Thermal spray coat valve stem with T-900

[kevlar49]

I am planning to specify thermal spray coating of a 316H fluid Coker (similar to FCC) slide valve with the following:

Triballoy 900 using JetKote with a hydrogen gas,
Minimum bond strength in the procedure qualification of 9ksi.
Minimum hardness is 650DPH 300g load
Grit blast the surface to be coated to a 3mil profile.


Do you have any advice for how I could further specify the coating to ensure good coating quality? What minimum and maximum coating DFT should I specify?

 

[EdStainless]

Is this common? Does it work well? I am a bit curious because you are putting a relativly brittle coating on a rather weak substrate.
Thickness is important, esp that there is no abrupt change.
You also need to think about the edges were the coating ends. This needs to be blended and not just stop.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[kevlar49]

After I sent this message, I decided to adjust the spec to read:

• The valve stem shall be coated per the Slide Valve Data Sheet, using:
• Triballoy 900 applied using the JetKote thermal spray equipment with a hydrogen gas,
• In the procedure qualification, minimum bond strength shall be 9ksi per ASTM C633 and minimum room temperature hardness shall be 650DPH (Diamond Pyramid Hardness) using a 300g load.
• Surface preparation shall be performed using chilled iron grit or alumina and the blast profile shall be at least a 3mil rough profile.
• Apply a 45° chamfer to all edges and a 1/8” minimum radius to all corners.
• All coated areas shall be with Deloro Stellite’s recommended minimum and maximum thickness range.

Brittle, yes, but i figured the hot hardness is what was needed. Stem has very tight tolerances so weld overlay would tend to distort it pretty bad.

NACE CORROSION PAPER 99272 data suggested that it would be a good fit.