Modification in pump piping to comply with nozzle allowable

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 6, June 2014)

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Modification in Pump Piping to Comply with Nozzle Allowable Harshal M Ghule

1, S. B. Belkar

2

1PG Student PREC Loni, India.

2HOD Mechanical dept. PREC Loni India.

Abstract— The load and stress imposed from a connecting

piping system can greatly affect the reliability of an

equipment; these loads either from expansion of a pipe or

from other source can cause shaft misalignment as well as

shell deformation interfering with the internal moving parts.

Therefore it is important to design the piping system to

impose a little stress as possible on the equipment, ideally, it is

not possible.

This project work is focused on to stress analysis of a pump

piping system as per process piping codes B31.3 by CAESAR-

II and rethinking the nozzle allowable loads provided by the

pump manufacture, to optimize the design and reduced the

design, material as well as manufacturing cost. To achieve

this, implement various methods. The loads which are

imposed on the pump nozzle can be reduced by possible re-

routing the piping system with less modification. But this re-

routing of a piping has its practical & layout limitation, so as

to overcome this difficulty, explores the methods for setting a

higher allowable loads without changing pump manufacturer

design consideration and size of pump. A more realistic

allowable should be established as per API 610 standard to

better balance equipment cost against piping engineering.

I. INTRODUCTION

It is common practice worldwide for piping designers to

route pump piping by considering mainly space, process

and flow constraints (such as pressure drop) and other

requirements arising from constructability, operability and

reparability. Unfortunately, pipe stress analysis

requirements are often not sufficiently considered while

routing and supporting piping systems, especially in

providing adequate flexibility to absorb expansion

contraction of pipes due to thermal loads. So, when “as

designed” piping systems are handed-off to pipe stress

engineers for detailed analysis, they soon realize that the

systems are “stiff” and loads on nozzles is to high to

comply with manufactures allowable so as suggest routing

changes to make the systems more flexible and to reduced

the nozzle loads. The piping designers, in turn, make

changes to routing and send the revised layout to the pipe

stress engineers to check for compliance again. Such “back

and forth” design iterations between layout and stress

departments continue until a suitable layout and support

scheme is arrived.

But this resulting in significant increase in project

execution time, which, in turn, increases project costs. This

delay in project execution is further worsened in recent

years by increased operating pressures and temperatures in

order to increase plant output; increased operating

pressures increase pipe wall thicknesses, which, in turn,

increase piping stiffness's further. Such increased operating

temperatures applied on “stiffer” systems increase pipe

thermal stresses and support loads. So, it is all the more

important to make the piping layout flexible at the time of

routing.

Many researchers were worked on modification of pump

piping. Peng et.al. [1] Identified that the current allowable

for piping loads on rotating equipment nozzle imposed by

the equipment manufacturers are too low. William et.al.

[2] studied the pump reliability problem which is

responsible for the large amount of maintainence budget

and lost opportunitycost at chemical plants, refinaryies, and

many electric utilities. James et.al. [3] had studies the

Horizontal process Pump modification to comply with API-

610.sixth edition forces and moments. James et.al. [4]

Worked on the API 610 Base plate and Nozzle loading

criteria. The base plate and nozzle loading criteria in the

December 1985 draft version of API610 7th Edition is

substantially different from the criteria found in the 6th

Edition. Takio Simizu et.al. [5] senior research engineer

in Ebara research company studied "The analysis of nozzle

load for process pump." Also discussed shaft end

displacement of centerlines mounted pump under nozzle

loads. L.C. Peng et.al.[6]had studied the "Equipment

reliability improvement through reduced pipe stress ". The

loads and stress imposed from a connecting piping system

can greatly affect the reliability of equipment. Charles

et.al. [7] Proposed various aspects for pump piping. They

studied "Design and Operation of Pump for Hot standby

service.”Peng et.al. [8] Found piping system is designed

based on the piping code created for each individual

industry. Peng,et.al. [9] Studied the "Treatment of support

friction in piping stress analysis".

It is always studied that how to overcome with this low

nozzle allowable provided by manufactures. So in this

research they have focused the various methods and

approach to comply this low allowable, without increasing

the project time, material and cost.


Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 4, April 2013)

785

Literature of past work does not adequately clarify the

proper innovative design of pump system and routine

modification in pump piping and Latest edition requirement

of API 610. So there is a need to modification in piping as

well as support friction factor consideration to reduce the

loads on piping nozzles.

II. DESIGN BASIS FOR STRESS ANALYSIS.

The applicable edition of the codes and standards shall

be that in effect on the contract date.

