Temper Bead Method

[arcpro]

Please share your experience regarding temper bead technique while welding so as to avoid PWHT in some cases.

[mechcolor]

Are you talking about the real time effectiveness of temper bead welding in order to avoid PWHT?

[ben]

Specifically about which material you are talking about?

[ashfaqanwer]

The temper bead welding methodology requires a procedure qualification for the repair job to be attempted.
The effectiveness of this technique strictly depends on the method of temper bead you choose among different used like half bead technique, controlled deposition, alternate temper bead etc. in combination with the material under question.

[arcpro]

Thanks.
I am talking about Cr-Mo steels and interested in knowing about the effectiveness of temper bead welding as to by-pass PWHT.
We are carrying out repair job on piping of Cr-Mo steels (P11, P22) with SMAW and the joints have already been post weld heat treated. Just want to know how should I proceed in going for temper bead welding so that I can avoid re-PWHT after weld repair job.

[ben]

It has been successfully proved with experiments that temper bead technique can easily help you so as to avoid PWHT for Cr-Mo steels as in your case.
See the guidelines given in ASME Sec. XI IWA-4600 "Alternates repair welding methods" and to comply with the requirements mentioned like procedure and welder qualifications.
HAZ area is the main concern regarding stress relieving and by employing the right qualified welding procedure along with qualified welder, it is possible now to have tempered HAZ area with allowable residual stresses and hardness values.
By the way what's the limitation of not carrying out re-PWHT in your case?

[mechcolor]

In order to be sure of the correct temper bead method is being adopted, qualification is to be made and following tests must be conducted for HAZ health verification:
1. Hardness
2. Charpy Impact
3. Bend
4. Microstructure analysis

[piiengineers]

Temperbead repair is a very serious repair. I am not sure how are the controls at your place are.It is very difficult to carry out Temperbead repair for already welded joint.The following are the procedure for the above technique,
 Weld as per approved WPS.
 Make sure that each consecutive layer is held back at least 1/16” or 3/32” on the previous layer to facilitate proper tempering of the previous layer.
 First layer to be deposited with 3/32” diameter electrode, grind the edges(toes) to a smooth configuration. Partly grind the first layer.
 Deposit second layer with 3/32” diameter electrode. Aim at the toe of the first bead to achieve a 50% bead overlap.
 Deposit 3rd layer with 1/8” diameter electrode and stringer technique, with approx 50% bead overlap
 All stop/starts should be ground.
 Take hardness after completing each weld layer

[arcpro]

Thanks piiengineers for providing me a detailed procedure.
We haven't undertaken any of the repair using this technique but in a day or two after forming a detailed procedure we are going for procedure qualification.Only then we would be using temper bead technique for repairs.
Mechcolor,
Thanks for some qualifications tips.
Ben,
Limitation is lesser time, many repairs and all welds require PWHT. Just to avoid PWHT if possible with temper bead technique.

[ben]

Yes it's possible but after careful procedure qualification and consent of licensor / client.