets in a row is one-half that in an adjacentrow, the distance between the rows shall be not less than 3d and notless than 0.2+ 1.15d ( see Table 4 Figs. H and K).

(iii) Where the number of rivets in the rows is twice that in the outer thedistance between adjacent inner rows is having the full number ofrivets shall be not less than 0.165+ 0.67d (see Table 4 Figs. H and K).

(b) Chain riveting;

(i) Where there is an equal number of rivets in each row, the distancebetween rows shall not be less 2d (see Table 4 Figs. C, E, and G).

(ii) Where the number of rivets in a row is one-half that in an adjacentrow, the distance between rows shall be not less than 3d (see Table4, Fig J.)

(iii) Where the number of rivets in the inner rows is twice that in theouter, the distance between adjacent inner rows having the full


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number of rivets shall be not less than 2d (see Table 4, Fig. J.)

Where d = diameter of rivet hole in inches.

= pitch of rivet hole in inches.


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NOTE. Where the number of rivets in the outer rows is less than the number ofrivets in the inner row, P shall be taken as the pitch of the rivets in the outer row.

Calculated Efficiency of Riveted Joints. (see Table 4)

The calculated percentage strength of a riveted joint shall be found from thefollowing formulae.

Equations 4 and 5 are applicable to any type of joint.

Equation 6 is applicable only to that type of joint in which the number ofrivets in the inner rows is double that in the outer row.

The lowest value given by the application of these formulae shall be taken as thecalculated percentage of strength of the joint.

(a) Percentage of strength of plate at joint compared with solid.

Plate = 100(p - d)

p

Equation 4

(b) Percentage of strength of rivets as compared with the solid.

Plate = 100 S1 (1.875a1 + a2) Equation 5

S x p x T

(c) Percentage of combined strength of the plate at the inner row of rivetholes and of the rivets in the outer row.

Plate = 100 ( p - 2d) + 100 (S1 x a x C) Equation 6

p S x p x T

Where

a = the sectional area of one rivet hole in the outer row of rivets.

a1 = the aggregate sectional area of the rivet holes in pitch P havingrivets in double shear.


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a2 = the aggregate sectional area of rivets holes in pitch p havingrivets in single shear.

p = the pitch of rivets in outer row in inches.

S1 = 85 per cent of the minimum tensile strength of the rivet bars intons per square inch or S1 may be taken as 23 tons per squareinch.

d = the diameter of rivet holes in inches.

S = the minimum tensile breaking strength of plate in tons persquare inch.

T = the thickness of plate in inches.

C = 1 for single shear and 1.875 for double shear.

NOTE In Equation 6, d = diameter of rivet holes in inner row of rivets.

26. END AND CIRCUMFERENTIAL JOINTS.

The calculated efficiencies of circumferential joints based on the thickness ofplate, determined by Equation 1, shall be not less than 38 percent for jointsconnecting end plates with cylindrical shells, or 42 percent for intermediatejoints. In no case, however, shall the efficiency of an intermediate joint be lessthan 50 percent of that of the longitudinal joints. Where the shell-plate thicknessexceeds 11/16 inch, the intermediate circumferential joints shall be double riveted.

27. THICKNESS OF BUTT STRAPS.

Where the thickness of the shell plates does not exceed ¾ inch, the thickness ofboth the inner & the outer butt straps shall be equal to the thickness of the shellplate.

Where the thickness of the shell plates exceed ¾ inch, the outer butt strap may bemade 0.875 of the thickness of the shell, but not less than ¾ inch. The inner buttstrap in such cases shall be made 1/8

th inch thicker than the outer butt straps orthe same thickness as the shell plate, whichever is less.


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28. DESIGN OF PLATES HAVING FLAT SURFACES.

Stayed flat Surfaces.

(a) Where flat end plates are flanged for connection to the shell the insideradius of flanging shall be not less than 1.75 times the thickness of theplate, with a minimum of 1 ½ inch.

(b) Where combustion chamber or firebox plates are flanges for connectionto the wrapper, the inside radius of flanging shall be equal to thethickness of the plate, with a minimum of 1 inch.

(c) Where the flange curvature is a point of support, this shall be taken atthe commencement of curvature, or at a line 3 ½ times the thickness ofthe plate measured from the outside of the plate, whichever is nearer tothe flange.

(d) Where a flat plate is welded directly to a shell or wrapper, the point ofsupport shall be taken at the inside of the shell or wrapper.

(e) Where flat plates are exposed to flame, the use of stiffeners, doublingplates, or stays with nuts on both sides of the plate is not permitted.

(f) The minimum diameter of stays shall be 7/8 inch or twice the thicknessof the plate, whichever is the greater.

The working pressure of & thickness of flat plates supported by stays shallbe determined by the following formula.

WP. c (t - 1)2 Equation 7

A2 + B2

where t = Thickness of plate in thirty seconds of an inch.

p = design pressure in pounds per square inch.

A = horizontal pitch of stays in inches.

B = vertical pitch of stays in inches.

c = constant.


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Where stays are irregularly pitched, D2 shall be taken instead of (A2 + B2); D

being the diameter, in inches, of the largest circle which can be drawn withthe circumference passing through three points of support withoutenclosing another point of support. No more than two points of supportmay be located on one side of any diameter of the circle.

Where various forms of support are used constant c shall be mean of thevalues for the respective methods adopted.

The flat end plates are to be completely covered by margins or circles.

(g) The value of the constant c in Equation 7 shall be as follows forscrewed and/or nutted stays:

(i) Where the stays are screwed through a plate not exposed to flameand are fitted with nuts and washers outside or pass through the plateand are fitted with nuts and washers inside and outside, in each casethe diameter of the washers being not less than two and a quartertimes that of the stay and not less than ¼ inch thick. (see Fig 16A.) C= 95

(ii) Where the stays pass through a plate not exposed to flame and arefitted with nuts inside and nuts and washers outside. The diameter ofthe washers being at least 3.5 times that of the stay and the thicknessat least two-thirds of that of the end plate (see Fig. 16B) C = 110.Where the washers have a diameter of at least two-thirds that of theplate, and the washers are securely riveted or welded thereto (seeFig. 16c) C =120

(iii) Where the plate is stiffened by strips of a breadth of at least two-thirds of the minimum pitch of the stays, the thickness being at leasttwo-thirds that of the plate and such strips are securely riveted orwelded thereto (see Fig. 16D) C = 130. Where the doubling platecovers the area supported between the stays so that the centre of therivets securing the doubling plate to the end plate is at least one-halfof the distance from the outermost stays to the nearest substantialpoint of support. C = 145.

