How to Evaluate Welding Procedures: A Practical Guide

A fabricator hands you a WPS that looks perfect on paper — all the boxes ticked, neat handwriting, a qualified welder’s stamp on it. Then the inspector asks one question: “Show me the PQR.” The shop goes quiet. That PQR was written three years ago for a different joint, a thinner plate, and a different filler metal. Nobody was lying; the paperwork simply never matched the job. Evaluating welding procedures is exactly the skill that would have caught it before the first arc was struck.

What Evaluating a Welding Procedure Actually Means

Evaluating a welding procedure means proving, with documented evidence, that a specified method of joining metal will produce sound, code-compliant welds under the actual conditions of the job, before production welding begins. Not after someone finds a crack in a critical joint.

Shops skip this step most often because the paperwork looks convincing. A WPS is a recipe, and a recipe with a stamp on it feels like proof. It is not.

The Four Documents in the Evaluation Chain

Every evaluation pulls on the same four links. Miss one, and the chain breaks.

1. The governing code or contract specification. The authority the job is judged against. It defines which variables must be recorded, which tests prove qualification, and the acceptance criteria. Without the code, there is no evaluation, only opinion.
2. The Welding Procedure Specification (WPS). The recipe: process, joint design, positions, base metal, filler metal, technique, electrical settings, gas, preheat, and interpass limits. A WPS written to AWS D1.1 is a written statement of essential variables, so it describes the plan rather than proving it works. AWS Form N-1 is the standard format.
3. The Procedure Qualification Record (PQR), also called a WPQR. The test evidence: coupon-based proof that the procedure as described produced welds meeting the acceptance criteria. A qualified WPS without a supporting PQR is an unproven procedure. ISO 15614-1 puts it plainly: the primary purpose of welding procedure qualification is to demonstrate that the joining process proposed for construction is capable of producing joints having the required mechanical properties for the intended application.
4. The Welder Performance Qualification (WPQ or WQR). Proof that the individual welder, on that process and in that position, can produce code-compliant welds, recorded on AWS Form N-4.

The Three-Part Evaluation Test

1. Does the procedure satisfy the governing code’s minimum requirements? Are all required variables present and inside their permitted values? A WPS missing preheat limits for a given material and thickness fails here.
2. Does the qualification evidence support the range the procedure claims? The PQR records as-welded values and test results. Do they support a 1/4 in. to 3/8 in. thickness range, or only one test thickness? This is where paper reviews quietly go wrong.
3. Does the procedure match the real production job? Joint configuration, material, thickness, position, process, and service condition. This question gets skipped most often, and it decides whether the job goes well.

AWS D1.1/D1.1M:2025 mirrors this logic: Clause 5 covers prequalification of WPSs, Clause 6 qualification of procedures and personnel, Clause 7 fabrication, Clause 8 inspection.

Three Things People Confuse With Procedure Evaluation

Welder qualification answers “can this person do this job?” Procedure evaluation answers “will this method work for this job?” A welder can be qualified on a procedure that is a poor choice for the work.

Production inspection answers “is this individual weld acceptable?” It accepts finished work. Procedure evaluation happens earlier and sets the rules inspection later applies, so inspection failures are often the first evidence a procedure was never properly evaluated.

WPS document review is only part of the work. Populated fields tell you the recipe is complete, not that it works or fits.

Who Does It, and When

On regulated work, a welding engineer or Certified Welding Inspector usually leads, with quality control verifying the record set; sectors like aerospace welding add more review layers. On structural steel, the engineer or fabricator owns the review. On small shop work, the fabricator evaluates their own procedure, where self-review discipline matters most.

Timing follows three moments: before bid or fabrication release, to confirm the shop can do the work it is pricing; before production, to confirm the job sits inside the qualified range; and after any change, when the qualified range may no longer cover the job.

A Scenario: A Perfect Paper Trail That Fails on the Floor

A shop holds a PQR for a 3/16 in. to 3/8 in. GMAW fillet weld on A36, qualified flat. The WPS is complete, the coupon passed bend tests, the welder’s stamp is current. Every document check passes.

Then the erection crew takes that procedure to a bridge girder and welds it vertical-up, outdoors, in a crosswind, on 1/2 in. plate. It was never qualified above 3/8 in., never qualified out of position, and the shielding gas cannot hold a stable arc in the wind. The paperwork was flawless and the welds were not. Nobody lied; it described a different job. Checking all-position electrode selection against the real position would have flagged it before the first arc.

Start With the Governing Code: Which Specification Applies

You cannot evaluate a welding procedure until you know which specification governs it. Every code defines its own required WPS variables, qualification test methods, and acceptance criteria. A procedure that is perfectly legal under one code can be completely invalid under another. With that in mind, identifying the correct code is the first checkpoint in any procedure evaluation.

The American Welding Society notes that it has authored more than 350 standards covering welding practices and procedures, with current editions including AWS D1.1/D1.1M:2025-AMD1, AWS D1.2/D1.2M:2026, AASHTO/AWS D1.5M/D1.5:2025, and AWS A3.0M/A3.0:2025. The full catalogue can be viewed at the AWS standards library. Which one applies will depend on the material, structure type, service, and jurisdiction.

