309 filler weld for 304 SS

[roniprabowo]

Dear all,
I have tube to tubesheet joint in our HE (tube and tubesheet is 304). Our WPS stated that the filler weld shall be 308.
But now our welder made a mistake by using 309 filler weld.
What should I do ???
I read from filler cataloque the different between 308 and 309 is carbon, chrome and nickel content. 309 has more content for them.
Is there any metallurgical point of view ?

 

[unclesyd]

There is no problem with the weld itself. There is a very, very slight possibility that problem could come from the process that the tube is exposed to, but this not very likely as your call out of 304 SS not 304L.
The error is to a higher alloy 309 SS, normally the high Cr & Ni will help. The dilution of the 309 SS on weld The 304 SS components is very high so the effect the carbon is minimized.
In fact 309 SS was the material of choice in welding 304 SS prior to the development of 308 welding wire.

What is the process material?

Have you seen any corrosion to the 304 SS in this service?

What is the size of the tubes?

 

[metengr]

Is the 304 ss tube and tubesheet material an L grade of ss? If so, using the 309 filler metal for seal welding could result in local corrosion attack in service because of increased carbon content of the seal weld deposit. I would probably remove the seal weld and re-repair with 308.


If the tube material is 304 ss, I would perform a Liquid Penetrant inspection of the seal weld to assure the weld deposit is free of solidification cracks. If so, I would leave it in service indicating acceptable disposition of a nonconformance on your repair record. Typically, the 309 is used for dissimilar metal welds joining 3XX to carbon or low alloy steels.

 

[EdStainless]

I presume that all of you qualification samples were done with 309 also? You have these to use to demonstrate that the mechanics are OK. You can also use these samples for testing NDE before you check the entire unit.
Metallurgy should be fine.
You will have a lot of work showing how your material control system failed though.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[SMF1964]

I think the materials concerns take a back seat to the code concerns. If this is a code welded structure, you should have a weld procedure qualification for the use of this filler material for this application (304-304). If not, then it is not an approved weld and you've got a problem.

 

[GRoberts]

Qualification wise, you would be ok using 309 instead of 308, as they are the same A No in ASME IX, unless you have a requirement for impact testing, then the AWS classification is a supplementary essential variable.
As far as the potential carbon problem, most manufacturers of 309 don't go near the top of the carbon range allowed in the AWS specification, so it is generally similar to 308. You would want to check your particular heat of 309 on this matter.