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[MW:6115] MW: 6112- DSS Flanges IGC TEST Pr E

By Materials & Welding
 
Dear Mr. Padmanabhan,
 
Please find the composition of ASTM182 F53 for your reference.This steel  is forged super duplex 2507 grade with max C-0.030%. In comparison to austenitic S.S grades e.g 304L, 316L this steel contains substantial amount of "Mo". Hence the chances of sensitization during intergranular corrosion test to A-262 Practice E could be substantially minimized, provided the maximum "C" content is very strictly maintained.
 
A-262 ,practice -E test could be done in either solution annealed or in sensitized condition (as mentioned below). Duplex alloys are very seldom designed for exposure to 675 deg C. Exposure to this temperature could cause formation of sigma phase which is detrimental to notch toughness and corrosion resistance (see the extract from ASTM A-923).
 
What's asked in Shell MESC--Practice E test With or without sensitization ?
 
2507 Duplex S.S as per the attached Sandvik's literature comfortably meets A-262 ;Practice E test. However it's not clear if this result is with or without exposure to sensitization temperatures.
 
If MESC clearly asks for practice -E test with sensitization you need to clarify this with the mill or the supplier before proceeding with the PO.
 
 
 
 
 
 
I hope this would throw some lights on your query.
 
Thanks.
 
Pradip Goswami,P.Eng.
Welding & Metallurgical Engineer/Specialist
Ontario Power Generation Inc.
Email-pgoswami@sympatico.ca,
 
Extract of ASTM A 262-Practice-E
 
24. Summary of Practice
24.1 A suitable sample of an austenitic stainless steel,embedded in copper shot or grindings, is exposed to boiling acidified copper sulfate solution for 24 h. After exposure in the boiling solution, the specimen is bent. Intergranular cracking or crazing is evidence of susceptibility.
 
24.2 Alternative Testing Procedures:
24.2.1 Unless prohibited by the purchaser in the purchase order, the supplier is permitted to meet the requirements of Practice E by performing a test in accordance with ISO3651–2, Method A, provided that the testing period shall be a minimum of 24 h. unless the supplier and purchaser shall agree upon preparation of welded test pieces to be tested in the as-welded condition.When a sensitization treatment is required,sensitization heat treatment T1 [700°C +/ 10°C(1292°F +/ 18°F), 30 minutes, water quench] shall be used
24.2.2 When this alternative test procedure is used, it shall be noted on the test rep
 
A 923 - 01,Standard Test Methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels:-Duplex (austenitic-ferritic) stainless steels are susceptible to the formation of intermetallic compounds during exposures in the temperature range from approximately 600 to1750°F (320 to 955°C). The speed of these precipitation reactions is a function of composition and thermo mechanical history of each individual piece. The presence of these phases is detrimental to toughness and corrosion resistance.

Correct heat treatment of duplex stainless steels can eliminate these detrimental phases in the mill product. Rapid cooling of the mill product provides the maximum resistance to formation of detrirncntal phases by subsequent thermal exposures

 
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of G Padmanabhan
Sent: Saturday, July 24, 2010 9:19 AM
To: materials-welding@googlegroups.com
Subject: [MW:6112] DSS Flanges IGC TEST Pr E

Dear all
As per Shell  MESC SPE 76/212,we have to carry out  IGC Pr E test  for ASTM A182 F53 flanges.  As per IGC test Pr E,Sensitisation to be carried out around 675deg C for 1 hour.Whether sensitisation required for DSS flanges.Kindly throw some light on above issue.



With Warm regards,

G.Padmanabhan

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