Welding 2
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Transcript of Welding 2
A Brief synopsis of:
Terms & Definitions
Duties & Responsibilities
Welding Imperfections
Mechanical Testing
Welding Procedures & Approval
Welder Approval
Any Questions ?*
1) Use a pencil only for the arrow line, but make all writing in ink
3) Do not forget to compare and sentence your report to the code provided
2) Report everything that you can observe
4) Do not forget to date & sign your report
5) Make any observations, such as recommendations for further investigation for crack-like imperfections*
Using the macro photographs and report sheets given to you, prepare your reports using the sheets given (20 min’s/macro)
Identify indications, then draw a line on the report sheet smaller macro photograph and number it. Using the boxes below, identify the number and indicate what you have identified
Place the size of the indication in the next box on the right, remembering to divide the dimension from photograph by 10
Use the following slides as guidance!
Macro Inspection Points1) Use a pencil for the arrow lines, but make all
writing in ink only
2) Do not forget to print your name
3) Do not forget to put the date
4) Do not forget to SIGN the report
5) Make any comments such as recommendations for further investigation for crack-like imperfections*
Macro Photo x 10*
09.20
Example Macro Photo
NOTE: PHOTOGRAPH IS AT X10 MAGNIFICATION
MATERIAL: LOW CARBON STEEL WELDING PROCESS: [MAG/GMAW]
1
Overlap + 2 pores# DEFECT SIZE ACCEPT/REJECT1
2
3
4
5
6
7
8
9
10
11 EXCESS WELD METAL
12 EXCESS PENETRATION
Laminations/inclusions*
2 3
Lack of side wall fusion*
4
Overlap*
5
Linear misalignment 0.4*
6
Lack of inter-run fusion + silica*
7
Gas pore/pipe ? Check penetrantLack of side wall fusion + silica*
8
Poor toe blend
9
11
4.7*1.4 Sharp*
All dimensions in mm
12
5°*Angular misalignment
10
Sharp 75° *
2.2 Ø *
Assess
To
Specification*
0.5 Ø max *
Continue with Practical Macro Inspection.
(Or as directed by your lecturer/presenter)*
10.45
Materials arriving at the site need to be inspected for the following:
1) Size
2) Condition
3) Specification*
Rolling Imperfections
LaminationsSegregation
Cold Laps*
Direction of rolling
Plate Inspection
Size
Condition (Corrosion, Mechanical damage, Laps, Bands and Laminations)
5L
Specification
Other checks may need to be made such as: distortion tolerance, number of plates and storage*
Pipe InspectionCondition (Corrosion, Damage, Wall thickness Ovality, Laminations & Seam)
Specification
Other checks such as: distortion, tolerance, number and storage*
Welded seam Size
LP 5
General discussion on areas of industry employing codes or standards*
Discuss the 3 areas of responsibility:
DesignManufactureTesting*
The 3 agencies generally identified in a code or standard:*
Codes & standards often do not contain all relevant data, but may refer to other standards*
1) The customer, or client*
2) The manufacturer, or contractor*
3) The 3rd party inspection, or clients representative*
Interpretation of Drawings & Weld Symbols
It could be strongly argued that without a thorough knowledge of weld symbols, a welding inspector is unable to fully carry out his full scope of work*
Welding SymbolsMost weld symbols contain 5 elements, which are:
1) The arrow line*
2) The reference line*
3) The symbol*
4) The dimensions*
5) The supplementary information*
a. 7 b. 10111*
5 x 100 (100)
1) Convention of the arrow line:
BS. BSEn & AWS a) Shall touch the joint intersection
b) Shall not be parallel to the drawing
c) Shall point towards a single plate preparation*
*
2) Convention of The reference line:
BS 499 (UK) & AWS A 2.4 (US)
a) Shall touch the arrow line
b) Shall be parallel to the bottom of the drawing*
*
Symbols: BS 499 (UK) & AWS A2.4 (US)a) Welds this side of joint, go underneath the reference line
b) Welds the other side of the joint, go on top of the reference line
c) Symbols with a vertical line component must be drawn with the vertical line to the left side of the symbol
d) All CSA dimensions are shown to the left of the symbol
e) All linear dimensions are shown on the right of the symbol i.e. Number of welds, length of welds, length of any (spaces)*
10 4 x 50 (50)*
Fillet weld
Double V
Double bevel
Double U
Double J*
Representation of welds done from both sides of the joint intersection, touched by the arrow head