A] Codes:-Comply with all applicable Codes including,

ASME, B31.3, Section VII, B16.5.

B] Standards:-Comply with the following applicable

Standards: API, API 610, WRC, WRC 107, WRC 297,

ASCE-7-05, EJMA

C] Basic Data for Analysis:-For analysis of stress it is

required to find out pressure,wight and temperature of the

fluid ,along with this loading type is important factor which

is to be consider while analysis.

Project Specification And Pump Piping Design

Parameters:- Lines which are connected to the deethaniser

centrifugal pump in propylene recovery unit has below

listed properties.

Suction Line No-

14"-1630-P-400-31174XR

Discharge Line No-

8"-1630-P-013-31174XR

Equipment - 1630-D-007

(Reflux Drum )

Equipment-1630-G-004A/B

(Reflux Pump)

Density of Fluid - .0004270

kg./cu.cm.

Pressure Rating 300

Operating Temperature - 49

Operating Pressure -18.2 bars

Design Temperature - 87 Design Pressure -32.65 bars

Mill Tolerance-12.5 Test Pressure = 48.98 bars

Corrosion Allowance-3.00mm Piping Material- A333 6

Piping Code-B 31.3 Equipment Standard-API610

Process layout of system

Piping designer and Layout engineer route piping as per

design requirement by considering various access ways,

maintenance requirement and process requirement as

shown in below fig

Caesar model formation is based on the initial routine

and possible support location shared by Piping Dept.

Design parameters is as per project design basis.

Caesar model is as shown in below Fig.



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Nozzle check with Initial Piping.

It is found that the nozzles are not qualified in the

existing routine as the initial system is very stiff. Even if

the nozzle is not passed in two times of allowable in API

610 then we will suggest possible route modification in

existing routine at clouded potion.

NODE Fa N. Fb N. Fc N.Forces

Check

Ma

N.m.

Mb

N.m.

Mc

N.m.

Moments

CheckRemark

70

Limits 24299 23401 13998 20899 13799 19599

2(OPE) 5297 921 2609 0.218 -530 -547 1760 0.09 Qualify

3(OPE) 5366 921 2879 0.221 -612 -831 1856 0.095 Qualify

4(OPE) 5204 1138 2528 0.214 -376 -392 2056 0.105 Qualify 11(SUS) 9347 -1094 -846 0.385 -323 -498 20 0.036 Qualify

500

Limits 4893 3781 3114 2576 3525 1762

2(OPE) -4480 2188 -1139 0.916 -499 -1041 -3258 1.849 Qualify

3(OPE) 38 311 -1154 0.371 -845 -764 -1091 0.619 Qualify

4(OPE) -4075 1995 -1262 0.833 -123 -1491 -2890 1.64 Qualify

11(SUS) 34 -363 -446 0.143 -411 -104 337 0.191 Qualify

750

Limits 4893 3781 3114 2576 3525 1762

2(OPE) -5298 3095 1938 1.083 1360 2854 -5094 2.89 Fail

3(OPE) -4998 2911 1719 1.021 937 2496 -4735 2.687 Fail

4(OPE) -1221 1721 1450 0.466 1613 1440 -3947 2.24 Fail

11(SUS) 39 -330 283 0.091 361 -275 266 0.151 Qualify

2130

Limits 3114 2491 2046 1762 2305 1180

2(OPE) 223 1402 1321 0.645 -188 510 -291 0.247 Qualify

3(OPE) 955 65 301 0.307 -194 108 108 0.11 Qualify

4(OPE) 223 1429 1350 0.66 -195 522 -293 0.249 Qualify

11(SUS) 962 -184 7 0.309 -112 -16 126 0.107 Qualify

2530

Limits 3114 2491 2046 1762 2305 1180

2(OPE) 98 716 743 0.363 147 150 -443 0.375 Qualify

3(OPE) 96 809 820 0.401 120 193 -443 0.376 Qualify

4(OPE) 968 -426 -405 0.311 60 -202 111 0.094 Qualify

11(SUS) 962 -202 -32 0.309 -99 -31 127 0.107 Qualify

In piping routine change some loop will apply to

increase flexibility and piping 3D model is as shown in Fig.

Piping Caesar-II model with route modification :-

As the Piping has rerouted the piping needs to be again

update the Caesar model as per latest routine which is as

shown in Fig.

In Stress analysis to reduced the nozzle loads due to

friction effect of support use 0.1 as a friction factor.

