Is ASTM A252 pipe piling prequalified under AWS D1.1?

A252 Grade 2 and Grade 3 are listed in the AWS D1.1:2025 prequalified base metal table. However, the higher carbon equivalent of Grade 3 (Fy = 45 ksi minimum) typically demands preheat verification per the code's preheat table even for prequalified WPS. PQR testing is required if the shop opts to exceed prequalified joint geometries or process limits.

What filler metal should I use for A252 Grade 3 pipe piling?

E7018 (SMAW) or ER70S-6 (GMAW) are the standard choices. Both provide adequate tensile overmatching for Grade 3 (Fu = 66 ksi minimum). Low-hydrogen classifications are mandatory at the joint's carbon equivalent and thickness levels — do not use E6010 or E6013 for the fill and cap passes.

How do I qualify a WPS for a pile splice in the field?

Most pile splices are butt joints welded in the 2G or 5G position depending on site constraints. A prequalified SMAW WPS meeting Clause 5 joint tolerances avoids PQR testing. If the contractor uses mechanized FCAW-G or SAW, a tested WPS with a PQR is required — the PQR test coupon must match the nominal wall thickness and joint geometry used in production.

What preheat is required for A252 pipe piling?

Preheat depends on the wall thickness and the heat of steel's actual carbon equivalent. A252 Grade 2 (up to ~0.40% C nominal) on wall thicknesses under 3/4 in typically requires 50–150°F preheat under AWS D1.1:2025 Table 6.3. Grade 3 heavier-wall pipe on high-restraint splices can require 200°F or higher. Always calculate CE from the actual MTR, not the nominal grade chemistry.

Oct 18, 20267 min read

ASTM A252 Pipe Piling WPS: AWS D1.1 Qualification Guide

Step-by-step WPS and PQR qualification guide for ASTM A252 Grade 2 and Grade 3 steel pipe piling under AWS D1.1:2025, covering carbon equivalent, preheat, and splice joint design.

WPS PQR AWS D1.1 Pipe Piling A252 Foundation Welding

ASTM A252 structural steel pipe is the workhorse of deep foundation work — driven into soil as bearing or friction piles for bridges, buildings, marine structures, and industrial facilities. Welded pile splices and connection welds to pile caps are structural welds that fall squarely under AWS D1.1 when the governing document is a structural steel specification or contract. Yet many fab shops and field contractors treat A252 as an afterthought, pulling a generic WPS off a shelf without checking whether it actually qualifies for the pipe's chemistry, wall thickness, and joint geometry.

This article walks through the AWS D1.1:2025 WPS qualification path for A252 pipe piling — what prequalified status covers, when you need a PQR, and what the CWI should verify before and during splice welding.

A252 Base Metal Grades and Chemistry

ASTM A252 specifies three yield strength grades:

Grade 1: Fy = 30 ksi minimum, Fu = 50 ksi minimum
Grade 2: Fy = 35 ksi minimum, Fu = 60 ksi minimum
Grade 3: Fy = 45 ksi minimum, Fu = 66 ksi minimum

The standard does not impose a maximum carbon content — it sets a minimum yield and lets the mill optimize chemistry to hit it. That creates a real weldability risk: some Grade 3 heats run with 0.35–0.45% carbon, pushing the carbon equivalent (CE) toward the upper boundary where preheat becomes significant.

Always review the material test report (MTR) for the actual heat chemistry before writing the preheat into the WPS. Do not use nominal ASTM minimums as your CE input.

The carbon equivalent formula referenced in AWS D1.1 is:

CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15

A Grade 3 heat with C = 0.42%, Mn = 1.10%, and no significant Cr/Mo/V/Ni/Cu yields CE = 0.42 + 0.18 = 0.60 — a value demanding 200°F or more preheat on wall sections above 1 inch under AWS D1.1:2025 Table 6.3.

Prequalified WPS Coverage Under AWS D1.1:2025

A252 Grade 2 and Grade 3 are listed among the prequalified base metals in AWS D1.1:2025 Clause 5. This means a shop can write a prequalified WPS for A252 splices using SMAW, SAW, GMAW (spray or globular transfer), or FCAW-G without running a PQR — provided the WPS strictly conforms to all Clause 5 limitations.

