Important Process piping questions 11 அககடடடபரக 2013 இலக 12:57 PM These are the important things in piping.
Q1. What is the minimum distance to be maintained between two welds in a pipe? Answer: - The thumb rule is that the minimum distance between adjacent butt welds is 1D. If not, it is never closer than 1-1/2". This is supposedly to prevent the overlap of HAZs. Minimum spacing of circumferential welds between centerlines shall not be less than 4 times the pipe wall thickness or 25 mm whichever is greater.
Q2. What are Weldolet and Sockolet? And where they are used? Answer:-Weldolet and Sockolet are basically self-reinforced fittings. Weldolet is used for Butt weld branch connection where standard tee is not available due to size restrictions and the piping is of critical / high-pressure service. Sockolet is used for socket welding branch connection, which require reinforcing pad.
Q3. What do you mean by Jacketed Piping? Answer: - Piping which is recognized as providing the most uniform application of heat to the process, as well as maintaining the most uniform processing temperatures where steam tracing is not capable of maintaining the temperature of fluid constant. Usually used for molten sulphur, Polymers service.
Q4. What is the basis of using of short radius & long radius elbow? Answer:- Long radius elbow are used for small pressure drop whereas short radius elbow are used for high pressure drops. For catalyst flows vary long radius elbows are used.
Q5. Normally where do we use the following? A. Eccentric reducers. B. Concentric reducers.
Answer: A. Eccentric reducers = Pump suction to avoid Cavitation, To maintain elevation (BOP) in rack. B. Concentric reducers = Pump discharge, vertical pipeline etc.
Q6. Concentric reducer is used in pump suction. (Yes / No). Explain. Answer:No. Air pockets may form if concentric reducer is used at pump suction, which results in cavitation and cause damage to Pump. To avoid this problem, Eccentric Reducer with flat side up (FSU) is used in Pump Suction.
Q7. How the pipe fittings are classified based on end connections? Answer: - Pipe fittings are classified based on end connection as: A. Socket weld fittings. B. Screwed end fittings. C. Beveled end or Butt weld fittings. D. Spigot socket fittings. E. Buttress end fittings.
Q8. From which side of pipe will you take a branch connection?
Answer:-W hen fluid is Gas, Air or Steam and Cryogenic Service – Topside.
When Fluid is Liquid – Bottom Side.
Q9. What is the difference between Pipe and Tube?
Answer: - Pipe is identified by NB and thickness is defined by Schedule whereas Tube is identified by OD & its thickness as BWG (Brimingham wire gauge or 1/100 inch).
Q10. From which size onwards NB of pipe is equal to OD of Pipe? Answer: -From the size 14” and onwards NB = OD of pipe.
Q11. What should be the radius of long radius elbow? Answer:1.5D (Where “D” is the diameter of the pipe.)
Q12. How can flanges be classified based on Pipe Attachment?
Answer: - Flanges can be classified based on pipe attachment as: -
Slip – on. : - The Slip-on type flanges are attached by welding inside as well as outside. These flanges are of forged construction.
Socket Weld. : - The Socket Weld flanges are welded on one side only. These are used for small bore lines only.
Screwed. : - The Screwed-on flanges are used on pipe lines where welding cannot be carried out.
Lap Joint. : - The Lap Joint flanges are used with stub ends. The stub ends are welded with pipes & flanges are kept loose over the same.
Welding Neck. : - The Welding neck flanges are attached by butt welding to the pipe. These are used mainly for critical services where the weld joints need radiographic inspection.
Blind. : - The Blind flanges are used to close the ends which need to be reopened.
Reducing. : - The reducing flanges are used to connect between larger and smaller sizes without using a reducer. In case of reducing flanges, the thickness of flange should be that of the higher diameter.
Integral. : - Integral flanges are those, which are cast along with the piping component or equipment.
ASME Code 11 அககடடடபரக 2013 இலக 12:21 PM These are the ASME/ASTM code used in oil and gas, power and chemical industry. Every oil and gas, power and chemical industry has to follow these standard for safety of their plants
ASME 31 code for pressure piping
A. ASME B31.1 - Power piping. B. ASME B31.2 - Fuel Gas Piping. C. ASME B31.3 - Process piping. D. ASME B31.4 - Pipeline Transportation system for liquid hydrocarbon & other liquid. E. ASME B31.5 - Refrigeration Piping. F. ASME B31.8 - Gas transmission & distribution piping system. G. ASME B31.9 - Building services piping. H. ASME B31.11 - Slurry transportation piping system.