Concave or Convex
Supplementary Weld SymbolsSupplementary Weld Symbols
Toes to be ground smoothly. (BSEn only))Site Weld
Weld all round
Ground flush
111
Welding process. Numerical BS En & BS
Further supplementary information, such as WPS number, or NDT may be placed in the fish tail*
3) Convention of The reference line:
BS En 22553 or ISO 2553a) Shall touch the arrow line
b) Shall be parallel to the bottom of the drawing
c) There shall be a further broken line above or beneath the reference line (Except where the weld is
symmetrical)*or *
Symbols: BSEn 22553. (ISO 2553)a) Welds this side of joint, go on the unbroken reference line
b) Welds the other side of the joint, go on the broken reference line
c) Symbols with a vertical line component must be drawn with the vertical line to the left side of the symbol
d) All CSA dimensions are shown to the left of the symbol
e) All linear dimensions are shown on the right of the symbol i.e. Number of welds, length of welds, length of any spaces
f) All leg lengths shall be preceded by z and throat by a or s*
z 10 4 x 50 (50)*
Weld Symbols on Drawings
88
5
a 5 b 8
8
BS 499 & AWS A 2.4
*
Weld Symbols on Drawings
8
z 8
5
a 5 z 8
8
BS En 22553 (ISO 2553)
or
or
z 8
a 5 z 8 *
Example:
Produce a drawing giving symbols for the welds given as shown below to the specification given
Weld Drawing BS 499
Symbol Drawing
MMA
111*
Example:
Student Symbols ExerciseComplete a symbols drawing for the welded joint given below to BS 499BS 499 && BSEn 22553BSEn 22553
10
All Fillet weld leg lengths are 10 mm *
20
30
35
15
7
All butt welds are MIG welded and all fillet welds with MMA
Solution BS 499 10a. 30
a. 20
10
a. 7 b 10
a. 35
a. 15
10
*
111 131
111 131
Solution BSEn 22553 z. 10
s. 30
s. 20
z. 10
a. 7 z. 10
s. 35
s. 15
z. 10
*
111 131
111 131
Special equipment used with method, for producing welds
Requirements:
To make a sound weld we need to
Protection
Properties
Heating
Cleaning
A welding process:*
Before continuing with the welding processes section, there are 2 safety related terms that should first be understood*
“Duty Cycle” relates to the current carrying capacity of all conductors, based on a 10 minute cycle i.e. 60% duty cycle means it can carry the specified current for 6 minutes in 10 then must rest for 4. A 100% duty cycle has no rest period requirement. (Explained fully in the WIS 5 course notes)*
Fume or gas Exposure Limit Effect on Health
Cadmium0.025Mg/m3Extremely toxic
General Welding Fume5Mg/m3Low toxicity
Iron5Mg/m3Low toxicity
Aluminium5Mg/m3Low toxicity
Ozone0.20 PPMExtremely toxic
Phosgene0.02 PPMExtremely toxic
Argon No OEL Value O2 air content to be
controlled
Very low toxicity
OEL/MEL (Occupational or Maximum Exposure Limit) which is used in reference to fume exposure such as that caused in arc welding. The value may be in PPM or mg/m3 depending on a particulate fume, or a gas. Typical values in EH/40 are*
Volts
Amps
OCV
Constant Current/Amperage Volt Amp Characteristic*
Large change in voltage =
Smaller change in amperage*
Welding Voltage*
Large arc gap*
Small arc gap
Electrode oven (Up to 350 °C)
Power return cable
Safety visor (With dark lens) *
Power source. Transformer/Rectifier
Holding Oven (Up to 200 °C)
Inverter power source
Electrode holder
Power cable
Power control panel
Electrodes
3) Electrode holder
1) A Transformer/Rectifier (Constant current type)
2) A power and power return cable
4) Electrode (To correct specification)
5) Correct visor & glass, all safety clothing and extraction
5) Electrode type & Ø
1) Amperage
3) Polarity
7) Electrode condition
9) Insulation / extraction
2) Arc Voltage
4) Speed of Travel
6) Duty Cycles
8) Connections
10) Electrode treatments*
3) Porosity
1) Slag inclusions
2) Arc strikes
4) Undercut
Most welding imperfections in MMA are caused by a lack of welder skill, the incorrect settings of the equipment, or the incorrect use, and treatment of electrodes*
Advantages:
1) Field or shop (Portable)
2) Range of consumables
3) All positional
4) *Quick electrode change
Disadvantages:
1) High skill factor
2) Short electrode length
5) Simple equipment
3) **Low productivity (OF)
4) High level of fume
5) Hydrogen control
* Enabling fast changes in material types to be welded** Comparatively uneconomic with other processes*
Inverter power source
Power cable
Flow-meter
Power control panel
Transformer/ Rectifier
