ASME B31.8.1.4
ASME B31.8.1.4
(OP)
The above referenced code, Paragraph (b) states that "when pipe that has been cold worked for meeting the specified minimum yield strength is subsequently heated to a temperature higher than 900 degrees F (482 degrees C) for any period of time or over 600 degrees F (316 degrees C) for more than 1 hr, the maximum allowable pressure at which it can be used shall not exceed 75% of the value obtained by use of the steel pipe design formula given in para. 841.1.1."
Based on the foregoing, I have to stress relieve a pre-fabricated header in its entirety which includes API 5L X65 x 42" x 0.938 WT line pipe. In my experience, this line pipe is not "...cold worked for meeting the specified minimum yield...". While it is cold rolled and expanded some for tube sizing, this, in my opinion, does not tie me to the ASME B31.8 841.1.4 para. requiring me to reduce the max. allowable pressure. Please advise of any concrete evidence either supporting or opposing my opinion.
Based on the foregoing, I have to stress relieve a pre-fabricated header in its entirety which includes API 5L X65 x 42" x 0.938 WT line pipe. In my experience, this line pipe is not "...cold worked for meeting the specified minimum yield...". While it is cold rolled and expanded some for tube sizing, this, in my opinion, does not tie me to the ASME B31.8 841.1.4 para. requiring me to reduce the max. allowable pressure. Please advise of any concrete evidence either supporting or opposing my opinion.





RE: ASME B31.8.1.4
RE: ASME B31.8.1.4
RE: ASME B31.8.1.4
How do I know that the pipe was not "cold worked"? It is purchased from an approved mill from the client I am working for, however, it was purchased from the secondary market. Although we have the MTR's and all checks out fine, the client is still asking about cold working - - I did not think pipe manufacturers performed any cold working specifically to meet a specified minimum yield strength for X60-X65 pipe.
RE: ASME B31.8.1.4
To make the customer happy ,heat treat samples at a couple temps and tensile test (hardness tests are not good for yield strength).
RE: ASME B31.8.1.4
You should be able to confirm none cold work by MTR. I don't have a MTR about line pipe on hand, but I got one ASTM A519 right here and it says seamless hot rolled. Another way to prove it has no cold work effect is to get a metallographic picture showing grain structures on a longitudinal direction. Cold work will give you elongated grain structure.