The Main Code Families

Different products fall under different codes for good reason. The ones you’ll run into most often are:

• AWS D1.1/D1.1M for structural steel buildings, towers, and other structural contracts. It is the most common structural code in North America and contains widely used prequalification rules.
• AWS D1.2/D1.2M for aluminum structures, including aluminum bridges and highway structures.
• AASHTO/AWS D1.5 for bridge welds, most often used by state departments of transportation.
• AWS D1.6 for stainless steel, with its own filler metal and qualification tables.
• AWS D1.3 for sheet metal and thin-gauge applications where burn-through is often the hardest obstacle to pass.
• API 1104 for pipeline welding and pipeline repair welds.
• ASME Section IX for qualification, read alongside the construction code such as Section VIII for pressure vessels, Section I for power boilers, or B31.1 and B31.3 for piping.
• ISO 15614-1 for international work, forming the basis for the pWPS-to-WPQR progression used by many shops.

How ASME Splits the Job

With ASME, the qualification and the construction requirements are two separate documents. ASME Section IX is what qualifies the procedure and welder, while the construction code dictates the actual build requirements.

Section IX Article II covers welding procedure qualifications, Article III covers performance qualifications, and Article V addresses Standard Welding Procedure Specifications. Its qualification variables are broken down by article: QW-402 for joints, QW-403 for base metals, QW-404 for filler metals, QW-405 for positions, and QW-406 for preheat.

A Section IX PQR alone will never be enough for a pressure-retaining item. Joint design, examination extent, PWHT, and acceptance limits are still enforced by the Section VIII, Section I, or B31 construction code that applies. Both documents must be satisfied for the evaluation to be valid.

Marine Work Adds a Federal Layer

U.S. marine engineering shows just how far a regulator can go beyond a consensus code. 46 CFR Part 57 adopts ASME Section IX for welding procedure and welder/brazer qualification, but with specific paragraphs limited, modified, or replaced as shown in the regulation’s table. Section 57.03-1(a)(2) requires each manufacturer or contractor to submit the results of the physical tests required by Section IX to the cognizant Officer in Charge, Marine Inspection, for approval. Section 57.04-1 confirms that specimen types and numbers follow QW-202 and QW-210.

For this work, approval isn’t an internal recordkeeping task. The test results must be submitted and approved by a federal officer before the procedure can be used.

Let the Service Environment Choose

Beyond product type, service conditions often dictate which code applies or how strictly it’s enforced. Cryogenic vessels demand impact testing, sour service pipelines require hardness limits and material traceability, fatigue-loaded bridge welds put emphasis on surface profile and crack initiation, and food-grade stainless tanks require surface finish and cleaning control that a structural code would never mention.

On top of that, the contract specification may be stricter than the code minimum, and the jurisdiction decides which edition is in force. For this reason, confirming the governing code and its edition must come before auditing the WPS against its variables or acceptance criteria.

For reference on the aluminum side of the house, if your code turns out to be AWS D1.2, read our guides to aluminum MIG welding and aluminum flux core welding for the filler and handling issues that D1.2 treats differently from carbon steel.

Anatomy of a Complete Welding Procedure Specification

A WPS is only as good as its weakest blank line. Handwritten forms run out of space, voltage ranges stretch from lab coupon to field weld, and preheat fields say “per code” because nobody wrote the number down. Every gap lets the procedure and the job drift apart.

What belongs on a complete WPS? AWS Form N-1 is the standard Welding Procedure Specification form used with AWS D1.1, and ASME Section IX Form QW-402 handles pressure and boiler work. AWS N-1 lists process and type, PQR number, joint design, position, electrical characteristics, base and filler metals, technique, shielding, and amperage or wire feed speed. ASME QW-402 covers the same ground in paragraph form.

Field by field: what a complete WPS must state

• Process and type. SMAW, GMAW, FCAW, SAW, or GTAW, plus manual, semiautomatic, or automatic. AWS D1.1 Clause 6.15 identifies which processes require qualification, and Clause 6.17 sets the tests each one needs.
• Joint design. Groove type (single V, double V, square, flare), angle, root opening, root face or land, and backing. A 60 degree V with a quarter inch root opening is a different procedure from a square groove.
• Welding positions. Flat, horizontal, vertical, overhead, and pipe positions such as 1G, 2G, 6G, or 6X. These limit where the procedure can run in production.
• Base metal specification, grade, and thickness range. Group, grade, and the thickness band covered. One material group does not automatically cover another.
• Filler metal classification. AWS classification (E7018, ER70S-6, E71T-1, ER308L), F-number, A-number suffix where applicable, diameter, and any impact requirement.
• Technique. Stringer or weave beads, single or multipass, electrodes per pass, and spacing, all classic non-essential variables in AWS D1.1.
• Electrical characteristics. Amperage, voltage, wire feed speed, travel speed, polarity, power source type, and transfer mode, where paper WPSs usually go vague.
• Shielding gas. Gas type and flow rate, or a statement that none is required for SMAW.
• Preheat and interpass temperature. Minimum preheat, maximum interpass, and method of measurement. “Per code” is not a number.
• Post-weld heat treatment. PWHT requirements, holding temperature and time, and heat-up and cool-down rates, where service calls for it.
• Backing, back-gouging, and consumables. Whether backing is used, whether back-gouging is required, grinding limits on the back side, plus manufacturer, lot identification, and storage or conditioning rules.

Essential, non-essential, and supplementary essential variables

Every code sorts WPS fields into three tiers, which is how a shop evaluates welding procedures by rule rather than by opinion.

