Welding procedure specification for duplex steel

Scope of PQR / WPS for material P-Number 10H

  • Material: ASTM A790 S31803 ASME B36.19M SMLS
  • Pipe size: NPS 2” Sch 80 (5.54 mm)
  • Joint design: Groove, included angle 60 – 70 deg, 6G position.
  • Welding process: GTAW deposit 5.54 mm, manual.
  • Code application: ASME IX

Suggest 3 test coupons for each PQR.

General information

Description of WPS, read more here.

QW-402 Joint details


  • QW-402.1 Groove design: see sketchSee ASME B16.25 – groove bevel ends.
  • QW-402.5 Backing: “None”,
  • QW-402.10 Root Spacing: “3.2mm”
  • QW-402.11 Retainers: “None”Retainer are not allowed on product weld of piping process.

QW-403 Base metal

Base metal of the test coupon as mentioned in the PQR, base metal qualification of WPS follow an assigned material in table QW-422 including of P number, group number, thickness qualification.


  • QW-403.5 Group no.: “1”, see QW-422,
  • QW-403.6 T limits: “2.77 to 11.08 mm”,
  • QW-403.8 T Qualified: “1.5 to 11.08 mm”, see Table QW-451.1,
  • QW-403.9 t pass > 13 mm: “None“,
  • QW-403.11 P Qualified: “10H”, see table QW-422,

QW-404 Filler metal

  • QW-404.3 Size:“2.4 mm”, refer to ASME II Part C SFA 5.9
  • QW-404.4 F Number: “6”, see table QW-432.
  • QW-404.5 A Number: “8”; see table QW-442,
  • QW-404.12 Spec. or Class. A/SFA.: “A/SFA 5.9 ER2209”,Note: ER2209 for duplex steels, ER2594 for super duplex steels.
  • QW-404.14 Filler: “Yes”;
  • QW-404.22 Consumable Insert : “None”,
  • QW-404.23 Filler metal product form: “Solid”,
  • QW-404.30 Max. Deposit thickness (t): “11.08 mm”, see to table QW-451.1,
  • QW-404.33 Classification: “-“ ,
  • QW-404.50 Flux: “None”.

Recommendation other filler metals, see annex A – table A.3 of API RP 582 2016 edition.

QW-405 Positions

  • QW-405.1 + Position: “All”,
  • QW-405.2 change position: “Vertical-uphill”,
  • QW-405.3 change vertical welding: “-“,

You should set up the test coupons at 6G position where you will be taken in different welding positions (low and high heat input). Because hardness and impact/corrosion test requirements are normally specified in the project for these material

QW-406 Preheat

Preheat temperature will effect to a quality of weldment such as high hardness value, impact test value at heat affected zone, etc.

  • QW-406.1 Decrease > 55 deg. C: “10 deg.C”,If the WPS application to ASME B31.3.
  • QW-406.2 Preheat maintenance: “-“,Not required for this electrode.
  • QW-406.3 Increase > 55 deg. C: “150 deg. C”,We recommend to refer preheat/interpass temperature in table 5 and subsection 8 of API RP 582; Table 330.1.1 of ASME B31.3; Appendix R of ASME VIII Div. 1.


  • QW-407.1 change PWHT: “None”
  • QW-407.2 change PWHT (T & T range): “-“
  • QW-407.4 T limits: “-“

QW-408 Gas

  • QW-408.1 Trailing or composition: “Argon”
  • QW-408.2 Single, mixture %: “99.997%”, refer to AWS A5.32,
  • QW-408.3 Flow rate: “10-18 lpm”,
  • QW-408.5 Backing flow: “99.997% Argon, 15-18 lpm”.
  • QW-408.9 Backing or composition: “None”,
  • QW-408.10 Shielding or trailing: “-”,

Note:Level of oxygen should not exceed 0.2% when back purging.Mix gas of 98% Ar and 2% Nitrogen for super duplex steels.

QW-409 Electrical characteristics

  • QW-409.1 Heat input: calculation HI = (V x A x 60)/ TS (travel speel – mm/minute).
  • QW-409.3 Pulsing current: “None”,
  • QW-409.4 Current and Polarity: “DC EN”,
  • QW-409.8 I & E range: “A: 60 – 80”, “V: 10-12”,
  • QW-409.12: Tungsten electrode: “2.4mm, 2%thoriated”,


  1. Follow project requirements about heat input, max. interpass temperature, hardness value, ferrite content, CVN test absorbed to set welding parameter.
  2. Restrict heat inputs to less than 2 kJ/mm for duplex steels and 1.75 kJ/mm for superduplex.
  3. Heat input calculation and limits of heat input value, refer to subsection 8.3 of Norsok M-601 2016 edition.

QW-410 Technique

  • QW-410.1 String/weave: “string”,
  • QW-410.3 Orifice, nozzle or gas cup size: size no.: “4 – 7”,
  • QW-410.5 Method cleaning: “grinding, wire brushing”,
  • QW-410.6 Method back gouge: “None”,
  • QW-410.7 Oscillation: “None”,
  • QW-410.9 Multi to single pass/ side: “Multi”,
  • QW-410.10 Single to multi electrodes: “Single”,
  • QW-410.11 Closed to out chamber: “None”,
  • QW-410.15 Electrode spacing: “None”,
  • QW-410.25 Manual or automatic: “Manual”,
  • QW-410.26 Peening : “None”,
  • QW-410.64 Use of thermal processes: “None”,

Code & specification requirementsMost offshore projects which make use of duplex and superduplex stainless steels specifyrequirements for a similar range of properties:

  • Strength.
  • Hardness.
  • Toughness (Charpy test).
  • Ferrite and microstructure.
  • Corrosion (ASTM G48A test).
  • Other common weld procedure requirements, eg NDT, bend tests.

Note: Impact testing is required for nominal wall thickness ≥ 6 mm.

ReferenceNorsok M-601 – Welding and inspection of pipingAPI RP 582 – Welding guidelines for the chemical, oil, and gas industries.

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Nguyen Duy Bien

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