Welding of 25 Cr Super Duplex Pipe 1

[jay165]

Any advice/sources of information for welding 25 Cr SD pipe (UNS 32750/32760)?

Also, has anyone ever used this material under ANSI B31.3, Chapter IX rules (High Pressure Piping)?

Thanks in advance!

 

[stanweld]

We recently welded some similar pipe to B31.3 using Sandvik R25.10.4.1 bare wire and qualified per ASME IX with additional testing per ASTM A-923. Used GTAW process and 250 F max interpass temp. No rejects.

 

[mcguire]

Note that the corrosion resistance of welds is noticably poorer than the base metal.

 

[kenvlach]

Some information on welding duplex & superduplex SS is included in Practical Guidelines for the Fabrication of Duplex Stainless Steels,

http://www.nidi.org/multimedia/tech...iterature_pdfs/other/39309_IMOA_Duplex_ii.pdf

As per stanweld, the filler metal for SD is 25Cr-10Ni-4Mo-N.
Note there is also post-welding cleanup info.

You can also contact the mfrs. AvestaPolarit, Usinor Industeel & AB Sandvik Steel. E.g.,

http://www.smt.sandvik.com/

Products -> Seamless Tube -> Sandvik SAF 2507 (S32750).

Product standards
Seamless and welded tube and pipe: ASTM A789; A790
Flanges: ASTM A182
Fittings: ASTM A182; (ASTM A815 applied for)
Plate, sheet and strip: ASTM A240, EN 10088*-2
Bar steel: ASTM A479, EN 10088*-3

Approvals
Approved by the American Society of Mechanical Engineers (ASME) for use in accordance with ASME Boiler and Pressure Vessel Code, section VIII, div. 1. There is no approval for UNS S32750 in the form of plate. However, according to the ASME paragraph UG-15 it is allowed to use the design values for seamless tube according to ASME section VIII, div. 1 also for plate.

ASME B31.3 Chemical Plant and Petroleum Refinery piping.
VdTÜV-Werkstoffblatt 508

NACE MR 0175 (Sulphide stress cracking resistant material for oil field equipment)

NGS 1609 Nordic rules for application of the non-standard steel SAF 2507 manufactured by AB Sandvik Steel.

other info from Sandvik:
"Impact strength
Sandvik SAF 2507 possesses good impact strength. The ductile brittle transition temperature is below -50°C (-58°F). The impact strength of welded Sandvik SAF 2507 is also good, although the values are lower than the base metal. The impact strength if gas-shielded arc weldments is minimum 27 J (20 ft lb) at a temperature of -50°C (-58°F)."

"Heat treatment
The tubes are normally delivered in heat treated condition. if additional heat treatment is needed after further processing the following is recommended.

Solution annealing
1040-1080°C (1900-1980°F), rapid cooling in air or water.

Welding
The weldability of Sandvik SAF 2507 is good. Suitable welding methods are manual metal-arc welding with covered electrodes or gas-shielded arc welding. Welding should be undertaken within the heat input range of 0.2-1.5 kJ/mm and with an interpass temperature of maximum 150°C (300°F). Preheating or post-weld heat treatment is not necessary.

Matching filler metals are recommended in order to obtain a weld metal with optimum corrosion resistance and mechanical properties. For gas-shielded arc welding use Sandvik 25.10.4.L, and for manual metal-arc welding the covered electrode Sandvik 25.10.4.LR."