Is there a surface build-up (metal spray) that meets MR0175?

[BigMac23]

I am trying to find a method of building up the seal areas of valve bodies. Is there a metal spray process that can build-up a surface .030in and is also NACE MR0175?

 

[SJones]

ISO 15156-2, A.2.1.5 "metallic coatings....are not acceptable for preventing SSC"

It is a natural requirement as you will never get a discontinuity free thermal spray coating. It's weld overlay only I'm afraid.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[unclesyd]

What type valve and what is the sealing surface your are needing to repair?

 

[BigMac23]

It is to a pig valve (three-piece ball valve). The seal area that needs repair is the body to closure static seal. There is damage to the seal area in the body and we are exploring options other than weld build-up for repair.

The substrate/body material is ASTM 'A350-LF2'(meets Nace MR0175/ISO 15156). Therefore I am not looking for a metallic coating to prevent SSC.

I am looking for a process to build-up an area enough to remachine a seal surface. My understanding of reading ISO 15156-2, A.2.1.5 is that spray metallizing is acceptable as long as it meets the requirements listed.

With regards to the first statement of ISO 15156-2, A.2.1.5 "metallic coatings....are not acceptable for preventing SSC", are these coatings acceptable for use in a H2S environment to prevent other corrosion if your base material meets? For example, if we were to build-up the seal area with electroless nickel plating to obtain a good sealing surface.

 

[unclesyd]

I know it’s done to the ball in ball valves. You might give these people a call. Ours were smaller 6".

http://www.electro-coatings.com/kantech.htm

If you decide to go the welding route take a look at the these machines.
I have used the Bortech and seen the Climax demonstrated. At one time you could rent a Climax Machine. A lot of shops have the Bortech machine

http://www.bortech.com/

http://www.cpmt.com/tool_over_bw.php

 

[SJones]

If the substrate meets ISO 15156 requirements then, by para 2 and items a) and b) of Part 2, A.2.1.5, the thermal spray would have no further requirements to meet. What caused the damage to the seal area? If it was corrosion, forget ENP as a means of providing corrosion protection. Again, if it was corrosion, weld overlay is really your only answer.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[BigMac23]

The damage is not corrosion. It is presumably damage from assembly/disassembly (scratches, galling, out of round). The repair is required strictly to build up the area for proper a sealing suface.

All the comments are appreciated.