Can a single WPS cover both A500 Gr. C and A992 as base metals?

Yes. AWS D1.1 allows one WPS to list multiple base metal specifications as long as both are prequalified or both are qualified by PQR. The WPS must document each base metal specification and the applicable essential variables from Table 6.6 that apply to the combination.

Which filler metal do I use when welding A500 HSS to A992 wide-flange?

For FCAW-G, E71T-1C or E71T-9C (AWS A5.36 classification) or E70T-5 for higher-restraint joints are common choices. The filler must deposit weld metal meeting or exceeding the tensile requirements of both base metals. Because A500 Gr. C and A992 have similar tensile strengths, standard E7X electrodes are appropriate.

Is a PQR required for A500 HSS to A992 connections under AWS D1.1?

Not necessarily. If both base metals are prequalified, the joint geometry matches Annex B, the process is one of the prequalified processes, and all other Clause 5 conditions are met, a prequalified WPS is valid. A tested PQR is required if any of those conditions cannot be met — for example, if the brace wall thickness triggers a PQR requirement or the joint detail is not prequalified.

What preheat is required for A500 Gr. C HSS connections under AWS D1.1:2025?

Preheat depends on the base metal category and thickness of the material being welded. A500 Gr. C follows the applicable preheat requirements in AWS D1.1:2025. Because HSS wall thickness is typically thin relative to heavy column flanges, the governing preheat is often driven by the base metal category rather than thickness alone. Always verify against the current governing edition of AWS D1.1.

WPS for A500 HSS to A992 Wide-Flange Column: AWS D1.1

How to build a prequalified or tested WPS for ASTM A500 Grade C HSS welded to A992 wide-flange columns under AWS D1.1:2025, covering dual base metals, filler selection, and Table 6.6 essential variables.

The HSS brace to wide-flange column connection is one of the most common joints in structural steel fabrication — braced frames, moment frames, and gravity columns all generate large quantities of this weld type. Yet writing a compliant Welding Procedure Specification (WPS) for an ASTM A500 Grade C tube welded to an ASTM A992 wide-flange section trips up quality managers more often than it should. The dual base metal issue, filler metal compatibility, and knowing when a Procedure Qualification Record (PQR) is required versus when a prequalified WPS suffices are the three questions that most often land in a CWI's lap at the start of a project.

This article walks through the decision tree for this connection type under AWS D1.1:2025.

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

Why This Connection Is Challenging to Document

Welding A500 HSS to A992 wide-flange looks straightforward on the drawing — a cope or slotted gusset, a groove or fillet weld at the tube end — but the WPS documentation has to handle two different ASTM specifications simultaneously. AWS D1.1 requires that every WPS clearly identify the base metals it qualifies. When the two base metals have different specifications, the engineer of record, the CWI, and the fabricator's QC manager all need to confirm that:

Both base metals are covered by the WPS (either prequalified or tested).
The filler metal is compatible with both.
The essential variables in Table 6.6 have been evaluated for both metals.
Preheat meets the more stringent requirement of the two materials.

Skipping any of these steps is one of the most common WPS deficiencies cited in third-party AISC audit findings.

Prequalified vs. Tested Path

Both ASTM A500 Grade B and Grade C, and ASTM A992, are listed among the base metals eligible for prequalified WPS use under AWS D1.1. This means that a fabricator can write a prequalified WPS — without running a PQR — provided all of the following are true:

The joint design matches a prequalified joint detail from AWS D1.1 Annex B.
The welding process is one of the prequalified processes (SMAW, SAW, GMAW, FCAW, or GTAW).
The filler metals are prequalified for that process.
All heat input, position, and electrode limits in Clause 5 are observed.
No Clause 5 exclusion applies (such as ESW or EGW, which are never prequalified).

The most frequent reason this connection ends up requiring a tested WPS is joint geometry: if the HSS end-cut creates a groove condition not described in Annex B, or if the slot-in-gusset detail requires a configuration that doesn't match a prequalified profile, the fabricator must qualify by test. Similarly, if the project specification requires notch-toughness (CVN) testing of the weld metal, supplementary essential variables from Table 6.8 are invoked, and a tested PQR with Charpy specimens is mandatory regardless of prequalified status.

For most standard braced-frame brace-to-gusset connections, however, the prequalified path is available and should be used. It eliminates PQR cost and accelerates submittals.

See prequalified WPS limitations under AWS D1.1 Clause 5 for the full exclusion list before assuming the prequalified path is available.

Filler Metal Selection for A500 to A992 Joints

A500 Grade C has a minimum tensile strength of 62 ksi (round sections) and A992 has a minimum tensile strength of 65 ksi with an upper limit on yield strength to ensure adequate ductility. Both materials fall within the range where standard E70-class filler metals provide overmatching or closely matching weld metal tensile strength.