Power control panel
Power return cable
Torch assemblies
Tungsten electrodes*
Ceramic shield cup
Gas lens
Torch body
Tungsten electrodes
Spare ceramic shielding cup *
Gas diffuser
Split collet
On/Off switch
Fitted ceramic shielding cup
Tungsten housing
The tungsten must have the correct vertex angle*
Grinding is done on a special jig, and on a dedicated wheel*
Correctly adjusted shielding with a gas lens will give good cover without turbulence*
Adjustments to the flow rate need to made according to joint design and gas type*
A fusible insert is pre-formed and placed filler material that is mainly used in the root of TIG welded pipes*
The Electric Boat Company of America, who developed it*
It is often termed an “EB insert” after*
Before welding
After welding*
1) A Transformer/Rectifier (Constant current type)
2) A power and power return cable
3) An Inert shielding gas. (Argon or Helium)
4) Gas hose, flow-meter, & gas regulator
5) TIG torch head with ground tungsten, collets, ceramics
6) Method of arc ignition (High frequency or lift arc)
7) Correct visor, all safety clothing and good extraction
8) Optional filler rod, to correct specification*
5) Tungsten type & Ø
1) Amperage
3) AC or DC + Polarity
7) Tungsten vertex angle
9) Gas type & flow rate
2) Arc Voltage
4) Speed of Travel
6) Duty Cycles
8) Connections
10) Insulation / extraction
11) Ceramic condition 12) Gas lens fitted*
2) Surface porosity (Loss of gas shield mainly on site)
1) Tungsten inclusions (Low skill, or wrong vertex angle)
3) Crater pipes (Bad weld finish technique i.e. Slope out)
Most welding imperfections with TIG are caused by a lack of welder skill, or incorrect setting of the equipment. i.e. Current, torch manipulation, welding speed, gas flow rate, etc*
4) Oxidation of S/S weld bead, or root by poor gas cover
Advantages:
1) High quality
2) High control of weld pool
3) All positional
4) Lowest H2 arc process
Disadvantages:
1) Very high skill factor
2) Range of consumable
5) Low inter-run cleaning
3) Loss of gas shield/site
4) Low productivity (O/F)
5) High ozone levels*
Videos
TWI
“Welding with covered electrodes”
ESAB
“TIG Welding Steels & Stainless Steels”
Or equivalent (1 hour)*
1) Use a pencil for the arrow lines, but make all written comments and measurements in ink only
3) Do not forget to compare and sentence your report
2) Report everything that you can observe
5) Do not forget to date & sign your report
6) Make any observations, such as recommendations for further investigation for crack-like imperfections i.e. penetrant testing*
WTC 7 Text Ref Section 17WIS 5 Text Ref Section 23Slides 52 - 60
The purpose of this session is to practice the reporting format required by CSWIP in the practical plate examination part of the CSWIP 3.1 Welding Inspectors exam
Remember, the responsibilities of a welding inspector are:
Observe
Report
Compare*.
To observe welding imperfections you are required to have good close vision acuity
A close vision acuity test will be given to you before your exam to establish if your vision meets the minimum standard required
Its not just the project that must meet the standard!!
You will also require a thorough knowledge of welding imperfections and their likely location, causes and implications*
After you have observed an imperfection and determined its type, you must be able to take measurements and complete a report *
The first report should be in the form of a repair map of the weld. (i.e. All observations are Identified Sized and Located)
Should the imperfection be a defect and require repair, it will need to be accurately found and re-identified*
The report map form used in CSWIP will look like the following:*
A
MEASURE FROM THIS
DATUM
E DGE
Page 1 of 3 VISUAL INSPECTION PLATE REPORT
Code/Specification used ________________________ Welding process _____________________ Joint type__________________
Name [Block capitals]__________________________ Signature ___________________________ Test piece identification
Welding position ______________________________________ Length & thickness of plate____________________ Date___________________________
Weld Face
All CSWIP 3.1 candidates should use there nominated pipe code for all your visual inspection practice, as this will help them become conversant with the specification
Practice this up and till the end of the day, or as directed by your course lecturer*