These parameters are known as WELDING VARIABLES, see QG-105 & QW-250.

  • Essential variables: A change shall require requalification of the WPS, see QG-105.1, QW-251.2, QW-401.1.
  • Supplementary essential variables, A change shall require requalification of the WPS (toughness), see QG-105.3 & QW-251.2, QW-401.3.
  • Nonessential variables, A change may be made in the WPS without requalification, see QG-105.3 & QW-251.3, QW-401.4.

Should read:

  • Application of new edition after 6 months published, see QG-100 d).
  • Organization responsibility, see QG-106.
  • Ownership transfer, see QG-107.
  • Term and definitions, see QG-109.2 and AWS A3.0.
    • Shall: mandatory.
    • Should: recommends.
    • May: optional.
  • Standard WPSs, see QW-500.
  • Guide to convert US Customary to SI Unit, see Appendix G.
  • ASME interpretation, almost published online

Welding Procedure Qualifications

1. How to prepare a WPS?

You don’t ignore the requirement in Section QW-200

  • QW-200.1. welding procedure specification.
  • QW-200.2. procedure qualification record.

2. What you learn in this section?

That is the contents of WPS and PQR, its definitions and changes. As my guidance in the top of topic about code term (shall, should and may) e.g. for “shall” term is used: contents of the WPS, the completed WPS shall described all of essential and non-essential variables.

If you are running PQR of GTAW process, please bring all welding variables in Table QW-256 to WPS and PQR.

Each company shall develop different standard format, but to make sure enough information in this code.

3. Knowledge and understand of welding variables

Depend on welding process, ASME given limitations for each process, see the legend footnote in each table requirement as follow:

  • (+) addition
  • (-) Deletion
  • (>) Increase or greater than,
  • (>) Decrease or less than
  • (↑) Uphill
  • (↓) Downhill
  • (←) Forehand
  • (→) Backhand
  • (¢) Change

4. Determine range of qualification

Check contract document and specification which range of material thickness and diameter intend to weld. Additional test or requirement should read, such impact test, hardness test, location …

Selection of base material grouping, see QW-420.

Selection of filler metal grouping, see QW-430.

Range of thickness limits and test specimens, see QW-450.

5. How many test coupons are enough for testing?

There are required in project specification and previously procedures are not cover, new PQR shall be qualified.

Small pipe size shall be added the test piece to enough test specimens, such pipe NPS 2” (min. 2 test coupons).

Dimension of test specimens, see QW-462.

T = coupon thickness excluding reinforcement;

W = specimen width, ¾ inch (19 mm);

x = coupon thickness including reinforcement;

y = specimen thickness;

  • Tension – reduced section, see Figure QW-462.1.
  • Tension – full section, see Figure QW-462.1.
  • Side bend, see QW-462.2.
  • Side bend for small pipe (OD<100mm), see note b in Table QW-462.3 (a).
  • Weld metal overlay, see Figure QW-462.5.

Sample of checklist:



  • pWPS No.: pWPS-01 rev. 00
  • Position: 6G, Uphill
  • Base metal: APL 5L Gr. X52N to APL 5L Gr. X52N, PSL 2, Normalized, SMLS, Max. 22 HRC.
  • Size: NPS 8” Sch-XS (12.7mm), L = 200 mm per side.
  • Electrode: ASME Part C, SFA5.18 ER70S-6
  • MTC type 3.1, approval mill and production may be required in classification rules.
  • Shielding gas: 100% Argon and 100% CO2.

--- Test required (for groove weld) ---

  • Mechanical test: 2 specimens - Reduced section tension (QW-150) and 4 specimens – Side bend (QW-160).

--- Optional ---

  • Visual inspection: QW-194.
  • RT: QW-191, full RT.
  • CVN toughness: 9 specimens – BM/HAZ/WM or 12 specimens – BM/FL/FL+2/FL+5, QW-170; -50 Deg. C, shearing percentage, Lateral expansion may record.
  • Hardness test: 1 specimen (NACE MR0175 hardness value is Vickers HV10 or HV5 (Max. 250 HV or 70.6HR 15N).
  • Macro test: QW-183.

