When a structural fab shop sets up FCAW-G for vertical joints on a multi-story steel frame, the first call from the CWI often comes around the second week: "Are you running that wire downhill on the CJP column splices?" If the answer is yes, and the WPS doesn't show a vertical-down test record, there's a nonconformance to write.
AWS D1.1:2025 has a specific and often misunderstood restriction on FCAW-G for vertical-downhill welding of CJP groove joints in structural steel. Understanding exactly what the code prohibits — and why — helps CWIs enforce it correctly and helps fab shops write WPS documents that don't get kicked back.
What AWS D1.1 Actually Says
AWS D1.1:2025 Clause 5 (prequalified WPS) limits the welding positions for each process and electrode type. For FCAW-G electrodes classified under AWS A5.20, the prequalified position table does not list vertical-down (3G progression downward or 6G with downhill progression) for CJP groove welds.
Prequalified WPS provisions exist to skip the PQR testing step — but only for process-position combinations the code has already validated through its own development testing. Vertical-downhill FCAW-G on CJP groove joints isn't in that validated set.
Under Clause 6 (qualification by test), a fabricator can develop a tested WPS for vertical-down FCAW-G on CJP groove joints. But the WPS must be supported by a PQR with mechanical test results from a test coupon welded in the vertical-down position — not a vertical-up PQR.
The practical result: most fab shops do not have this PQR, so most FCAW-G WPS documents do not cover vertical-down on CJP groove joints.
The Technical Reason: Arc-to-Fusion-Surface Geometry
Vertical-downhill welding with FCAW-G creates a specific failure mode that prompted AWS's restriction:
Pool flooding the fusion line. When welding downhill, gravity pulls the molten weld metal down ahead of the arc. On a groove joint, the molten pool can advance faster than the arc melts the base metal sidewalls. The result is a weld bead that sits on top of the groove face rather than fusing into it — the classic incomplete fusion defect that RT and UT later reveal as a planar indication.
Flux-cored wire drag. FCAW-G wires produce a slag system that's designed to support a flat or overhead weld pool. Running downhill, the slag behavior changes; there's a higher probability of slag entrapment at the toes and between passes in multi-pass CJP joints.
Heat input relationship. Higher travel speeds typical of downhill runs reduce heat input — which seems beneficial for distortion, but on thick multi-pass CJP joints it means each pass is putting less heat into the groove face, increasing the likelihood that the prior pass bead profile creates a shadow zone the next arc doesn't fully penetrate.
AWS D1.1's prequalified WPS framework excludes combinations where the fusion risk is elevated enough to demand proof. Vertical-down FCAW-G on CJP is that combination.
Which Electrodes Are Affected
The restriction applies to standard FCAW-G electrodes classified per AWS A5.20:
- E71T-1C, E71T-1M (including J and H4 suffix variants) — not rated for vertical-down on CJP groove welds under prequalified provisions
- E71T-9C, E71T-9M — not rated for vertical-down on CJP groove joints
- E71T-12C, E71T-12M — same restriction
AWS A5.20 does include a position designator "P" in the supplemental diffusible hydrogen and position classification system. An electrode identified with P in its supplemental test report has been tested by the manufacturer for vertical-down welding. However, that manufacturer's test does not automatically create a prequalified WPS — it means the electrode can be used in a Clause 6 tested WPS for vertical-down.
The practical implication: even with a P-designated electrode, the fabricator still needs a PQR supporting the vertical-down CJP WPS, with tensile, bend, and macro specimens from a test plate welded downhill.
CWI Enforcement Points
When reviewing a job's WPS documents for vertical structural joints, verify:
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Position column on the WPS. Does it show "3G" or "5G" or "all positions"? If it shows vertical, confirm the direction (up or down). Vertical-up and vertical-down are separate qualifications.
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PQR position. If the WPS claims vertical-down coverage, pull the supporting PQR. The test coupon position recorded on the PQR must match. A PQR run 3G vertical-up does not qualify vertical-down per Table 6.6 — position is an essential variable under AWS D1.1:2025 Table 6.6.
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Electrode classification. Confirm the wire used in production matches the electrode classification on the WPS. Switching from E71T-1C to E71T-9C between jobs is an essential variable change (filler metal classification) requiring WPS revision.
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Welder qualification. Welder performance qualification (WPQ) follows weld position: a welder qualified 3G uphill is not qualified for 3G downhill. The two are tested and documented separately.
