Can I switch from one E7018 brand to a different manufacturer's E7018 without requalifying?

Yes, in most cases. Changing electrode brand within the same AWS classification is not an essential variable under AWS D1.1:2025. The classification — E7018 — defines the mechanical properties and electrode characteristics. If the new electrode carries the same AWS A5.1 classification, the existing WPS and PQR cover it. The exception is when the project spec requires documented filler metal approval; confirm with the owner's QC plan.

Does switching from E7018 to E7016 require a new PQR?

Yes. E7016 and E7018 are different AWS A5.1 classifications — different electrode covering type, which affects deposition characteristics and weld properties. A change of filler metal classification is an essential variable under D1.1:2025 Table 6.6 and requires requalification by PQR test.

Can you substitute ER70S-3 for ER70S-6 on a qualified GMAW WPS?

ER70S-3 and ER70S-6 are different AWS A5.18 classifications. Changing the classification is an essential variable under D1.1:2025 Table 6.6, so technically a separate PQR or prequalified procedure is needed. In practice, many shops write the WPS to cover both by conducting a PQR with both electrodes, or by using two separate prequalified WPS documents.

Does changing the hydrogen designator — say, from E7018-H8 to E7018-H4 — require requalification?

No. The hydrogen designator (H4, H8, H16) is a supplemental marking that indicates diffusible hydrogen content. Changing from H8 to H4 is a reduction in hydrogen — a more conservative choice — and is not listed as an essential variable in D1.1:2025 Table 6.6. The base classification E7018 remains unchanged. Document the change in the WPS revision notes for traceability.

Filler Metal Substitution: When You Need a New PQR

Changing electrode brand, classification, or strength level on an existing WPS triggers different requalification rules under AWS D1.1:2025. Here is how to tell them apart.

Electrode substitutions happen constantly on production floors: a supplier changes their line, an approved brand is on back-order, a foreman grabs a box that has the same strength rating but a different part number. The question every QC manager and CWI faces is whether the substitution invalidates the WPS — or whether it's a paperwork update and nothing more.

AWS D1.1:2025 is specific about which filler metal changes are essential variables (requiring a new PQR or a new prequalified procedure) and which are not. Knowing the difference saves time and prevents unnecessary procedure qualification tests — or, on the other side, prevents shipping welds made under an invalid procedure.

What Makes a Filler Metal Change an Essential Variable

Under AWS D1.1:2025, the controlling concept for filler metal essential variables is the AWS classification of the electrode or wire. The classification is the string on the label: E7018, ER70S-6, E71T-1C, E70T-5, and so on. Each classification specifies minimum mechanical properties, electrode composition or coating type, and position capability. When the classification changes, the code treats it as a material change to the procedure.

The specific rule in Table 6.6 (D1.1:2025 essential variables by process) is a change in filler metal specification or classification. "Specification" refers to the governing AWS A5 document (A5.1 for SMAW, A5.18 for GMAW, A5.20 for FCAW, A5.17 for SAW wire, and so on); "classification" is the alphanumeric designation within that spec.

If either the specification or the classification changes, the change is an essential variable and the procedure needs to be requalified — either by running a new PQR test or by rewriting the WPS as a prequalified procedure that covers the new electrode.

Same Classification, Different Brand: No Requalification Needed

The most common substitution scenario — changing from one manufacturer's E7018 to a competitor's E7018 — does not require requalification. Both electrodes carry the same AWS A5.1 classification. The brand is not part of the essential variable. A WPS qualified on Lincoln's E7018 covers Miller's E7018, ESAB's E7018, and any other electrode certified to the same A5.1 classification.

This is true for all AWS A5 specifications: brand is not the variable, classification is. The practical implication is that shops can change suppliers, take advantage of pricing, or cover a shortage without triggering a procedure rewrite — as long as the new electrode carries the same AWS classification printed on the box.

One caveat: some owner quality plans, military contracts, or nuclear work scopes require pre-approved electrodes or manufacturer qualification. Those project-level requirements sit on top of D1.1:2025 and may require additional approval documentation even when the code itself does not. Read the project quality plan before making substitutions on those jobs.

Classification Change Within the Same Strength Class

If the substitution changes the classification designation — E7018 to E7016, ER70S-6 to ER70S-3, E71T-1C to E70T-4 — that is an essential variable change requiring requalification.

