17-4PH compressor impellers

[tgmcg]

Does anyone here have any operating experience with 17-4PH compressor impellers in H2S service?

 

[sms]

Can't say I have used them in H2S service, but I have used that material in a number of other services. It's probably ok as an impeller, but I have had several problems with it as a shaft material, particularly in regard to thermal stability. I would not buy a 17-4 PH shaft for a compressor.

What exactly are you looking for?

-The future's so bright I gotta wear shades!

 

[tgmcg]

We're purchasing a centrifugal compressor for an unspared critical service application in a refinery H2 system. An EPC contractor started this project and is handing it over to us, the client. I'd have stuck with a proven alloy like SEA 4330, which is standard in all our other H2 recycle machines. Others have had problems with 410ss impellers in similar service, and I've seen references of 17-4PH being susceptible to chloride SCC. I do not like the idea of using unproven materials or designs in critical service machines, but am looking for evidence of any comparable experiece, positive or negative. I've not doubt the compressor will run, but no confidence that it will run continuusly for 5 yr.

Classic end-user vs OEM clash of priorities.

 

[bvsrtt]

I had experience in using 17-4 PH material for centrifugal compressor impellers for FCC application with a H2S of 5-8%

It was our practice to use 13%Cr steel AISI 410 grade for the FCC wet gas compressors in refineries. The impellers used to have limited life and effect of erosion was predominant and the impeller blade wall thickness was frequently reduced due to lower yield strength 63 kg/mm2 For AISI 410 for H2S environment as per NACE

NACE MR 0175 allows use of precipitation hardenable steels (like 17-4 PH) with yield strength max 68 Kg/mm2. This has provided longer life and better erosion resistance. we henceforth started using 17-4 PH for all our FCC wet gas compressors impellers with H2S upto 8 % I can remember.

hope this provides a supporting answer

bvsrtt

 

[tgmcg]

bvsrtt,

Many thanks for the helpful info. We have some erosion issues on a couple of other machines. Perhaps we should look take a closer look at 17-4PH for the high erosion areas.

 

[monaco8774]

We operate a compressor in a field with 400ppm H2S and the we changed teh inlet guide vanes and first stage impellers to 17-4pH, actually dramatically improved the errosion resistance as we were forming sulphide at the inlet