API 5L Gr B

[lomli]

hi,

I 'm a process engineer, i m not a specialiste in materials,

my question is:

for above ground installations ( filtraion lines 14", metering lines, headers...)for a natural gas pipeline what's the difference between the use of API 5L X70 and API 5L Gr B, which is the most useful and recomanded pleae? (of course each one has its specific thikness )

what are the critirias of selection between these materials

is it false to use API 5L Gr B ?

 

[zdas04]

There are a lot or reasons for selecting a specific material. The X70 you mentioned has a much higher Specified Minimum Yeild Strength (SMYS), so a thinner wall pipe can carry a higher pressure. There is a price for the higher strength. The price is that the material is more brittle and less tough and requires different welding proceedures.

Often times designers will go to a higher SMYS material to increase pipe ID (reduce wall thickness) for flow reasons. I tend to do it beacuse of availability (if a project calls for Schedule 160 in a Grade B, the lead time for the Sched 160 might be just too long for the project, I might be able to do the same job with Sched 80 X70 which might be more common).

David