(iv) Where stays are passed through the plate and are fitted with nutsboth inside and outside (see Fig. 16A) C = 96.

(v) Where stays are screwed through the plate and are either fitted withnuts on the outside or a full fillet weld is run round the end of the


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stay (see Fig. 16E and F) C = 86 when the plates are not exposed toflame. C = 75 when the plates are exposed to flame.


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95

110

120


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(vi) Where stays are screwed through the plate and a light sealing weld isrun round the end of the stay, or where stays are screwed through theplate and riveted over to form substantial heads (see Fig.16g or H) C= 57 when the plates are not exposed to flame. C = 50 when theplates are exposed to flame.

(vii) Where the point of support is a marginal stay tube. C = 64 or 80when the plates are not exposed to flame, dependent on means ofsecuring. C = 56 or 70 when the plates are exposed to flame.Dependent on means of securing (see Fig. 17).

(viii) Where the point of support is a line of rivets securing gusset or palmor link stay (see Fig. 22, 23, or 24). C = 90 when the plates are notexposed to flame. C =80 when the plates are exposed to flame.

(h) Where the flat plate is flanged for attachment to the shell, or wrapper(see subclause (c) above) (see Fig. 18). C =110 when the plates are notexposed to flame. C = 96 when the plate is exposed to flame.

(i) The value of the constant C in Equation 7 shall be as follows or stayssecured by welding to flat plates which are stress relieved and notexposed to flame. Where plates are exposed to flame these constantsshall be reduced by 12 ½ per cent.

Where plates are not stress-relieved these constants shall bereduced by 10 per cent.

NOTE: Where a plate is exposed to flame and not stress-relieved theconstant C must be reduced by 22 ½ per cent.


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(i) Where stays are screwed through the plates and, in addition are filletwelded to the plates on the outside, the size of weld being 0.35 of thediameter of the screwed portion of the stay (see Fig. 19A).

(ii) Where plain stays are strength welded into the plates (see Fig. 19B)C = 86.

(iii) Where plain bar stays pass through holes in the plates and aresecured as shown in Fig. 19c. C = 90.

(iv) Where plain bar stays pass through holes in the plates and are fittedon the outside with washers and are secured as shown in Fig.19D. C= 100.

(v) Where plain bar stays pass through holes in the plates and are fittedon the outside with washers as shown in Fig. 19E and F. C = 110.

(vi) Where plain bar stays pass through holes in the plate and fitted onthe outside with washers as shown in Fig. 19g. C = 120.

(vii) Where plain bar stays pass through holes in the plate and a full-filletweld is run round the end of each stay (see Fig. 19H). C = 57.

(viii) Where plain bar stays pass through holes in the plate and full-filletwelds are run round each stay on both sides of the plate (see Fig.19i). C = 96.

(ix) Where a gusset stay or a link stay anchor is welded to the end plateas shown in Fig 27. C = 80.

(x) Where the flat plate is welded directly to the shell or wrapper (seesub-clause (d) above). C = 110.

(j) (i) For the crown plates of fireboxes supported by welded-on girdersprovided with waterways, Equation 7 shall apply.

(X2 + Y2) being substituted for (A2 + B2) where X = width of waterwaysin girder plus the thickness of the girder in inches. Y = pitch of girdersin inches. C = 70.


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(ii) For the crown plates of fireboxes supported by continuously welded-on girders Equation 7 shall apply: D2 being substituted for (A2 + B2)where D = distance between inside faces of girders in inches.C = 48.

(k) In case of boilers where the end plates are supported in the steam spaceby a single substantial tee bar (continuously fillet welded to the platewith not less than 3/8 inch fillet welds or securely riveted to the plate)extending across the plate to the commencement of curvature of theflange or the toe of the fillet weld securing the end plate to the shell, orwhere such plates are supported with a deep bulb extending across theplates as described above, the thickness of the plate shall be determinedby Equation 7 the values of D and C being as follows.

(i) For the portion of the plate above the stiffener

D = diameter in inches of the largest circle passing through thecentre of the tee or bulb bar and the commencement of flangecurvature of the inside of the shell, whichever is applicable. C = 80.

(ii) For the portion of the plate below the stiffener;

D = diameter in inches of the circle passing through the centre of thetee or bulb bar and two adjacent screwed stays: C = 55.

or D = diameter in inches of the circle passing through the centre ofthe tee or bulb bar and the centre line of the top row of tubes: C = 35.

(l) For smaller boilers not fitted with stay tubes the working pressure of theend plate outside the tube-nest shall be determined either in accordancewith Rule 89 or from the formula;

M = K ( t - 1) Equation 8W. P.

Where M is the unsupported margin adjacent to a point of support.

and K = C

8

Where C = constant as given for Equation 7.

Where this alternative is adapted the entire end plate area outside the tube


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plate nest shall be covered by marginal areas.

(i) Locomotive boiler tube plate not fitted with stay tubes the maximumworking pressure shall be determined by Equation 11.

W.P. = C (t - 1)2 Equation 11M2

Where W. P. = working pressure in pounds per square inch.

t = thickness of the plate in thirty seconds of an inch.

M = 4 times the mean pitch in inches of the tubes.

C = 50 for plates exposed to the flame.

C = 60 for plates not exposed to the flame.

(ii) The minimum thickness of any tube plate shall be

T = ½ inch where the diameter of the tube holes does not exceed 2inch (see also Equation 13).

T = 9/16 inch where the diameter of the tube hole exceeds 2 inch(see also Equation 13).

(iii) The support afforded by plain tubes shall not be taken to extendbeyond the area enclosing the outer edges of the tubes.

29. PITCH OF TUBES.

The spacing of tubes shall be such that the minimum width in inches of anyligament between the tube holes shall not be less than

D + 1 Equation 128 2


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Alternatively, the thickness and cross section of the plate between the tube holesshall be not less than

0.125D + 0.1875 = minimum thickness in inches Equation 13

0.17D + 0.025 = minimum cross section in square inches Equation 14

where D is the diameter in inches of the tube holes.