For FCAW-G — the dominant process in structural fab shops for this connection type — E71T-1C electrodes per AWS A5.36 (or A5.20 for non-A5.36-classified wires) are the most common choice. SMAW with E7018 is equally valid and preferred in restricted positions or for the root of a full-joint-penetration (CJP) groove weld. SAW with compatible wire-flux combination is used in shops with positioners.

The key selection criterion is ensuring the filler is listed as prequalified for the process in AWS D1.1 if you are pursuing the prequalified path. Substituting a filler not on the prequalified list — even a seemingly equivalent electrode — converts the WPS to a tested procedure requiring a PQR.

For more on filler substitution rules, see filler metal substitution and WPS requalification under AWS D1.1.

Essential Variables Under Table 6.6

AWS D1.1:2025 Table 6.6 governs the essential variables for SMAW, SAW, GMAW, FCAW, and GTAW tested WPS. A change to any essential variable listed in Table 6.6 requires a new PQR or re-qualification of the WPS. Even for prequalified WPS, the essential variable framework defines what constitutes a new procedure.

For the A500 HSS to A992 column connection, the Table 6.6 variables that most frequently trigger requalification decisions are:

Base metal group. If A500 and A992 fall into different prequalified base metal groups, the WPS must either qualify for both groups or the fabricator must run a PQR that demonstrates the procedure works across the combination.

Filler metal classification. Changing from E71T-1C to a different AWS classification — even to another E71T series — requires re-evaluation under Table 6.6. The A5.36 electrode classification system introduced the -G designator category that requires special handling per the 2025 edition rules.

Welding process. Switching from FCAW-G to SMAW to complete a connection in the field is a process change that cannot be done under the original FCAW WPS. Field WPS coverage for SMAW repairs must be separately qualified or prequalified.

Position. A WPS qualified in the flat (1G/1F) position does not automatically qualify vertical (3G/3F) or overhead (4G/4F) positions. Fabricators routinely miss this when a field crew needs to weld a brace connection in a position the shop WPS wasn't written for.

For a comprehensive breakdown of Table 6.6 row-by-row, see AWS D1.1 Table 6.6 essential variables explained.

WPS Documentation Requirements for Dual Base Metals

The AWS D1.1 WPS form (Annex M) provides fields for base metal specification and thickness range. For this connection type, document both A500 Gr. C and A992 in the base metal field, separated clearly (e.g., "ASTM A500 Gr. C and/or ASTM A992"). The thickness range must bound the actual HSS wall thickness on the lower end and the column flange thickness on the upper end.

The CWI reviewing the WPS submittal will look for:

Both base metals explicitly identified.
Filler metal classification and AWS specification (A5.36, A5.1, or A5.17 as applicable).
Position coverage that matches how the connection will actually be welded in the shop or field.
Preheat and interpass temperature stated in degrees Fahrenheit (or Celsius), not as "per code."
Minimum and maximum heat input range if CVN testing was required.

One common audit finding: the WPS lists only "ASTM A500" without specifying Grade B or Grade C. Grade C has a higher minimum yield and tensile strength than Grade B, so a WPS written and tested for Grade B may not support Grade C without re-evaluation.

Preheat Considerations

AWS D1.1 preheat requirements are a function of the base metal specification category and thickness. A500 and A992 are both carbon or high-strength low-alloy steels covered under standard AWS D1.1 preheat tables. For most standard HSS wall thicknesses (3/16 to 5/8 inch wall), the minimum preheat for ambient conditions is either no preheat or a modest preheat, depending on the specific material chemistry and the applicable table category.

However, when the brace connects to a heavy column flange — for example, a wide-flange column with a 2-inch flange — the column thickness drives the preheat category. The thicker metal controls the preheat determination for that joint, which can require preheating even when the HSS wall by itself would not.

Document the actual minimum preheat temperature on the WPS in absolute terms. "Per AWS D1.1" is not an acceptable preheat entry because it shifts the burden to the welder and inspector to look up the value on the floor, increasing the chance of a non-conformance.

See dissimilar-thickness connections and WPS heat input controls for related coverage on multi-thickness joint documentation.

Building the WPS Submittal Package

For AISC-certified fabricators and projects requiring WPS submittals to the engineer of record (EOR), the package for A500-to-A992 connections should include:

The signed WPS (Annex M form recommended).
Supporting PQR(s) if the tested path was used.
Filler metal manufacturer's certification or data sheet confirming the AWS classification.
WPS revision history if any parameters were changed since original issue.

Start your WPS program before steel arrives on the shop floor. Filler metal changes, process swaps for field work, and position additions are the most common reasons a project stalls at the inspection hold point because the WPS submittal is not current.

Compare WPS software options vs. spreadsheet-based WPS management to see how software can streamline multi-metal WPS libraries for structural fab shops.