Can a seated beam connection use a prequalified WPS, or does it need a PQR?

A seated connection typically uses prequalified fillet welds under AWS D1.1:2025 Clause 5, so no PQR is required provided the base metals, process, electrode, and joint geometry all meet prequalified requirements. A stiffened seat with a specified CJP groove weld may require a tested WPS.

What position are shop welds on a seated connection typically made in?

Shop welds on a seated angle or seat plate are usually made in the flat (1F) or horizontal (2F) fillet weld position. Field welds attaching a seat to a column in erection can be in the vertical (3F) or overhead (4F) position, requiring a WPS that qualifies those positions.

What minimum fillet weld size applies to a seat angle welded to a column flange?

AWS D1.1:2025 Table 7.7 sets minimum fillet weld sizes based on the thicker of the two base metals joined. For a 3/4 in. seat angle on a 5/8 in. column flange, the thicker part is 3/4 in., which requires a 5/16 in. minimum fillet weld. Rule library based on AWS D1.1:2025; verify against your governing edition.

Can a CWI reject a seated connection weld based on fit-up gap?

Yes. A root opening between the seat plate face and column flange face up to 1/16 in. is acceptable; gaps from 1/16 in. to 3/16 in. require the fillet weld leg to be increased by the amount of the gap; gaps over 3/16 in. require joint fit-up correction before welding per AWS D1.1:2025.

Seated Beam Connection Weld Procedures Under AWS D1.1

CWI guide to WPS requirements, fillet weld sizing, fit-up tolerances, and common inspection findings for stiffened and unstiffened seated beam connections per AWS D1.1:2025.

Seated beam connections appear throughout structural steel framing—secondary floor beams, roof framing, retrofit work, and legacy buildings where bolted-only framing was standard. From a welding inspection standpoint, a seated connection presents a specific set of challenges: tight access for the welder, T-joint fillet welds under compression, and fit-up gaps that directly affect effective throat. This guide covers what a CWI needs to know about WPS selection, weld sizing, fit-up tolerances, and the most common rejection findings.

What a Seated Connection Is and Why It Gets Welded

A seated connection transfers the beam end reaction through a horizontal bearing surface—a seat angle or plate—that is welded to the supporting column. Unlike a shear tab (single plate) or clip-angle (double angle) connection that transfers shear through the beam web, a seated connection bears the beam end on a horizontal element attached to the column face or web.

Unstiffened seat angles use a single structural angle with the horizontal outstanding leg as the bearing surface. The vertical leg is welded to the column with a pair of vertical fillet welds. Under light to moderate loads, this is sufficient.

Stiffened seat plate assemblies are used for heavier reactions. The assembly consists of a horizontal bearing plate stiffened by a vertical plate welded perpendicular to it, forming a T-shaped seat that is then welded to the column. The structural engineer may specify fillet welds for lighter loads or CJP groove welds for high-load transfer applications.

Top clip angles or angles are attached above the beam bottom flange for lateral stability. They carry no significant vertical reaction but are required by the connection design and must be inspected.

Seated connections appear most often as shop welds on the column—the seat is welded to the column during fabrication, then the beam is set on the seat during erection. Field welding of seats to already-erected columns is also common in retrofit and renovation work.

WPS Requirements: Prequalified vs. Tested

For the great majority of seated connections on structural carbon steel—ASTM A36, A572 Grade 50, A992, A500—the fillet welds can be executed with a prequalified WPS under AWS D1.1:2025 Clause 5. No PQR test is required if:

Base metals are on the AWS D1.1:2025 prequalified base metal list (Annex B).
The welding process and electrode are prequalified (SMAW E7018, FCAW-G E71T-1C/-9C, GMAW spray with ER70S-6, SAW, or GTAW).
Joint geometry matches an Annex B prequalified T-joint or corner-joint fillet weld detail.
All WPS parameters (amperage, voltage, travel speed, preheat, interpass temperature) stay within the prequalified ranges of Clause 5.

When the structural engineer specifies a CJP groove weld on the stiffened seat vertical plate—common on heavy transfer girders and high-rise column splices—the prequalified groove joint geometry and all Clause 5 limits must be satisfied, or a tested WPS backed by a PQR under Clause 6 is required. For any seat welded to high-strength steel such as ASTM A514 or A517, a tested WPS is required because those steels are not on the prequalified list.

Minimum Fillet Weld Size and Design Weld Size

AWS D1.1:2025 Table 7.7 governs minimum fillet weld sizes based on the thickness of the thicker base metal being joined. This is a floor, not a specification—the structural engineer determines the required design weld size from the connection reaction force. The CWI enforces both:

The code minimum from Table 7.7 must be met regardless of what the drawings say.
The design weld size shown on the erection drawings must be met.