American institute standard used for Oil & Gas, Power
A. The American Petroleum institute (API). B. The American Iron & Steel institute (AISI). C. The American Society for Testing and materials (ASTM). D. The American National standard institute (AISI). E. The American welding society (AWS). F. The American Water Works Association (AWWA). G. The American Society for Mechanical Engineers (ASME).
Different sections of ASME code
A. ASME section I : - Rules for construction of power boiler. B. ASME Section II : - Materials. Part A – Ferrous materials. Part B – Non-Ferrous materials. Part C – Specification for electrodes & filler wire. Part D – Properties. C. ASME Section IV : - Rules for construction of Heating Boiler. D. ASME Section V : - Non- destructive Examination. E. ASME Section VI : - Recommended rules for care & operation of heating boiler. F. ASME Section VII : - Recommended guidelines for care of power boiler. H. ASME Section VIII : - Rules for construction of pressure vessels. (Division I & II) I. ASME Section IX : - Welding & Brazing qualification.
ASME standard used for piping element
Flanges 1. ASME B16.1 : - Cast iron pipes flanges & flanged fittings. 2. ASME B16.5 : - Carbon steel pipes flanges & flanged fittings. (Up to 24”) 3. ASME B16.47 : - Large Diameter steel flanges. (Above 24”)
Butt welded fittings
1. ASME B16.9 : - Steel butt welding fittings. 2. ASME B16.28 : - Butt-welded short radius elbows & returns bends.
Gasket 1. ASME B16.20 / API -601: - Metallic gaskets for pipe flanges- Spiral wound, Octagonal ring Joint & Jacketed flanges. 2. ASME B16.21 : - Non metallic gasket.
Socket & Threaded fittings 1. ASME B16.11 : - Forged steel socket welding & threaded fittings.
Valves 1. ASME B16.10 : - Face to face & end to end dimension of valves. 2. ASME B16.34 : - Flanged & butt-welded ends steel valves (Pressure &Temperature ratings) except Ball, Plug & Butter fly Valves.
Pipes 1. ASME B36.10 : - Welded & Seamless wrought iron pipes. 2.ASME B36.19 : - Stainless steel pipes.
ASTM Material 11 அககடடடபரக 2013 இலக 12:32 PM These are ASTM material code used for piping material section as the service of the fluid.
ASTM Material used in Pipes
1. Carbon Steel:- ASTM A53 Gr. A/B, ASTM A106 Gr. A/B/C, ASTM A333 Gr.1/Gr.6
2. Alloy Steel:- ASTM A335 Gr.P1/P2/P5/P7/P9/P11/P12/P22
3.Stainless Steel:- ASTM A312TP304/TP304L/TP304H/TP308/TP310/TP316/ TP316L/ TP316H/TP317/TP321/TP321H/TP347/TP347H/TP348/TP348H.
4. Nickel Steel:- ASTM A333Gr.3/ Gr.8.
ASTM Material Wrought Iron Fittings
1. Carbon Steel:- ASTM A234Gr.WPA/B, ASTM A420 Gr.WPL6.
2. Alloy Steel:- ASTM A234 WP1/WP5/WP7/WP9/WP11/WP12/WP22
3. Stainless Steel:- ASTM A403 WP304/WP304L/WP304H/WP309 /WP310/WP316/ WP316L/WP316H/ WP317/WP321/WP321H/WP347/WP347H/ WP348
