Welding Procedure Qualification Question

[RobsVette]

Hi everyone,

I have a question regarding a welding procedure qualification.

Recently, we performed a repair on a boiler tube that was slighly less than 3/16" diameter. However, our welding procedure only qualifies us down to 3/16" because we originally qualified the procedure using a 1/2" piece of plate. Under normal circumstances I would just weld the procedure on a .375" piece of plate and do teh required bend and tensile tests.

However, the material here is SA-335 Grade P91. So all I have access to is the original piece of pipe that was welded. This is a 1.25" OD x .179" thickness piece of tubing. Is there any way I can use this piece of tubing to qualify a new procedure for the correct diameter? I looked through the usual spots in section IX but the answer is not apparent.

Thanks in advance for any help.

Rob

 

[bpv66]

I'm assuming you mean the original boiler tube is less than 3/16" thick (not diameter/typo?).

If you were to qualify a new WPS with the 1.25" OD x 0.179" thick tube it would be qualified for a base metal thickness range of 1/16" to 0.358" and all diameters. See Table QW-451 of ASME Section IX. Diameter is an essential variable for the welder only, not the WPS. So you should be good to go.

Keep in mind Section I, Table PW-39-5 requires postweld heat treatment of P15E material (P91). Therefore your test coupon will have to be postweld heat treated.

 

[RobsVette]

My question was more how do you qualify the WPS using such a small piece of pipe? Normally we weld a piece of plate that is .375" thickness x 12" long and cut strips to do bend and tensiles on. How do you do that with such a small piece of pipe? With such a small coupon would I have to make more than one weld, since either 2 tensions plus 2 face bends or 2 root bends (or alternatively 4 side bends) are required?

Thanks for the quick response.

 

[metengr]

Yes, you can use the existing small diameter pipe/tube to qualify the WPS. Look at QW-462.1 (e) and QW-462.3(a).

 

[RobsVette]

Ok last quesiton. When you look at QW-462.3(a) the note indicates that for piping that is 1" diameter and less (which is what I have) you can create the bend specimens by cutting the piece into 4 quarters and using that. I assume this would cover me for me face and root bends, but would I actually have to weld another whole coupon to do the tensiles? I see the other diagram QW-462.1 (e) which permits you to tension the entire weld, as long as you grind it smooth.

I want to make sure I am understanding this correctly, because as pointed out, the coupons need to be stress relieved. Thus was the reason for my original question.

Thanks for the replies so far.

Rob

 

[metengr]

Yes, weld a second coupon for this diameter for tension testing. When you have 3" or smaller it becomes more difficult to obtain tension specimens that meet QW-462.1 (c) because of curvature. On your small diameter tubing, it is preferred to use QW-462.1(e).

 

[gtaw]

Why not qualify the WPS using plate?

You are not qualifying the WPS for notch toughness or for PWHT, so plate would be much easier to test with.

Best regards - Al

 

[metengr]

Why not qualify the WPS using plate?

Re-read the OP. 2nd sentence.

 

[gtaw]

There it is in the third paragraph.

Best regards - Al