What is a Certified Mill Test Report (CMLT) for welding electrodes?

A CMLT is a manufacturer-issued document showing the actual mechanical and chemical test results for a specific lot of electrodes, confirming the lot meets the AWS filler metal specification (e.g., A5.1, A5.18, A5.20).

Does AWS D1.1 require a CMLT for every electrode lot?

AWS D1.1 does not explicitly mandate CMLT retention, but AISC certification and most owner specifications do. Best practice is to file CMLTs with your electrode receiving log and keep them for the life of the fabricated structure.

What happens if a welder uses an electrode that doesn't match the WPS filler metal classification?

That is a WPS deviation, which constitutes a non-conformance. The affected welds must be evaluated, and the deviation documented. Depending on severity, additional NDE or weld replacement may be required.

Can I use a brand-name electrode not specifically named in the WPS?

Yes, provided its AWS classification matches the WPS. The WPS governs by AWS classification (e.g., E7018), not brand name. Confirm the electrode lot CMLT matches the required classification and hydrogen designator.

Filler Metal Certifications for AWS D1.1 Compliance

What filler metal certifications an AWS D1.1 structural fab shop must document—CMLTs, classification testing, and what AISC auditors look for.

Why Filler Metal Documentation Gets Fabricators in Trouble

AISC certification audits and owner-specification submittals routinely turn up the same gap: the WPS names an electrode classification and a CWI signs the daily weld logs, but nobody can produce the certification records that prove the electrodes actually in the shop match what the WPS requires. The fabricated steel ships, the project closes, and the paper trail is missing.

That gap matters because AWS D1.1:2025 Clause 6.3 requires that the filler metals used in production conform to the AWS filler metal specification referenced in the WPS. Proving conformance means maintaining documentation. This article explains what that documentation looks like, which specifications govern each common electrode family, and what you need to have on file before an AISC surveillance auditor opens the electrode cage.

AWS Filler Metal Specifications Referenced in AWS D1.1:2025

AWS D1.1 delegates electrode classification requirements to the AWS A5-series specifications. The ones that matter most in structural carbon-steel fabrication are:

A5.1 / A5.1M — Covered electrodes for SMAW (stick). This covers E6010, E6013, E7014, E7018, E7018-1, E7024, and the rest of the carbon-steel SMAW electrode families. Low-hydrogen designators (H4, H8, H16) are tested per Annex A of A5.1.

A5.18 / A5.18M — Carbon-steel electrodes and rods for GMAW and GTAW. Covers ER70S-3, ER70S-6, and similar solid wire. No hydrogen designator on GMAW wire; the diffusible hydrogen concern in gas-shielded wire is primarily about moisture contamination of the contact tips and base metal, not the wire itself.

A5.20 / A5.20M — Carbon-steel electrodes for FCAW. Covers the E71T-1, E71T-8, E71T-9, E71T-12, and E71T-GS families. Hydrogen designators (H4, H8, H16) apply to the gas-shielded grades (FCAW-G). The designation scheme includes position, slag system, and polarity information.

A5.17 / A5.17M — Carbon-steel electrodes and fluxes for SAW. Both the wire (e.g., EL12, EM12K) and the flux (e.g., F7A2) classifications appear in the WPS; the combination of wire + flux determines the deposit classification.

A5.23 / A5.23M — Low-alloy steel electrodes and fluxes for SAW. Used when the base metal is higher-strength (A572 Gr. 65, A913, HPS 70W) and deposit chemistry must match.

Note: AWS D1.1:2025 Table 6.6 row 4 removed A5.36 from the allowed filler metal list for GMAW and FCAW essential variables. This is a 2025 change from the 2020 edition—if your WPS cites A5.36 for GMAW/FCAW, it needs updating. Rule library based on AWS D1.1:2025; verify against your governing edition.

What a Certified Mill Test Report (CMLT) Contains

Electrode manufacturers are required by the AWS A5-series specifications to provide certified documentation—commonly called a Certified Mill Test Report, or CMLT—for each lot they produce. A properly formatted CMLT will show:

Lot or heat number (traceability identifier on the electrode package label)
AWS classification (e.g., E7018-H4)
Test date and test lot size
Chemical analysis of the deposited weld metal (C, Mn, Si, S, P, Cr, Ni, Mo, V at minimum)
Mechanical test results: tensile strength, yield strength, elongation, and notch toughness where required by the specification
Diffusible hydrogen test results when the electrode carries an H-designator
Manufacturer's certification signature or stamp

When you receive electrodes, match the lot number on the box to the CMLT. If the vendor cannot supply a CMLT, that is a quality-system red flag—legitimate AWS-classified electrode manufacturers test every lot.

