Is welding anchor rods to base plates covered by AWS D1.1?

AWS D1.1 covers structural steel welding broadly. Anchor rod-to-base plate welds on structural steel column bases typically fall under D1.1 unless the project specification cites a different code. Always confirm with the project specification before writing the WPS.

What filler metal is typically used for anchor rod-to-base plate welds?

For common mild steel anchor rods (ASTM F1554 Grade 36 or Grade 55 with Supplement S1) and A36 base plates, E7018 (SMAW) or ER70S-6 (GMAW) are standard choices. Grade 105 rods with higher yield strength require filler metals matched to the base metal strength level.

Can a prequalified WPS cover anchor rod welds?

It depends. The base metal must be in the prequalified list, the joint geometry must match a prequalified groove or fillet configuration, and the anchor rod material specification must be verified against prequalified base metal classifications. When uncertain, PQR-qualify the procedure.

Who inspects anchor rod welds — shop CWI or field CWI?

Both may be involved. Shop-fabricated base plate assemblies with pre-installed anchor rods are inspected in the shop before shipment. Field-welded anchor rods set after concrete placement require a field CWI. Assign inspection responsibility explicitly in the inspection and test plan.

Anchor Rod and Base Plate Weld WPS: AWS D1.1 Requirements

Anchor rod-to-base plate welds need a WPS covering base metal grade, joint geometry, preheat, and field position. AWS D1.1 compliance for shop and field fabrication.

Column base plates and anchor rod assemblies seem like straightforward weldments. They are also persistently under-documented in fabrication quality programs. When a third-party auditor or AHJ asks for the WPS used to weld 1.5 in. F1554 Grade 55 anchor rods to a 3 in. thick A36 base plate, the answer is often silence — or a WPS pulled from a file that doesn't match what was actually done.

The welding happens routinely. The procedure documentation is frequently missing or incorrect.

What Governs Anchor Rod-to-Base Plate Welding

AWS D1.1 applies to structural steel welding broadly, which includes base plate fabrication and field-installed anchor rod assemblies. For most building and industrial structural projects, D1.1 is the governing welding code. Confirm with the structural specification — some EOR offices specify AISC 303 (Code of Standard Practice) provisions which reference D1.1 by default. Process and power generation projects may invoke ASME IX instead.

The point: there is a governing welding code, and anchor rod welds need a WPS that complies with it. Treating base plate welds as miscellaneous or uncoded work does not reflect current fabrication quality practice and creates audit exposure.

Anchor Rod Base Metals and the WPS Matching Problem

Anchor rods are most commonly specified to ASTM F1554. This standard covers three grades with meaningfully different weldability:

Grade 36: Yield strength ≥ 36 ksi, chemistry similar to A36. Weld-friendly with standard filler metals and no special preheat beyond code minimums for the applicable plate thickness.

Grade 55: Yield strength ≥ 55 ksi with stricter chemistry. The standard includes Supplement S1 specifying weldability requirements — confirm that Grade 55 rods are ordered with S1 when welding is required. Without S1, the chemical composition may fall outside ranges that make preheat prediction reliable.

Grade 105: Yield strength ≥ 105 ksi. High-strength, requires careful filler metal selection and typically elevated preheat. The WPS for Grade 105 anchor rods should be PQR-qualified on representative base metal, not adapted from a WPS written for mild steel rods.

Under AWS D1.1, the WPS must identify the base metal specification and grade. F1554 Grade 36 and Grade 55 (with S1) are frequently treated equivalently to A36 or A572 Grade 50 for WPS purposes, but this equivalency should be documented in the PQR base metal section or confirmed against the prequalified base metal list.

If the base plate is A36 and the anchor rod is F1554 Grade 36, filler metal selection is straightforward: E7018 (SMAW), E71T-1C/M (FCAW-G), or ER70S-6 (GMAW) match the strength level and are compatible with both base metals. For Grade 105 rods, higher-strength filler metals may be required depending on the design, and the WPS and PQR need to reflect that specifically.

For an overview of filler metal classification designations and their WPS implications, see AWS A5 filler metal classification and WPS selection.

Joint Configurations: Fillet, Groove, and Plug Welds

The joint type depends on the connection design detail:

Fillet welds are the most common configuration — anchor rods welded around their circumference to the top face of the base plate. The WPS needs to specify fillet weld size range, electrode or wire classification, process, and minimum preheat. Don't write "fillet weld, anchor rod" without the weld size range and process parameters; an inspector cannot verify compliance from a WPS that vague.

Groove welds (PJP or CJP) appear when anchor rods are set into machined sockets in the base plate and groove-welded for maximum load transfer. These configurations are less common in standard commercial construction but show up in heavily loaded equipment bases and seismic moment frame anchorage. Groove geometry must be documented in the WPS.

Plug welds appear when anchor bolts pass through plate holes and are welded flush. AWS D1.1 covers plug weld WPS requirements separately from groove and fillet; confirm the hole diameter, depth of fill, and plug weld diameter are specified in the WPS.