Key Clause 5 constraints that commonly trap A252 pile work:

Joint geometry. Pile splices are typically CJP butt welds between pipe sections of equal or unequal diameter. Prequalified joint configurations for pipe apply, and root opening and bevel angle tolerances are tighter than field crews sometimes assume. CJP groove welds require full penetration — a common field shortcut of partial-penetration splice welds is not a prequalified joint under Clause 5 and requires a tested WPS.

Wall thickness. Most prequalified joints have a minimum base metal thickness of 1/8 inch. A252 pipe ranges from light-wall (3/16 in) to heavy-wall (1 inch or more). Verify the prequalified procedure's qualified thickness range covers the production wall.

Process limitations. FCAW-S (self-shielded) with E71T-8 or E71T-11 electrodes is excluded from many prequalified joint configurations. GMAW short-circuit transfer is not prequalified for groove welds. If your field crew favors FCAW-S for fast out-of-position work, the WPS must be qualified by test.

Preheat. Even a prequalified WPS must apply the minimum preheat from AWS D1.1:2025 Table 6.3 based on the actual base metal CE and the nominal wall thickness. A prequalified WPS does not waive preheat — it only waives the PQR coupon testing.

When a PQR Is Required

A tested WPS (Clause 6) with a PQR is required for A252 pile work in these situations:

FCAW-S process: self-shielded flux-cored wire is not prequalified for groove welds in AWS D1.1
Mechanized or orbital welding: pipe pile splices using mechanized GMAW or orbital GTAW require an Clause 6 WPS
Unlisted joint geometry: custom internal back-ring splices, tapered transitions between pile diameters, or eccentric splices not matching Annex B joint designs
Heat input outside prequalified limits: some heavy-wall, high-preheat pile applications use higher heat input than prequalified parameters permit
Owner-specified testing requirement: project specifications or bridge owners often mandate a PQR even when the code would allow a prequalified WPS

For a tested WPS, the PQR test coupon thickness must represent the production wall. The essential variables for SMAW under AWS D1.1:2025 Table 6.6 require requalification if the wall thickness of the production pile falls outside the qualified thickness range from the PQR coupon. A common mistake is qualifying on a 1/2-inch test plate and then using the WPS on 3/4-inch-wall production pipe — outside the qualified range.

Filler Metal Selection

For A252 Grade 2 (Fu = 60 ksi), an E7018 (SMAW), ER70S-6 (GMAW), or E71T-1 (FCAW-G) filler matches or exceeds base metal tensile strength. Grade 3 (Fu = 66 ksi) is also adequately covered by E70XX fillers — AWS D1.1 does not require tensile overmatching beyond the minimum filler-to-base-metal compatibility requirement.

Low-hydrogen filler is mandatory for A252 Grade 3 and for any heat where CE > 0.45%. For SMAW, that means H8 or H4 suffix electrodes. E6010 is acceptable for the root pass only on a prequalified open-root joint — it must not be used for fill and cap passes where the CE warrants low hydrogen.

Preheat the joint to the WPS-specified temperature before striking the first arc with E6010 root passes — the 6G or 5G open-root first pass is the highest-risk location for hydrogen-assisted cold cracking in restrained pipe pile joints.

Preheat and Interpass Temperature

Preheat for A252 pile welding should be calculated from the MTR heat chemistry using the AWS D1.1:2025 Table 6.3 categories. Field CWIs frequently see three situations:

Grade 2, light wall (< 3/4 in), CE < 0.45%: Minimum preheat typically 50°F (essentially ambient above freezing). Verify ambient temperature — AWS D1.1 prohibits welding when base metal temperature is below 32°F without preheating to at least 70°F.

Grade 2, heavy wall (≥ 3/4 in), or Grade 3 any wall thickness with CE 0.45–0.55%: Minimum preheat 150–200°F. Measure with contact pyrometer or temp-stik at least 3 inches from the weld groove on both sides.

Grade 3, heavy wall, CE > 0.55%: Minimum preheat 200°F or higher; high restraint at pile caps may justify 250°F per engineering judgment. Document preheat temperature in the WPS and on the welder's traveler card.