6. Selection of test coupon

Test coupon shall be either plate or pipe, qualification in plate also qualifies for pipe welding and vice versa, see QW-120, QW-210 and Figure 461.3 & 461.4.

I recommend performing the test coupon on groove weld instead of fillet weld, except mockup test and overlay test coupon.

Third party or Client invites to endorse document such ABS, DNVGL, BV, LR, …

To cover a min. 1.5 mm to 50.8 mm thickness, I recommend testing at least 3 test coupons:

  • Test coupon 1: GTAW on pipe NPS 2” 5.54 mm WT, see limitation in QW-403.6.
  • Test coupon 2: GTAW + SMAW on pipe NPS 8”, 12.7 mm WT, see range of qualification and limitation in Table QW-451.1 note and combination of welding procedures in QW-200.4 b), QW-200.2 f).
  • Test coupon 3: GTAW + FCAW on plate 25.4 mm WT.

When QW-403.6 apply?

  • Test coupon 1 cover from 2.77 mm to 11.08 mm.
  • Test coupon 2 cover from 12.7 mm to 25.4 mm.
  • Test coupon 3 cover from 16.00 mm to 50 mm.
  • Combination of test coupon 1 and 2 (GTAW + SMAW) shall cover 2.77 to 25.4 mm, see QW-200.4 a) and QW-200.2 f) are allowed.


  • All groove tests qualify for all fillet weld on all base metal thickness and all diameter, see Table 451.4, QW-202.2
  • If you want to get a welder certificates, see QW-301.2, Table 461.9 and then selection of test position.
  • Limitation thickness qualification when toughness required in PQR, see QW-405.2.
  • A combined welding procedure are required QW-200.4.
  • CVN test with sub-size specimen and reduce temperature, see Table 323.3.4 and Table 323.3.5 of ASME B31.3 2016.

Specimen location see Figure 463.1, the following guidance to set up the test coupon and take properly location of specimens in groove weld:

  • GTAW: for small diameter, 6G position, manual.
  • SMAW: for diameter greater than NPS 4”, 6G position, manual
  • FCAW/GMAW: for diameter greater than NPS 4” with backing (support weld metal), 3G position, semi-automatic.

7. Type of test required

Test required in Table QW-451.1 to Table QW-451.4 and QW-453 as instruction in the checklist.

  • Tension test
  • Guided-bend test
  • Macroscopic test
  • Toughness test
  • NDT test
  • Chemical analysis

Additional test specimens recommend performing test such CVN test (04 locations of WM, FL, FL+2, FL+5), hardness test comply with NACE MR0175, corrosion test, chemical analysis …, also see contact requirements.

8. Tools and equipment

Format template for recording,

Multi-function welding gauge, tape measurement, square steel ruler, depth gauge, caliber…

Temperature devices or tempil stick,

Oxygen purging monitor device (if any)

Welding machine, calibration in good condition,

Gas for shielding or backing

Other requirements in the contract document.

9. Material

Base material check thickness, size, length per test piece and diameter, groove angle, backing plate must suitable with base metal or the same P-number.

Welding consumables check size, type, classification, gas for shielding, backing or trailing.

Base metal test report shall minimum a document type 3.1 or higher, approval mill (if required), test value, hardness survey, …

Welding consumable test report should review mechanical properties, recommend to use material type 3.1 “AW – As Welded”.

10. Preparation of pWPS by trial test

Minimum length of test coupon shall enough length for clamp to jaw, recommends 200 mm in length per side.

Set up test coupon at test position.

All welding parameters will record to update in the pWPS such Amperage, Voltage, Travel Speed, Pass, Layer, welding electrode, gas, follow rate, …

Carefully check heat input values to control A, V, travel speed or energy, calculation of heat input see QW-409.1.

11. Official test

Set a coupon at test position, marking location of test such 6G/3G, top and bottom, identification of taken specimens, …

Duties of before/during/after welding should be checked.

Check Before Welding

  • Position: properly tack welding.
  • Welding machine: calibrated and ready for using.
  • PQR template: ready for recording.
  • Welding consumable: already baked and dry out.
  • Welder: available with ID for checking by Third Party (if any).
  • Inspection tool: certified and ready for using
  • Fit-up inspection: as per pWPS.
  • Preheat temperature: min. pre-heat temperature check by Tempilsik or digital temperature.