Essential variables are the ones where a change invalidates the qualification. A complete joint penetration groove weld and a fillet weld are different procedures, not a tweak. Filler metal F-number group is another essential variable in AWS D1.1, as is base metal group in many codes. In marine work under 46 CFR Part 57, base metal grouping is elevated to an essential variable for all procedure specifications, modifying QW-253, QW-254, and QW-255 to make QW-402.4 part of the essential variable list.

Non-essential variables can change freely. Travel speed adjustments within the qualified window, bead sequencing, weaving patterns, electrode angle, and cleanup between passes are typical examples.

Supplementary essential variables sit in the middle: they can change without full requalification, but only with additional testing. Charpy V-notch impact is the classic case, so a more demanding impact temperature needs a supplementary impact test, not a full PQR cycle. The same applies to some corrosion or sour service requirements.

Specific values versus ranges

Two WPS styles sit side by side: one states a single setpoint (260 amps, 26 volts, 12 inches per minute), the other a range (240 to 280 amps, 24 to 28 volts, 10 to 14 inches per minute). Ranges are more useful because production rarely hits a number exactly.

Here is the rule that saves jobs: a range can never be broader than the qualification evidence supports. If the PQR records as-welded values of 250 amps and 27 volts, the WPS range must stay inside what was proven. A WPS reading “200 to 350 amps” on a procedure qualified at 250 amps is unproven at both ends of its window.

The pWPS to WPQR progression

Internationally, ISO 15614-1 makes the progression explicit. Clause 4 covers the preliminary welding procedure specification, the pWPS. Clause 5 covers the welding procedure test, Clause 7.5 sets acceptance levels, and 7.6 covers retesting. Clause 8 sets the range of qualification, and Clause 9 defines the welding procedure qualification record, the WPQR.

The pWPS is the recipe you intend to test. Run it, and the results become the WPQR, with the production WPS written inside the range the WPQR proves. Same logic as a PQR in ASME and AWS terms.

One marine wrinkle matters here. Under 46 CFR 57.03-1(d), approval of procedures using E6012, E6013, E6014, E6024, E7014, or E7024 electrodes is limited to the type, size, and brand tested. Change any of those three and you need a new qualification test, a reminder that filler metal details are not decorative paperwork.

For aluminum work the same logic applies with different consumable and shielding values, and this aluminum MIG guide covers the specifics.

Qualification Evidence: Reading the PQR and the Test Results

A procedure qualification record (PQR), or WPQR in international practice as used throughout ISO 15614-1, is the signed lab report that proves a welding procedure was actually tested and passed. The WPS is the recipe, and the PQR is the proof. Without a supporting PQR, a qualified WPS is unproven, no matter how complete the form appears. The evaluation isn’t whether the paperwork looks correct, but whether the test results justify the ranges the procedure claims. This level of scrutiny is taken especially seriously in fields such as aerospace welding.

What Must Be On a PQR

A valid PQR must document the exact conditions under which the coupon was welded. At a minimum, that includes:

• Process, joint design, base metal, and filler metal specifications
• The thickness and diameter of the test coupon
• The welding position(s) tested
• Preweld, interpass temperature, and any post-weld heat treatment
• As-welded electrical values (amperage, voltage, travel speed, wire feed speed, polarity, and transfer mode)
• Shielding gas type and flow rate
• Results for every specimen, with as-welded values
• The name of the testing laboratory, along with signatures and dates

If a PQR omits as-welded values or fails to name a laboratory, it is a claim of evidence, not evidence itself.

Matching Tests to What They Prove

Every test on a PQR answers a specific question. The exact requirements come from the code named on the record. For example, ASME Section IX defines tensile requirements in QW-150 and bend requirements in QW-160, while AWS D1.1/D1.1M has its own acceptance criteria that must be read directly from the applicable code.

Test	What it Proves	Acceptance Notes
Visual Examination (ASME QW-191)	Surface soundness	No cracks or fusion-type discontinuities. Undercut and profile must meet code limits.
Guided Bend Test (QW-160)	Ductility of weld and HAZ	No open discontinuity greater than 1/8 in. in the weld or heat-affected zone.
Macroetch	Fusion and root geometry	Must show complete fusion, complete root penetration, and no cracks. This is often checked when verifying techniques such as carbon arc gouging.
Tensile Test (QW-150)	Weld metal strength	Must meet the minimum strength required by the code for the base metal and joint.
Fracture Test	Fracture location	Fracture must occur in an acceptable location for the joint configuration.
Radiography or UT	Internal soundness	Cracks, incomplete fusion, and incomplete penetration are rejected outright, with strict limits on elongated slag based on thickness.
Charpy V-Notch (Impact)	Toughness at service temperature	Only required when specified by the code, with absorbed energy tested at the designated temperature.

Comparing As-Welded Values to the Job

The most important skill in reading a PQR is comparing its as-welded values to the ranges on the WPS and to the demands of the job at hand. A coupon can pass while still leaving critical variables out of range.

Variable	WPS Range	PQR As-Welded	This Job	Call
Amperage	130-180 A	155 A	175 A	Inside range
Travel Speed	6-14 in./min	9 in./min	12-13 in./min	Inside, near limit
Preheat	200-250 °F qualified	225 °F	300 °F min on 1 in. plate	Outside range, requalify
Shielding Gas Flow	20-30 cfh	25 cfh	35 cfh for windy outdoor work	Outside range
Position	Flat and horizontal	Flat only	Vertical-up on the vessel shell	Outside range

Preheat is often the trap. Since it’s an essential variable, a higher required preheat cannot be extrapolated from a passing coupon at a lower temperature.

