Welding Procedure Specifications and Quality Documentation

What Is a Welding Procedure Specification?

A Welding Procedure Specification (WPS) is a written document that tells a welder exactly how to make a specific weld. It lists every variable that affects weld quality — base metal type, filler metal classification, shielding gas, amperage range, voltage range, travel speed, preheat temperature, and more. The WPS is not a suggestion; it is the governing instruction set for the weld. When you work under a code — AWS D1.1 for structural steel, ASME Section IX for pressure piping — you are required to weld within the ranges written on the WPS. Deviating from those ranges without authorization is a code violation and can result in rejected welds or unsafe structures.

WPS documents are qualified through testing called a Procedure Qualification Record (PQR). The employer or fabricator tests sample welds under controlled conditions, documents the results, and uses that data to support the WPS. As a welder, you will typically receive a completed WPS — you read it, you follow it, and you document your compliance.

FCAW-S Versus FCAW-G WPS Documents

Flux-cored arc welding comes in two modes: self-shielded (FCAW-S) and gas-shielded (FCAW-G). Each has its own WPS because the shielding method is an essential variable.

• FCAW-S WPS: No external shielding gas. The electrode flux generates its own protective atmosphere. The WPS will show "None" or "N/A" in the shielding gas field. Common in outdoor structural work and field erection.
• FCAW-G WPS: Requires an external shielding gas, typically 75% Argon / 25% CO₂ (C25) or 100% CO₂. The WPS will specify the gas type and flow rate in cubic feet per hour (CFH). Using the wrong gas, or forgetting the gas entirely, is an essential variable violation.

When you pick up a WPS, the first check is: does this document match the process I am about to use?

Reading the Essential Variables

Essential variables are parameters whose change requires re-qualification of the procedure. On a FCAW WPS, key essential variables include:

• Base metal P-number: Metals are grouped by P-number (from AWS or ASME). P1 is carbon steel. Welding a P3 chrome-moly steel with a WPS written for P1 is not permitted.
• Filler metal classification: The AWS classification printed on the electrode spool or tube — for example, E71T-1C for a gas-shielded electrode or E71T-8 for a self-shielded electrode. Using a different classification without an approved WPS change is a violation.
• Position: The WPS lists approved positions (1G, 2G, 3G, 4G for groove welds; 1F through 4F for fillet welds). A WPS qualified for 1G flat position does not authorize you to weld in the 3G vertical position.
• Preheat and interpass temperature: The WPS states a minimum preheat temperature and a maximum interpass temperature. Preheat prevents cold cracking by slowing the cooling rate. Interpass limits prevent overheating, which can degrade the heat-affected zone. You measure these with a contact thermometer or temperature-indicating sticks before striking an arc and between passes.
• Electrical characteristics: Polarity (DCEN or DCEP), amperage range, and voltage range. Running outside these ranges changes heat input, which changes the weld's mechanical properties.
• Travel speed: Expressed in inches per minute. Excessively fast travel creates a narrow, undercut bead; excessively slow travel causes excessive heat input and may cause burn-through.
• Technique: Stringer bead versus weave, maximum weave width, electrode angle, and work-to-electrode distance (wire stick-out).

Before you strike an arc, set your machine, check your gas flow if FCAW-G, measure preheat, and confirm each parameter against the WPS.

The Weld Traveler

A weld traveler (also called a weld data sheet or weld log) is the job-site document that travels with the weldment through fabrication. It records what actually happened during welding — as opposed to what the WPS says should happen. A complete traveler includes:

• WPS number referenced
• Base metal heat number (traceability to the mill certificate)
• Filler metal lot or heat number
• Preheat temperature recorded (measured, not assumed)
• Interpass temperature recorded for each pass or as required by the WPS
• Welder stamp or ID
• Date of welding
• Inspector's signature

Every field must be filled in. Blank fields are unacceptable — if a field does not apply, write "N/A" and initial it. Incomplete travelers can hold up an inspection, delay a project, and create legal liability.

Visual Inspection Report

A visual inspection (VT) report documents what the inspector observed on the completed weld surface. Under AWS D1.1, visual inspection is the first and most commonly required examination method. The inspector checks:

• Crack indications — none permitted in structural welds
• Porosity — size and frequency limits apply
• Undercut — depth and length limits apply per code
• Overlap — cold lap at the weld toe is rejectable
• Weld size and profile — fillet leg size must meet drawing requirements; groove welds must be full with allowable reinforcement height

The report records the joint ID, the acceptance criteria used (cite the code and clause generally), the finding for each discontinuity type, the accept/reject decision, and the inspector's signature and date.

Safety During Documentation Activities

Documentation happens at or near the work area. Welding slag and spatter remain hot long after the arc stops — always wear leather gloves when handling recently welded coupons. Keep the contact thermometer probe clean and calibrated; a dirty tip reads low and may cause you to start welding on an insufficiently preheated part. Never handle coupons near running welding equipment without confirming the machine is in a safe, non-welding state. If you are reviewing paperwork inside a welding booth while another student is welding nearby, use your safety glasses — grinding and chipping operations can throw debris unexpectedly.

Why This Matters for Your Credentials

NCCER Welding Level 2 emphasizes WPS compliance and documentation as a core competency. AWS D1.1 Certified Welder testing requires that the test weld be performed to a qualified WPS. ASME Section IX pipe qualification is documented on a Welder Performance Qualification (WPQ) record that parallels the traveler concept. Employers in structural steel, pressure vessel, and pipeline work expect you to read, follow, and document a WPS without supervision from day one on the job.