30. FLAT PLATE MARGINS.

The amount of support in relief of stays which may be attributed to the side ofthe shell, or end plates shall not exceed that found by the following formula –

Width of margin in inches = k (t - 1) Equation 17W.P.

Where W.P. = working pressure in pounds per square inch.

t = thickness of plate in thirty-second of an inch.

k = 3.47 where plate is exposed to flame.

k = 3.7 where plate is not exposed to flame.

The margins shall be measured from the centre line of rivets in the nearest row ofthe seam by which the flat plate is attached, or where the plate is flanged, fromthe commencement of curvature or from a line two and a half times the thicknessof the plate distant from the side of the flange next to the inner radius of thecorner, whichever is the nearer to the flange.

Where the flat plate is not flanged for attachment to the shell but is welded, thewidth of the margin shall be measured from the inside of the shell.


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31. Design of Bar Stays, Screw Stays and Girder Stays.Longitudinal Bar Stays, Nuts and Washers -

General requirements. The diameter of each bar stay shall be such that the stresscalculated on the net sectional area at the bottom of the thread or at the leastdiameter of the stay, whichever is smaller, shall not exceed:

Range of TensileStrength of Bar.-

Maximum AllowableStress on Bar Stay

Tons/sq. in lb./sq. in.

26/30 10,000

28/32 11,000

30/34 12,000

32/36 13,000

Each bar stay shall be provided with an external nut and washer.

External nuts shall be of mild steel of thickness in accordance with B.S.916 andshall be faced on the contact surface. When the bar stay pass through clearingholes in the end plates, internal nuts of thickness not less than two-thirds of thediameter of the threaded portion of the stay shall also be fitted. Where bar staysare screwed into the end plate, internal nuts may be omitted.

NOTE:

Bar stays may be attached by welding by one of the methods shown Fig.19

32. FIREBOX CROWN STAYS.

Where firebox crown stays are directly attached to a semi-cylindrical outercasing and the firebox top is cambered and fitted with stays, the thickness of theouter casing shall be sufficient to provide not less than three engaging threads, ofwhich not less than one shall be a full thread in stays not normal to the surface; ifthe thickness of the plate is not sufficient to give one engaging full thread theplate shall be reinforced.


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33. GIRDER STAYS FOR FIREBOX CROWNS.

(a) The proportions of girders supporting crown plates of rectangularfireboxes where the ends of the girders are supported by the vertical endor sideplates shall be calculated by the following formula:

W.P. = C x S x T x d2 Equation 35L2 x Y

Where W.P. = working pressure in pounds per square inch

S = minimum tensile strength of material in tons per sq. inch.

T total thickness of the girder stay in inches.

D = depth of girder stay in inches.

L = length of the girder stay in inches measured between theinside of the tube plate and firebox plate.

Y = pitch of girder stay in inches.

C = 700 for steel plates or forgings.

C = 600 for steel castings.

(b) Where girders are welded to the crown plate the dimensions of the weldshall be such that the stress, calculated on an area equal to the sum ofthe effective lengths of the welds attaching each girder multiplied by theeffective throat thickness, shall not exceed 7.500 lb/sq. in. multiplied bythe appropriate weld factor in table 6.

34. TABLE 6. WELD ATTACHMENTS.

Form of Weld Weld Factor

Full penetration butt weld 0.7

Double fillet weld 0.65


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The load on the welds shall be taken as that due to the working pressure actingon the area L Y; L and Y being as defined in sub-clause (a) above.

35. GIRDER SLING STAYS.

Sling, links, pins, rivets of slung girders and their connections to the shell shallbe sufficient to carry the whole load that would otherwise be carried on the toesof the girders.

36. SLING STAYS.

The section of least strength, whether of stays, links, pins or rivets, shall be usedin calculating the working pressure of the stays. For parts in tension a stress of9,000 lb per square inch on net section and for parts in shear a stress of 8,ooo lbper square inch on net section shall not be exceeded.

37. DOUBLING PLATE FOR DIRECT CROWN STAYS.

Where direct crown stays are fitted to a semi-cylindrical outer casing, a doublingplate having a thickness not less than that of the casing plate shall be riveted tothe casing. The doubling plate shall be of such a length and width that all thecrown stays pass through it.

38. LOADS ON STAY TUBES AND SOLID STAYS.

Stay tubes and solid stays shall be designed to carry the whole load due topressure on the area to be supported. In each case the area shall be calculated asfollows;

(a) For a stay tube within the tube nest area the net area to be supportedshall be the product of the horizontal and vertical pitches, in inches, ofthe stay tubes less the area of the tube holes embraced. Where the pitchof the stay tubes is irregular, the area shall be taken as the square of themean pitch of the stay tube (i.e. one-quarter the sum of four sides of anyquadrilateral bound by four adjacent stay tubes), less the area of theplain tube holes embraced.

(b) For a stay tube in the boundary row, or for a bar stay, the net area to be


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supported shall be the area, in square inches, enclosed by the boundarymargin and lines passing midway between the stays and adjacent pointsof support, less the area of any tubes or stays embraced.

(c) In the case of a bar stay where there are no stay tubes in the tube nestthe area supported shall extend to the tangential boundary of the tubenest.

39. TABLE 8 GROSS LOADS SUPPORTED BY STAY TUBES(LB.), 9 threads per inch or welded.

Minus Threads Plus Threads or Welded.Tube

ThicknessOutside Dia. ¼” 15/16” 13/16” ¼” 15/16”

2 7075 9191 8007 10308 12425

2 ¼ 8127 10613 9111 11781 14266

2 ½ 9181 12034 10215 13253 16106

2 ¾ 10235 13456 11321 14726 17947

3 11289 14878 12425 16199 19788

3 ¼ 12342 16299 13530 17671 21629

3 ½ 13395 17721 14634 19143 23469

40. COMPENSATION FOR OPENINGS IN SHELLS.

General Rule: Where the major axis or diameter of any hole cut in thecylindrical shell is greater than two and a half times the thickness of the shellplate plus 2 ¾ in compensation shall be provided. The sectional area to becompensated (Figs. 34 and 35) measured in the plane paralleled to thelongitudinal axis of the shell which makes this area a maximum, shall be theproduct of the length of the opening, including any rivet holes in the plane andthe thickness of a seamless shell of similar material calculated in accordancewith Rule 75 for the same working pressure. Applications of the general rule toriveted construction and welded construction are given in (a) & (b) respectively.