Supplementary Variables and Failures

Some tests carry more weight depending on service conditions. In the AWS D1.1 framework, Charpy V-notch is a supplementary essential variable, meaning a change in the impact requirement requires additional testing. For marine fabrication, these requirements are strict. Under 46 CFR 57.04-1, fabricators must submit physical test results to the cognizant Officer in Charge, with specimen types and numbers following QW-202 and QW-210. These demands are expanded further for low-temperature service and are covered by established marine welding standards and practice.

If a coupon fails, the original procedure is no longer qualified. Codes may allow retesting, and only a passing retest can form the basis of the record. Failed and passed tests cannot be averaged. Additionally, retesting cannot cure an out-of-scope change made prior to welding the coupon. Moving from manual to machine welding is also its own process change, requiring a separate qualification.

Ranges of Qualification: The Most Overlooked Step

Nobody qualifies a welding procedure for a single point. You do not qualify for 3/8 in. plate. You qualify for a range of plate thickness, diameters, positions, base metals, and filler metals. The test coupon is one point inside that envelope, and production welding must stay inside it.

Get this wrong and everything downstream in the evaluation chain falls apart. A PQR can be valid, the WPS complete, the welder fully qualified, and the job still non-compliant because the production weld sits outside the qualified range. It is the most common reason a good-looking procedure fails in the field.

How Each Code Builds the Range

Codes build ranges differently, but the logic is identical: start with the as-welded test coupon, then extend coverage outward under defined conditions.

ASME Section IX handles this in QW-250, which sets the range of qualification for groove and fillet welds. The range picks up:

• Thickness range for the base metal
• Pipe diameter range, smallest to largest qualified
• Base metal grouping through P-numbers
• Filler metal grouping through F-numbers
• Welding position, tested and therefore qualified

Grouping is permission to extend, not a blanket waiver. A procedure covers a group only when the specific mechanical and impact requirements are satisfied.

AWS D1.1/D1.1M takes a different structure. Table 6.3 lists common requirements for WPS qualification and personnel performance qualification, while Clause 6.18 covers weld types for welder and operator performance qualification. D1.1 treats CJP groove, PJP groove, and fillet welds as separate qualification categories with separate limits, so the range you hold depends on joint type. Its table of qualified production positions is where most position mistakes get caught.

ISO 15614-1 organizes ranges in Clause 8: general provisions, manufacturer ranges, parent material ranges, ranges common to all procedures, and process-specific ranges. Clause 8.4 of the current edition notes that degree of mechanization is no longer an essential requirement, where earlier editions treated it as a distinguishing factor, so manual, semi-automatic, and automatic variants can share one range. ISO also allows a new WPQR range to be built from an existing qualified WPQR when the technical intent of the testing requirements has been met.

How Filler Metal Grouping Actually Works

Qualify a procedure with an E7018 electrode, F-number 6. Then buy E7016 electrodes, also F-number 6 but carrying an added “A” suffix. The distinction that gets missed constantly:

• The F-number groups filler metals by mechanical property class and lets you extend the qualified range across the group, provided the strength and impact requirements are met for the joint.
• The A-number suffix is a separate requirement. An A classification means the electrode is approved for impact-toughness applications and comes with a specified minimum notch toughness. You cannot buy your way into impact compliance by swapping to a different F-number electrode, so filler metal substitution has to clear F-number grouping and A-number requirements separately.

Changing to an electrode outside the F-group forces requalification. Staying inside the group while changing the A classification does not cover you either, because the toughness requirement has changed. Every shop that swapped an E7018 for an E7016 on a bridge job has a story.

A Worked Example

Consider a GMAW procedure on A36 steel, qualified on coupon at 3/16 in., with the PQR showing the test plate at 3/8 in. Does it cover 1 in. plate?

No. The qualified range covers the tested thickness plus a specified amount of additional thickness, and the coupon cannot exceed the thickness limit for full penetration testing under most codes. A 3/8 in. coupon does not represent the heat distribution, dilution, and restraint of a 1 in. joint. Positions follow the same logic: a fillet weld qualified flat does not cover vertical-up production, where gravity works against the puddle and defect risk rises. Look up the code’s position table rather than assume.

Common Range Parameters and How to Read Them

Parameter	How to Read It
Thickness range	Find the tested thickness on the PQR, then apply the code’s extension rule. Thicker, requalify.
Diameter range	Smaller than the tested diameter is usually allowed; larger is not, due to internal reinforcement.
P-number group	Check the production grade is in a qualified group and meets the minimum tensile requirement.
F-number group	Same group is allowed if strength and impact requirements are met; check the A suffix.
Position	Check the qualification table. Flat-only does not cover vertical-up or overhead.
Joint type	Codes qualify these separately. PJP is not CJP.
Process and type	Confirm the process and type (manual, semi-automatic, automatic) match the WPS you will run.

The practical takeaway: pull the range parameters from the PQR and set them beside the job’s actual requirements, meaning material grade, thickness, joint configuration, position, and filler metal. If any line does not match, you are outside the range.