The Caesar-II model shows various temperature

consideration i.e. Pump standby, which as shown in Fig



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Fig.Pump Piping Caesar-II Model with Pump B Operating and A

stand by

Fig.4.8 Pump Piping Caesar-II Model with Pump A Operating and B

stand by

III. CAESAR-II OUTPUT. NODE DISPLACEMENT IN SUS

CASE

In sustain case the displacement in Y direction i.e. in

vertical downward, should not be more that the specific

value in design basis . In this design basis in sustain case

sagging should not be more than 8 mm.As the sagging is

more than 8 mm then its shows that restrain which is

provided is not sufficient. even if the system is passed in

sustain stress. so Piping stress Engineer to check sagging

and needs to provide supports accordingly.

By using Caesar-II software, analysis of system is

carried out and result is tabulated below

Maximum Stresses in piping system

11 (SUS) W+P1 Load Case

Code stress Check Passed

Highest Stresses: (N./sq.mm)

Code Stress Ratio (%): 49.7 @Node 20

Code Stress: 67.1 Allowable 134.8

Axial Stress: 66.6 @Node 30

Bending Stress: 36.4 @Node 1720

Torsion Stress: 1.8 @Node 1760

Hoop Stress: 134.7 @Node 30

3D Max Intensity: 139.7 @Node 30

16 (OCC) L16=L12+L11 Load Case



Code Stress Ratio (%): 43 @Node 1720





































20 (EXP) L20=L2-L11 Load Case





Axial Stress: 2 @Node 1360




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Hoop Stress: 0 @Node 30




















































PipingNozzleCheck.

Nozzle Check Criteria By API-610.

If we considered nozzle allowable 2times of the API

then we have to comply "Annex F".

Annex F (Horizontal pumps):

F.1.1 Acceptable piping configurations should not cause

excessive misalignment between the pump and driver.

Piping configurations that produce component nozzle loads

lying within the ranges specified in Table 4 limit casing

distortion to one-half the pump vendor’s design criterion

(see 5.3.3) and ensure pump shaft displacement of less than

250 μm (0,010 in). [13 3]

F.1.2 Piping configurations that produce loads outside

the ranges specified in Table 4 are also acceptable without

consultation with the pump vendor if the conditions

specified in F.1.2 a) through .1.2 c) below are satisfied.

Satisfying these conditions ensures that any pump casing

distortion will be within the vendor's design criteria and

that the displacement of the pump shaft will be less than

380 μm (0,015 in).



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a) The individual component forces and moments acting

on each pump nozzle flange shall not exceed the

range specified in Table 4 (T4) by a factor of more

than 2.

b) The resultant applied force (FRSA, FRDA) and the

resultant applied moment (MRSA, MRDA) acting on

each pump nozzle flange shall satisfy the appropriate

interaction equations below.

[FRSA/(1,5×FRST4)]+[MRSA/(1,5×MRST4)]≤ 2.......(F.1)

[FRDA/(1,5×FRDT4)]+[MRDA/(1,5×MRDT4)]≤ 2....(F.2)

c) The applied component forces and moments acting on

each pump nozzle flange shall be translated to the

centre of the pump. The magnitude of the resultant

applied force (FRCA), the resultant applied moment

(MRCA), and the applied moment shall be limited by

Equation (F.3), Equation (F.4) and Equation (F.5) (the

sign convention shown in Figure 20 through Figure

24 and the right-hand rule should be used in

evaluating these equations). [13 3]

FRCA<1.5(FRST4+FRDT4).......................................(F.3)

|MYCA|<2,0(MYST4+MYDT4)...............................(F.4)

MRCA<1,5(MRST4+MRDT4)..................................(F.5)

IV. RESULT AND DISSCUSION

Condition 1- Nozzle Load with initial routine

DESIGN CONDITION :

PRESSURE: 33.8 kgf/cm square

TEMPRATURE: 87 C

Fx = Fc Fy = Fa Fz = Fb Mx = Mc My-Ma Mz = Mb

750 8" RFFE 300 # / N1/A 1938 3095 5298 5094 1613 2854 Operating Load System Fail

500 8" RFFE 300 # / N1/B 1262 4480 2188 3258 845 1491 Operating Load System Fail

3114 4893 3781 1762 2576 3525 Allowabel Load As Per API 610


2130 6" RFFE 300 # / N2/A 1350 962 1429 293 195 522 Operating Load System Pass

2530 6" RFFE 300 # / N2/B 820 968 809 443 147 202 Operating Load System Pass

2046 3114 2491 1180 1762 2305 Allowabel Load As Per 2 API 610

Node No Nozzel DiscriptionForces In N Moment N-m

Type of Loads Remark

RATING: 300 # OPERATING CONDITION :

NOZZLE SIZE: 219 NB (6") PRESSURE:

SCH THICK : XS (12.7 mm) TEMPRATURE:


EQUIPMENT NO: 1630-G-004 A/B SPEC : 31174XR

NOZZLE NO: N2 Discharge Nozzle SYSTEM Discription: DEETHANISER REFLUX PUMP

NOZZLE SIZE: 219 NB (8")

SCH THICK : XS (12.7 mm)



NOZZLE NO: N1 Suction nozzle SYSTEM DISCRIPTION: DEETHANISER REFLUX PUMP

RATING: 300 #

Condition 2- Nozzle Load After route modification.

