P22 Quenched Pipe Weld

[swsweld]

Hello All,

Code is ASME B31.1 2014.
Issue is a 32" P22 Sch60 pipe weld just below flush that had water inadvertently released and 'quenched' the weld enough to cause the heat treat chart to drop below the WPS inter-pass temp. The temp. dropped from 500F to 250F briefly. 400F-600F is WPS inter-pass range. In cases where chrome pipes were quenched during PWHT, replacing all affected pipes was the course of action.

The code will not address this directly. This is an NCR at best but is it necessary to replace the pipe and 90 elbow? Hydrogen bake out was performed and pending RT. Safety and quality are the top concerns but schedule and commercial are also considerations. That is, we will replace if necessary but no contractor wants to replace unless absolutely necessary. That is a huge expense. I do not represent the contractor.

Seeking advice on options on the path forward. We have a chart that shows a temp. drop. You can't ignore that. Replacement is worst case scenario. Is a partial machine/grind/reweld of 50% reasonable? Complete cut out and re-weld of the same material, no replacement? Boat Sample? Hardness test? Brittlement, ductility and grain structure are concerns but how to determine if the weld/pipe was 'actually' damaged.

Thanks for any advi

 

[metengr]

Since this is a non-conformance, as a minimum, I would perform surface NDT (wet fluorescent MT) and portable hardness testing on the pipe and weld. The results of the hardness testing and NDT should provide enough information to determine if further action is warranted, like weld repair with PWHT or a second PWHT.

 

[swsweld]

metengr,

Thanks for the feedback. Your advice seems reasonable. We don't have hardness test requirements on P22 that must be met, but comparing the results of the 'quenched weld' to a couple of welds on the same line that were not 'quenched' should provide valuable information. In some cases, doing too much as in replace when it isn't necessary, can do more harm than good.

 

[weldstan]

Was this weld quenched during initial PWHT during its initial exposure to 500F and was the PWHT resumed to completion? If so metengr's WFMT is recommended. Whereas temperature control within the temperature range stated during PWHT is not required by B31.1, I do not see a reason for the NCR. Interpass temperature WPS requirements would not apply since weldout would have been completed.

 

[DekDee]

weldstan,
Interpass temperature WPS requirements would not apply since weldout would have been completed.

The way I read the post was weld was not completed when the weld was quenched.
"Issue is a 32" P22 Sch60 pipe weld just below flush that had water inadvertently released and 'quenched' the weld enough to cause the heat treat chart to drop below the WPS inter-pass temp"

 

[swsweld]

The weld was 'sprayed-for lack of a better term' during weld out. PWHT has not been performed. This weld had greater than 25% deposition so I'm not worried about root cracking but it was not controlled cooling as required in 'Interruption of Welding" It was a rapid cool down, therefore I think an NCR would be valid. Additionally, I would have preferred a MT been performed before welding resumed but that didn't happen.

 

[weldstan]

My bad. In your case, write the NCR and assure that RT/UT (recommend both) is performed on the completed weld after PWHT. I would not concern myself with replacing the affected pipes, especially if quenching was primarily done on them. The weld itself may have been quenched from a higher temperature depending on where your T/C's, were placed.