Check During Welding

  • ​Welding parameter: such as voltage, amperage, current & polarity, travel speed, time, gas, backing gas, follow rate within range allowed in pWPS.
  • Material: filler metal on each process, gas compositions (%).
  • Weld bead: check thickness of weld metal deposit, run out length within range allowed in pWPS.
  • Cleaning each weld pass/layer: properly clean by brushing, grinding.
  • Priority, root layer must be carefully inspected full weldment, any imperfections of lack of root fusion, incomplete penetration, burn-out,… which are caused of rejection.
  • Rest layers to be finished as per pWPS.

Check After Welding

  • ​Visual inspection to make sure no crack, complete penetration and complete fusion of base metal and weld metal.
  • PWHT application (if any).
  • Upon completion, the test coupon will perform non-destructive test and destructive test.
  • NDT after welding: surface NDT and/or volume NDT after PWHT.

Identification marking on the test coupon, weld ID, location of test specimens.

Destructive test

  • Check sample number, quantity and quality of test sample.
  • Check size, thickness and gauge length of test sample.
  • Verification of lab test, mechanical calibration, test standards, certificate and their approval status, such ISO 17025, personnel qualification.

Evaluation of test result or acceptance criteria:

  • Tension test, see QW-153
  • Guide bend test, see QW-163,
  • Fillet-weld test, see QW-181
  • Macroscopic test, see QW-183,
  • Impact test, see QW-171,
  • Tube to tube-sheet, see QW-193.
  • NDT, see QW-195,
  • Hardness test, refer to NACE MR0175 part 2 or part 3,
  • Another requirement in contract document.

Welding parameters shall be recorded into the PQR.

12. Update test reports in PQR

Update the actual records to PQR,

Do not apply range of qualification.

If third party are invited to witness the test, official document should endorse, date and sign.

Form here.

13. Issue WPS

After receiving the test report, you need to issue a WPS for fabrication.

Thickness and diameter qualification see Table QW-451.

14. Welder qualification in WPS

Thickness and diameter range of qualification see Table QW-452, also see QW-301.2.

Form here.

15. Significant articles in ASME section IX

Article I - Welding General Requirements

QW-150 Tension Tests

QW-153 Acceptance Criteria-Tension Tests

QW-160 Guided-Bend Tests

QW-163 Acceptance Criteria-Guided Bend Tests

QW-170 Notch-Toughness Tests

QW-180 Fillet-Weld Tests

QW-182 Fracture Tests

QW-183 Macro Examination-Procedure Specimens

QW-191 Volumetric NDE (RT & UT)

Article II - Welding Procedure Qualifications

QW-200 General

QW-210 Preparation of Test Coupon

QW-214 Corrosion-Resistant Weld Metal Overlay

QW-216 Hard-Facing Weld Metal Overlay

QW-250 Welding Variables

Article IV - Welding Data

QW-400 Variables

QW-402 Joints

QW-403 Base Metal

QW-404 Filler Metal

QW-405 Position

QW-406 Preheat

QW-407 Post Weld Heat Treatment

QW-408 Gas

QW-409 Electrical Characteristics

QW-410 Technique

QW-420 Base Metal Groupings


QW-252 through QW-269 Welding Variables Procedure Specifications

QW-422 Grouping of Base Metals for Qualification

QW-430 F‐Numbers

QW-432 Grouping of Electrodes and Welding Rods for Qualification

QW-440 Weld Metal Chemical Composition

QW-442 A-Numbers Classification of Ferrous Weld Metal Analysis for Procedure Qualification

QW-450 Specimens

QW-451.1Groove-Weld Tension Tests and Transverse-Bend Test

QW-451.2Groove-Weld Tension Tests and Longitudinal-Bend Test

QW-461 Positions

QW-462 Test Specimen

QW-470 Etching — Processes and Reagents


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Disclaimer: is based on information from multiple sources and our experience with welding and inspection scopes. It is not a replacement for manufacturers directions and is only to provide reminders for inspector.

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