4. Nickel Steel:- ASTM A420WPL6/WPL8.
ASTM Material Forged Fittings
1. Carbon Steel:- ASTM A181. ASTM A105, ASTM A350 LF1/2.
2. Alloy Steel:- ASTM A182F1/F2/F5/F7/F9/F11/F12/F22.
3. Stainless Steel:- ASTM A182F6/F304/F304L/F304H/F310/ F316/F316L/F316H/F321/ F321H/F347/F347H/F348.
4. Nickel Steel:- ASTM A350 LF3, ASTM A522.
ASTM Material Cast Fittings
1. Carbon Steel:- ASTM A216, ASTM A352 LCB/C.
2. Alloy Steel:- ASTM A217 WC1/WC6/WC9/C5/C12.
3. Stainless Steel:- ASTM A217 CA15, ASTM A296 CA15, ASTM A351 CF8/CF3/CH20/ CK20/CF 8M/CF 3M/CF 8C/HK40
34 Nickel Steel:- ASTM A352LC3.
ASTM Material Plates
1. Carbon Steel:- ASTM A285, ASTM A515, ASTM A516
2. Alloy Steel:- ASTM A387 Gr.2/Gr.5/Gr.7/Gr.9/Gr.11/Gr.12/Gr.22.
3.Sainless Steel:- ASTM A240 TP410/TP405/TP430/TP304/TP304L/ /TP310S/ TP316/TP316L/TP317/TP321/TP347/TP348
4 Nickel Steel:- ASTM A203 Gr.D/Gr.E, ASTM A353
Piping abbreviations 8 ஜஜலல 2013 இலக 09:03 PM
piping design blogs 21 ஜஜனக 2013 இலக 09:02 PM 1 Petroleum communities
http://www.egpet.net/vb/
2 Piping Info
http://piping-info.blogspot.in/
3 Society of Piping Engineers and Designers
http://www.spedweb.com/
Piping design tips & guide 8 பபரவர 2012 ·
Pdms piping and equipments modeling commands Posted Date: 20-Jul-2011 Category: Computer & Technology Author: Harjit Singh Member Level: Gold Rating: 3 out of 53 out of 53 out of 5 Points: 30 (Rs 20) In this article I shall let you know regarding the 3D piping designing software plant design management system (PDMS), overview of PDMS, its uses, its commands. This is one of the best software for designing the big plants with more accuracy. There are different modules in the pdms for designing of the plants. Overview of PDMS These day lots of 3D piping designing software are available in the market. Every software has own limitations and uses. The engineering designing consultancy companies are selecting this software as per their business model, as per requirement of the project and the client demands for particular software in which they want the project. Right now 3D piping designs software are available in the market are Plant design management system (PDMS), Plant Design System (PDS), Cad Pipe, Cad works, and spid3D etc. In these software's I shall you let you know regarding plant design management system (PDMS). Plant design management system (PDMS) is used for 3D designing of the oil and gas offshore platforms, refineries, chemical plants and nuclear power plants. The purpose of using that software is that we can see the actual model of offshore platform, refineries etc which is going to build actually in the site. With the use of the 3D software companies can reduce overall costing of the project from 10% to 30% in the form of time saving of the project, material saving of the object. Big engineering procurement and construction companies like Technip, Flou, Pertofac, Sumsung heavy industry, Worley person, Aker solutions many more company are using these 3D software like pdms and pds. These software are used globally in their business operations. Now every MNC company has their offices in different part of the world. So while designing of these
platforms, refineries, and chemical plants every office has to contribute their role on that project as per their specialty. In PDMS work can we done globally. It means if design office at London did some work on that project. The other employees of Mumbai office can see that work in the model online and work accordingly. PDMS software is produce by Aviva industries. PMDS is best 3D designing software. We can design the entire plant in the PDMS. To use the PDMS software by any company they have to buy the numbers of license as per their requirements. PDMS contains 9 modules on which designing can be done in the model Piping modeling Equipment modeling Structure module HVAC Design Hanger and supports or MDS Cabling System Cable trays Design temples Room design Advantages of PDMS 1. To see the actual model of the plant in the software with exact dimensions. 2. To reduce the material from 10% to 30% from the manual calculations of the material of the project. 3. We can save time while designing the project in pdms. Designing project in 2d like AutoCAD taking much more time as compared to pdms. 4. In pdms we check the piping clashes of the piping, equipment and other inter disciplines. 5. Designing is of piping is more accurate. Because we can see all space around the plant. 6. Very less chance of rework, if the designing is done on the pdms. This helps us to save fabrication time on the yard. 7. The accuracy is more in pdms as compared to other 2D software 8. Pdms can generate the material take off report of each every component in the pdms, which is not possible in 2d software. From the material take off report we can get exact quantities of material which are going to use in the plant for fabrication purpose. We can order that material as the material take off reports. 9. From pdms we can run isometric drawing of the piping for fabrication purpose automatically. In AutoCAD isometric drawings are taking too much time. 10. Modification of any pipe, equipment or structure can be done easy as compared to other software.
