P91 filler wire and Cr content issue

[engrshanas512]

I just want to some important/critical points on the subject:

The whole dispute we had on welding was the root pass for P91 for the first layer itself which should be 8 and above. However code allows after welding 1st layer PMI reading should be 7.2 and above.

ASME Section II part A calls for P91 material / ASME Section I PMI recommendation range from 7.2 minimum to 10.4 chrome content.

ASME section II part C calls for filler wire and electrode the minimum limit is 8 cr.

ASME AI is also particular to ensure filler wires used for P91 welding are in compliance to ASME code to certify the boiler. Boiler ASME stamping is the time when all records are verified afterwards they allow us to do the synchronization/power up.

My personal opinion based on the results about 1st layer which is low and past incidents on ESSAB copper coated is matching ( Not acceptable). Would like to know your help on this please.

Thank you

 

[Duwe6]

"ASME section II part C calls for filler wire . . ."
"ASME Section II part A calls for P91 . . . "

IIC is just a manufacturing spec for fillers & electrodes -- period. ASME IIA is a manufacturing spec for ferrous materials. Period.

They have no bearing on what is required to make a joint that satesfies the Code-of-Construction requirements. What is your construction Code? ASME Sect 1?
And what does the [approved] WPS require? Your AI can guide you on this, but YOU are supposed to know these essential things.

You are required to use what is specified on your WPS(s) - no more, no less. The WPS should give the SFA spec & grade of the filler, to properly join that SA spec and grade of the basemetal. The ESAB filler you want to use, does it have an appropriate SFA spec # and grade for your WPS? If that answer is yes, you are done. Now you have to ensure that ONLY specified fillers are used during every part of the welding. The usual problem is that the welder runs out of the 'special' filler you ordered in for P91 work, and the boss yells at him to 'hurry up'. So he grabs some 5-Cr, or even P-1 filler wire and hurrys to complete the welds. You have to order based on the WPS, then constantly check to ensure that that is the only thing used on the P91 welds.

 

[jwhit]

Keep in mind that a PMI is just an estimate of composition that allows you to say the material is similar to P91 or whatever alloy you happen to be checking. A recommended range is just that, it isn't really mandatory. Has anyone checked the instrument used for PMI to verify it is working properly at the Cr range you need? Just a couple little thoughts to maybe help you out.

 

[Duwe6]

And XRF [x-ray fluorescence] only 'looks' at the top layer of atoms. You are guaranteed to get a 'false'* reading unless the surface layer had been filed off to expose the underlying alloy.

*this reading is only 'false' in that it does not represent the bulk of the metal. The reading was taken on the surface oxide layer, and was accurate for that top 1 to 2 atomic layers.

 

[engrshanas512]

Thanks my friend and it is solved now. Issue was seen on the plate