The most common version of this in structural shops is substituting between SMAW electrode types. E7018 (iron powder, low hydrogen) and E7016 (low hydrogen without iron powder) are both 70 ksi class electrodes, but they are different AWS A5.1 classifications with different coating compositions. Substituting E7016 for E7018 on an E7018-qualified WPS is not permitted under the same PQR.

For FCAW, moving from E71T-1C to E71T-8 (self-shielded) is a double change: different classification and change from gas-shielded to self-shielded process. That requires both a new classification and a process change requalification. For more on how FCAW process type affects WPS qualification scope, see FCAW-S vs FCAW-G essential variable differences.

Strength-Class Upgrade or Downgrade: Always an Essential Variable

Moving from a 70 ksi class electrode (E7018, ER70S-6, E71T-1C) to an 80 ksi class electrode (E8018-C3, ER80S-D2, E81T1-Ni1) or vice versa is an essential variable in every case. The first digits of the classification encode strength; changing strength class changes the mechanical properties of the deposited weld metal in ways that affect the procedure's qualification range.

For standard A36 and A572 Grade 50 structural work, an upgrade to 80 ksi class filler metal is not required and gains nothing mechanically. Shops that substitute E8018 for E7018 to cover a shortage may find they need a new PQR even though both electrodes exceed the base metal strength. The 10 ksi strength jump is a new variable regardless of direction.

The exception is a reduction from a higher class to a lower class when the lower class still exceeds the base metal minimum tensile requirement. For qualified procedures on high-strength steel using E8018, moving down to E7018 would underperform the base metal and is not an acceptable direct substitution. Undermatching is a separate topic covered in undermatching filler metal WPS rules under AWS D1.1.

Hydrogen Designator Changes

The supplemental hydrogen designator — H4, H8, H16 on SMAW electrodes; similar markings on FCAW wires — indicates the maximum diffusible hydrogen content in mL per 100 g of deposited weld metal. H4 ≤ 4 mL/100g, H8 ≤ 8 mL/100g, H16 ≤ 16 mL/100g.

Changing the hydrogen designator does not change the base classification. E7018-H4 and E7018-H8 are both E7018 under AWS A5.1. Moving from H8 to H4 is a more conservative choice (lower hydrogen risk); moving from H4 to H16 increases hydrogen potential. Neither direction is listed as an essential variable in D1.1:2025 Table 6.6 for a PQR-qualified procedure.

That said, the WPS should document the hydrogen designator for traceability and field verification. If your WPS was written against E7018-H4, note the change to E7018-H8 in the WPS revision log and confirm the base metal thickness and preheat combination remain appropriate for the higher hydrogen level. On high-strength or thick sections, H16 may be inappropriate even if it is not technically an essential variable — consult the preheat and electrode conditioning guidance in low-hydrogen electrode conditioning for H4, H8, H16.

SAW Flux and Wire Combination Changes

SAW introduces a filler variable that SMAW and GMAW do not have: the flux-wire combination. Both the wire classification and the flux designation are essential variables under D1.1:2025. Changing flux manufacturer or flux designation — even when the wire stays the same — may require requalification.

AWS A5.17 classifies SAW wire-flux combinations together, so the WPS needs to identify both. If the shop changes from one flux brand to another, even with the same wire, verify whether the new flux-wire combination has been run in the PQR or qualifies as prequalified under D1.1:2025 Clause 5. SAW electrode-to-flux interaction is not a situation where "same wire = same result" applies. See SAW essential variables and flux reconditioning under AWS D1.1 for the full SAW variable list.

Practical Decision Tree for Filler Metal Substitutions

When a substitution comes up, a QC manager or CWI needs to answer three questions in order:

Does the new electrode carry the same AWS A5 classification as the original? If yes — same spec, same classification — no essential variable change. Update the WPS with the new product information and move on.
Is the classification different but within the same strength class? If yes, this is an essential variable. A new PQR or prequalified procedure covering the new classification is required before production.
Is the strength class different? Also an essential variable, regardless of whether the new electrode is stronger or weaker. New qualification required.

The hydrogen designator and electrode brand are not essential variables under D1.1:2025 and do not trigger requalification on their own. They should still be documented in WPS revisions for traceability.

For shops managing WPS libraries across multiple projects and filler metal sources, tracking classification-level coverage by process is straightforward in a purpose-built tool — see wpswelding.com/pricing for how the platform tracks approved filler metals against each WPS and flags substitutions that would breach essential variable boundaries.

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