Is CJP groove weld always required for a truss chord splice?

Yes for tension chord splices intended to develop full member strength. Compression chord splices may permit PJP if direct bearing transfers the compression force and the design explicitly confirms it — but CJP is the more common and conservative default. Confirm the joint type with the engineer of record before drafting the WPS.

Can a prequalified WPS cover a truss chord splice groove weld?

Yes, if all prequalified joint, base metal, and process requirements are satisfied. Flange thicknesses and groove geometries that fall within the prequalified joint tables in Annex B can use a Clause 5 prequalified WPS without a PQR. Thick chord sections and non-standard joint geometries more commonly require Clause 6 qualification.

How much NDE is required on chord splice welds?

AWS D1.1:2025 typically requires 100% UT on CJP groove welds in primary tension members. For cyclically loaded trusses such as crane bridges or overhead conveyor structures, the cyclic acceptance criteria and potentially MT on the weld toe apply. The NDE specification in the project ITP should confirm the required coverage.

What chord alignment tolerance applies after welding?

AWS D1.1:2025 and the AISC Code of Standard Practice set limits on member straightness and splice offset. The fabrication drawing typically specifies the allowable axis offset at the splice. CWIs verify this with a straight edge and offset measurement against the chord's design axis after welding and before the member is accepted.

Truss Chord Splice WPS Requirements Under AWS D1.1:2025

Truss chord splices carry full member force in tension or compression. Here's how WPS selection, preheat, and NDE requirements differ between chord types.

Truss chord members carry the primary axial forces in a structural truss — tension in the bottom chord, compression in the top chord under typical gravity loading. When a chord must be spliced at mid-span or at a panel point transition, the splice weld must transfer the full member force across the joint without a reduction in stiffness or load capacity that would degrade structural performance.

Chord splices are among the more demanding WPS applications in structural fabrication. They combine the full-penetration requirements of moment-connection flanges with the alignment precision that axial-load-carrying members require. Getting the WPS, preheat planning, and inspection sequence right matters here more than on many other joint types.

What a chord splice involves structurally

A chord splice is a butt joint between two chord segment ends. In design, the splice is usually treated as a full-strength connection — the weld must develop the full design capacity of the chord cross-section. For tension chords, the groove weld must develop the tensile capacity of the base metal. For compression chords, the compressive bearing area and weld configuration must transmit the full compression force without eccentricity or stability loss at the joint.

Chord members take many forms: wide flange shapes (W-shapes), tee sections cut from W-shapes, channels, hollow structural sections (HSS), or built-up box sections in heavy industrial truss work. The joint geometry of the splice — and therefore the WPS requirements — depends on the cross-section type.

CJP groove weld as the baseline requirement

For tension chord splices in structural trusses, AWS D1.1:2025 requires a complete joint penetration (CJP) groove weld. CJP groove welds develop the full plate or flange thickness in tension; the prequalified joint configurations in Annex B cover the butt joint geometries used in most chord splice applications.

PJP (partial joint penetration) groove welds are not appropriate for primary tension chord splices. PJP welds carry a throat penalty that reduces tensile capacity, and the unfused root acts as a fatigue initiation site in cyclic service. They are sometimes acceptable in compression chord splices where the compressive load transfers through direct bearing and the weld's role is positioning and stability — but even then, most engineers specify CJP to maintain consistent bending stiffness at the splice and eliminate root discontinuities.

See: CJP vs. PJP groove weld WPS requirements

WPS selection for chord splice groove welds

Process selection. SMAW low-hydrogen (E7018) for root and fill is a reliable shop choice for chord splices in A572 Grade 50 members. FCAW-G (E71T-1 or E71T-9) fill over an SMAW root pass is the high-deposition alternative for heavier chord sections. All-GMAW spray transfer works for clean shop conditions with good fit-up. The chosen process must have access to the root in the groove geometry; a tight, deep groove in a heavy W-shape flange restricts electrode angles.

Position. Shop-fabricated chord splices are typically welded in the 1G (flat) or 2G (horizontal) position with the member on rollers or a positioner. Field splices at erection joints may require 3G (vertical) or 4G (overhead) qualification if the erection sequence cannot reposition the member. Position qualifications on the WPS and WPQ must cover the field position before production welding begins.

Joint geometry. W-shape chord splices involve separate groove welds in the two flanges and the web. The groove configuration for the web and for the flanges may use separate WPS records if the process, polarity, or current range differs, or a single WPS covering both if essential variables align. Verify that the groove angle, root opening, and root face dimensions on the joint fit-up drawing match the WPS-qualified ranges before fit-up acceptance.

