ATUL KHATRI
Mechanical
- Apr 13, 2018
- 15
Dear all,
This code is explicitly developed for design, construction, operation and maintenance requirements for piping , pipelines, and distribution systems in hydrogen service.
Material performance factors have been included to account for the adverse effects of hydrogen gas on the mechanical properties of carbon and low allow steels operating within the hydrogen embrittlement range.
Above is the brief about ASME B31.12
Question:
As i believe we normally use B 31.3 for process piping irrespective of fluid service.Did any one come accross the requirement of using B31.12 instead of 31.3 from client side?
I found that there are differences in allowable stress values as well as compare to B31.3.
This code is found bit conservative compare to B31.3.For example this code has indroduced one more factor "Material Performance Factor" in pipe wall thickness calculation under internal pressure to address the loss of material properties associated with hydrogen gas service.
Also the nominal thickness which calls for PWHT requirement for weldments are still limited to 20mm thk for P-No 1 material where in parallel 31.3 completely exempt the PWHT till 25mm thk and for higher it can be waived off by application of prehaet at 95deg c.
Looking for some detailed discussion or literature on this issue.
This code is explicitly developed for design, construction, operation and maintenance requirements for piping , pipelines, and distribution systems in hydrogen service.
Material performance factors have been included to account for the adverse effects of hydrogen gas on the mechanical properties of carbon and low allow steels operating within the hydrogen embrittlement range.
Above is the brief about ASME B31.12
Question:
As i believe we normally use B 31.3 for process piping irrespective of fluid service.Did any one come accross the requirement of using B31.12 instead of 31.3 from client side?
I found that there are differences in allowable stress values as well as compare to B31.3.
This code is found bit conservative compare to B31.3.For example this code has indroduced one more factor "Material Performance Factor" in pipe wall thickness calculation under internal pressure to address the loss of material properties associated with hydrogen gas service.
Also the nominal thickness which calls for PWHT requirement for weldments are still limited to 20mm thk for P-No 1 material where in parallel 31.3 completely exempt the PWHT till 25mm thk and for higher it can be waived off by application of prehaet at 95deg c.
Looking for some detailed discussion or literature on this issue.
