A/SA 691 P91 Welded Vs A335 P91

[ravera]

A number of years back I worked with a domestic E&C getting A/SA 691 P91 pipe approved for use in Power Plant construction. After months of testing and qualification in Europe, the welded pipe was finally approved. I am trying to understand the current B31.1 and Section 1 requirements related to the use of welded construction (Pipe) in power (boiler) applications. Specifically, where can welded be utilized AND where does the code still mandate a seamless product.

thanks for the input on this topic.

 

[metengr]

Section I does not permit the use of A 691 material (see ASME B&PV code, Section I, PG-9). At the last code meeting I attended, there was some talk about re-opening this item. Basically, for Power Boiler application, Section I has administrative authority (see Section I for boundaries of boiler components). Beyond the first isolation valve for main steam piping in single boiler design, B31.1 has administrative authority and A 691 piping can be used.

ASME B31.1 does permit use of A 691 pipe material (see Mandatory Appendix A, Table A-2.

 

[davefitz]

see comments to the same question in the metal and metalurgy forum

Also, if the pipe is being seam welded by a mon + pop forge, make sure they cool the pipe from the 1900 F normalizing temp fast enough to prevent ferrite formation.