The same range logic applies to aluminum, where filler selection and position control dominate the outcome. Our guides to aluminum MIG welding and aluminum flux core welding cover those process choices, and how to prep aluminum properly is worth reading before you blame the procedure when the real issue is surface preparation.

Prequalified vs. Qualified by Test: What You Can Skip

Every accepted welding procedure reaches the shop by one of two routes: proven with test coupons, or written to a code’s prequalification requirements so the coupon work was unnecessary.

What Prequalification Actually Means

Under AWS D1.1/D1.1M, prequalification of a welding procedure specification is exemption from the WPS qualification requirements. The code publishes the variable combinations it has already studied and accepted, so a fabricator matching those values exactly inherits the exemption instead of proving the procedure again by test.

The payoff is speed. A prequalified procedure skips the destructive testing of Clause 6: no macroetch coupons, no bend tests, no tensile specimens, no radiography, no lab work to schedule and pay for. That is the difference between releasing a WPS on Monday and releasing it six weeks later after machining, testing, and a report.

There are commercial gains too. Prequalified procedures are widely recognized by engineers of record and by large structural and erection companies, so a shop set up to run them can quote code work without building a testing program from scratch.

How to Tell Which Route a Procedure Took

AWS Form N-1 carries explicit check boxes for whether the WPS is prequalified or qualified by testing, and for a test-qualified procedure it calls for the supporting PQR number. If the box is empty, ask. If the PQR number is missing, ask louder. An unexplained form is a documentation defect worth flagging in the evaluation record.

ASME organizes qualification differently. Section IX Part QW divides into Article I for general requirements, Article II for welding procedure qualifications, Article III for welding performance qualifications, Article IV for welding data, and Article V for Standard Welding Procedure Specifications. The general ASME rule is qualification by testing; Article V is the exception, allowing SWPSs in recognized cases, roughly the counterpart to prequalification but on a narrower list.

International practice adds a continuity rule. ISO 15614-1 states that specifications and qualification of welding procedures made in accordance with previous editions may be used for any application for which the current edition is specified, with ranges of qualification of previous editions remaining applicable. Check this before assuming a procedure must be rebuilt.

Where Prequalification Stops Being Free

Prequalification is conditional, not universal. If any prequalified value departs from what you intend to weld, the exemption is gone and the procedure returns to the testing route. The variables that most often change casually on the shop floor:

• Groove details — angle, root opening, root face, beveled or square preparations
• Filler metal — electrode classification or strength level, including a move to a different F-number group
• Preheat and interpass temperature — lower preheat than the prequalified value means requalification
• Heat input — exceeding the prequalified range voids the exemption
• Position — prequalified positions must cover the production position
• Technique — stringer versus weave, single versus multipass, number of electrodes, electrode spacing
• Joint configuration — CJP versus PJP, and the joint geometry itself

These details live in the prequalification variable tables, the same tables you consult when judging whether a test-qualified procedure still covers the job. A test-qualified procedure can often be stretched because the PQR establishes a range. A prequalified procedure has no range to stretch; it was never tested.

That is why process selection matters more than people expect. A fabricator chasing aluminum flux core welding for a production run should check early whether the process and joint details fit a prequalified route or a test route, since that sets the schedule before a coupon is cut. The same applies to a pedestrian bridge, a pressure vessel, or a cast aluminum housing repair. If the joint does not line up with a published prequalified configuration, assume testing is coming and price it in.

Even where a prequalified procedure exists, it is not always the fastest path. A shop with high volume in one material, thickness range, and joint type can amortize one test qualification across hundreds of production welds, and a test-qualified procedure may cover configurations no prequalified option reaches. Choose based on the work in front of you, not on a rule that one route is always better.

Matching the Procedure to the Actual Job

Passing the document review only gets you halfway. Two WPS can sit side by side, both properly qualified, and still be completely wrong for the job in front of you. The gap is everything the paperwork never describes: access, weather, heat control, and service conditions.

So the second half of evaluating a welding procedure is a fit assessment. You hold the qualified procedure against the real job and ask a different question: not “is this procedure legitimate?” but “is this procedure right for this job?”

Most shops run this on a single sheet that travels with the job package.

Job parameter	What to check	Source
Joint type and configuration	CJP, PJP, or fillet; groove angle, root opening, root face, backing	Drawing vs WPS joint design
Base material spec and grade	Grade inside the qualified base metal grouping	PQR base metal data
Material thickness	Production thickness inside the qualified range	PQR range of qualification
Welding position	Production position equals the qualified position	WPS and PQR positions
Process capability	Manual, semiauto, or auto, and whether the machine holds the settings	Equipment list
Preheat and interpass	Required minimums, and how you will measure them in the field	WPS and material spec
Heat input limits	Maximum heat input and interpass caps	WPS and code limits
Shielding gas and flow	Gas type, flow rate, site supply	WPS and gas supplier
Post-weld heat treatment	Whether PWHT is required, plus furnace capacity and schedule	Code and PWHT procedure
Nondestructive examination	RT, UT, MT, or PT level required, in house or subcontracted	Contract specification
Surface prep and coating	Cleaning, pre-coating, back-gouging, paint-over temperature limit	Coating specification
Service conditions	Corrosion, temperature, pressure, fatigue or cyclic loading	Design basis

Aluminum adds its own rows. Getting the aluminum prep right before the arc is struck moves weld quality more than most shops expect, because oxide behaves nothing like carbon steel prep.

