QW-404 Filler Metal Selection

Accordance with ASME BPVC Sec. IX, Filler metal selection base on the applicable processes and project specification. The WPS qualification are essential determined by mechanical test and suplemetary essential by touchness test (except weld overlay).

The purpose of WPS qualification is to pass the mechanical properties, if any failure in mechanical test shall be retested by another test specimen or re-qualification. So, the min. specified tensile strength of filler metal selection must be equal to or higher than the min. specified tensile strength of base metal (read more QW-153 for tension test - acceptance criteria. Below guideline for your reference:

1- Selection Filler Metal as table QW-432 to determine F-Numbers, and QW-442 to determine A-Number.

F-Number determination are depended on the applicable process and material specification. In addition to project specification should be met. Example, you want to run PQR of welding process GTAW for ER70S-G but specification requires a ER70S-6. I sure that the comparative cost of ER70S-6 is higher than ER70S-G and may also be ordered from orversea or from manufacturer. So, you need to learn more at QW-404.12 for supplementary essential variable on either select ER70S-G or ER70S-6, and its further application.

Alternative F-Number for welder Performance Qualification as QW-433.

Below electrode specifications for reference and selection:

ASME SFA 5.1: Carbon steel electrode for SMAW.
ASME SFA 5.4: Stainless steel electrode for SMAW.
ASME SFA 5.5: Low alloy steel electrode for SMAW
ASME SFA 5.9: Bare stainless steel for welding electrode and rod.
ASME SFA 5.17: Carbon steel electrode and fluxes for SAW.
ASME SFA 5.18: Carbon steel electrodes and rods GTAW, GMAW.
ASME SFA 5.20: Carbon steel electrode for FCAW.
ASME SFA 5.22: Stainless steel electrode for FCAW.
ASME SFA 5.23: Low alloy steel electrode and fuxes for SAW.
ASME SFA 5.28: Low alloy steel electrode and rods for GTAW and GMAW.
ASME SFA 5.32: Welding shielding gas.
ASME SFA 5.36: Opening classification for gas metal arc welding.

A - Number

Identification of weld metal chemical composition designated on the PQR and WPS are accordance with table QW-442 (for Ferrous metal).

  • Chemical analysis of weld metal deposit taken from the test coupon, or
  • From filler metal specification or manufacturer's test report,

Elements are used to determine chemical analysis: C; Cr; Mo; Ni; Mn; Si.

2 - Standard Welding Procedure Specification guidance

If you want to run PQR for SMAW process, material ASTM A106 Grade B to ASTM A312 TP316/316L (P-No. 1 to P-No.8).So, we may refer a standard welding specification of AWS B2.1-1/8-228, and learn more at guidance to choice the filler metal

AWS Specification: AWS A5.4 E316L-15, 16, 17;

A-No.: 8 and F-No. 5;

3 - Prequalification of WPSs (Carbon steel)

It may refer to AWS D1.1 Table 3.2 - Filler Metals for Matching Strength. You may question a reason of qualification as ASME but I guide to learn more at AWS D1.1. Yes, It is the pre-qualification procedure as AWS rules for your reference if you are a beginner because it benefit to offer filler metal to make a good WPS and also meet the current specification.

Related questions?

How to prepare a welding procedure Specification?

Please read more: Guide to make a WPS

What are the different between the min. specified tensile strength required in filler metal specification and an actual tensile strength of filler metal in material test certificate?

Evaluate tensile strength value and acceptance criteria of WPS qualification based on the min. specified tensile strength of filler metal. An actual tensile strength as stated in MTC for reference and review to accept or reject the MTC.

What are the different between ASTM A312 TP316 and TP316L? Which material should select to run a PQR?

TP316 and TP316L are grouped in table QW-422, there are different at Carbon content and tensile strength. TP316 is min. specifed tensile (75 kpsi) and C% <0.08%,  TP316L is min. specifed tensile (70 kpsi), C% < 0.03%. TP316L is a stablized material.

If you want to run PQR must be offered base metal dual grade TP316/316L, that material are complied with 2 grades of tensile stength > 75 kpsi and %C < 0.03%.

ASMT A312 type 316 and 304 is the same P-No. 8 and A-No. 8 (F-No. 8 GTAW). Can we alternate weld with filler metal either ER316L or ER308L and vice versa?

Did you do it on product weld? I has tested the weld on the test coupon and found fusion weld. But it is impacted on project specification are failed at Ferrite  Test and PMI test. So, please dont do it and run out the project specification.

Which standards are used for reference?

Please refer to the standard welding procedure specifications as ASME BPVC Section IX, Mandatory Appendix E - Permitted SWPSS.


To minimize cost and the number of welding procedure that you need to have a look to product and service application, and its procedure can combine together or not. Please note that the running PQR for further fabrication and application, don't waste it after the first job.

Nguyen Duy Bien

Enjoy learning and researching, reading book. Knowledge welding inspection painting inspection.

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