Procedure qualification through AWS

[praba karan]

Dear experts,

For procedure qualification as per ASME SEC IX- "Multiple PQRs may support one WPS",

Likewise can we follow the same practice in AWS also?  Because which is not mentioned directly on the code that we can use multiple PQRs to support one WPS.(And I'm not using prequalified WPS)

Thanks & regards

Prabaharan

[Sajeersayed Ali]

5.2.2 Combination of WPSs. A combination of qualified and prequalified WPSs may be used without qualification
of the combination, provided the limitation of essential variables applicable to each process is observed.

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[james gerald]

I suppose you can support only for welding positions.

Unlike ASME Sec.IX code for process vessels & piping where the Load is uniform and the materials are restricted by code it allows for combination.

But AWS D 1.1, you are subjected to Static, Dynamic & cyclic loading as well and as such there is no statement like ASME Sec.IX like combining WPS/PQR. Moreover you prepare WPS for 1 Pressure vessel and it is easy to control in the shop but whereas AWS D1.1 say for example offshore platforms, you have many varied components like Beam, Plates, girders, tubulars etc.. and it is difficult to control. Only for need based WPS to be used for AWS D1.1.

Thanks & Regards

J.Gerald Jayakumar

0091-8838619635

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[james gerald]

Just to add, Pressure vessels is designed mostly for Internal pressure & external pressure.

section 5.2.2 is for combination of qualified & prequalified WPS and not pertaining PQR's.

Thanks & Regards

J.Gerald Jayakumar

0091-8838619635

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[sridhar cn]

AWS D1.1 does not restrict the number of PQRs supporting a WPS. Clause 6 requires only that essential variables be validated by procedure 

qualification testing. Where a single PQR does not cover all required variables of a production WPS, multiple PQRs may be combined to provide 

full technical support. Therefore, using multiple PQRs to support one WPS is fully acceptable and code-compliant. 

Sridhar.

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[Md Usman Ghani]

Just for clarification

Can any one share, WPS, for ss410 to SS316,

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[sridhar cn]

Giving below are the hints for WPS (both ISO / AWS) for joining SS 410 (martensite) to SS 316 (austenitic). 

This should be supported by a PQR qualification. 

WPS: Dissimilar Joint: SS 410 vs. SS 316 

1. General Information:

Process: GTAW (Root) + SMAW / GMAW (Fill & Cap); Type: Dissimilar stainless steel welding

2. Base Materials:

SS 410 (UNS S41000) – 410 Martensite SS to  SS 316 – Austenitic SS; ASME sec. IX P no 6 (410) to Pno 8 (316)

3. Joint Details:

Joint Type: Butt joint;  Thickness Range (Qualified): xx mm – xx mm (based on the PQR)

Root Gap: 2–3 mm; Bevel Angle: 60° included; Backing: Optional (SS backing or GTAW root) 

4. Filler Metal:

Primary Choice: ER309L / E309L (for welding);  Alternative (for critical service): ERNiCr-3 (Inconel 82)

GTAW: ER 309L / ER NiCr-3; SMAW: E 309L / ENiCrFe-3; GMAW: ER309L

(309L acts as a buffer to handle dilution & prevent cracking; Ni-base reduces risk of martensite cracking)

5. Welding Parameters: GTAW (root) Polarity: DCEN ; Shielding gas: Argon (99.99%) Flow rate: 10–15 L/min

SMAW (fill/cap).Polarity: DCEP; GMAW (Optional) Mode: Spray / Pulse; Gas: Ar + 2–5% CO₂ or Ar + 2% O₂ 

6.Preheat & Inter-pass Temperature: Preheat  200-300 degC (for SS 410 to avoid cracking); Inter-pass 250 deg.C. 

7. PWHT (for SS 410): SR at 650-700 deg C; Holding time- 1hr / 25 mm thick; Cooling- Controlled furnace cooling. 

8. Special Technique: Buttering recommended on SS 410 side with ER309L to void cracking; Stringer beads preferred (no weaving)

9. Inspection & Testing: 100% VT+ PT + RT / UT – As per the requirement;  Hardness check (important on 410 side & HAZ) 

Trust above details will help you to prepare your WPS & PQR.

 

Sridhar.

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[Sankaran Sp]

Dear Mr Sridhar,

good & wishes for detailed explanation for welding of dissimilar material . All the inputs & parameters are found as good and meeting the standard requirements. small suggestion on PWHT temperature as given below:

as per ASME sec VIII div-1 for 410 type steel- PWHT temperature will be 760deg C, kindly check & proceed further       

Regards,

Sankaran.SP

Welding & Metallurgy expert

Coimbatore, India. 

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[sridhar cn]

 Dear Mr. Sankaran,

1.  For SS 410 (martensitic stainless steel), PWHT directly affects hardness, toughness, and risk of cracking. Metallurgically SS 410 forms untempered 

     martensite after welding, so PWHT is mandatory in most cases. PWHT is required to temper martensite, reduce hardness, and relieve residual stresses.

2.  Applicable Standards / References: ASME Section II / IX – Material & Welding Qualification. AWS D1.6 – Structural Welding Code (Stainless Steel); 

     Industry practice for martensitic (410/420 series) SS materials.

3.  Evaluation of PWHT Temperature Options:

   Option 1: 650–700°C (Selected range)- Achieves effective tempering of martensite. Reduces hardness to acceptable range (~200–250 HV). Maintains 

     optimum balance of strength and toughness. Minimizes risk of over-tempering, grain coarsening and loss of mechanical properties.

   Conclusion: Metallurgically stable and widely accepted range for SS 410.

   Option 2: ~760°C (Higher range) - Produces further softening (lower hardness), may improve ductility marginally, however it introduces risks of over-

     tempering resulting in reduction in tensile strength, possible degradation of creep/structural properties. This typically used when hardness reduction is 

     critical (e.g., NACE/ field service requirement), when the weld is too hard (>~250–275 HV), and for thick restrained joints. Not required unless hardness 

     reduction is specifically mandated and service conditions demand higher ductility. 

     Conclusion: Not preferred for general applications. 

4.  Code Compliance: ASME and AWS do not mandate a fixed PWHT temperature for SS 410. They require a PQR demonstrating acceptable properties, 

     control of hardness, strength, and soundness. The selected range 650–700°C complies, as it produces acceptable mechanical properties during qualification.

5.  Justification: The PWHT temperature range of 650–700°C is selected because, It ensures adequate tempering of martensitic structure; Achieves required 

     hardness  reduction  without compromising strength; Avoids risks associated with higher temperature exposure (~760°C); Aligns with established industry 

     practice and metallurgical principles. Meets procedure qualification and code acceptance criteria. 

6.  Conclusion: PWHT at 650–700°C (1 hr/25 mm, furnace cooling) is technically justified, code-compliant, and optimal for SS 410 weldments. PWHT at ~760°C   

     is not necessary and is only to be used when specifically required by design or hardness criteria. 

7. The choice: Depends upon the field requirements.

 

Sridhar.

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