Does changing from E7016 to E7018 require PQR requalification under AWS D1.1?

These electrodes have different usability designators and slag systems under AWS A5.1. Because the electrode classification is an essential variable in Table 6.6, changing the full A5.1 designation — not just the trade name — requires either a new PQR or amendment to cover the new electrode. If the existing PQR was run with E7018, E7016 is a different classification and triggers requalification.

Is electrode diameter an essential variable for SMAW under AWS D1.1:2025?

Yes. Maximum electrode diameter is an essential variable for SMAW in Table 6.6. Increasing beyond the qualified maximum requires a new PQR qualification test. Decreasing diameter is typically acceptable within the ranges stated on the WPS.

Does changing polarity from DCEP to DCEN require SMAW requalification?

Yes. Current type and polarity are essential variables for SMAW in Table 6.6. Any change requires PQR requalification because polarity directly affects arc characteristics, penetration profile, and deposition rate — all factors tested during PQR mechanical testing.

If I increase preheat on my SMAW WPS, does that trigger requalification?

No. Increasing preheat above the qualified minimum is conservative and is not an essential variable. Reducing preheat below the qualified minimum is an essential variable and requires requalification or a new PQR at the lower preheat level.

Nov 13, 20267 min read

SMAW Essential Variables: AWS D1.1:2025 Table 6.6 Guide

CWI reference for SMAW essential variables in AWS D1.1:2025 Table 6.6 — which changes require PQR requalification for structural shielded metal arc welding.

WPS SMAW AWS D1.1 Essential Variables PQR CWI

New to procedures? Start with WPS welding: what a welding procedure specification is, with a filled-in example.

Shielded metal arc welding remains the dominant process for structural field welding and repair work in AWS D1.1 shops. Yet essential variable violations on SMAW welding procedure specifications are among the most common audit findings CWIs encounter — often because welders and foremen make process adjustments without recognizing they have crossed a PQR qualification boundary.

This guide walks through the SMAW-specific essential variables as defined in AWS D1.1:2025 Table 6.6, explains when each change triggers requalification, and identifies the most frequent shop-floor mistakes that create compliance gaps.

Rule library based on AWS D1.1:2025; verify against your governing edition — the AHJ or contract may specify 2020 or earlier.

What Are Essential Variables?

AWS D1.1 divides WPS parameters into three categories:

Essential variables are parameters where a change beyond the qualified limit invalidates the PQR qualification. If the shop changes an essential variable in production, the WPS must either be requalified by test or the production parameter must be brought back within the qualified range.

Supplementary essential variables apply only when the WPS is qualified with Charpy V-notch (CVN) impact testing. These are listed separately in Table 6.8 and are only invoked when CVN qualification is required by the contract documents, design drawings, or applicable code supplement.

Nonessential variables are parameters that the WPS must list but that can be changed without requalification — only the written WPS needs to be updated and re-approved.

Understanding which category each parameter falls into is the foundation of sound WPS change management.

SMAW Essential Variables Under Table 6.6

Process Change

Any change away from SMAW — to FCAW-G, GMAW, SAW, or any other process — is an essential variable. SMAW and FCAW-G produce welds with different microstructural characteristics, penetration profiles, and slag systems, so a PQR run with one process does not cover the other.

This is frequently misunderstood in shops that add FCAW equipment and attempt to use existing SMAW PQRs on the same joint configuration. See Adding a New Welding Process Under AWS D1.1 for the full requalification path when introducing a new process to an established program.

Electrode Classification

A change in AWS A5.1 (carbon steel) or A5.5 (low-alloy) electrode classification is an essential variable. This includes:

A change in the strength class — E60XX to E70XX, or E70XX to E80XX
A change in the usability designator that reflects a different slag or flux system
A change in the low-hydrogen suffix that moves to a higher hydrogen level (H4 to H8, for example)

What does not automatically trigger requalification: switching between two electrodes with identical AWS classification designations from different manufacturers. If the full A5.1 or A5.5 classification string is the same, the product change alone is not an essential variable — but the shop still needs to maintain mill certifications confirming classification compliance.

For H-suffix changes and their interaction with CVN qualification requirements, see Electrode H-Suffix Classification and WPS/PQR.

Electrode Diameter

Maximum electrode diameter is an essential variable for SMAW. Using an electrode larger than the maximum listed on the qualified WPS requires either requalification or amendment of the PQR qualification to encompass the new size.

The rationale: larger diameter electrodes deposit more heat per unit time under typical operating parameters, which changes the heat-affected zone profile and may affect the mechanical test results the PQR is based on. A WPS qualified with 5/32" maximum electrode allows smaller diameters such as 1/8" without requalification, but moving to 3/16" does require it.

Current Type and Polarity

Current type (AC or DC) and polarity (DCEP or DCEN) are essential variables. This creates a common problem for shops that run both AC machines and DCEP-capable inverters on different work and want to consolidate WPS documents. A PQR run with DCEP does not qualify DCEN — the arc physics are fundamentally different, penetration profiles differ, and the PQR must be run with the specific current type and polarity the shop intends to use in production.

Confirm current type and polarity are explicitly stated on both the WPS and the PQR — vague entries like "DC" without polarity are a deficiency and an audit red flag. See WPS Current Type and Polarity Essential Variable for documentation requirements.