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(a) Riveted Construction. Where frames, pads, or branches are secured byrivets the compensating area Y shall be calculated as follows (see Fig34).

(i) The cross-sectional area of the frame or pad, excluding rivet holes,or in the case of a branch the cross-sectional area of the wall of thebranches or flange excluding rivet holes, minus the sectional area ofthe branch of the same bore having a thickness calculated byEquation 1 for the same working pressure using C = 2.75, J = 65when butt welded and J = 95 when seamless, plus the thicknessrequired to withstand external loads. The area shall be measuredwithin the limits specified in Fig. 34.

Due allowance shall be made in cases where the material used for thebranch and/or compensating ring differs from that of the plate towhich it is attached.


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(ii) The area obtained by multiplying the difference between the actualshell thickness by a length 2 (3in. + Ts - d)

where Ts = thickness of shell plate in inches.

d = diameter of rivet holes in inches.

In cases where the sum of (i) and (ii) is less than the sectional areato be compensated, a compensating plate shall be fitted having atotal net cross-sectional area equal to the amount of the deficit.


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INSPECTIONS

41. BOILER INSPECTORS.

Boiler Owners will use a recognised inspection body with the appropriatequalifications and experience for their boiler inspections.

42. INSPECTION REQUIREMENTS FOR LOCOMOTIVEBOILERS.

Background.

There are a considerable number of locomotive boilers, of riveted or part rivetedconstruction, which are of advanced age and which come under periodicinspection by a Boiler inspector.

The purpose of these instruction is to provide adequate and uniform inspectionprocedures for locomotive boilers to ensure that they remain safe.

Prior to restoration, many of these boilers spent, in some cases many years,without effective protection against internal or external corrosion.

Boiler inspectors should be alert to age related defects.

The prime purpose of the inspection is to establish that the locomotive is safe.

The examination covers the boiler and its fittings, its ancillary equipment. It isintended that the boiler and its fittings be thoroughly examined but in most casesthe adequacy of the injectors can be determined by visual examination whileoperating under steam. Unless there are indications of fault or neglect it is notintended that the ancillary equipment be subjected to a mandatory strip downexamination at any specified period of time.

43. Inspection Frequency.

This section sets out the general inspection requirements for locomotive boilersin terms of inspection frequency.

All locomotive boilers in which steam is to be raised are subject to the


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certification requirements of the Federation of Rail Organisations of NewZealand Boiler Code, and as part of that certification process, are required tohave an annual periodic inspection by a Boiler Inspector.

At five year intervals the annual periodic inspection shall also include ahydraulic test of 1.3 x maximum safe working pressure.

At ten year intervals the annual periodic inspection in addition to the above shallalso include a close visual inspection of all waterside, fireside and externalsurfaces of the boiler including its shell, tube plates, fire box, foundation ring,stay bars, stay tubes and other stays. A hydraulic test of 1.3 x maximum safeworking pressure shall also be carried out.

Boilers in intermittent service which have fully documented and detailed records,which are also drained, stored dry and housed under proper cover, may have theexternal surfaces examination extended on the recommendation of a BoilerInspector. This would not include extending the period of the hydraulic test.

The above details are given as a general guide and do not restrict a BoilerInspector from applying additional or more frequent inspections or tests when hehas any reason to require additional assurances that the boiler is safe.

For boilers in intermittent service account should be taken of the manner inwhich the Boiler has been housed. Boilers stored outside and exposed to theweather may require their external surfaces to be examined at less that 10 yearintervals.

Where the owner has recently carried out extensive repairs, or where he believesthat suitable documentation could be provided to indicate that some, or all of theexaminations designated for the ten year examination have been complied withalready, written application may be made to the respective Boiler Inspector foran exemption. On consideration of all material provided, a written reply will besent by the Boiler Inspector, to the owner giving the decision, detailing anyconditions which apply and specifying when the next ten year inspection shall becarried out.

44. Periodic Inspection Requirements.

This section sets out the objectives of the various inspections detailed inparagraph 2.


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45. Annual Periodic Inspections.

The annual periodic inspection is to determine that the boiler and the variousfittings are in a good and safe condition and that with adequate and proper careand attention by the owner, the boiler will remain safe.

Factors which are taken into account by the Boiler Inspector in undertaking theexamination will include the manner in which the boiler is used, the manner inwhich the boiler is prepared for storage, the manner in which the boiler is stored,the extent of corrosion and grooving, the condition of the stays, the extent ofscale in the boiler and the skills available to maintain it in a good and safecondition.

The annual periodic inspection will include a close visual examination ofinternal steam/waterside surfaces of the boiler shell end plates, fire box,foundation ring, and all stay tubes, smoke tubes, stay bars plus the firesidesurfaces of the firebox, tube plates and tubes to ensure that no cracking, groovingor general wastage has occurred. With the larger locomotives any broken staysfound shall be noted and the position recorded. The visual inspection should becarried out with all surfaces dry. The Boiler Inspector may request the removal ofcladding and lagging in the way of known problem areas

Every locomotive boiler shall be inspected under steam by a Boiler Inspector inthe presence of the regular engine driver as soon as possible after each periodicinspection. The inspection shall include testing of the safety valve, theexamination and safe operation of the engine and its steam operated equipmentplus all fittings, valves and injectors.

If at any time, for whatever reason, smoke tubes are removed the BoilerInspector should be advised so that a thorough internal examination of the boilercan be undertaken at that time. This would reduce the extent of the followingperiodic inspection.

The annual periodic inspection may include a hydraulic test although this shouldnot be necessary unless possible fault indications are detected as a result of thevisual examination.

Owners who may propose to clean any parts of locomotive boiler by use of thesand blasting, shot blasting, or any similar process shall first notify their localSenior Engineer Surveyor.


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Where, as the result of any inspection, the Engineer Surveyor requires majorrepairs to be carried out the owner should be advised by the Boiler Inspector inwriting as to the exact nature and extent of those repairs. A hydraulic test of 1.3x maximum safe working pressure shall be applied after the completion of anysuch repairs to the boiler.