DESIGN CONDITION :

PRESSURE: 33.8 kgf/cm square

TEMPRATURE: 87 C


750 8" RFFE 300 # / N1/A 505 8501 2347 3191 352 2066 Operating Load System PASS

500 8" RFFE 300 # / N1/B 360 9524 2516 3447 342 1666 Operating Load System PASS

6228 9786 7562 3524 5152 7050 Allowabel Load As Per 2 API 610


2130 6" RFFE 300 # / N2/A 1350 962 1429 293 195 522 Operating Load System Pass

2530 6" RFFE 300 # / N2/B 820 968 809 443 147 202 Operating Load System Pass

2046 3114 2491 1180 1762 2305 Allowabel Load As Per API 610


NOZZLE NO: N1 Suction nozzle SYSTEM DISCRIPTION: DEETHANISER REFLUX PUMP

RATING: 300 #

NOZZLE SIZE: 219 NB (8")

SCH THICK : XS (12.7 mm)

Node No Nozzel DiscriptionForces In N



NOZZLE NO: N2 Discharge Nozzle SYSTEM Discription: DEETHANISER REFLUX PUMP

Moment N-m

RATING: 300 # OPERATING CONDITION :

NOZZLE SIZE: 219 NB (6") PRESSURE:

SCH THICK : XS (12.7 mm) TEMPRATURE:



V. DISSCUSION

To comply with nozzle allowable we will try to compare

the result before route modification and after route

modification as Condition-1 it is cleared that the external

load on pump nozzle is higher than the allowable given by

the API 610 standards or Vendor.



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So to overcome this difficulties we will plan to route

modification in existing routine and also increase the

nozzle allowable for the same nozzle by complying API

610 Conditions Condition-2. In route modification we

increase the flexibility of pump piping by adding extra

elbows and loops. which reduced the circumferential

movement. In above nozzle loading chart the nozzle

allowable loads is considered to be 2 times of API 610 and

comply all condition of API 610

VI. CONCLUSION

By following the proper guideline of pump piping &

support philosophy, the forces & moments which is on the

nozzles are kept within allowable as per API 610.and

ASME section VIII DIV-1/2. Also increase the nozzle

allowable loads to reduces the design cost by complying

with allowable standards,

The low equipment allowable nozzle loads forced piping

engineers to use excessive pipe loops coupled with

complex restraint arrangement to meet the requirements.

This not only increase capital expenditure but also increase

potential operational problems. Vibration, cavitations, and

loss of net positive suction head (NPSH) are some of the

common operating problem resulting from excessive piping

loops To overcome the above difficulties, we have increase

the Pump allowable loads than the vendor without violating

API 610 standard.

REFERENCES

[1 ] L. C. Peng and A.O. Medellin " Rethinking the allowable pipe load

on rotating equipment nozzle " pp

[2 ] William D Marscher "Avoiding Failures in centrifugal

Pumps"(1999).

[3 ] James E Steiger "Horizontal process pump modifications to comply

with API-610 sixth edition force and moments"(1981)

[4 ] James E Steiger "API 610,Baseplate and nozzle loading

criteria"(1981).

[5 ] Tokio Shimizu and Hironori Teshiba "Analysis of nozzle load for process pump".

[6 ] L.C.Peng "Equipment Reliability Improvement through Reduced Pipe Stress"(1993).

[7 ] Charles C.Head & David G.Penry ."Design and operation of pumps

for hot standby services".

[8 ] L.C Peng "Understanding piping Code stress evaluation paradoxes

and ASME B31.3 Appendix P".(2013). pp 6-13.

[9 ] L.C. Peng "Treatment of support friction in Piping stress analysis".

[10 ] L.C. Peng "The Art of designing Piping Support System".

[11 ] "Code Piping Stress Analysis Seminar Notes". pp 8-50

[12 ] Code ASME B31.3 2004 .pp 1-38.

[13 ] Standard API 610. 10th Edition 2004. pp 110-113

Modification in pump piping to comply with nozzle allowable

Engineering

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