16" super duplex UNS S32750

[jonesey]

Hi,
developing a new pipe spec in UNS S32750 for use in seawater service. Up to around 8/10" you can get seamless pipe to A 790, after this it seems welded pipe to ASTM A928 is used (better control of the ferrite/austenite levels in the weld i've been told). The welded pipe use plate of ASTM 240 UNS S32750. I can't find basic stress allowances for ASTM A240 UNS S32750 in ASME which i need to calculate my wall thicknesses. Can anyone help ??

 

[SJones]

What's wrong with page 176 of ASME B31.3?

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[jonesey]

Hi Steve,
i'm looking at page 176 of ASME B31.3 2004 and as far as i can see materials on this page are nickel & nickel alloy ie: ASTM B materials. Page 164 lists stainless steels plates/sheets but only A240 S32760 is listed ?

martin.

 

[SJones]

Do we have the same copy? Two thirds down, two lines above the heading "Plates And Sheets".

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[SJones]

OOps - 2002. I'll just check 2004. Ho hum.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[jonesey]

Steve,
Maybe you have misunderstood. I have the properties for ASTM A790 S32750. What i need are the properties for A240 S32750 as this plate is used to make welded pipe to ASTM A928.

martin

 

[SJones]

Well neither A928 or A240 S32750 are in ASME B31.3. Is there anything stopping you imposing supplementary requirements onto A790 to bring it to a commensurate level with A928, particulary as A928 doesn't actually get down to specifics on ferrite measurement? I would expect the plate material to be in ASME VIII but can data for plate be applied directly to pipe?

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[jonesey]

I can't see there are any supplementary requirements to A790 that can bring it up to the same level as A928. I'm beginning to wonder if i am going the right path ? We can't be the first company in the world to request welded pipe in A928 UNS S 32750.
The company has an extra requirement when purchasing welded pipe in UNS S32750 that states, and i quote ' Determined in accordance with ASTM E562, ferrite content: base material 35-55%, welds 25-60%'

 

[SJones]

They won't be supplementary requirements written in the ASTM standard you will have to supplement the ASTM with a project specification. Have a look in the following for some ideas:

http://www.standard.no/imaker.exe?id=3789

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[jonesey]

I had a copy of the relevant norsok data sheet, D52. This matches closely with our company requirements. However i still have no basic allowable stress values for A240 U32750 to enable me to document our wall thickness calculations. Is it accepatbale to use the stress values for A790 U32750 (seamless pipe), bearing in mind that the wall thickness calculation 3a in B31.3 304.1.2 contains a factor for weld efficiency ?

 

[SJones]

Doesn't A790 cover welded pipe also? And, as it doesn't specify any particular welding process or starting material whatsoever, one would assume that A928 could be considered a specific subset of A790 for the purposes of ASME B31.3. Still, you know what they say about assume... I bet EdStainless can help us out here.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[jonesey]

yes, A790 also allows welded pipe, but without addition of filler material. A928 is with addition of filler material and apparently this method is preferred as it allows better control of the ferrite/austenite levels in the weld material - or so i've been informed. I've sent a mail to Outokumpu (manufacturer of S32750) tohear if they can provide me with the info i need. I've had a look in ASME VIII code cases to see if this material is under evaluation but our copy only goes up to 1999, and A240 S32750 was not named in this edition.

 

[SJones]

A790 doesn't appear to actually EXCLUDE addition of filler metal. Seems like you are out of luck on the ASME 2004 front as well.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/