WMBU P4 Superheater Lower Bend 1

[GemmellG]

Primary Superheater lower bend (SA-213-T11) 2 1/2" X 0.220” was incorrectly weld repaired (weld metal build-up) using E7018-A1. Area welded was approximately 2" x 8" Long. Primary Superheater is in a very hot location of the boiler. Client is aware of the situation. Is this something that should be address immediately or can it wait until next scheduled outage.

 

[berkshire]

What would happen if this weld failed?
B.E.

You are judged not by what you know, but by what you can do.

 

[GemmellG]

There could
Be a smelt water
Reaction Explosion

 

[metengr]

How much of the tube wall thickness was weld restored using carbon steel weld metal? Depending on deposit thickness, it may not be an issue. When is the next scheduled outage?

 

[GemmellG]

Lowest reading was 0.112" Code min is 0.109". Next outage is one year.

 

[metengr]

Based on the stated remaining wall thickness, the lower strength material will locally creep but being surrounded by original base material which has higher creep strength, you should be able to remain in service until the next outage.

 

[weldstan]

Agree with metengr plus you used C-1/2 Mo filler t further strengthen the recommendation.

 

[racookpe1978]

Pressure is from the inside out, right?
Weld repair is on the outside of the pipe bend though, so the creep is reversed from the above, isn't it?

(Softer material is on the outside of the pipe, so it is NOT restraining the stressed inner higher-strength material, but instead will simply "give" immediately as fast as the inner material yields over time. )

So the weld repair does not appear to give you more time, but may have removed margin you previously had.

 

[0707]

If you don´t repair it you can have an unexpeted shutdown, a steam leakage, somebody can be hurt and also downstream units will have to shutdown. If you are the owner of the unit you have to balance the consequencies and take or not the risk.