Can the same WPS cover both shop and field welding?

Technically yes if the WPS is conservative enough to cover field conditions. In practice, most shops maintain separate WPSs because field-specific constraints (wind protection, position, access) push field WPSs toward different processes and parameters.

Why is FCAW-S so common for field work?

Self-shielded flux-cored welding (FCAW-S) doesn't rely on an external shielding gas, so wind doesn't blow the shielding away. It's the dominant process for structural steel erection in the US.

What wind speed is too high for gas-shielded welding?

AWS D1.1 generally cites 5 mph as the threshold above which gas-shielded processes require windbreaks. Above ~15-20 mph, even with windbreaks, weld quality degrades enough that work should be deferred.

WPS for field welding vs shop welding: the differences that matter

Field welding adds wind, weather, position constraints, and access challenges that shop welding doesn't have. Here's how to write a field-welding WPS that survives reality.

Field welding looks like shop welding from the outside, but the conditions are different enough that the WPS needs to be different too. Wind, weather, position constraints, lighting, and access all shift the procedure. Here is what a field-welding WPS captures that a shop-welding WPS doesn't.

Process selection

Shop production gravitates toward processes with the best deposition rates and indoor-environment compatibility:

FCAW-G (gas-shielded flux-cored)
GMAW spray or pulsed
SAW for thick plate

Field erection gravitates toward processes that tolerate weather:

FCAW-S (self-shielded flux-cored) — the dominant field process
SMAW with low-hydrogen rods
Hybrid GTAW root + SMAW fill on pipe

The field-vs-shop process gap is large. Trying to use a shop process in the field — GMAW spray on a windy beam-to-column connection, for instance — produces porous welds that fail visual and radiographic inspection.

Wind protection

The WPS for field gas-shielded work must address wind:

Wind protection:
  Maximum allowable wind speed at the arc: 5 mph [2.2 m/s]
  Windbreak required when wind speed exceeds: 5 mph
  Windbreak type: tarpaulin or rigid panel, minimum 1 ft beyond joint perimeter
  Wind speed verification: anemometer at the arc, every 30 minutes
  Suspension trigger: wind speed > 15 mph; defer work

The WPS for self-shielded processes (FCAW-S, SMAW) can be less restrictive on wind, but should still specify a suspension trigger.

Preheat in the field

Field preheat is harder than shop preheat. Cold steel in winter, no easy access to a furnace, propane torch quality varies:

Preheat method:
  Primary: propane or oxy-fuel torch
  Backup: electrical resistance heating blanket
  Heating pattern: heat to required temp, then verify with calibrated crayon
  Verify location: 3 in [75 mm] from joint centerline, on the heat-applied side
  Cold-weather note: ambient < 40°F [4°C] requires preheat regardless of code minimum

The "cold-weather note" is common in field WPSs. AWS D1.1 doesn't require preheat above some thicknesses, but the AHJ or owner may require it anyway when ambient is cold.

Position

Field welding often involves positions that shop welding can avoid:

Overhead (4G groove, 4F fillet) on column-to-base-plate work from below
Vertical-up (3G) on splices and erection joints
5G and 6G on pipe field welds

The supporting PQR must qualify the position(s) the WPS claims. A shop PQR welded in 1G alone doesn't authorize 4G field work.

Access and visibility

Field WPSs sometimes need to address physical constraints:

Joint cleaning standard. Shop has grinders; field may have only wire brushes.
Visual inspection access. Some field joints can be inspected from one side only; the WPS should note this.
Tack weld accessibility. Field tack welds may need to hold rigid alignment for hours; tack spacing should reflect this.

Documentation in the field

Production records for field welds are harder to maintain than shop records:

Time-temperature data for preheat / interpass is often crayon-verified (no thermocouple log)
Welder stamp goes on the weld but assignment paperwork lives at the trailer office
Daily inspection logs depend on field CWI presence

A WPS for field work should explicitly state what production records will be kept and by whom.

Sample field WPS scope statement

Scope: FCAW-S production welds on ASTM A992 wide-flange field splices,
       beam-to-column moment connections, and column-to-base-plate
       connections. Thickness 1/4 in to 1-1/2 in. Positions 1G/2G/3G/4G
       and corresponding fillet positions. Field application.

The "field application" tag flags this WPS as field-only. Pair with a corresponding "shop application" WPS for the same scope used indoors.

Common field-WPS findings

WPS authorizes outdoor gas-shielded process without wind protection. Welds will be porous when wind picks up.
Preheat method specified as "torch" without acceptance criteria. No way to verify.
Joint cleaning standard not adjusted for field constraints. Welder told to grind to brick when only a wire brush is available.
WPS doesn't address position progression direction. Some field welds are vertical-down by necessity (overhead pipe); position progression must be qualified.
CWI coverage assumed but not specified. Field welding without a CWI in the loop is itself a finding for AISC-certified erectors.

A WPS tool that supports "scope tagging" (shop vs field) and "environmental conditions" (wind, ambient temperature, preheat method) makes field WPSs explicit instead of accidental.