46. Five Yearly Periodic Inspection.

The periodic inspection carried out every five years may also include in additionto the normal annual periodic inspection requirements a check on the thicknessof various parts of the boiler and may require the removal of some cladding andinsulation. The minimum thickness of areas not clearly visible on the watersideshall be established and recorded by closely sweeping the area with an ultrasonicthickness probe. The Boiler Inspector may recommend the ultrasonic thicknessexamination of additional specified areas as a result of the visual examination.

Where thicknesses are to be checked by non destructive means the examinationshall be carried out by a competent operator.

A hydraulic test shall also be carried out on the boiler pressure parts at five yearintervals at a test pressure of 1.3 x maximum safe working pressure.

47. Ten Yearly Periodic Inspection

The periodic inspection carried out at ten year intervals shall be a comprehensiveexamination of all internal and external steam/waterside surfaces of the boilershell, end plates, firebox, foundation ring, stay tubes, smoke tubes, stay bars,plus the fireside surfaces of the firebox, tube plates and tubes to ensure that nocracking, grooving or wastage has occurred.

During this inspection all cladding and lagging shall be removed. In specialcases it may be necessary to remove smoke tubes.

All boiler mountings which cover boiler shell plate surfaces shall be removedprior to the ten year examination. All mounting studs shall be inspected andreplaced as necessary.

In addition to the close visual examination by an Engineer Surveyor thethickness of the various pressure parts shall be determined by a competent


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ultrasonic operator. All areas where grooving, pitting or wasting has occurredand this has reduced the thickness to less than 80% of the original thickness shallbe permanently recorded in a manner which will enable them to be quicklyrelocated and rechecked as may be required at any future date.

Where boilers are fitted with “Flannery” flexible stays the stay cup caps shall beremoved to check that the ball has not failed at its head. Ultrasonic testing of staymay be used.

With the cladding and lagging removed the pressure parts shall be subjected to ahydraulic test at a test pressure of 1.3 x maximum safe working pressure.

48. Hydraulic Tests.

Hydraulic tests where specified shall be witnessed by a Boiler Inspector, andshall use water at temperatures preferably between 10 C and 60 C. All air shallbe removed from the boiler and its fittings prior to any significant pressure beingapplied.

The hydraulic test shall last for a period of at least 30 minutes and during thisperiod the boiler shall remain tight to the satisfaction of the inspecting BoilerInspector.

Pressure gauges shall be checked independently or be checked against a standardor master gauge whenever an hydraulic test is carried out.

49. Crack Detection Grooves.

All boilers having lap riveted longitudinal joints shall have crack detectiongrooves cut in those joints

Locomotive Boilers which already have had crack detection grooves cut whichdiffer slightly from those details given on the diagram shown below will still beacceptable without modification subject to the approval of the Boiler Inspector.

The grooves are required to give a positive indication of the presence of cracksor grooving of the boiler shell plate adjacent to the inside edge of a lap rivetedlongitudinal joint. The grooves shall be cut in a circumferential direction on theoutside surface of the upper plate of the lap joint commencing at the longitudinalcentre line of the second row of rivets (numbered from the external visible plateedge) and extending in length not less than two plate thickness beyond the inside


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lap edge of the riveted joint. The grooves shall be between 4mm and 5mm wide,half the plate thickness in depth and not more than 600 mm apart. The groovesshall be readily accessible for visual examination at any time.

The following diagram shows the general details of the crack detection grooves.

Ultrasonic testing may be used in place of crack detection grooves.


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50. Fusible Plugs.

All locomotive boilers shall be fitted with suitable fusible plugs irrespective ofthe fuel used.

At each annual inspection the fusible plugs shall be removes and all scalecovering the metal in the plug shall be cleaned off. In cases where an inspectionreveals there is deterioration the fusible plug shall be replaced.

51. General.

It is essential that Boiler Inspectors examining these boiler carry out a detailedexamination and, where problems or defects are found advise their respectiveOperations Manager accordingly so that factual information can be assembledand supplied to other Boiler Inspectors.

Owners shall retain or prepare a suitable log book for recording all essentialoperations, maintenance, repair and testing information relating to the boiler. Thenames of the persons carrying out the various work or operations and theorganisation they work for should be recorded and signed. The Boiler Inspectorwill sign such inspection and testing details as they may be involved with. It isanticipated that the compiling and ongoing use of the log book will assist in amore detailed record existing for Locomotives. The log book will help to identifythose owners who are setting and maintaining good operating and maintenancestandards and should in appropriate cases, when trends are recognised, enableadjustments to be made to the statutory inspection procedures.

Owners of Locomotive boilers who may as time proceeds sell them to otherpersons should make those persons aware of the sequence of periodic inspection,and where the boiler is, in terms of time, with-in that sequence.


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BOILER MANAGEMENT & MAINTENANCE

52. GENERAL GUIDANCE ON LOCOMOTIVE BOILERMANAGEMENT

General guidance on the management, examination, repair, maintenance andoperation of railway locomotive boilers. In drafting it, the special needs of thoseminor railways whose staff lack boiler expertise have been taken into account.

A defect in a locomotive boiler which allows an escape of steam can give rise tosevere scalding or even death of persons on the footplate. The principal dangersto be guarded against are:

(a) collapse of the firebox due to broken stays or low water level;

(b) collapse of fire tubes or superheater flues;

(c) bursting of copper steam pipes in the cab through work hardening;

(d) blow-out of wash-out plugs, fusible plugs, mud hole door joints andgauge glasses;

(e) reversal of draught (blow-back).

A factor to be borne in mind when considering these dangers is that manypreserved locomotives are very old and some have lain in a scrap yard for anumber of years without any protection against internal and external corrosion.

Saturated or superheated steam or red hot coals are likely to be discharged intothe cab if any of the events described into the cab if any of the events describedin para 2 occur. As an example of steam temperatures, saturated steam at a gaugepressure of 13 bar g (190 psig) has a temperature of 195C. Scalding fromcontact with the steam will be almost instantaneous and in most cases it will beimpossible to stop the escape of steam, so that the only way to avoid extensiveburns will be to flee from the footplate.


