RE: [MW:7141] MW: 7122- Stem material in NACE service

For shafts, stems and pins it cross refers to A.3 ( applicable for Environmental and materials limits for austenitic stainless steels used as valve stems, pins and shafts)

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Nivendkar Vinayak (Mumbai - Piping)
Sent: Wednesday, September 22, 2010 1:49 PM
To: materials-welding@googlegroups.com
Subject: RE: [MW:7139] MW: 7122- Stem material in NACE service

 

 

Dear Sir,

 

Thank you very much for your reply. Our services is related to off shore environment (gas).

Based on your reply, I have some additional doubt regarding interpretation of NACE MR 0175/ISO15156- 3: 2003. refer  to the Table A.1 guide to use of the material selection.

If we have Trim SS316 then in this table there are no table reference has been specified for Austenitic SS., this mean that we have to follow table A.2  for valves internals in SS.

 

Correct me in I m wrong. 

Lastly I have also suggested UNS 20910material for shaft . but vendors are not in position to  agreed with interpretation.

 

Thanks

Vinayak

 

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of pgoswami
Sent: Wednesday, September 22, 2010 4:54 AM
To: materials-welding@googlegroups.com
Subject: [MW:7132] MW: 7122- Stem material in NACE service

 

Hi Vinayak,

 

MR-0175,Table A-3 accepts  UNS 20910 for valve stems, pins and shaft under any combination of  temperature ,PH₂S, chloride concentrations, subject to maximum 35HRC  hardness levels in solution annealed  +cold worked condition. See Table-3 for details ,due to copy right issues there’re problem to post extracts of this standard.

 

Table A.30 — Environmental and materials limits for martensitic precipitation-hardened stainless steels used in compressors components, recommend 17-4 PH (S17400, ) for any environment combinations as stated above . MR-0175-3 does not accept this alloy for valve components.

 

UNS S31600 stainless steel may be used for compression fittings and instrument tubing even though it may not satisfy the requirements stated for any equipment or component in Table A.2.- Environmental and materials limits for austenitic stainless steels used for any equipment or components.

 

By  all means UNS 20910(or Nitronic 50, see attached) would a better alloy for valve parts due to better mechanical strength and galling resistances.

 

You may have to convey MR-0175-3 requirements for individual components clearly to the vendor. What’s the intended service Offshore or Onshore(refining) environments??

 

Thanks

 

 

Pradip Goswami,P.Eng.

Welding & Metallurgical Engineer/Specialist

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

 

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Nivendkar Vinayak (Mumbai - Piping)
Sent: Tuesday, September 21, 2010 4:06 AM
To: materials-welding@googlegroups.com
Subject: [MW:7122] Stem material in NACE service

 

Dear All,

 

Could you please guide me for selecting valve stem material for NACE MR0175,  When the trim is SS 316.

 

If we refer Table.A.3 of MR 0175/ISO15156- 3: 2003

There they had clearly specified as S20910 for valve stem, pins and shaft .

 

Now some vendor is only specifying 316 (may be A479 ) and 17-4 pH.  Are this materials are correct to accept?

 

What exact material we have to take? vendor are not clear about the NACE requirement of latest edition.

 

Please advice me to select correct material.

 

Thanks in advance .

 

Regards,

Vinayak Nivendkar