B31.3 Plate Shell

[rickylee]

does B31.3 allow the designer to use A 516-70 as a rolled plate shell without complying to ASTM A 672?

the stress tables show pipe A 516-70 Spec A672 and then another listing for plate A 516-70. is the plate reference used only as flat plate?

 

[metengr]

Yes, for plate (not necessarily flat plate) applications. If you review Table A-1 in Appendix A of ASME B31.3, the SA-516 Grade 70 is listed under the plate specification, while SA-672, which is electric-fusion welded steel pipe, is listed under the pipe specification. The reference to SA-516 Grade 70 is the plate material used to fabricate the electric fusion welded pipe under the SA-672 Specification. The allowable stresses are comparable in Table A-1 for plate supplied under SA-516 Grade 70 and pipe supplied under SA-672 Grade C70.

 

[rickylee]

yes while this seems logical, I need something more concrete. I heard of a code intrepretation on the matter, do you know of it?

Rick

 

[metengr]

I can look. What exactly is your specific application?

 

[rickylee]

simply rolling a shell from plate.

Rick

 

[NozzleTwister]

While y'all are talking about high strength pipe with a mill tollerance of 0.01", let me caution you on the fittings(elbows & tees) that you might use with that pipe. Many times ASME A234, Grade WPB fittings are specified to use with A672-C70 pipe. These fittings have a lower allowable stress and a 12.5% mill tollerance.

I just want to warn that your fittings as well as the pipe need to be suitable for your design conditions. You may need to specify heavier wall fittings or purchase fittings with a specified minimum wall as opposed to a nominal wall.

NozzleTwister
Houston, Texas

 

[rickylee]

I heard the code interpretation is 1990 vintage. Anyone have it? (rolled shells from plate)

Rick

 

[metengr]

rickylee;
I looked, and I don't have B31.3 Interpretations dating back to 1990. However, I would suggest your review ASME SA-672 in detail. This specification covers steel pipe fabricated from pressure vessel quality steel plate.

Per B31.3, for pressure retaining components, you can have the shell made from pipe using this Specification (SA-672) or you can roll and weld the shell component from SA-516 Grade 70 steel plate; the Code permits this. The only difference is that you will need to verify adequacy of design (minimum wall thickness) for the shell plate and follow the NDT requirements for welding the shell plate using B31.3.

If the shell was supplied as long seam welded pipe under the SA-672 Specification, as long as the wall thickness meets design requirements for B31.3, this is acceptable. The NDT of the long pipe seam has already been performed under SA-672.

 

[rickylee]

Yes I have read A672 in detail. There are other issues besides the long seam such as flaw detection.

What you are saying seems obvious but some customers want proof from the code. I have located the Code Interpretation 8-36 where the code committee addressed exactly this issue and endorsed the use of plate outside of A672.

Thanks, case closed.

Rick