11. Pdms is user friendly with other software like Ceaser II for stress calculations and With AutoCAD to import the data from pdms to these seawares. 12. We can design supports for piping in the hanger and supports module. Pdms is commands based software. While operating the software we required some command to use the software. These are the few commands which are using in the PDMS piping design module Axes at CE= to check the axes of component like North, South, East, West direction Q axes at ph= to check the head of the branch of the pipe. Q axes at pt= to check the tail of the branch of the pipe. Q Hstu= to show the branch head tube attribute Q Lstu= to show the branch tail tube attribute Q Hbore= to check the arrive bore or diameter of the component Q Tbore= to check the leave bore or diameter of the component Q Spre= to check the specification of the particular component Q pspec= to check material class of the pipe. New elbow choo all= to create new elbow through command line New tee choo all= to create new tee through command line New gasket choo all= to create new gasket through command line New flange choo all= to create new flange through command line New olet choo all= to create new olet through command line Unclaim all= to remove claim the by user so other user can work in that pipe, equipment, member,structure. Getwork= to refresh the design model. After get work all the change done any user will show in the model. Axes at hpos= To check the branch head axes Axes at tpos= To check the branch tail axes Q ltle= to check the length of the spool between the two component Conn ph to fir member= to connect the branch head to first member of the next branch by common line Conn pt to fir member= to connect the branch tail to last member of the next branch by common line Q ori = to check the orientation of the component Dist= to give the distance between two component Clea= to give the spool length between the two component Conn= connect to the member Fconn= to component forcefully Q styp= to check the component selection type Q dtxr= to check the detail text description of the component Q mtxx= to check the material of the component
Q mode= to check the mode weather it in forward mode or backward mode Q para= to check the parameter of the component Dir tow next= to connect the next member by direction Q ref= to check the reference Add all the pipe within vol ce 500= all pipes to added in the area 500 around the selected component. Incl= to include the component from one branch to other branch Ori and p3 is up= to orientate the point 3 of the tee in up direction Own= navigate the owner of component Q angle= to check the angle of the component Q atle= to check the length of the first tube of the branch Attype ccnn= comment attachment without dimensions Attype cccc= comment attachment with dimensions Attype xxxx= to set the attachment for isometric break up Ch ce= to check the data inconsistency Dir tow next elb= to align the elbow with next elbow Dir tow id@= to align the elbow by using mouse click on the component Q hcon= to check head connection attached with which branch Q tcon= to check tail connection attached with which branch Q ispec= to check the insulation of pipe Ispec nulref= to remove the insulation of the pipe Mtoc dotd= to appear the component in doted in the isometric Mtoc off= to remove the material off the component. With this command material of the component will not appear in isometric Nex conn= connect to next component Nex thro ce= align the next component in same direction Q p3 = to check the p3 point of the component Q pa= to check arrive point Q pl= to check the leave point Attype flow= to create the flow direction attachment These are the few commands which are using in the PDMS equipment design module. New site= for creating the new site in pdms New zone= for creating the new zone in pdms New equi= for creating the new equipment in pdms New sube= for creating the new sub equipment in pdms New nozzle= for creating the new nozzle in the pdms New box= for creating new box in the pdms New cylinder= for creating new cylinder in the pdms Conn idp to idp= to connect design point of two cylinder/box etc.