Rule library based on AWS D1.1:2025; verify against your governing edition. Position and essential variable tables may differ in the 2020 and earlier editions.
WPS Options for Vertical Structural Joints
A fab shop that wants or needs to weld CJP groove joints vertically has these paths:
Vertical-Up FCAW-G (Most Common)
The standard solution. E71T-1 and E71T-9 electrodes are well-suited for vertical-up welding of CJP groove joints. AWS D1.1:2025 Clause 5 includes vertical-up FCAW-G in its prequalified scope (within the thickness limits of Clause 5). A prequalified WPS for vertical-up FCAW-G doesn't need a PQR.
The tradeoff: vertical-up is slower and typically requires more welder skill to manage the pool, especially on wider groove openings. Some shops try to switch to vertical-down to improve production rate — which is exactly the scenario that leads to the WPS violation described above.
SMAW E7018 Vertical-Up (Conservative Fallback)
For the few shops that need a fallback for vertical joints and have a long SMAW history, AWS D1.1:2025 Clause 5 prequalifies E7018 (low-hydrogen) for vertical-up CJP groove welds across a wide thickness range. Slower deposition rate, but no PQR required.
FCAW-G Vertical-Down by Tested WPS
If production demand is high enough to justify it, develop a Clause 6 tested WPS for vertical-down. You'll need:
- A test assembly welded in the vertical-down position
- Mechanical tests per Table 6.6 (tensile specimens, guided-bend specimens)
- Macro specimen showing fusion at both groove faces
- Results recorded on a PQR, signed by the responsible party
- No essential variable changes between the PQR test and production welding
This path is appropriate for high-volume column splice programs where vertical-down speeds up throughput enough to offset the PQR cost.
GTAW Root + FCAW-G Fill, Vertical-Down
Some contractors develop a hybrid WPS with GTAW for the root pass (which can be run downhill more safely due to lower amperage and better arc control) and then FCAW-G for fill and cap runs in vertical-up. This is a valid approach but requires a multi-process WPS with separate essential variable documentation for each process segment. See also multi-process WPS essential variables under AWS D1.1 for the documentation framework.
Production Control After WPS Approval
Even with a valid vertical-down tested WPS, production monitoring matters:
Travel speed. Vertical-down runs have a natural tendency to speed up as welders gain confidence. Faster travel = lower heat input = higher fusion risk on groove sidewalls. The WPS should specify a travel speed range, and the CWI or welding supervisor should verify compliance on first-article welds.
Root pass inspection. For CJP joints with a backing bar, the root pass is the highest-risk pass for vertical-down fusion issues. Full visual inspection of the first pass before proceeding is standard practice — any cold lap or toe fusion issue must be removed by grinding before the next layer.
NDE method selection. UT is more sensitive to planar lack-of-fusion indications than RT. For vertical-down CJP groove welds — especially under a tested WPS where the fabricator accepted higher risk — UT is the preferred NDE method. See NDE method selection for structural welds for how to select the right technique for each joint type.
Common Misunderstandings
"The foreman said we've been doing it for years." Long-standing shop practice and AWS D1.1 compliance are different things. A prior EOR who didn't know to check is not precedent. If the current contract specifies AWS D1.1:2025, the current WPS documents govern.
"The wire says it's all-position." AWS A5.20 electrode classification uses position designators that describe the electrode's capability, not what's prequalified under AWS D1.1. An all-position electrode can still require a tested WPS for vertical-down CJP groove welds.
"We have a 1G and 3G PQR — that covers everything." Under AWS D1.1:2025 Table 6.6, position is an essential variable. The 3G PQR covers the vertical position but the progression direction (up vs. down) is also part of the essential variable record. A 3G PQR with uphill progression does not qualify a downhill production WPS.
For fab shops looking to streamline WPS management and avoid exactly these kinds of position/progression errors, a software-based WPS library that tracks essential variable coverage by position and progression eliminates the manual cross-check risk. See how modern WPS tools compare to spreadsheet management at /pricing.
Vertical-down FCAW-G on CJP structural groove welds is one of the more common compliance gaps found during third-party WPS audits. The restriction isn't a bureaucratic technicality — it reflects real fusion risk that process development testing has documented. A shop that understands the restriction and its roots makes better decisions about when to invest in a vertical-down tested WPS and when to stick with proven vertical-up procedures.