I have previously worked on several combined cycle power plant projects in the UK where the ASME B31.1 Code was used for the design of power piping. Currently, what British Standards could be used as an alternate to ASME B31.1 Code for Power Piping design and what are the primary differences?
davefitz,
Thank you for your response. For heavier pipe walls, say 3 inch and greater, can you still maintain a 9 degree/min cooling rate without creating other issues due to the differential temperature across the material?
Metengr,
Thank you for the response. Sorry, I didn't phrase my question properly. It is my understanding that you can not locally N+T P91 because you will still be left with an intercritical temperature HAZ at the outside of the treated induction heated zone. That HAZ would be created by the...
For hot induction bending of P91 piping, the induction heated zone will produce an adjacent zone where intercritical temperatures will be experienced. In this case, the entire spool must be re-normalized and re-tempered in accordance with latest code cases. If P91 piping with improper N+T at a...
metengr/davefitz,
Thank you for your responses.
With regards to my P91 welding question-
For B31.1 power piping applications, there is obviously a limit as to how much spool can be normalized and tempered as a complete assembly so PWHT of a large number of P91 field welds is the only option...
metengr:
Thank you. Another question-
For P91 induction bending, with induction temperature around 1900 F, normalizing is required with soak temperature of 1900 to 1950 F. When welding P91, only PWHT of less than 1470 F is required but welding process temperature would be over 1900F. Is the...
For the normalizing and tempering heat treatment of P91 piping after induction bending, is there one particular document or published source that can be used to establish the specific ramp up rate of heating, soak time, and ramp down rate of cooling for A335-P91 materials? Most of the current...
A B31.1 power piping project was suspended for several years due to financial issues and is now being re-started. The documentation that identified the specific welders that performed each field weld on B31.1 non-boiler external piping appears to be missing. If the documentation can not be...
