Welding P1 TO P1

[bladeo]

Gents,Have to weld a 12 inch sch.120 pipe P1 to P1,can't pwht due to poor engineering design. Won't bore you with details. Would like to weld with inco 82. 1)Butter with inco,maintain 200F preheat,max interpass 350F using narrow weld beads to include HAZ 2)Blend butter passes with flapper and PT. 3) Fill remainder of joint with inco 82.Have also considered temper bead. B31.8 requires no pwht for this wall thickness,b31.3 does require pwht which is the code I'm bound too. Two questions,
Good or bad idea using the inco in lieu of pwht? Any clue why one code requires pwht and the other does not? I'm no metallurgist so if i'm missing the boat feel free to point it out. thanks

 

[Mr168]

How are you going to put a 200 degree preheat on something if you can't PWHT? Is it a matter of not bringing the component up to the necessary PWHT temperatures?

 

[DVWE]

Read 331.2.2.

It basically says whatever you do needs customer approval and WPS qualification.

 

[metengr]

bladeo;
Temper bead could be used without the need for an austenitic filler metal, like Inco 82. I would qualify a temper bead weld procedure using ASME Section IX, QW-290.4.

This is nothing new and could be used for your application, especially on P-No 1 base material.

 

[bladeo]

Thanks for the quick replies.The actual problem area is about 12 inches for the weld centerline and is designed for 175F if we bring the pwht temp.to 1200F we will surely fry the problem area.The plan is to make a trial run to see just how far the heat will radiate, we may have to reduce the preheat or maybe not. We will qualify a procedure exactly how the weld will be made in the field.I did get client approval.Sounds like metenger is in favor of tempering.Thanks again, feel free to provide more input.

 

[stanweld]

bladeo,
Welding with a temper bead technique is not tempering (PWHT). Please review QW-290, ASME IX for details. Under B31.3, the Owner has the option not to PWHT if PWHT will be detrimental to the pipe system or a componenet therein.

What is the part that can only experience 175F maximum temperature? I assure you that the weld can be induction heated to 1100 F and one can maintain a maximum temperature of 175 F 12" from the weld centerline.

 

[bladeo]

sorry bad choice of words.monolithic isolation joint.I agree with the welding,the contractor made one weld,that they should not have made. we tested across the joint with a megger after welding and the joint tested greater than 5meg ohms as vendor requires.I'm just concerned that applying 1200F for one hour will melt the isolating fill material that is only 12 inches from the joint.I feel certain we can make the weld just want to meet code.thanks

 

[Ballbearing1]

Bladeo,
As DVWE has stated if you follow 331.2.2 and have customers approval and a new qualified WPS you should have no problems at all. After all it is only P1 and only 1/4" over not requiring PWHT at all,
Regards,
BB