Mark with (nam) all nozz for ce= to mark the all nozzle of equipment with name in pdms Q level= to check the level of the component Axes at p1= to check p1 point of the primitive Axes at p2= to check p2 point of the primitive New cylinder copy prev by n 500= to copy the previous cylinder by north direction by 500 Which MNC companies are using PDMS Big engineering procurement and construction companies like Technip, Flou, Pertofac, Sumsung heavy industry, Worley person, Aker solutions many more company are using these 3D software like pdms. PDMS uses in the following industries 1. For designing oil and gas project for offshore platforms and onshore refineries. 2. For designing of the Chemical plants 3. For designing of the power plants 4. For designing of the nuclear power plants. 5. For designing of big distilleries Less awareness in the people regarding PDMS in India There are very less numbers of user of PDMS in India, so the chance of getting the job is very good in big MNC companies. Anyone can lean PDMS with minimum qualification for that I.T.I, Diploma, B.Tech. The initial salary will be around 30k for beginning in the job in pdms. After certain years of experience in pdms and with good technical knowledge peoples can get handsome salary from MNC companies and there is lot of more chance of getting the job in abroad on the basis of PDMS. After getting the training candidates get the job of PDMS designer, PDMS Engineer in the oil and gas designing consultancy companies. There is very less training center for PDMS in India. Interested persons check more from the below source PDMS Training Institute in India.
List softwares for Design and Engineering survey 11 அககடடடபரக 2013 இலக 10:49 AM
computer Administrator
List softwares for Design and Engineering survey :
GHS 13 : 800usd http://www.ghsport.com/ bocad V 22 : 1500usd shaftdesigner V 1.2.6 = 3500usd NAPA 2010 : 1500usd for unlimited and Server http://www.napa.fi/
NUPAS HULL VERSION 6.02 : 1200usd for 50years License/Server-Clients http://www.nupascadmatic.com/
CADMATIC PIPING DESIGN : 2500 usd/unlimited /46Licenses available for 40years Licenses http://www.nupas-cadmatic.com/
PLANT DESIGN MANAGEMENT SYSTEM 12 : 600usd for all modules Licensed http://www.aveva.com/Products_and_Services/Product_Finder/AVEVA_PDMS.aspx
AVEVA MARINE 12.1sp2 : 10 000usd for Lastest version/50years Licensed. http://www.aveva.com/Products_and_Services/AVEVA_for_Marine.aspx
FORAN 3D_V7.1 : 6000usd for unlimited Licensed http://www.senermar.es/NAVAL/inicio/es
SMART MARINE 3D : 4000usd for unlmited crack http://www.intergraph.com/products/ppm/sm3d/default.aspx
NESTRIX 2008 : 800 usd http://www.nupas-cadmatic.com/
ORCAFLEX : 2000usd
http://www.orcina.com/SoftwareProducts/OrcaFlex/index.php
MOSES ULTRAMARINE : 600usd http://www.ultramarine.com/
OPTIMOOR : 500usd http://www.tensiontech.com/software/optimoor.html
SACS 5.4 : 500usd http://www.sacs-edi.com/
PARAMARINE V6.1 : 10 000usd for Dongle Emulator http://www.defensefile.com/Customisation/News/Naval_Systems/Bridge_Systems/Qin etiQs_GRC_-_Canada_buys_Paramarine_Seagoing_for_Submarines_Software.asp
MAXSURF 16 : 750usd http://www.formsys.com/
AUTOSHIP 10 : 250usd for 6 modules : autoPlate-AutoHydro-AutoPower-Autostructure and AutoYatch http://www.autoship.com/
SHIPCONSTRUCTOR 2012 : 1500usd for unlimited Dongle emulator http://www.shipconstructor.com/
TRIBON M3 sp 5 : 800usd for 9999Licensed Server http://www.aveva.com/Products_and_Services/AVEVA_for_Marine.aspx
SHIPFLOW : 850usd http://www.flowtech.se/index.php? option=com_content&task=view&id=42&Itemid=20
ORCA 3D : 500usd http://www.orca3d.com/Orca3dJ/
Navcad 2009.7 Licensed : 500usd http://www.hydrocompinc.com/navcad/default.htm
Propcad 2010 : 500usd http://www.hydrocompinc.com/propcad/default.htm
CAESAR 2011 : 800usd PVELITE 2012 : 1500usd
http://www.coade.com/
NAUTICUS hull 2011 : 1500usd nauticus machinery 2011 : 4000usd SESAM 2011 : 1500 usd. http://www.dnv.com/services/software/publications/2008/no_2/softwareconferencehovik.asp
MAXSURF 15.01 : 750usd http://www.formsys.com/
Fastcam : 1500usd
tubeCam : 1500usd
Almacut : 2000usd
http://www.almacam.com
shipweight 10
www.shipweight.com
shipflow 4.7
Poseidon 12 http://www.gl-group.com/en/maritime_software/poseidon.php Deeplines 4.5 : 2000usd http://www.principia.fr/expertise-fields-software-products-deeplines-126.html Diodore : 2000usd http://www.principia.fr/expertise-fields-software-products-diodore-132.html Intool V8 keygen : 2000usd PDS 8 : 2000usd
Friendship-framework 2.4 https://www.friendship-systems.com/products/friendship-framework
Leonardo Hull Leonardo shaft Leonardo propeller http://www.rina.org/en/index.aspx
all intergraph softwares available.