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Management

Responsible persons

The safe operation of steam boilers depends upon the correct managementapproach. The examination, testing repair and maintenance of boilers should becarried out to an adequate standard, and this in turn requires the choice ofsuitable persons both to carry out and supervise these functions. Records shouldalso be kept of steaming time, examinations, repairs and the extent ofmaintenance carried out. To ensure that all this is successfully achieved, it isstrongly recommended that each railway organisation appoints one person totake responsibility for co-ordinating the work necessary to ensure the safety ofthe boilers on their railway. Each person so appointed will be referred to in thispublication as the responsible person.

Responsible persons should be appointed in writing by the railwayorganisation. They should be made aware of their responsibilities and duties, andbe given authority to prohibit the raising of steam in any boiler if in doubt aboutits safety.

53. Fittings and Attachments.

For safe operation of a locomotive boiler the following fittings and attachmentsshould be included:

(a) At least one safety valve, fitted directly onto the boiler. There should beno means of isolating the safety valve from the steam boiler.

(b) A steam pressure gauge independently connected to the steam space andmarked in a distinctive manner to indicate the maximum permissibleworking pressure and be visible to driver and fireman.

(c) At least two methods of determining boiler water level. Preferably bothof these will be the transparent type of gauge, but a set of two or threetest cocks is acceptable in place of a second transparent gauge. Unlessthe transparent gauge is of the Klinger reflex type, it must be providedwith a transparent safety guard to protect persons on the footplate inevent of gauge glass breakage. The fitting of a thin backing plate tothe transparent safety guard, painted in alternate black and white


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diagonal stripes, greatly assists in the observation of the level of waterin the gauge glass and is recommended. It is also recommended thatwater gauge fittings incorporate ball valves to restrict the flow of steamand water in the event of breakage of the gauge glass. Where necessarythe water gauges may be illuminated by a lamp.

(d) A device for determining the water content of the locomotive watertanks or tender water tank. This can be a gauge test cocks or a plasticgauge glass and shall be visible from the locomotive footplate and,where applicable, operable from it.

(e) At least one fusible plug in the firebox crown.

(f) An easily visible and permanent means of identification for the boilerand, adjacent thereto, the maximum permissible working pressure forthe boiler should be marked.

(g) There should be two means of supplying feed water to the boiler whileit is under steam pressure.

54. Boiler Inspection and Testing By the Railway.

In addition to the examination by a Boiler Inspector, boilers should be inspectedinternally and externally by the responsible person as follows:

(a) under steam pressure prior to wash-out to look for signs of leakage attubes, stays, seams, fusible plugs etc.;

(b) after wash-out, before plugs and doors are replaced, and again afterplugs, doors and any other fittings are replaced;

(c) before bringing a boiler into use which has been laid up for a periodduring the currency of the certificate of thorough examination to lookfor evidence of deterioration resulting from the effects of corrosion.

These inspections would normally be carried out by the railway’s own staff, ifsufficiently experienced in these maters, or by an expert retained by them forthe purpose. Their object is to ensure that the boiler remains fit for continuedservice until either it is inspected again or the next periodical examination iscarried out by the Boiler Inspector who must be advised if signs of significantdeterioration are seen.


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The inspections should include the following:

(a) Water spaces, to ensure that all scale, dirt and sludge were removedduring the wash out, paying particular attention to the spaces around thebase of the firebox and to the firebox crown and the condition of visiblestays for necking. Corrosion, pitting and wastages’;

(b) The firebox, for bulging that may indicate the presence of broken stays,and for wasted stay heads, rivet heads and stay nuts:

(c) The condition of the element in fusible plugs

(d) The inside and outside of the visible parts of both small and large tubesfor signs of pitting:

(e) The water side of the boiler shell at foundation ring level for signs ofgrooving;

(f) The bottom of the smokebox tube plate for corrosion due to theaccumulation of damp soot;

(g) Water gauge fittings and test cocks to ensure that all passages are clean;Note It should be possible to insert a rod not more than 1/16 in diametersmaller than the openings (or a square-section rod with a diagonal of thesame dimension). Care must be taken when inserting the rods not todamage any curved pipes some-times fitted inside the boiler behind theupper gauge fitting. In case of fittings with coupled cocks it should bepossible to pass the rod simultaneously through both cocks when thecoupling rod is fitted and the cocks are in the open position. (h)gaugeglasses for signs of pitting, flaws or streaks; if these are found, the glassmust be replaced;

(h) The alignment of any re-fitted gauge frame fittings; this should bechecked by passing a rod through them; misalignment is a prime causeof gauge glass breakage;

(i) Steam pipes in the smokebox;

(j) Fittings in the smokebox for security, since any obstruction in the pathof the exhaust steam could cause a serious blow-back through thefirebox into the driving cab;

(k) Operation of the regulator.


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55. OPERATION

Means of escape in an emergency.

Since the risk of an escape of steam or boiling water into the cab cannot beentirely eliminated, those on the footplate should be able to escape quickly inthe event of trouble. Unless the locomotive is standing at a platform speedyegress from the footplate is not easy. The opening at the side of the footplate isnarrow, there may be a pair of doors to be opened and the steps are not easy todescend, especially for someone unfamiliar with them. If the train happens tobe travelling above a slow speed ,injury on reaching the ground is likely andindeed, it is not unknown for footplatemen and others who are familiar withlocomotive steps to slip and fall under the wheels of a moving locomotive orfollowing vehicle.

For this reason, it is recommended that the number of persons travelling on thefootplate of a steam locomotive be kept to a minimum and not to exceed fourunless either;

(a) special arrangements are made to protect persons from an escape ofsteam, such as provision of a suitable screen, or

(b) the locomotive is standing at a platform where access to the cab isrelatively easy and the boiler pressure is maintained at substantially lessthan its maximum permitted working pressure.

However, even four persons may be excessive in some very small cabs orthose with particularly difficult means of egress.

56. USING THE BOILER

Under no circumstances may the maximum permissible working pressurespecified for the boiler be exceeded.

Maintaining correct water level in the boiler is, of course, essential to safeoperation and this in turn depends on the gauge glass correctly registering thelevel. The glass and cocks should be blown through when taking over alocomotive to ensure that no scale obstructs the orifices between boiler andglass; this should be carried out in the following manner:


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(a) For separate test cocks.

(i) Shut top and bottom cocks.