What to Keep on File and for How Long

There is no single universal retention requirement embedded in AWS D1.1 itself, but several governing documents pile up requirements:

AISC 207-23 (Quality Management System for Steel Construction) — Requires that filler metal certifications be retained as quality records. The duration is tied to the product: for structural members, AISC typically expects records to be kept for the life of the structure or a minimum of 10 years, whichever is longer.

Owner and EOR specifications — Many owner specifications for bridge, seismic, or critical structure work specify retention of 10–25 years or "life of structure."

Your own QMS — If your shop is AISC-certified, you have a written Quality Management System. The filler metal section of that QMS should specify retention periods, the responsible custodian, and the filing method.

Practical minimum: For most commercial structural work, maintain CMLTs for a minimum of 10 years, cross-referenced to the job number and purchase order on which those electrodes were used.

Electrode Receiving and Issuance Log

A CMLT on file is necessary but not sufficient. The second document that AISC auditors look for is an electrode receiving and issuance log, which closes the chain of custody between "we received electrodes with this lot number" and "welder Smith used them on beam line 7 on job 2024-118."

A minimal log entry for each electrode shipment includes:

Date received
Vendor and PO number
AWS classification, brand, and diameter
Lot or heat number (from the box label—must match the CMLT)
Quantity received
Storage location (for low-hydrogen electrodes, the rod oven assignment)
Issued-to welder and date, cross-referenced to weld log or traveler

This log is your audit trail. Without it, even a complete CMLT binder proves only that you bought the right electrodes—it does not prove they were the ones deposited in the structure.

Low-Hydrogen Electrode Storage Requirements

AWS D1.1:2025 Clause 7.3 sets mandatory storage and reconditioning requirements for low-hydrogen SMAW electrodes. These requirements are part of production compliance, not just procurement, but they affect filler metal documentation:

Unopened hermetically sealed containers: no special storage required until opened
After opening: must be stored in a holding oven at 250–300°F (120–150°C) or reconditioning must be performed if exposed for more than 4 hours (E70XX series) or 2 hours (E80XX and higher)
Reconditioning temperatures and cycles are electrode-classification-specific; consult Clause 7.3.3

Your electrode log should capture open-container dates and oven storage entries. If low-hydrogen electrodes are found outside the holding oven, that is a non-conformance, not just a housekeeping issue—it directly affects the diffusible hydrogen level in production welds.

Hydrogen Designators and Demand-Critical Welds

For welds subject to CVN supplementary essential variables (AWS D1.1:2025 Table 6.8), or for demand-critical welds in AISC 341-22 seismic applications, the hydrogen designator on the electrode classification (H4 or H8) is an essential variable. Changing from E7018-H8 to E7018-H4 within the same base classification is NOT a free upgrade—it requires requalification when the WPS specifies an H-designator. Your CMLT confirms that the lot you received actually meets the claimed designator, which is why the document exists.

What an AISC Auditor Looks For

During a surveillance audit or certification review, the AISC auditor will typically:

Pull a fabrication traveler for a completed job and identify the WPS used.
Cross-reference the WPS filler metal classification against the electrode receiving log for that job.
Ask for the CMLT corresponding to the lot number issued against that job.
Check the CMLT against the electrode classification on the WPS (including hydrogen designator if specified).
Verify that the lot was stored properly per your QMS and Clause 7.3.

If you cannot complete steps 2–4 in under 10 minutes during an audit, your document control system needs work. For more on building an audit-ready package, see AISC Fabricator Certification Audit WPS/PQR Common Failures.

Setting Up a Defensible System

You do not need expensive software to maintain defensible filler metal records. A folder structure (physical or digital) organized by year and job number, with a master electrode lot index, covers most commercial fab shops. The key elements are:

CMLT binder: One CMLT per lot received, filed by lot number with a cross-reference index
Receiving log: Spreadsheet or paper log with all fields listed above
Issuance log: Tied to weld travelers, capturing welder, date, job, and lot number
Oven log: Daily temperature recording for holding ovens, signed by QC personnel

If your shop has 10 or fewer welders and runs under 50 jobs per year, a single binder and a two-tab spreadsheet are adequate. At higher volume, a QMS software system that captures lot traceability alongside your WPS assignments pays for itself quickly at audit time.

For a complete view of how filler metal records fit into your overall qualification packet, see WPS and PQR Record Retention and visit WPS Welding pricing to see how the platform keeps your documentation audit-ready automatically.