guaranty on Duplex Weld repair

Date 03-18-2019 23:50

Guarantee against what?

There is more to welding than simple producing a “sound” weld that is free of rejectable discontinuities, i.e. defects. What about excessive ferrite? What about Sigma phase?

Al

By Joey

Date 03-19-2019 03:00

Maybe you are referring to a warranty for any future repair / replacement to the work that the contractor has done.
It's normal to pay high if you want to have a longer warranty to the items you buy.

Definitely a good information to know about the warranty (years) that the contractor agreed to provide.
That will be a barometer on whether the contractor is committed to produce good quality work.

By Shane Feder (****)

Date 04-09-2019 10:21

I agree 100% with Al's comments.
100% radiography means nothing in regards to the acceptability of Duplex S/S.
When welding Duplex S/S the monitoring of heat input to ensure the metallurgical properties are not compromised is the single most important issue.
All your welds could be "cooked" and metallurgically unsound but still pass 100% radiography.
Best of luck,
Shane

By Joey

Date 04-11-2019 09:03

Hi Shane & Al

Thanks for your valuable input.

Talking about monitoring of heat input on actual work, what is the best method of doing that when the welding process is SMAW?
I know that you have to control the welding speed, but how to control it as Inspector when you are not watching the welding all the time? I think max interpass temperature is much easier because you can provide a tempelstick to the welders.

I have an on going job to replace the bottom plate of storage tank, which found to have leaks due to stress corrosion cracking.
The plate materials are Typ 304L and the repair contractor is using SMAW process & E308-16 electrodes. The joint design was changed from lap joint to butt joint with backing strip.

The welding inspector was engaged to monitor the actual welding work and to ensure the heat input will not exceed the max requirements of 1.5 KJ/mm.

Is it the Heat Input or max interpass temperature should be monitored closely so as to avoid the same problem (stress corrosion cracking)?

What is your take on this issue?

Best Regards
Joey

By Are Aye (*)

Date 04-11-2019 10:12

Hi Joey,

That's a good question. Its like 10 welders for 1 welding inspector.
But since it is a repair job I guess all activities depends on ITP/Approved Procedure.
Also Welders should fully read and understand the given WPS.

A Repair job normally a hold-point for us, at lest 2 welding inspectors allocated for one welder.
Not only Heat input and interpass temperature need to be monitored but all the essential variables especially for such materials critical to SCC.

Just my thoughts :grin:

Regards,
AreAye

By Shane Feder (****)

Date 04-11-2019 11:40

Joey,
I am presuming you are the Clients Rep.
The contractor should be (hopefully) giving you a Daily Weld Log where they have done random inspections of all welders work with a record of the calculated heat input for each welder to ensure they are complying with the WPS (max 1.5 Kj/min)
You need to review these Logs and ensure the numbers are adding up.
Then you need to actually perform random tests yourself - firstly to confirm what the contractor is telling you and secondly to give yourself confidence.
I had an offshore project in Thailand where the Daily Log Sheets were all looking good but when I had a walkaround I discovered major weaving (almost blocking out) on a 14"butt weld.
No way in the world that complied with the WPS or maximum allowable heat input.
You cannot be present for every weld to ensure heat input / interpass temps are complied with but you can put the fear of god into the contractor if you catch something and start writing NCRs.
Good luck,
Cheers,
Shane