Hard-facing SA335 Gr.91

[iam42]

Hey Guys,

Does anyone have any experience of hard-facing Gr 91 alloy. I have never attempted anything like this and we may have a customer who is interested in pursuing this. The pipe ID would have to be clad for a solid containing slurry.

Any comments would be welcome.

Hard-facing consumable: Postalloy 2826-SPL

Design Temp: 707F

Design Pressure: 290 psig

Code of Construction: B31.3

Thanks

 

[metengr]

This is a problem because of the complex nature of Grade 91 steel. If you intend to use an inlay of hardfacing, this will require elevated preheat, a possible interface to be applied before the hardfacing with a thermal treatment at between 1385-1425 deg F followed by the application of the hardfacing over the interface. You will need to qualify a weld procedure for the inlay using ASME Section IX.

Why was Grade 91 even selected when the service temperature is only 700 deg F??

 

[iam42]

Meteng,

Thanks for the reply.

I have absolutely no idea why Gr 91 was specified. I am having communication problems at the moment due to a language barrier.

I am meeting he customer face to face tomorrow and hopefully he can shed some light on his reasoning.

I was thinking along the same idea as you by using an inconel buttering layer and then applying the hardfacing.

Thanks

 

[BillPSU]

Many years ago I worked at a company which produced coal grinding equipment and slurry pipe elbows and pipe. They made castings out of Ni-Hard. This is not Gr91 but would be an excellent abrasion resistant material. Is there a reason why this material is not being called out in today's designs. I saw them machining this material using carbide. They literally pushed the material off the castings.

Bill

 

[EdStainless]

My hunch is that they selected 91 thinking that it would have the combination of strength and corrosion resistance to stand up in the application without surface treatment, and now they find that it wont.
They would be ahead to drop back to an alloy that is less heat treat sensitive and hard face it.
Doing this to 91 will be very problematic, if they care about the final properties at all.


= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[iam42]

Thanks for all the input guys, it looks like I may have convinced our customer to look at other options.

Thanks Again.