(ii) Open drain cock and water should disappear from gauge glass;leave drain cock open.

(iii) Blow through top cock and close again.

(iv) Blow through bottom cock and close again.

(v) Shut drain cock.

(vi) Open top and bottom cocks and water should rise in gauge glass.

(b) For coupled test cocks.

(i) Shut top and bottom cocks.

(ii) Open drain cock and water should disappear from gauge glass;leave drain cock open.

(iii) Open top and bottom cocks slowly in order to blow through andclose again.

(iv) Shut drain cock.

(v) Open top and bottom cocks and water should rise in gauge glass.

Boiler temperature (pressure) should be raised and lowered gradually, so as tominimise stresses due to uneven expansion. This is particularly important withoil-fired boilers.

57. MAINTENANCE AND REPAIRS.

Records.

A record should be kept of all boiler steaming days, wash-outs, reported defects,repairs, inspection or other maintenance work carried out on a boiler. Thereshould be a separate record for each boiler so that there will be no doubt whenany boiler is next due for maintenance etc.


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Maintenance schedule.

A maintenance schedule should be drawn up which would lay down frequenciesof boiler wash-out and inspection and of all other maintenance work on theboiler and its fittings. The schedule should be approved by the ResponsiblePerson, who if necessary should take suitable advice, and the Boiler Inspectorshould be informed. It is important that each railway determines frequency ofwash-out and related maintenance and inspection on the basis of the nature of theboiler feed water, its treatment and locomotive usage. If in any doubt aboutwash-out frequency, the railway should seek advice from the Boiler Inspector.

58. WATER TREATMENT.

Mineral salts present in solution in boiler feed water are responsible for theproduction of scale which, in additions to reducing boiler efficiency, can causelocal overheating by insulating parts heated by the fire from contact with thecooler water in the boiler; the over heated parts may be subject to acceleratedcorrosion and loss of mechanical strength. Acidic water tends to cause corrosionand pitting. In order to minimise these problems the feed water should beanalysed and, where appropriate, suitably treated; advice may be obtained fromspecialists in this field or from the suppliers of the reagents. Re-analysis may beneeded from time to time to ensure continuing correct treatment.

The problems arising from salts in the water are overcome in three ways, namely.

(a) suitable treatment of the boiler feed water either by softening or byadding reagents to the feed water;

(b) frequent or continuous blowing down of the boiler;

(c) wash-out of the boiler.

Soft waters are likely to be acidic and may require treatment to neutralise acidity.

In view of its importance in respect of washout periods or rate of boilerdeterioration, all water treatment should be authorised by the Responsible personand discussed with the Boiler Inspector.


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59. Blow-down.

It will be appreciated that as steam contains no salts, the salts from theevaporated water remain in the boiler. To prevent concentrations reachingunacceptable levels some boiler water may be drawn off by blowing down andreplaced by fresh feed water.

Certain precautions are necessary when manually blowing down in addition tothe obvious one of ensuring that no one is scalded by the escaping water andsteam. Water level must be maintained and a good fire should be kept in thefirebox in order to maintain sufficient steam pressure to work the injectors.When using T.I.A. Blow-down equipment ensure track side is clear.

The interval between boiler wash-outs depends on the condition of the feedwater and the extent of steaming and of blowing down; it should be laid down bythe Responsible Person.

Much boiler trouble can be traced to over rapid cooling preparatory to washingout or water changing. It should always be arranged that boiler washing out andwater changing shall only be begun after the boiler, when full of water, hascooled down to the temperature of the cold water that will be used for washingout or changing.

The most important factor in boiler washing where hard scale is to be removed isto maintain an adequate pressure of water which, if less than 60lb/in2 whichshould be boosted. The smallest booster pump that can reasonably be used is onedelivering 10,000gal/h against a pressure of approximately 70lb/in2 which is justsufficient to supply one ¾ in nozzle. Straight and offset nozzles are used. Duringthe washing out of the boiler shell and firebox water spaces vigorous rodding isnecessary to remove scale, brass wire rods being used to avoid damage. It is mostimportant that descaling be done thoroughly

Wash-out plugs and mud-hole doors must not be removed until the boiler iscompletely free of steam pressure which can be determined by opening injectorsor other open-ended fittings; the steam pressure gauge should not be relied uponfor this purpose. Mud-hole doors and bolts should be carefully examined aftereach removal in view of the corrosion that takes place. Owing to the taper andfine pitch of the threads some care is necessary when replacing wash-out plugs toavoid crossed threads; a fatal accident may result from any attempt to tightenthese when under steam pressure. The threads of plugs should be thoroughly


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cleaned before replacing and, when fitted, must engage all threads in the plate.When re-tapping plug holes or renewing plugs, care must be taken to ensure thetap and plug has the correct taper and pitch of thread.

60. Boiler Tubing.

No boiler tubes should be replaced without prior approval of the BoilerInspector. Only approved tools should be used for the work and it is stronglyrecommended that only five or six-roller expanders are used for expanding thetube ends as their use will generally improve the life expectancy of the tubeplates. All tubes obtained as replacements should be to British Standardspecification BS 3059: Part 1: 1978, or equivalent standard; they may be eithersolid drawn or electric resistance welded. A copy of the relevant material and testcertificates for such tubes should be retained by the Responsible Person.

N.Z. Govt. Railways Code 43. Dated 31/3/67. When a boiler requires re-tubingnew tubes can be used or the old tubes removed from boiler can be piece ended.Tubes and flues withdrawn from boilers shall have all scale removed by a tubeand flue cleaning machine and, if the resultant examination shows them to besuitable for service for at least three years, they are to be pieced as follows.

(a) 1 ¾ inch and 2 inch diameter tubes shall have three inches cut from thesmoke-box end and at least six inches cut from the firebox end. A newpiece of tube of the appropriate diameter, at least 12 inches long, shallbe pieced to the firebox end of the shortened tube by a butt weld usingthe electric arc process.

(b) Flues shall be pieced with a butt weld using the electric arc process.

(c) Tubes and flues shall be annealed at both ends before being expanded inboiler and passed into service.

(d) Tubes are expanded into fire box and smoke box tube plates. At firebox end tubes may be beaded over or seal welded. If seal welded nopart of tube may extend past end of weld. After seal welding tubes mustbe lightly re-expanded.

