Overlay welding of CS vessel

By kamyac Date 02-28-2006 03:06

Dear All,

Being very new to this forum, appreciate if anybody could share the techniques of applying 316L stainless steel overlay by welding onto carbon steel pressure vessels. Need to know the process mostly used, the nos of SS layer, type of elctrodes, and type of testing required.

In house specification is requesting for 309 to be deposited onto the CS surface before applying 316L electrodes. The 309 will act as a buffer in between the CS surface and the 316L. Any comments?

By - Date 02-28-2006 03:28

your request for information is generic in terms of what process, the # of layers, etc.

Using a 309/309L as a butter pass is quite common before going to the 316L overlay. The process mostly used is dependent on accessibility to the surface you will be welding. If the area is easily accessible, sub-arc welding is a common welding process for overlaying. If accessibility is limited, flux core welding is another option. Next, the number of layers will depend on the factored corrosion equation you are trying to maintain. Depending on your customer requirement you may need at least 1/4" of exposed 316L. Of course, it could be more or it could be less. Number of layers can also depend on whether the overlay will be machined down after welding, or left in the as-welded condition. Type of electrodes will depend on what process you choose. Finally, the required tests will depend on your customer specifications. I know this answer is probably not much help to you, but most of what you are asking is dependent totally up to you and the specification requirements.

By kamyac Date 03-01-2006 01:21

TQ Cmeadows for the reply,

The reason I'm asking because the supplier is now proposing to overlay without 309/309L as a buffer pass. Have anybody experienced overlay technique without buffer pass i.e welding of 316L directly onto the CS surface. Is there any precautions or special tests required for such process? TQ Guys..

By - Date 03-01-2006 01:44

I don't think you will encounter any problems going directly with the 316L without the 309/309L butter pass. Ferrite is sufficient to overcome cracking possibility, and strength is near that of a 309/309L. There are many fabricators that overlay CS without a 309/309L butter pass and do it successfully.