If the design calls for a 1/4 in. fillet but Table 7.7 requires 5/16 in. for the plate thickness involved, the 5/16 in. governs. The CWI should flag any drawing that specifies a weld size below the AWS D1.1 minimum during pre-weld documentation review—before the welder strikes an arc.

Rule library based on AWS D1.1:2025; verify against your governing edition.

Preheat Requirements

AWS D1.1:2025 Table 6.3 sets minimum preheat and interpass temperatures based on base metal type, thickness, and process. For A36 and A572 Gr. 50 seat plates under 3/4 in. thickness welded with a low-hydrogen process (E7018, E71T-1C), Table 6.3 typically requires no preheat or a minimal 32°F (0°C) minimum ambient. For thicker seats—common on stiffened assemblies over 1 in. thick—preheat requirements increase.

The CWI verifies preheat before the first pass and monitors interpass temperature throughout the weld sequence. Temperature-indicating crayons, contact pyrometers, or infrared guns are all acceptable methods. Preheat must be applied to both the seat plate/angle and the column at the joint.

Fit-Up Tolerances and Root Opening

The interface between a seat plate's vertical face and the column flange face is a T-joint. AWS D1.1:2025 permits a root opening of up to 1/16 in. (2 mm) with no adjustment. For root openings between 1/16 in. and 3/16 in. (5 mm), the fillet weld leg size must be increased by the amount of the root opening to maintain effective throat. Root openings over 3/16 in. require corrective action—shimming, rewelding, or fitting—before welding begins.

The CWI should check fit-up before tacking when present at the shop. Once tacked, pulling the gap closed is difficult and rewelding tacks to correct fit-up is a nonconformance that requires documentation.

Common CWI Inspection Findings

Undersized fillet welds. The welder's view of the weld pool is partly blocked by the angle or seat plate geometry. Short-arc processes (SMAW, FCAW-S) are prone to underrunning the specified size when the welder works in the horizontal (2F) position with the column in the horizontal fixture position. Measure both weld legs at a minimum of three points per weld run.

Poor fusion at the weld toe on the column face. If the seat plate or angle sits with a slight misfit or undercut on the column fillet radius (k-zone), the welder may hesitate to carry the weld to the full base metal edge, leaving a notch at the column face. This is a visual nonconformance requiring the CWI to document and route through the nonconformance disposition process.

Overwelding on the stiffened seat vertical plate. Fabricators sometimes apply excessive weld size out of habit on stiffened seat assemblies, depositing a 3/8 in. fillet where 5/16 in. was specified. AWS D1.1 does not prohibit oversize fillet welds unless the structural engineer restricts it (for thin seats, weld heat distortion can camber the seat plate upward, affecting bearing). Review the contract requirements before accepting obvious overwelding.

Missing top clip angle or inadequate size. The top clip is easy to forget, particularly on large column assemblies with many pieces. The CWI's weld map or traveler checklist should include the top clip as a required weld item.

Arc strikes on the column base metal. In tight shop conditions, welders may inadvertently strike arcs on the column web or k-zone while positioning for the seat fillet welds. Arc strikes on structural steel must be treated per AWS D1.1:2025 Clause 4.8—ground smooth and visually or magnetically inspected for cracks.

Qualification Range and Position Considerations

A WPS qualified for the horizontal fillet weld position (2F) covers the flat fillet position (1F) per AWS D1.1 qualification rules. A shop WPS covering 2F positions is therefore adequate for most seated connection shop work. For field welding where the erection sequence places the welder overhead (4F) or vertical (3F), the WPS must specifically qualify those positions—a 2F-only qualification does not extend to them.

Base metal thickness coverage is also a qualification consideration. A prequalified SMAW E7018 WPS covers base metals from the minimum prequalified thickness through unlimited thickness on the side being welded. For thick stiffened seats (over 1-1/2 in.), confirm the WPS includes an appropriate preheat schedule for the carbon equivalent of the specific heat of steel, per the CMTRs.

Documentation Checklist for the CWI

At minimum, inspection records for seated connections should capture:

Measured fillet weld leg size (both legs, three measurement points)
Root opening (pre-weld fit-up check when witnessed)
Preheat temperature and measurement method
Visual acceptance per AWS D1.1:2025 Clause 8 (no cracks, no undercut exceeding limits, no overlap, no excessive convexity)
Weld process, electrode classification and lot/heat number, WPS number, and welder ID stamp

For NDE-specified connections, confirm that MT or UT is scheduled, executed, and the results filed in the weld traveler before the assembly is shipped. See also the WPS submittal package checklist and NDE documentation requirements for audit packet integration.

For shops building seated connections as part of an AISC-certified fabrication program, the connection weld records feed directly into the AISC audit packet. Review AISC fab cert audit common failures to see where seated connection welds typically create gaps. To generate a WPS for your specific seat configuration, compare plans and start your trial.