Stellite Hard Facing

[nickypaliwal]

Stellite hard facing by weldoverlay can cause inter-metallic phases and thus embrittlement in Duplex Stainless Steel. It is recommended to do hard facing by thermal spray.

Are there vendors supplying stellite hardfacing for valves trim by thermal spray. As the vendor says stellite thickness requirment is min. 1mm which is only feasible by weld overlay.

Kindly advise.

 

[SJones]

Where does the requirement for 1 mm hard facing thickness come from? The standards that you normally work with, such as Shell MESC SPE 77-302, demand only a minimum 0.13 mm finished thickness after spraying. Same too of Statoil as per the attached.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[nickypaliwal]

Vendors say that a thickness of 0.13-0.25 mm would be very less for stellite and will not stay for long. Are there manufacturers providing hard facing by HVOF for the valve trim ?

What I have observed is that vendors tend to avoid harfacing due to the thermal spray requirement. They would happily accept stellite facing by weldoverlay.

Also Austenitic stainless steel (ASS) can also face sensitization due to weldoverlay of stellite. However, we generally do not have any restriction for ASS.

 

[SJones]

77-302 requires deposition of tungsten carbide - cobalt. The issues with weld deposition of Stellite onto austenitic and duplex stainless steels are outlined in the Kennametal Stellite guidelines. These are the reasons why 77-302 and Statoil require a thermal spray deposition. The thickness differential is not surprising when comparing typical hardness values: HRC 61 for JetKote 117 versus HRC 42 for HVOF Stellite 6.

Stick to the 77-302 requirement, or change the valve supplier to one that will comply.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[nickypaliwal]

Thanks Steve ....