When a Qualified Procedure Is Still the Wrong Choice

Qualification tells you the procedure works under test conditions. It never tells you the procedure can be executed on your job.

• Access. A 60-degree groove with a 1/4 in. root opening works fine on flat plate and may be impossible inside a closed vessel where nothing can reach the root. Check access first.
• Weather and shielding. A GMAW procedure qualified with a 75/25 argon-carbon dioxide mix loses shielding in a crosswind, and porosity follows. Wind screens, tents, or a different process may be needed. Fume control comes with it: OSHA 1910.252 requires local exhaust or general ventilation to keep toxic fumes, gases, and dusts below the maximum allowable concentration, and requires welding consumables and flux materials in the employer’s hazard communication program.
• Purge control. Stainless and high-alloy joints need back purge with controlled gas, flow, and oxygen level. A qualified TIG procedure does not help if the root side sees air. The aerospace TIG guide covers the purge discipline these alloys demand.
• Preheat reality. Thick or high-carbon steels need controlled preheat and interpass temperature. A WPS qualified on an oven-heated coupon is not a plan for a plate that chills fast in a January shop.
• Hydrogen and heat input. High-strength steels need low-hydrogen consumables, control of diffusible hydrogen, and heat-input limits to avoid HAZ softening. The code may permit the material, but the WPS still must respect those limits.

The Position Problem

Position is the most commonly missed variable in a fit assessment. A procedure qualified flat and then run vertical-up changes the welding speed, the heat input you can sustain, and the defect risk. In vertical-up the puddle runs ahead of you, travel speed slows, and the root is far more likely to lack fusion or undercut. Flat qualification does not cover vertical-up unless the range says so.

This is where code structure matters. AWS D1.1/D1.1M carries dedicated prequalification and qualification requirements for CJP groove welds, PJP welds, fillet welds, and tubular connections, each with its own variable limits and its own table of production positions qualified. A fit check that looks at one category misses plenty. When you are picking consumables for a position change, the all-position rod guide shows what an electrode is actually rated for.

Green, Amber, Red

Most shops need a three-color call they can defend later.

• Green: qualified, every production variable inside its range, no mitigation needed. Release to production.
• Amber: qualified, but a production variable sits near a limit or a site condition needs a mitigation such as wind protection, purge, or preheat sequencing. Use it only with the control written down.
• Red: out of range, so it cannot be used. Requalification or a new procedure is the only path to production.

Amber is not a soft green. It is a qualified procedure running under conditions the qualification never imagined, so somebody has to own the control.

Common Mistakes and How to Catch Them

Most evaluation failures are not exotic. They are the same handful of shortcuts, repeated on job after job: a procedure approved on paper that nobody traced back to its test evidence, a filler metal swapped for cost, a prequalified procedure stretched past its stated limits. The table below pairs the symptom you will actually see with the root cause behind it and the specific check that catches it.

Symptom-to-cause reference for welding procedure evaluation

Symptom	Likely cause	The check that catches it
Every box on the WPS is filled in, but nobody can produce a matching PQR	The WPS was evaluated on paper and the supporting test evidence was never read	Ask for the PQR number and revision, then confirm it covers the thickness, position and process on the WPS. A qualified WPS without a supporting PQR is an unproven procedure
A WPS that looks identical to one from a job two years ago	The procedure was copied forward without requalification	Compare the PQR thickness range and position with today’s actual plate and joint, and check the PQR date against current code requirements
Filler metal quietly changed to a cheaper product	The new electrode falls in a different F-number group	Read the F-number on the procedure and the classification on the wire. Moving outside the qualified group forces requalification regardless of brand
Coupon was flat position, production is vertical-up	Position limits were ignored	Check the qualification position against the production position. Vertical-up changes speed, heat input and defect risk, so the two are not interchangeable
A prequalified WPS run with a wider groove, larger root opening or different preheat	The procedure was used outside the prequalified variable limits	Compare the job against the prequalification tables in AWS D1.1/D1.1M. Any deviation removes the exemption and sends the procedure back to testing
Undercut, spatter and irregular bead profile on an otherwise approved joint	Production ran outside the qualified amperage, voltage or travel speed window	Log the actual machine settings against the WPS range on a daily traveler. A procedure qualified at 260 amps is not qualified at 320 amps
Hard, cracked heat-affected zone on thick or higher-strength steel	Preheat or interpass temperature was wrong or missing	Check the preheat table against the material and thickness. NRC inspection guidance notes that qualification depends on the thickness of the test section and points to AWS D1.1 Table 4-8 for how qualification tests cross over to welding products, thicknesses and positions
PQR is a scanned sheet with no test laboratory, no as-welded values and no signatures	Documentation is incomplete, so the evidence cannot be audited	Reject the record and re-test. The as-welded values are the actual proof; a typed summary is not
The shop quietly switched from SMAW to FCAW, or from manual to automatic	A process change was treated as a shop-floor decision rather than a qualification trigger	Flag the change and requalify. Why SMAW remains popular is a fair question, but changing process is an essential variable, not a preference
Radiography passed on every joint, yet the owner still rejected the work	Passing NDT was treated as proof that the procedure was adequate	Separate the two claims. NDT shows this weld met the acceptance criteria; it says nothing about whether the procedure was right for the service. NRC guidance also recommends a 24 to 48 hour wait before final acceptance testing on higher-strength steels because of delayed hydrogen cracking, and that final NDT be performed after PWHT
One welder ran the entire job, regardless of position	Welder performance qualifications were never checked against the specific WPS and position	Pull each WPQ and confirm the procedure, position and diameter range are covered. A general all-position rod selection says nothing about a welder’s ticket
Backing rings left on where production removes them, or vice versa	Production practice drifted from the qualification coupon	Compare the coupon setup with the shop setup. 46 CFR Part 57 illustrates the principle in 57.03-1(b), which requires backing rings to be left in place unless they are to be removed in production
A welder moved from one plant to another and the paperwork stayed behind	Continuity of records was lost	Follow 46 CFR 57.05-2, which addresses transfer of performance qualifications: the qualifying plant transfers the welder’s employment records and identification data, and the new plant accepts the welder as qualified

