duplex ASME VIII div. 2 2

• Jun 7, 2004

• #2

LSThill

Mechanical

Oct 10, 2002

1,120

US

Do you Mean RE: 2205 Duplex SS (S31803), (UNS S31803)

 

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• Jun 9, 2004

• Thread starter
• #3

marc1000

Materials

May 26, 2004

8

GB

Isthill,

UNS31803 among all the others; in table AHA-1 there is not one duplex stainless steel mentioned. Only austenitic and some martensitic and ferritic stainless steels.

 

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• Jun 9, 2004

2
• #4

metengr

Materials

Oct 2, 2003

15,478

US

The duplex stainless steels are limited as to their service temperature range because they can form sigma phase or other intermetallic phases that can significantly reduce toughness.

The approximate useful service temperature range I have seen published for duplex stainless steels are -50 deg C to 280 deg C. If I had to guess, this is probably the reason for not endorsing these materials in Div 2 applications.

 

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• Jun 9, 2004

• Thread starter
• #5

marc1000

Materials

May 26, 2004

8

GB

metengr,

I know the limitations of duplex SS: low temperature toughness and possible embrittlement at long exposure time to temperatures around and above 475°C. But is this a reason not to incorporate this into ASME VIII div. 2? In Div. 1 f.e. the use of UNS 31803 is also limited to 600°F.

 

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• Jun 9, 2004

• #6

metengr

Materials

Oct 2, 2003

15,478

US

marc1000;
My reasoning for limiting the duplex ss is based on the statements in AG-100 (Scope) particularly paragraph e. Div 2 deals with vessel design related to high pressures and it may well be that a more conservative approach is being used to restrict materials, in comparison to Div 1 rules.

 

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