Why use SAW for thick plate?

Deposition rate. SAW deposits 4–10x as much weld metal per hour as SMAW or FCAW, with deep penetration and clean appearance. For multi-pass groove welds on plate over 1 inch thick, SAW pays for itself fast.

Is SAW prequalified on A516-70?

Yes, in most configurations. A516-70 is listed in Table 5.3 (Group II equivalent) and Table 6.9. With matched filler per Table 5.4 and a prequalified joint, SAW is prequalified under Clause 5. ASME Section IX qualification is also typical for pressure vessel work.

What's the most common ASME-equivalent essential variable for SAW?

Number of electrodes. Single-wire SAW versus twin-wire SAW (parallel or tandem) are different essential variables under both AWS D1.1 Table 6.6 and ASME IX QW-253. Switching counts requires requalification.

SAW WPS for A516 Grade 70 thick plate pressure-vessel work

Submerged arc welding (SAW) on A516 Gr. 70 thick plate is high-deposition, high-quality, and tightly documented. Here's a full WPS — including the ASME crossover.

Submerged Arc Welding (SAW) on A516 Grade 70 thick plate is the standard for pressure-vessel shells, large structural girders, and other heavy-section work. SAW's high deposition rate and clean, deep-penetration welds make it indispensable above ~1 inch thickness. Here is a complete WPS for shop SAW.

Identification block

WPS number: WPS-25-021
Revision: 0
Date: 2026-05-08
Code: AWS D1.1/D1.1M:2025 (also referenced for ASME Section IX dual-qualified scope where applicable)
Scope: Single-wire SAW groove welds on ASTM A516 Gr. 70, thickness 1 in to 4 in, in 1G position only
Status: Prequalified per Clause 5 (single-wire, flat position); ASME IX qualified per attached PQR for pressure-vessel applications

Process and joint

Process: SAW (Submerged Arc Welding), mechanized
Number of electrodes: Single wire
Joint detail: B-U4a (double-V groove without backing, with backgouging) from Annex B — typical for thick plate
Joint sketch: embedded as figure 1

Base metal

Specification: ASTM A516 Gr. 70
Group number: Group II (Table 6.9, 2025 edition)
ASME P-number (if dual-qualified): P1 Group 2
Thickness range: 1 in (25 mm) to 4 in (100 mm)
Form: plate

Filler metal and flux

Filler classification: A5.17 EM12K (or A5.23 for higher-strength alloy applications)
Flux classification: A5.17 F7AZ-EM12K-H8 (Lincoln Granular Flux, e.g.) — neutral or active flux per classification
Wire diameter: 5/32 in or 3/16 in
Storage: flux re-conditioned per manufacturer recommendation; typically 600–800°F [315–425°C] for 1–2 hours before use after exposure to humidity

The flux is part of the filler classification for SAW. Document the flux brand and lot.

Position

1G groove (flat) only — SAW is not practical in any other position
1F fillet (flat) optional

Electrical

Current: DC
Polarity: DCEP (or DCEN for higher deposition with reduced penetration)
Amperage range:
- 5/32 in wire: 400–650 A
- 3/16 in wire: 500–800 A
Voltage range: 28–36 V
Travel speed range: 16–28 ipm
Wire feed speed: controlled by power supply; documented per pass

Preheat and interpass

Minimum preheat: per Table 5.8 — for A516-70 Group II at thickness > 3/4 in, typically 150°F [65°C] or higher
Maximum interpass: 500°F [260°C] (non-CVN); CVN-required pressure-vessel work tighter per Table 6.8
Method: contact thermocouple, calibrated; verify both sides of plate for thick sections

ASME Section IX considerations

For dual-qualification work (where the same WPS is used on both AWS D1.1 structural and ASME IX pressure-vessel applications), additional documentation applies:

ASME P-number and F-number listed
A-number (chemical composition of weld metal) listed
PQR contains ASME-required tensile, bend, and (for some materials) impact data
ASME IX QW-253 essential variables verified independently of AWS Table 6.6

Most shops maintain ASME IX-supporting PQRs separately from AWS D1.1 PQRs, even when the test coupon is the same.

Technique

Multi-pass pattern: programmed travel; layer per pass to limit heat input
Slag removal: automated chipping or wire brush between passes
Backing: mandatory for B-U2; backgouging from second side for B-U4a
Cleanliness: flux must be dry; verified before each shift

Common pitfalls on this SAW WPS

Number of electrodes mislabeled. Single-wire and twin-wire are essential-variable distinct under both AWS and ASME.
Flux brand not listed. "EM12K" alone is insufficient — flux is part of the classification.
Polarity flip without requalification. DCEP and DCEN produce different penetration profiles; switching is essential.
Preheat below Table 5.8 for thick plate. A 4-in plate at 50°F preheat is non-compliant.
Dual-qualified scope claimed without ASME PQR. AWS D1.1 prequalification doesn't satisfy ASME IX. Pressure-vessel work requires its own PQR.

For pressure-vessel shops, a WPS tool that supports both AWS D1.1 and ASME IX essential-variable cross-checks prevents the most common dual-qualification mistakes.