Interpass temperature maximum is the same as for other structural steel under AWS D1.1 — typically 400°F for SMAW and 450°F for GMAW/FCAW. Heavy-section pile caps with continuous passes can accumulate interpass temperature quickly; post an interpass temp limit on the WPS and CWI should verify compliance with a non-contact IR thermometer.

Joint Design for Pile Splices

AWS D1.1:2025 Annex B prequalified groove joints apply to pipe in the same way as structural shapes. Common configurations for pile splices:

Single-V groove with backing ring: The most common shop splice for full-penetration pipe pile. The backing ring (a steel backing) is welded to the inside of the lower pile section before the upper section is fitted. Backing material must be steel of the same or compatible base metal group. The backing ring qualifies as a permanent steel backing — it stays in place.

Double-V groove (symmetric or asymmetric): Used for large-diameter, heavy-wall piles where back-gouging and back-welding is practical. Requires back-gouging to clean metal before welding the second side.

Field splice without backing: If the inside diameter is inaccessible, the first pass must be a sound open-root pass. This typically limits the process to SMAW or GTAW root passes followed by FCAW-G or SMAW fill.

CWI Inspection Checkpoints

Before the first arc on an A252 pile splice, the CWI should verify:

MTR review: base metal CE confirmed; WPS preheat matches actual CE
Filler metal: lot, classification, and storage verified (low-hydrogen electrode from a sealed container for H8/H4 SMAW; reseal opened containers per AWS D1.1 filler storage requirements)
Joint geometry: bevel angle, root opening, root face, and alignment within WPS and prequalified tolerances
Preheat: temperature measured with pyrometer, not temp-stik alone for critical joints
Welder qualification: WPQ covers the process, position (2G for horizontal rotation, 5G for fixed pipe), and material group

After welding, visual inspection per AWS D1.1:2025 acceptance criteria applies. UT is appropriate for CJP pile splice welds and is preferred over RT for pipe diameters below 24 inches due to geometric limitations of radiographic film placement.

Documentation for Foundation Projects

Foundation welding records are part of the structural special inspection package required by IBC Chapter 17. The CWI inspection report for each pile splice should record: pile number and location, WPS number and revision, welder ID, preheat and interpass temperatures measured, visual inspection result, and NDE method and acceptance. The pile erection log from the geotechnical contractor and the pile splice welding inspection log should be cross-referenced by pile number in the closeout package.

If your fab shop manages this documentation in spreadsheets today, a purpose-built WPS management platform keeps the WPS, PQR, and welder WPQ linked to each production weld record — reducing audit prep time from days to hours. Explore the weld procedure management tools at WPS Welding.

Rule library based on AWS D1.1:2025. Verify against your governing edition — the AHJ or contract may specify 2020 or an earlier edition.

Frequently asked.

Is ASTM A252 pipe piling prequalified under AWS D1.1?: A252 Grade 2 and Grade 3 are listed in the AWS D1.1:2025 prequalified base metal table. However, the higher carbon equivalent of Grade 3 (Fy = 45 ksi minimum) typically demands preheat verification per the code's preheat table even for prequalified WPS. PQR testing is required if the shop opts to exceed prequalified joint geometries or process limits.
What filler metal should I use for A252 Grade 3 pipe piling?: E7018 (SMAW) or ER70S-6 (GMAW) are the standard choices. Both provide adequate tensile overmatching for Grade 3 (Fu = 66 ksi minimum). Low-hydrogen classifications are mandatory at the joint's carbon equivalent and thickness levels — do not use E6010 or E6013 for the fill and cap passes.
How do I qualify a WPS for a pile splice in the field?: Most pile splices are butt joints welded in the 2G or 5G position depending on site constraints. A prequalified SMAW WPS meeting Clause 5 joint tolerances avoids PQR testing. If the contractor uses mechanized FCAW-G or SAW, a tested WPS with a PQR is required — the PQR test coupon must match the nominal wall thickness and joint geometry used in production.
What preheat is required for A252 pipe piling?: Preheat depends on the wall thickness and the heat of steel's actual carbon equivalent. A252 Grade 2 (up to ~0.40% C nominal) on wall thicknesses under 3/4 in typically requires 50–150°F preheat under AWS D1.1:2025 Table 6.3. Grade 3 heavier-wall pipe on high-restraint splices can require 200°F or higher. Always calculate CE from the actual MTR, not the nominal grade chemistry.