PWHT of Inconel 625 cladding

[nickt1960]

I am reveiwing a contractor WPS for cladding F65 forging materials with 625 CRA in two layers up to 5 mm thick. Base material qualified is for 25.4 mm upwards. I note that the procedure is qualified with PWHT at 600 to 630 Celcius at one hour per inch - max 3.3 hours.

I am uncomfortable with PWHT of Inconel. Is this common practice when it comes to cladding processes?

 

[nickt1960]

I should have added that the cladding process is mechanised TIG.

Cheers

 

[Carburize]

It is standard practice to carry out a post weld heat treatment in order, among other things, to achieve the required hardness in the heat affected zone of the base material.

 

[GRoberts]

It is a common practice to specify inconel where austenitic stainless steel would normally do because inconel does stand up to PWHT better than austenitic stainless in many applications. It does not harm the mechanical or corrosion properties that I am aware of. I encounter a lot of applications where inconel is welded over an area to be joined, sent through a PWHT, then joined to the other piece without PWHT.

 

[sayee1]

See NACE MR 0175, page 14, clause 5.2.1 states "Overlays applied to carbon and low alloy steel or to martensitic stainless by thermal processes such as welding, silver brazing, or spray metallizing systems are acceptable for use in sour environments, provided the substrate does not exceed the lower critical temperature during application"

ISO15156-Part 2 “Petroleum and natural gas industries-Materials for use in H2S containing environments in oil & gas production” Clause A.2.1.5, states that welded overlays are acceptable if the maximum hardness of the base metal substrate is below 250HV (22 HRC)

So the client would not be wrong in asking for PWHT if for sour service. Need more details to reply on the same.

Thanks and regards
Sayee Prasad R CEng MWeldI MIOMMM


If it moves, train it...if it doesn't move, calibrate it...if it isn't written down, it never happened!

 

[nickt1960]

Thanks one and all!

 

[sayee1]

Only thing to remember and ensure that the PWHTtemperature is lower than the tempering temperature of the Q&T for F65

Thanks and regards
Sayee Prasad R CEng MWeldI MIOMMM


If it moves, train it...if it doesn't move, calibrate it...if it isn't written down, it never happened!

 

[mcisajp]

We have a joint of 1.25Cr-1/2 Mo , line to vessel in hydrogen reformer service, that showed a defect in Rx after PWHT. After removing the transverse crack the digged area is 1x3/4 " with depth of 9 mm. We are planng to fill with TIG and Inconel 82 3/32" , preheating at 150 C and covering wiht mineral fiber after weld is completed. After cooling down we will X-ray again and put in service, without a new PWHT...

Any commnents

 

[metengr]

First off, it would be of benefit if you could start a new thread instead of tagging it to an existing thread.

My comments - as long as you do not contact the P-No 4 (1.25% Cr - 0.5% Mo) base material directly, I see no problem with your repair.

 

[metengr]

Second comment - after re-reading your post it would appear that you have no cladding, and are performing a local weld repair directly to the P-No4 base material?

If this is the case, I would strongly suggest you perform a "temper bead" weld repair to the base material using the Inco 82 filler metal. The elimination of PWHT is permitted for P No-4 material, if you use a temper bead repair method. Simply using an austenitic filler metal with conventional welding does not permit excluding PWHT.

If you have the NBIC (National Board Inspection Code) book handy, I would review Alternative Welding Method 4 for specific guidance.

 

[stanweld]

mcisajp,
Assuming that the repair is to the weld in the P-4 to P-4 joint, is your welding procedure qualified per ASME Section IX or an appropriate NBIC Alternate Method without PWHT? We have qualified a number of procedures for repairs similar to that which you are planning and have achieved a high level of success. Depending on the thichness of the joint, your preheat seems too low. I would also recommend a temper bead technique.

 

[schrijen]

depending on the time but 626 will embrittle below 825 C during the heat treatment. There are many publications about it.

 

[metengr]

You mean Inconel 625. This drop in ductility has been known, but for most applications does not normally present a problem.

 

[schrijen]

Yes sorry I mean Inc.625
You are right, but than do not allow side bend testing during the qualification tests other wise you can run in a lot of discussions with respect to fitness for purpose.

 

[metengr]

schrijen;
In that case, butter with Inconel 82, PWHT and follow with Inconel 625 cladding to assure qualification of bend testing.