Hello everybody in this forum. I'm curious as to why the "A" and "B" coefficients found in B31.1 Appendix B for carbon steel are slightly different now than they were back in 1986. A and B are 7.4 and 4.7 now and were 7.23 and 4.60 back in 1986. Regards and thanks for the replies.

Patrick LaPointe P. E.

Science marches onward. This was revised by the comittee based upon new data becoming available. The piping systems don't know or care about it one way or another.