A WPS that says only "fillet weld" without joint configuration, weld size range, and process parameters will not pass CWI or auditor review.

Position and Access: Shop vs. Field

Shop fabricated assemblies can usually be oriented for flat (1F) position welding on a positioner. This is the preferred configuration — flat position provides the best weld quality, easiest access, and easiest visual inspection.

Field anchor rod welding after concrete placement is a different situation. Rods projecting from set anchor bolt templates may be in horizontal or overhead position depending on the geometry. If field welding is anticipated, the WPS must cover the relevant positions, and each field welder must have a WPQ that includes those positions.

For D1.1 position qualification coverage, see Welding position qualification limits under AWS D1.1.

Access after concrete: A critical timing issue. Once concrete is poured and the anchor rod template is embedded, the weld area at the base plate interface is concealed. If the design requires welds below the top plate surface — e.g., at a leveling plate or grout-fill joint — those welds must be inspected and accepted before the concrete or grout covers them permanently. Document this as an inspection hold point in the project ITP (inspection and test plan).

Preheat and Plate Thickness

Base plate thickness on heavily loaded column bases can be substantial — 2 in., 3 in., or 4 in. plates are common on large industrial or multi-story frames. AWS D1.1 preheat requirements scale with base metal thickness and carbon equivalent. A WPS written for 3/4 in. shop plates does not cover the preheat requirements for a 3 in. base plate with a high-restraint multi-rod anchor group.

Document the preheat requirement explicitly on the WPS, tied to the plate thickness and base metal grade. Relying on the welder to determine the required preheat from memory or habit is both a code violation and an audit failure point. For more on preheat documentation practice, see Preheat and interpass temperature on a WPS.

High-restraint configurations — multiple anchor rods welded to a thick base plate simultaneously, or anchor rods welded after the plate is already bolted to a column section — increase residual stress and hydrogen cracking risk. Preheat should be set conservatively for restrained assemblies.

Essential Variables That Matter for Anchor Rod WPS Validity

For SMAW, GMAW, or FCAW anchor rod welds backed by a PQR, AWS D1.1:2025 Table 6.6 governs which changes trigger requalification. Rows that surface frequently:

Base metal change: Moving from F1554 Grade 36 to Grade 105 is a significant change. The PQR run on mild steel rod does not cover high-strength rod; a new qualification is required.

Filler metal classification change: Switching from E7018 to E8018 to match Grade 55 or Grade 105 rods requires attention to whether Table 6.6 treats this as a requalification event for the applicable process.

Thickness increase beyond qualified range: If the PQR was run on 1 in. plate and production base plates are 3 in., check whether the thickness falls within the qualified range per Table 6.6. Thick plate requalification is frequently overlooked when shops adapt standard structural WPSs to base plate work.

Position addition: A shop WPS qualified only in flat position cannot be applied to overhead field welds without requalification or a separate WPS covering overhead position.

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

Inspection Access Problems

The most persistent inspection challenge on anchor rod work is access after concrete placement. Once poured, the weld zone at the base plate is inaccessible. This makes pre-pour inspection non-negotiable:

Examine weld visual acceptance before forms are closed or grout is placed
Verify anchor rod plumb and spacing while access exists
MT on weld toes where specified — before concrete conceals the area
Document that inspection was completed and accepted in the inspection record

If the welding is done in the shop on fabricated base plate assemblies, inspection happens before shipment. If anchor rods are field-welded after concrete placement, schedule the field CWI inspection immediately after welding — not after the next phase of construction has proceeded.

Subcontractor WPS Compliance

When anchor rod field welding is subcontracted to a separate field welding crew — distinct from the fabrication shop — their WPS, PQR, and individual welder WPQs need to be reviewed and accepted before work starts. Subcontractor welding crews on industrial projects frequently produce WPS documents that are generic or cover different base metal grades than what is actually in the field. Verify the documents match the actual anchor rod spec and base plate grade.

For guidance on reviewing and accepting subcontractor WPS packages, see Subcontractor WPS acceptance under AWS D1.1.

Building the WPS Package

A complete anchor rod-to-base plate WPS package includes:

WPS describing process, base metals (base plate grade + anchor rod spec and grade), filler metal classification, joint configuration, weld size range, preheat/interpass temperatures, position, and pass sequence for multi-pass welds
PQR supporting the WPS (or documented prequalified clause reference)
WPQ for each welder performing these welds, covering all positions used
Inspection record documenting preheat verification and visual acceptance before concrete concealment

An organized package answers auditor questions immediately. Missing WPQ documentation for a field welder on a completed and grouted base plate is a non-conformance report that is difficult to close out once the work is buried. See how WPS Welding tracks WPS coverage and welder qualifications in one place.

For broader audit package management across multiple WPS types, see Building an audit-ready WPS library.