b31.1 & SA 691 P22(2.25 Cr 1 Mo) rolled & welded 3/8" thk

[davefitz]

There seems to be a contradiction in the B31.1 welding rules for fabrication and the SA 691 specificaiton for rolled and welded piping.

B31.1 table A2 permits longitudinally welded 2.25Cr pipe per astm A 691,but only classes which require heat treatment
B31.1 table 132 allows fabricationwithout PWHT for thicnesses below 0.5" thik- in our case , the outlet of the HP bypass dumpto condenser is 3/8" thick
ASTM A 691 does not permit elimination of PWHT for those classes permitted by B31.1

So , the fabricator wishes to use the table 132 exclusion cirteria, but table A2 + A691 requires some form of heat treatment. Is table 132 valid or not?

"Nobody expects the Spanish Inquisition! "

 

[metengr]

Table 132 in B31.1 only deals with welds and welded attachments to pipe (which has been supplied by a material specification). Pipe supplied under B31.1 requirements has been formed and welded under ASME SA material specification requirements. B31.1 deals with pipe and how it is bent, cut, welded, hung....

 

[davefitz]

Meteng:
I agree , but it still is not a clear cut case- a longitudinal weld to fabricate a pipe is yet a weld to a pipe.I suppose it will be settled by addtionally adding to the specification a required PWHT irrespective of table 132.



"Nobody expects the Spanish Inquisition! "

 

[metengr]

davefitz;
This is a first that I have heard regarding this kind of interpretation for Table 132. I think by virtue of the materials specification as stated in Appendix A-2 you have no choice but to follow what is required by ASME/ASTM SA/A 691 material specification. I don't have time but I would check for any interpretations regarding Table 132.