Tuesday, June 15, 2010

[MW:5589] FW: 5586] A479 Type 316L v/s A 276 XM19 (Nitronic 50)]

Nilesh,

 

What is your service environment ? Upstream ( Offshore/Onshore Oil and Gas Production, where MR-0175 -2003  is heavily applicable) or downstream, petroleum refining where MR-0103- 2007, Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments is applicable.

 

Nitronic-50 (SA-276 XM19)  is a popular material for  rotating component , due to superior galling and pitting resistance and other corrosion resistances.  If you look at NACE MR-0175, Table D-1, SA-276 XM19, is listed under UNS-S20910. The PRE(Pitting resistance Equivalence) of this alloy is more (29-38) as compared to SA 479 316L SS   (23-28).

 

MR-0175  accepts  SA-276 XM19 all levels and with any combinations of temperature, pH2S, chloride concentration and in situ pH occurring in production environments, while the same freedom does not hold good for 316L S.S. 

 

 Also NACE MR-0103 -2007  (for downstream petroleum refining) accepts this alloy. Any SA-276 XM19 or Nitronic 50 alloy shall be procured in:-

 

·         Solution annealed condition and cold formed for good finish

·         Max hardness 35HRC.

·         This alloy is an unconventional austenitic stainless steel, which a large addition of “Mn”, typically 5.0% as against 2.0% for 316L S.S.

·         Would last longer due to better mechanical properties ( 100 KSi) as against 70 Ksi for 316L S.S.S.

·         If pump shafts have to be reclaimed at any later stage of service, always matching electrodes( E/ER-209) would be better for this alloy.

 

To summarize this alloy SA-276 XM19 –Nitronic-50 would be more favored than 316L S.S for the amine services and more aggressive services if substantial sour service (MR-0175) requirements prevail.For long term performance this alloy would outperform 316L S.S

 

316LS.S.S is also a popular alloy in the industry, due to ease of availability and fabrication. But if the design requirements are  for offshore applications  then this alloy has it’s limitations  due to chloride SCC. However for downstream refining environment this alloy could perform equally well. It may be a good idea to get the pump casings made from this alloy(316) and rotating components made Nitronic-50 (depending on your projects' requirements) 

 

I have attached a few documents for your information. Hope this would help. 

 

Thanks.

 

 

Pradip Goswami,P.Eng.

Welding & Metallurgical Engineer/Specialist

Ontario Power Generation Inc.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

 

---------------------------- Original Message ----------------------------

Subject: [MW:5586] A479 Type 316L v/s A 276 XM19 (Nitronic 50)

From:    "Darji Nilesh (Mumbai - Machinery)" <N.Darji@ticb.com>

Date:    Mon, June 14, 2010 7:52 am

To:      "'materials-welding@googlegroups.com'"

<materials-welding@googlegroups.com>

--------------------------------------------------------------------------

 

Vendor agreed for a 276 XM19 (Nitronic 50) for Pump Shaft Material. Now He wants to change it to A 479 Type 316L Material.

 

Application is for : Amine service (Lethal Service / NACE is applicable).

 

Which one is better / suitable material...Furnish Properties of both Material.

 

Thanks and regards,

 

Nilesh.

 

 

 

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