Notice the pattern. Nearly every one of these is caught by a document review that takes fifteen minutes, not by a failed test coupon. That is the practical argument for evaluating procedures before production rather than after a rejection: the expensive discoveries are already written in the paperwork, and the paperwork is cheap to read.

A Repeatable Step-by-Step Evaluation Workflow

Judging a procedure by feel is where shops get burned. A repeatable workflow turns “looks good to me” into a documented answer that survives an inspector’s question, a client review, or an audit. Run the same ten steps in the same order, and gaps a paper review misses surface before the first arc is struck.

1. Identify the governing code and contract specification. Start with what the work actually is, not with what the shop usually does. Structural, pressure-retaining, piping, and client-specific work each pull different rules, and contracts often add requirements on top of the code.
2. Confirm the edition in force. The edition named on the drawings or purchase order controls, not the binder copy. Check the current edition at AWS standards, and ask the engineer of record if the contract is silent.
3. Decide prequalified or test-qualified. AWS D1.1 exempts a prequalified procedure from Clause 6 qualification testing, while ASME IX generally requires qualification by test before use. That choice sets the evidence you assemble. See the ASME Section IX qualification guidance.
4. Audit the WPS for completeness. Compare the form against the code’s required variable list: process, joint, position, base metal, thickness, filler metal, technique, electrical settings, shielding gas, preheat and interpass, and PWHT. A blank field or an “as required” note is an incomplete specification, not a flexible one.
5. Read the PQR and check it against the WPS. A qualified procedure with no supporting PQR is unproven. Under ASME IX, the qualification records form the evidence base behind the PQR. Confirm every essential variable matches and that as-welded values sit inside the ranges the WPS claims.
6. Map the ranges onto the real job. Put actual production values next to the qualified ranges.
7. Verify the five core ranges. Filler metal, base material, position, joint configuration, and thickness. AWS D1.1 requires welders to be qualified under Clause 6, and Clause 6.18 sets the weld types used for welder and welding operator performance qualification, so that position and joint logic applies to procedures. Position coverage deserves special attention here.
8. Confirm welder qualifications cover the procedure and position. The AWS Form N-4 test record captures the actual values used in qualification alongside the range variables. Every welder on the job needs a WPQ covering the procedure, position, and joint type.
9. Check preheat, interpass, PWHT, and heat input against the service condition. Match them to the material, thickness, and the service environment: corrosion, temperature, pressure, or fatigue loading.
10. Document the evaluation, the gaps, and the decision. Record gaps even when you pass, since the next revision is compared to this file. ISO 15614-1 clause 9 covers the welding procedure qualification record, the document a complete evaluation ends with.

Records to Retain

Record	What it proves
Code and contract specification	Which rules govern this job
WPS (AWS Form N-1 format)	Its procedure and claimed ranges
PQR or WPQR	Test evidence behind those ranges
Welder test records (Form N-4)	Who is qualified to run them
NDT and repair records	How the procedure performs in production
Evaluation record and change log	The decision and its reasoning

Requalification Triggers

Re-evaluate when any of these change:

• Process or transfer mode change, SMAW to FCAW or manual to automatic
• Filler metal change outside the qualified F-number group
• Thickness outside the qualified range
• New joint type, groove detail, or root opening
• Production position the procedure never qualified
• Added or removed supplementary essential variables (impact testing)
• Changed preheat, interpass, PWHT, or heat input limits
• New base metal grade or specification

Feed Production Data Back Into the Library

Reject rates, NDT trends, and repair rates are data you already own. A high slag reject rate or rising repair count means the ranges are too broad, the settings are drifting, or the filler and gas choices need work: tighten the ranges, retire the procedure, or retrain. When one job repeats often enough that qualification testing no longer pays for itself, move it onto a prequalified procedure. On AWS D1.1 work, prequalified SMAW procedures and their GMAW equivalents remove the coupon cost and the release delay.

Digital Forms and Version Control

Once a shop runs many revisions, paper stops working. Keep one-page checklists, controlled revision numbers, and one approved location for every form. The aerospace and pressure-vessel side of the trade shows how fast document control becomes the whole job. An audit trail showing which revision a weld was made under beats any saved sheet of paper.

Conclusion: Make Procedure Evaluation a Habit, Not an Event

A welding procedure is not evaluated because someone asked for a form to be filled out. It is evaluated because three claims must be true before steel is joined: the procedure satisfies the governing code, the qualification evidence supports the range it claims, and the procedure matches the real job in front of you. Fail any one of those and everything downstream inherits the problem.