Joint Type

The joint type qualified by the PQR establishes production coverage. A groove weld PQR qualifies groove welds; a fillet weld qualification qualifies fillet welds of a size range. Under AWS D1.1, a CJP groove weld PQR also qualifies fillet welds of any size for the same process and base metal group, but not vice versa. See Groove Weld Qualifies Fillet Weld Under AWS D1.1 for the cross-qualification rules.

Base Metal Group Changes

AWS D1.1:2025 assigns structural base metals to groups based on chemistry and mechanical properties. Changing to a base metal outside the group or groups qualified by the PQR is an essential variable. A WPS qualified with A36 covers other metals in the same group, but not A514, which requires separate PQR qualification with the higher-strength material and typically stricter preheat and mechanical test requirements.

For the complete group structure and cross-coverage rules, see AWS D1.1 Table 6.9 Base Metal Groups.

Preheat Reduction

Reducing minimum preheat below the qualified minimum is an essential variable. The qualified minimum is the preheat maintained during the PQR coupon weld. Increasing preheat in production is never an essential variable — it is a conservative adjustment.

For shops using the Annex B alternative preheat method based on carbon equivalent, any preheat established by that calculation must still meet the qualified minimum from the PQR if the WPS is a tested (Clause 6) procedure. Annex B governs prequalified WPS preheat, not tested WPS preheat. See AWS D1.1 Annex B Alternative Preheat by Carbon Equivalent for the calculation approach.

PWHT

Adding or removing postweld heat treatment is an essential variable. A PQR run without PWHT does not cover production welding that includes PWHT. The thermal cycle fundamentally alters weld metal and HAZ microstructure and mechanical properties, so the mechanical tests in the PQR are only valid for the PWHT condition under which they were performed. See PWHT on a WPS for documentation requirements.

Position

For tested WPS qualification under Clause 6, the position tested on the PQR determines the positions qualified in production. A PQR run in flat position (1G/1F) covers only flat position production. Qualification in vertical (3G/3F) covers vertical and flat. Full position coverage requires testing in overhead (4G/4F) or combining multiple PQRs.

The complete position qualification matrix for AWS D1.1 is detailed in Welding Position Qualification Limits Under AWS D1.1.

Supplementary Essential Variables for CVN-Qualified WPS (Table 6.8)

When the design contract or governing specification requires CVN impact toughness verification, the supplementary essential variables from AWS D1.1:2025 Table 6.8 are activated in addition to the standard essential variables in Table 6.6.

For SMAW, the most significant Table 6.8 items involve changes to the electrode classification's toughness-related characteristics, preheat reduction below CVN-qualified minimums, and PWHT changes. Two notable 2025 edition updates:

Table 6.8 now sets a minimum test specimen thickness floor of 1/2 in [12 mm], reduced from 5/8 in [16 mm] in the 2020 edition — meaning thinner plate production can now be supported by CVN-qualified PQRs.
Preheat reduction alone no longer triggers CVN requalification under Table 6.8; only an increase in maximum interpass temperature does.

For the complete CVN essential variable story, see CVN Supplementary Essential Variables: AWS D1.1 Table 6.8.

Common SMAW Essential Variable Mistakes

Upgrading electrode strength without requalification. Substituting E8018 for E7018 on an A36 joint "just to be safe" changes the electrode classification — an essential variable — without any benefit to joint performance and without a qualifying PQR at the higher strength level.

Running wrong polarity in the field. SMAW welders accustomed to AC-qualified procedures sometimes connect to DC power. The WPS must specify the qualified current type, and foremen should verify the machine setting before each weld starts.

Assuming identical trade name means identical classification. Two suppliers may both market their product as "E7018" but differ in A5.1 classification suffix. Always compare the full AWS designation printed on the electrode package, not just the trade name.

Applying prequalified preheat rules to tested WPS. Prequalified (Clause 5) WPS preheat is governed by Table 5.11 rules. Tested WPS preheat minimum is set by the PQR qualification test. Reducing preheat on a tested WPS based on Table 5.11 calculations is not permitted without a new PQR.

Managing SMAW Essential Variables in Production

For systematic WPS change management, see Essential Variable Change in Production — CWI Decision Guide and WPS Requalification Triggers Checklist.

If your shop needs to centralize WPS documentation, track essential variable changes, and automate PQR coverage checks, WPS Welding software offers tools built around AWS D1.1:2025 Table 6.6 rules with built-in essential variable validation.

FAQ

Frequently asked.

Does changing from E7016 to E7018 require PQR requalification under AWS D1.1?: These electrodes have different usability designators and slag systems under AWS A5.1. Because the electrode classification is an essential variable in Table 6.6, changing the full A5.1 designation — not just the trade name — requires either a new PQR or amendment to cover the new electrode. If the existing PQR was run with E7018, E7016 is a different classification and triggers requalification.
Is electrode diameter an essential variable for SMAW under AWS D1.1:2025?: Yes. Maximum electrode diameter is an essential variable for SMAW in Table 6.6. Increasing beyond the qualified maximum requires a new PQR qualification test. Decreasing diameter is typically acceptable within the ranges stated on the WPS.
Does changing polarity from DCEP to DCEN require SMAW requalification?: Yes. Current type and polarity are essential variables for SMAW in Table 6.6. Any change requires PQR requalification because polarity directly affects arc characteristics, penetration profile, and deposition rate — all factors tested during PQR mechanical testing.
If I increase preheat on my SMAW WPS, does that trigger requalification?: No. Increasing preheat above the qualified minimum is conservative and is not an essential variable. Reducing preheat below the qualified minimum is an essential variable and requires requalification or a new PQR at the lower preheat level.