All repairs to and replacement of superheater flue tubes, whether welded orscrewed, should be undertaken under the supervision of the ResponsiblePerson or boiler-smith nominated by him. All tubes should be to BS 3059 :Part 1 : 1978, solid drawn only or an equivalent standard. Material and test


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certificates should be obtained and retained by the Responsible Person.

61. Firebox stays.

Any work required on firebox stays, rivets and studs should be notified to theResponsible Person who should ensure that it is properly supervised. Testcertificates should be obtained for all materials needed, and retained by theResponsible Person. Expert advice should be sought, if necessary, on thechoice of materials for replacement to ensure the suitability of physicalproperties and comparability with designed strength requirements. Especialcare is necessary in the case of copper stays since the phosphorus deoxidisedarsenical copper that was normally used in the past is difficult to obtain in theappropriate form.

62. Patches.

The Boiler Inspector should give his written consent to any patching andshould confirm that he approves the use of the materials and the method ofdoing it.

63. Welding.

Welding should only be carried out on the structure or components of a boilerby properly qualified and currently certified welders. A copy of the welderscertificate should be lodged with the Responsible Person. No boiler,particularly those of 2% nickel steel, should be repaired by welding withoutthe prior knowledge of the Boiler Inspector.

64. Steam pipes and joints.

Copper steam pipes leading to injectors and other boiler fittings may work-harden and crack, thereby scalding persons on the footplate; they should beannealed whenever they are removed and at the time of boiler overhaul and newpipework must be annealed before use. Steel pipes should be dismantled andinspected at boiler overhauls.

All joints to boiler fittings should be made metal to metal where this practice wasan original design feature. Otherwise joints should be made using a high grade


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jointing material of the minimum practicable thickness. No jointing compoundother than graphite types should be used and this compound should be usedwherever possible as it aids disassembly after a long period. Mineral or vegetableoils and greases should not be used as jointing compounds. All mud-hole doorjoints should be of an approved pattern; materials such as cast lead are onlyappropriate in special circumstances.

65. Boiler lay-up.

A boiler can deteriorate more quickly when laid up than when in service, soadequate protection during any lay-up period is essential.

Immediately prior to laying up, the boiler tubes should be thoroughly cleaned toremove any deposit which may contain acid residues from the combustion of thefuels, and the fire and grate should be cleaned. Smokebox and firebox doorsshould be left open to allow ventilation and prevent build-up of condensation.The blast pipe should be capped.

Corrosion on the water side is best prevented by filling the boiler completelywith water as corrosion is reduced if air is not present. However, in freezingweather it will be necessary to drain the boiler and to provide as muchventilation as possible by removing all mud-hole doors and inspection plugs.

During a lay-up of several years duration periodical examination isrecommended to ensure that undue deterioration is not taking place.

66. Hydraulic pressure testing.

The Boiler Inspector will advise if hydraulic pressure tests are required atpressures above working pressure.

For a hydraulic test:

(a) Cold water should be used.

(b) All air must be excluded from the boiler and pipework subjected to thetest.

(c) There should be no sign of leakage or other defect whilst the hydraulicpressure is maintained, which should be for a minimum period of 30minutes to allow any seepage to become apparent.


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67. Safety valves.

If safety valves require attention they should be overhauled by an expertacceptable to the Boiler Inspector, and then tested elsewhere than on theboiler.


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HANDY HINTS

68. WASHOUT PLUGS.

Washout plugs are made from gunmetal. If a plug leaks don’t try to stop leak byhammering with spanner. The plug should be bedded in using fine grindingpaste. Wash off all grinding paste and refit plug using a paste made up of tallowand flake graphite. Do not over tighten plug.

69. PAD WELDING.

If a stay head that has been riveted over is wasted away, grind the stay head flushwith the firebox plate and then pad weld over stay. Using a Weldcraft rod 3.15no bigger. Pad weld an area about 2" square over stay. First run below stay about1" below stay centre and 2" long. Clean off slag and lightly peen weld with ballpeen hammer. Next run above first run so that weld penetrates top half of firstrun. Clean off slag and peen again. Repeat this until a 2" square covers stay. Themain thing about pad welding is to lightly peen the weld so that the metal isstretched so that the weld metal on cooling does not contract and form stress onthe firebox plate. The pad welding must be done slowly so that heat from eachweld has dissipated before next weld and the boiler plate is kept as cool aspossible. This will keep the stay head from leaking until it can be replaced.

The bottom corners of fireboxes were also pad welded, also bottoms ofsmokebox tube plates.

70. SUPER HEATER ELEMENTS.

Super heater elements should be tested to 1,000lbs. Sq. inch after repairs orbefore placing in boilers.

71. PRESSURE GAUGES.

Pressure gauges to be tested every two years.


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72. FIREBOX PATCHING.

All areas in firebox can be patched i.e. bottom half of firebox, new crown sheetsor small patches in areas of plate wastage. The patch is to be same material asfirebox plates and is to be secured by stays. That is the area to be patched is to becut out between stays with rounded corners. The stay is holding the boilerpressure, the weld is only stopping it leaking. A full penetration weld is used, theroot run to be made by TIG. Welding.

73. INSIDE INSPECTION OF BOILER.

If a nozzle can be obtained from a miners carbide lamp and fitted to a length ofcopper tube about 2 foot long and a length of rubber hose fitted to other end. Theother end of rubber hose is then fitted over welding tip of oxyacetylene welder.Turn on the acetylene and light the nozzle. A brilliant white flame of the nozzleis then inserted in washout hole and the inside of the boiler is lit up. Looking inwashout holes or using mirrors you can see every part of the inside of the boiler.


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DRAWINGS

74. Safety Valves

(i) Ramsbottom Safety Valve


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1/32” Gap

0.008” Gap


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75. Standard Mud Plugs


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76. Fusible Plugs


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77. Gauge Glasses

s


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78. Seal Welding of Tubes


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79. Locomotive Firebox

B33101 - Boiler Code - ATHRAathra.asn.au/library/B33101_Boiler_Code.pdf · BOILER CODE Issue...

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Transcript of B33101 - Boiler Code - ATHRAathra.asn.au/library/B33101_Boiler_Code.pdf · BOILER CODE Issue...