Steel backing. Most shop chord splices use steel backing bars on the root side of the groove. For statically loaded tension chords, backing removal is not always required but improves root quality and eliminates the backing-to-base-metal fillet weld as a fatigue detail. For cyclically loaded trusses — crane bridges, overhead conveyor structures, fatigue-critical industrial frames — backing removal and root back-gouging are standard practice in tension zones. See: CJP root pass inspection under AWS D1.1

Preheat requirements for heavy chord sections

Chord members in industrial trusses commonly use plate thicknesses or flange thicknesses of 1 in [25 mm] or greater. For A572 Grade 50 at 1 in, the minimum preheat per AWS D1.1:2025 prequalified conditions is typically 150°F [65°C] at ambient temperature. Cold ambient conditions, higher carbon equivalent, or high-restraint joint geometry require preheat above the table minimum.

The high-restraint nature of a chord splice — two chord segments with their full cross-sections butted together, often with steel backing — means transverse shrinkage is constrained from both sides. High-restraint CJP groove welds with insufficient preheat are a recognized cause of transverse hydrogen-induced cracking. The crack typically initiates in the heat-affected zone beneath the weld and may not surface visually for 24–72 hours after welding.

Preheat must be verified before arc strike and maintained as the interpass temperature minimum throughout the weld. For a multi-pass chord splice on a heavy W-shape, the interpass temperature minimum equals the preheat minimum, and the interpass maximum is typically 550°F [288°C] unless the WPS specifies otherwise for low-heat-input applications. See: Preheat and interpass temperature on a WPS

Tension chord vs. compression chord: what's different

Tension chords:

CJP groove weld required; steel backing removal required for fatigue-sensitive cyclic-load trusses
100% UT on CJP groove welds in primary tension members is the standard NDE scope
For cyclically loaded trusses, cyclic acceptance criteria apply — zero detectable undercut at the weld toe, stricter porosity limits
Postweld inspection of the root side is critical; UT to verify full root fusion before the joint is closed and back access lost

Compression chords:

CJP groove weld may still be specified by design, but direct bearing between machined ends can reduce the tensile demand on the groove weld
Some designs permit PJP groove welds with bearing fit; verify with the EOR — do not interpret a lack of explicit specification as permission
NDE sampling rate may be reduced if the design treats the splice as compression-bearing only, but full coverage is still common practice
Weld profile and alignment control remain critical to maintain column cross-section geometry under compressive load

See: Column splice weld procedure under AWS D1.1

NDE requirements for chord splice welds

CJP groove welds in primary tension chord members receive the full NDE treatment under AWS D1.1:2025:

Visual inspection of the completed weld, from both accessible sides, before UT or other NDE begins. Profile, undercut, crater cracks, and surface porosity are evaluated at this stage.

Ultrasonic testing (UT) on the full weld volume at 100% coverage is standard for primary tension chord splices. The acceptance table in Section 8 — static or cyclic, depending on the loading designation — governs the accept/reject thresholds. A UT technician who has only worked to static acceptance criteria should be briefed on the cyclic table before starting examinations on crane bridge or conveyor structure chord splices. See: UT acceptance criteria for structural welds under AWS D1.1

Magnetic particle testing (MT) is added when the specification requires surface NDE on fatigue-detail weld toes, or when the UT examination identifies near-surface indications that warrant surface method confirmation.

Welding sequence and distortion control

A chord splice in a W-shape requires a deliberate pass sequence to control angular distortion across the flange width and to maintain chord-axis alignment through the joint:

Weld the flanges first. The flanges carry the dominant share of bending stiffness. Completing the flange groove welds first establishes the chord alignment before the web constrains any residual angular error.

Balance passes across both flanges. For wide flanges, alternating heat input between the top and bottom flange during fill passes prevents a net angular pull toward one side. The sequence should be specified in the WPS technique section, not left to welder judgment.

Complete the web last. The web groove weld locks in the geometry established by the flanges. Welding the web before the flanges are complete introduces angular restraint at the flange-to-web intersection that complicates distortion correction.

Verify alignment at each sequence step. Use a straight edge and offset template to confirm the chord centerline is within fabrication tolerance before advancing to the next phase. A misaligned flange groove weld that is corrected before the web is welded takes minutes to fix. The same error discovered after the web is complete, with the cross-section fully restrained, may require heat straightening. See: Weld distortion control and sequence documentation

The WPS should specify the pass sequence explicitly. AWS D1.1:2025 requires the WPS to address technique, and for a W-shape chord splice, the sequence is a technique variable with direct consequences for product quality.

CWI inspection hold points for chord splices

Before welding:

Verify groove geometry (bevel angle, root opening, root face) against WPS qualified ranges
Check backing bar fit and tack weld placement
Measure and record preheat at the joint

During welding:

Check interpass temperature before each pass
Verify alignment at the flange sequence completion point before starting the web

After welding:

Visual acceptance against the loading-category criteria (static or cyclic)
UT examination per the NDE specification and acceptance table
Dimensional check of chord-axis offset and member straightness against fabrication drawing tolerances
NDE records signed, cross-referenced to the WPS and PQR

Chord splice inspection records belong in the same audit packet as the qualified WPS and the PQR backing record. When regulators or owners request complete documentation tracing a weld from procedure qualification through production NDE, chord splices with scattered records create delays. WPS Welding ties the NDE report to the qualified procedure and test record in a single file, ready for review at any stage.

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