PDMS Commands Piping Modeling 11 அககடடடபரக 2013 இலக 11:45 AM These are the PDMS Piping Commands which are used while modeling in the PDMS. Designer can use this commands while modeling in PDMS. These PDMS piping commands are helps to designer while modeling
1. Axes at CE = to check the axes of component like North, South, East, West direction 2. Q axes at ph= to check the head of the branch of the pipe. 3. Q axes at pt= to check the tail of the branch of the pipe. 4. Q Hstu= to show the branch head tube attribute 5. Q Lstu= to show the branch tail tube attribute 6. Q Hbore= to check the arrive bore or diameter of the component 7. Q Tbore= to check the leave bore or diameter of the component
8. Q Spre= to check the specification of the particular component 9. Q pspec= to check material class of the pipe. 10. New elbow choo all= to create new elbow through command line 11. New tee choo all= to create new tee through command line 12. New gasket choo all= to create new gasket through command line 13. New flange choo all= to create new flange through command line 14. New olet choo all= to create new olet through command line 15. Unclaim all= to remove claim the by user so other user can work in that pipe, equipment, member,structure. 16. Getwork= to refresh the design model. After get work all the change done any user will show in the model. 17. Axes at hpos= To check the branch head axes 18. Axes at tpos= To check the branch tail axes 19. Q ltle= to check the length of the spool between the two component 20. Conn ph to fir member= to connect the branch head to first member of the next branch by common line 21. Conn pt to fir member= to connect the branch tail to last member of the next branch by common line 22. Q ori = to check the orientation of the componen 23. Dist= to give the distance between two component 24. Clea= to give the spool length between the two component 25. Conn= connect to the membe 26. Fconn= to component forcefully 27. Q styp= to check the component selection type 28. Q dtxr= to check the detail text description of the component
29. Q mtxx= to check the material of the component 30. Q mode= to check the mode weather it in forward mode or backward mode 31. Q para= to check the parameter of the component 32. Dir tow next= to connect the next member by direction 33. Q ref= to check the reference 34. Add all the pipe within vol ce 500= all pipes to added in the area 500 around the selected component. 35. Incl= to include the component from one branch to other branch 36. Ori and p3 is up= to orientate the point 3 of the tee in up direction 37. Own= navigate the owner of component 38. Q angle= to check the angle of the component 39. Q atle= to check the length of the first tube of the branch 40. Attype ccnn= comment attachment without dimensions 41. Attype cccc= comment attachment with dimensions 42. Attype xxxx= to set the attachment for isometric break up 43. Ch ce= to check the data inconsistency 44. Dir tow next elb= to align the elbow with next elbow 45. Dir tow id@= to align the elbow by using mouse click on the component 46. Q hcon= to check head connection attached with which branch 47. Q tcon= to check tail connection attached with which branch 48. Q ispec= to check the insulation of pipe 49. Ispec nulref= to remove the insulation of the pipe 50. Mtoc dotd= to appear the component in doted in the isometric 51. Mtoc off= to remove the material off the component. With this command
52. material of the component will not appear in isometric 53. Nex conn= connect to next component 54. Nex thro ce= align the next component in same direction 55. Q p3 = to check the p3 point of the component 56. Q pa= to check arrive point 57. Q pl= to check the leave point 58. Attype flow= to create the flow direction attachment
PDMS commands Equipment Modeling 11 அககடடடபரக 2013 இலக 11:41 AM 1.
New site= for creating the new site in pdms
2.
