B31.3 Allowable Stress Design Basis Confirmation

[MEDK]

B31.3 Piping Code
High strength materials for 4550 psig at 200 °F
10" nominal pipe diameter

We have a high pressure CO2 liquid injection line per the above. The recommended materials are API 5L X65 for pipe; MSS SP75 WPHY 65 for butt weld fittings; and A694 F65 for forgings (flanges and socket weld fittings). The only material listed in the allowable stress tables is the pipe material. MSS SP-75 is a listed material in Table 326.1, but there are no allowable stress listings. Not sure about the A694 as yet, still need to check it out. Per paragraph 302.3.2(d) the allowable stresses can be determined, as I understand it. Having determined the allowable stresses, then per paragraph 302.2.2 and maybe 302.2.3 the wall thickness requirements for the other items can be confirmed.

Please comment if you see any flaws in this procedure.

Thanks,
MEDK

 

[JohnBreen]

Lets see if we can get metengr into this discussion.

 

[gr2vessels]

knock, knock,...
May I..?
gr2vessels

 

[metengr]

Hi John;
Yes, the door is open for gr2vessels, we don't want anyone to feel neglected, especially engineers.

First off, in ASME B31.3, I would refer you to the section on Materials, Chapter III. Here are specific rules for unlisted material, namely ASTM A 694. This material could be used but you would need to jump through hoops to obtain the necessary allowable stress values. The determination of allowable stress values could be based on the methodology in ASME B&PV Code, Section II, Part D, Appendix 1 or using B31.3, 302.3.2.

I would suggest you go with an alternative material for flanges and butt weld fittings. As a guide, I would review material listed in ASME B16.34, Groups 1.1-1.4 or A 234, A 420, and other materials in ASME Section II, Part D, as mentioned in ASME B16.9.

 

[gr2vessels]

As usually, nothing more to add to metengr reply, perhaps only that I would use B31.3, 302.3.2...
cheers,
gr2vessels

 

[MEDK]

John, gr2vessels, metengr:

Thanks for taking the time to read and respond to my inquiry.

metengr, I agree with all your comments. Some confirmed my conclusions, and some were an additional help. This exercise has been quite frustrating to get this piping specification in compliance to B31.3. Especially when materials are not listed in the allowable stress tables in the strengths required to meet the design requirements. From my evaluation, I need allowable stress values in the range of 25000 psi or greater. Thus the reason for the high strength material recommendations (primarily from a contracted metallurgist). Again, as you point out, getting the allowable stress values is quite a challenge. Trying to get the physical properties at greater than room temperature are also in question as our technical library is limited. But that's a different subject. I was a bit curious about a reference to B16.34 which I think is for flanged, threaded, and welding end valves. And unless I did not make a through search, the other referenced materials did not have high enough allowable stresses per ASME Section II Part D.

I am about to the point of suggesting to the managers that we purchase a specification to cover this application. Do any of you know of sources that would do this? I think PIP has some but not sure about others.

Thanks, John, for your posts on another of my questions. I think Mr. Dave Diehl is going to have the B31.3 materials group address the Alloy 625 butt weld fitting issue in the April meeting. May be too late for this project, but at least it may be addressed.

Thanks to all again.

MEDK

 

[JohnBreen]

MEDK

Great timing though as Dave emailed us the draft agenda for the April meeting (Puerto Rico) yesterday. So this is the time to get it on our dance cards. One of us can write an inquiry and walk it through the meetings and likely have an Interpretation or Case by the end of the week.

Regards, John.