The cost side of that equation is lopsided. A careful evaluation might take an hour of reading: a code clause, a WPS, a PQR, and drawings. The failure side is a rejected weld, a repair that has to be re-NDT’d and re-documented, a slipped ship date, or a fitness-for-service review questioning a joint nobody can prove was properly qualified. Evaluate the procedure properly and the inspection milestone becomes a formality instead of a fight.

This is why evaluation belongs in the plan rather than at the end. AWS D1.1/D1.1M treats prequalification, qualification, fabrication, and inspection as four distinct but connected stages. You cannot inspect your way back to a procedure that was never qualified for the thickness you welded. The same logic holds across codes: ISO 15614-1, AWS D1.1, and ASME Section IX all require a written record that supports production welding. That record is a deliverable, not paperwork overhead.

The arc of the evaluation

Six moves, in order. Choose the code that actually governs the work. Read the WPS field by field, the way you would read a blueprint. Read the PQR and check what the test coupon actually proved. Respect the range of qualification, because the coupon defined a window, not a point. Judge the fit against the real job: position, thickness, service condition, shop reality. Then document the decision, the gaps, and who signed off on it.

Once those six are a habit, the rest gets easier. Build a one-page evaluation checklist for each code you work in. Keep a change log on every procedure you rely on: date, what changed, why, and whether requalification was triggered. Revisit a procedure whenever the base material grade changes, the thickness range moves, the service condition shifts from ambient to cryogenic, corrosive, fatigue-loaded, or pressure-retaining, or the filler metal classification changes. Those are the moments when a procedure that was fine last year quietly stops being fine.

Two supporting habits make the habit stick. Keep your procedure library clean so an inspector finds the current revision in seconds. And watch production feedback: reject rates, NDT trend data, and repair history show which procedures are actually working and which are merely qualified. When volume supports it, that evidence is the argument for moving toward prequalified procedures, which trade test coupons for speed.

One more thing the evaluation should cover

Welding is a hazardous operation whether or not the paperwork is beautiful, so the control of exposure belongs in the same evaluation conversation. NIOSH identifies welding fume exposure and manganese as recurring occupational hazards, with a recommended exposure limit of 1 mg/m³ TWA and 3 mg/m³ STEL for manganese and an OSHA permissible exposure limit of 5 mg/m³ ceiling. Local exhaust, fume extraction, and respiratory protection are part of the process decision, not a separate procurement detail. If you are reviewing a shop’s welding program end to end, our guides to aluminum flux core welding and aluminum MIG welding cover process-specific fume and shielding details in more depth.

Good evaluation is quiet work. Nobody wins a contract for reading a PQR carefully, but plenty of shops lose work, money, and credibility when they skip it. If you have built a repeatable evaluation workflow, or you have run into a case where the paperwork looked right and the weld still failed, tell us how you handled it.

Frequently Asked Questions

What is the difference between a WPS and a PQR?

The WPS is the recipe — the written set of essential variables describing how the weld will be made. The PQR is the evidence — the record of the test welds and their results that proves the procedure meets the governing code. A WPS without a supporting PQR is an unproven procedure, and on most code-governed work it will not be accepted for production.

Do I need to requalify a procedure if I only change amperage or voltage?

Not if the change stays inside the range established by the qualified PQR and recorded in the WPS. Amperage, voltage, and travel speed are typically part of a qualified range, but going outside that range is a change to an essential variable and requires requalification. Always check the code’s variable table before assuming a setting is covered.

How long does a welding procedure specification stay valid?

Welding procedures do not expire on a fixed schedule in the way some welder qualifications are time-limited. A WPS remains valid as long as it complies with the code edition in force for the work, the supporting qualification record is available, and no essential variable has changed. What does expire is your confidence in it, so periodic re-verification against current codes and job conditions is good practice.

Should I evaluate a structural job against AWS D1.1 or ASME Section IX?

Match the code to the work. AWS D1.1 governs structural steel fabrication, while ASME Section IX is the qualification code for pressure vessels, boilers, and piping, and it is used together with the applicable construction code. Evaluating a pressure-retaining weld against D1.1 alone will miss requirements such as impact testing, and evaluating a building frame against Section IX wastes time on requirements the job does not have.

Can a prequalified WPS be used for any application?

No. Prequalification is conditional on conforming to every applicable prequalified requirement — the groove details, filler metal, preheat, heat input, position, and technique all have to match what the prequalified provisions specify. Deviate from any of them and the exemption is gone, and the procedure returns to qualification by testing.

What disqualifies a welding procedure during an audit or inspection?

The usual findings are a missing or incomplete PQR, a production weld outside the qualified range for thickness, position, filler metal, or base metal, a process change without requalification, or a welder running the procedure without a matching performance qualification. Documentation gaps alone are frequently enough to fail the review, because the code expects the record to prove the qualification.

Which tests are used to qualify a welding procedure?

It depends on the code, process, and service conditions, but the usual set includes visual inspection, guided bend tests, macroetch examination, tensile testing, and volumetric examination such as radiography or ultrasonic testing, with Charpy V-notch impact testing added where toughness is required. The governing code and the contract specification determine which of these actually apply.

Who is responsible for evaluating a welding procedure?

Legally and contractually, the responsible organization is the manufacturer or contractor performing the work, with the welding engineer, QA/QC lead, and certified welding inspector carrying out the review. Some contracts assign the evaluation to the engineer of record, and regulated work such as marine fabrication may require the results to be submitted to the cognizant Officer in Charge for approval.