Prepare pWPS for duplex stainless steel

The supplementary essentials should note in pWPS, in additional to specification requirement.

1. Heat Input
A maximum heat input of 2.5kJ/mm should be acceptable for the duplex steels and 2.0kJ/mm maximum for super duplex.

2. Consumables and as-welded deposits
Duplex:

  • Nitrogen: 0.14% (Min.)
  • Nickel: 8.0% (Min)
  • Molybdenum: 3.0% (Min)

Super duplex:

  • Nitrogen: 0.2% (Min.)
  • Nickel: 9.0% (Min)
  • Molybdenum: 3.5% (Min)

3. Gas
Shieding gas/ Backing gas composition shall be argon or nitrogen with argon mix are essential variable.
Oxygen content of the back purging gas shall max. 0.50% (5000 ppm).

4. Additional
Preheat and interpass temperature recommend are shown in API RP 582 2016 table 5.
Hardness test: max. 320 HV10 for DSS, max. 350 HV10 for SDSS.
Ferrite content: AWS A4.2M

  • Weld metal: 30 to 60%
  • HAZ: 40 to 65 %
  • Base metal: 40 to 60%
    Corrosion test: ASTM G48 or ASTM 923.
    Impact test, note to record the lateral expansion ( minimum 0.38 mm).
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