New zone= for creating the new zone in pdms
3. New equi= for creating the new equipment in pdms 4. New sube= for creating the new sub equipment in pdms
5. New nozzle= for creating the new nozzle in the pdms 6. New box= for creating new box in the pdms 7. New cylinder= for creating new cylinder in the pdms 8. Conn idp to idp= to connect design point of two cylinder/box etc. 9. Mark with (nam) all nozz for ce= to mark the all nozzle of equipment with name in pdms 10. Q level= to check the level of the component 11. Axes at p1= to check p1 point of the primitive 12. Axes at p2= to check p2 point of the primitive 13. New cylinder copy prev by n 500= to copy the previous cylinder by north direction by 500
! Pressure Relief Valve Piping Design Posted by Ankit Chugh on 10:19 AM 2 Comments . Block valves are usually provided upstream (and downstream if discharging into a closed system) of pressure relief valves where necessary to permit on stream isolation and maintenance of the PR devices without interrupting process unit operations.
Where block valves are used, the installation should conform to the requirements of Section VIII of the ASME Boiler and Pressure Vessel Code when protecting an unfired pressure vessel. These valves are typically installed so that they are car sealed open (CSO). Mechanical interlocks or key systems are usually required for spared PR valve installations to help ensure continuous safety protection of the system.
Generally, the most difficult and important feature associated with sizing relief valve discharge lines and headers is the determination of the maximum probable flow. The flow is based on the number of valves which may discharge simultaneously owing to a fire or to abnormal process conditions. To do this, the layout of the unit must be considered along with many possible abnormal operation conditions.
The permissible back pressure must also be determined. Generally, the back pressure should not exceed 10 percent of the set pressure for unbalanced safety valves. Balanced pressure-relief valves will operate satisfactorily at higher back pressures (approximately 30 percent of the set pressure), and consequently their use will sometimes result in a more economical relieving system.
Pressure relief valve discharge piping should be sized so that any back pressure that may exist or develop will not reduce the capacity of the pressure relief valve below that required to protect the equipment. Regardless, the discharge piping for each pressure relief valve should not be smaller than the nominal pipe size of the pressure relief valve outlet.
For gas, vapor, or flashing liquid service the inlet piping pressure drop at design flow should not exceed 3 percent of the safety relief valve set pressure. Nor should the inlet piping to a pressure valve be smaller than the valve inlet nominal pipe size. The inlet piping includes all piping between the protected equipment and the inlet flange of the valve. Excessive pressure drop in the inlet piping will cause valve chatter (extremely rapid opening and closing of the valve) which may lower the valve capacity and damage valve seating surfaces.
Pressure relief valves should be located so that the inlet piping is short and direct and self-draining with no pockets. However, on installations where pressure pulsations or turbulence are likely to effect the pressure relief valve (e.g., discharge side of reciprocating compressors and pumps), it may be desirable to locate the valve farther from the source in a more stable pressure region. The differential between operating and valve set pressures is also important when the operating pressure is not steady. A large differential will tend to reduce valve maintenance costs.
On certain vessels, pressure relief valve leakage and consequent premature shutting down of the process unit can be anticipated. For getting details on various types of Valves, checkout Gotstock. These vessels should be provided with a sufficient number of pressure relief valves (and accompanying block valves) so that in the event of pressure relief valve leakage it will be possible to shut off any one defective valve and replace it while the vessel is in service and still retain full calculated relieving capacity.
Pressure Outlet Piping Discharge to Atmosphere Outlet piping for pressure relief valves discharging flammable vapors directly to the atmosphere should normally be equipped with steam and drain connections controlled from grade, as shown by Fig. 1.
Snuffing steam to pressure-relief atmospheric vent Outlet piping from pressure relief valves should be equipped with drains or otherwise suitably piped to prevent accumulation of liquids at the valve outlet. Pressure relief valve outlet piping for water or other liquids should be self-draining.
Separate pressure relief valve lines should be provided for each valve discharging directly to the atmosphere. On towers, the pressure-relief valve vent piping should be extended at least 10 ft (3 m) above the nearest working platform within a radius
of 40 ft (12 m). Outlet piping should be arranged so that the pressure-relief valve discharge will not impinge on any equipment.
