Electric Arc Welding Procedure: The Complete Guide to WPS, PQR, and Code-Quality Welds

Table of Contents

What Is an Electric Arc Welding Procedure? The Complete Definition

An electric arc welding procedure is a written, controlled recipe for joining metal with an arc. It records the base metal, filler metal, joint design, electrical settings, welding position, preheat, and technique — every variable that decides whether a weld holds under load or cracks on the first cold morning.

A weld is not just a pretty bead. It is a structural promise, and the procedure is the document that makes that promise repeatable. Codes therefore treat it as a controlled record, not a casual set of numbers.

Base metal and filler metal
Joint design and fit-up
Electrical parameters — amps, volts, polarity, travel speed
Position, preheat, and technique

A Shop Story: The Weld That Looked Perfect

A fabricator once asked me to “just make it stick” on a trailer repair. No procedure, no settings sheet — just a dial and a hunch. The bead looked clean, so we loaded it up. Two weeks later the tongue cracked beside the weld: the amperage had been too hot for the thin wall, and nobody had specified a root gap. The weld passed the eye test and failed the road test.

That is the point of a procedure. It replaces guesswork with variables somebody already tested and proved. For welders building hand skills, structured welding practice and a written procedure work together.

WPS, PQR, and WPQ: Three Documents Everyone Confuses

Most confusion starts with three lookalike documents. The Welding Procedure Specification (WPS) is the instruction sheet. AWS A3.0 defines it as a document providing the required welding variables for a specific application to assure repeatability by properly trained welders. The Procedure Qualification Record (PQR) is the proof behind it: it documents the actual variables used to weld a test coupon and the mechanical test results that prove the procedure works.

The Welder Performance Qualification (WPQ) is a different animal. It proves a person can follow the WPS and produce sound welds — not that the procedure itself is correct. A WPS without a PQR is a wish; a WPQ without a WPS is a welder shooting in the dark.

Qualified, Prequalified, or Just Informal?

Not every procedure carries the same legal weight. A fully qualified WPS is backed by a PQR and approved and dated by the organization that authorizes it. A prequalified WPS skips destructive testing by relying on joint and material rules a code already trusts. A hobbyist’s informal approach is just experience and feel, with no documentation.

Quick Note: A WPS is only valid when approved and dated by the organization that authorizes it. An unsigned, undated sheet is a draft, not a controlled procedure.

Structural codes take this seriously. AWS D1.1, the backbone of steel construction welding, was originally published in 1928 as the Code for Fusion Welding and Gas Cutting in Building Construction. For simpler applications, AWS also publishes Standard Welding Procedure Specifications (SWPS).

What the Rest of This Guide Covers

This guide walks the full path: the physics of the arc, every WPS variable, how PQR testing works, electrical parameters and heat input, base and filler metals, safety (guided by OSHA’s welding standard), defects, process comparison, and how to build your own procedure. It is written for hobby welders, fabricators, engineers, and inspectors alike — anyone who wants welds that look good and survive.

Whether you are dialing in TIG polarity or setting up a first wire feeder, the logic holds: define the variables, test them, and write them down. If you are new to the gun, start with a solid beginner’s guide to using a wire welder, then learn to read the bead with our breakdown of good versus bad MIG welds.

In the end, an electric arc welding procedure is one of the most honest documents in a shop. Everything on it was earned by burning, bending, and breaking metal on purpose — so the weld you make tomorrow can be trusted today.

How the Electric Arc Actually Works: Physics Behind Every Procedure

Every value on a WPS traces back to one physical event: an electric arc. Strip away the paperwork and you find a controlled, sustained electrical discharge leaping the gap between electrode and workpiece, ionizing the gas between them, and converting electrical energy into concentrated heat. Understand that mechanism and the numbers on the form stop looking arbitrary.

What an Electric Arc Really Is

An arc begins when the gap between the electrode and the metal becomes ionized—atoms lose electrons, become charged particles, and turn an insulator (air) into a conductor. Once that channel opens, current flows, and the resistance of the ionized gas converts electrical energy into heat. The result is extreme: arc welding temperatures commonly reach 6,500°F to over 10,000°F. That is hot enough to melt steel on contact and far more concentrated than a gas torch, which is exactly why the arc can fuse metal in seconds while leaving the surrounding plate cool enough to touch.

Quick Note: An electric arc is essentially a controlled, sustained electrical discharge—electricity deliberately forced to jump a gap through ionized gas, regulated precisely enough to melt metal instead of wrecking the equipment.

Arc Temperature vs. Other Heating Methods

It helps to put those temperatures in perspective. An oxy-acetylene flame peaks around 5,600°F, and a blacksmith’s forge runs cooler still. The arc sits well above both, and—critically—it delivers that heat in a tight, localized column rather than spreading it across the plate. Narrow heat-affected zones, deep penetration, and fast travel speeds all flow from that concentration. A procedure tunes the arc’s energy density so the metal melts where you want and stays solid where you don’t.

Five Processes, Five Rulebooks

The world’s welding procedures govern a whole family of arc processes, and each carries its own variable set and qualification rules. Welding processes used in precision manufacturing range from manual stick to fully automated submerged arc, and the physics shifts with each one.

SMAW (stick): the flux coating on the electrode decomposes to create shielding gas and slag, so no external gas is required.
GTAW (TIG): uses a non-consumable tungsten electrode, giving the operator independent control of current and filler.
GMAW (MIG) and FCAW (flux-cored): both use a continuously fed wire electrode that doubles as filler metal, fed through a replaceable contact tip.
SAW (submerged arc): buries the arc under a blanket of granular flux for high-deposition, automated work—see robotic submerged arc welding in practice.

AWS B2.1 specifies qualification requirements for SMAW, GTAW, SAW, GMAW, FCAW, plasma arc, electroslag, and other arc processes—confirming that one procedure cannot cover them all.

Polarity, Electrode, and Shielding: The Variables Behind the Variables

How an arc behaves depends heavily on polarity. Swap the leads and you move where the heat concentrates: electrode-positive pushes more heat into the work, electrode-negative into the electrode. That single choice changes penetration, deposition, and even whether aluminium oxides break down—the reason TIG polarity gets its own full discussion. Electrode type matters just as much, since a tungsten rod and a flux-coated stick behave nothing alike. So does the shielding medium: gas, flux-derived vapor, or submerged granular flux all change arc stability and bead chemistry. Arc stability is itself a variable: too little shielding and the arc wanders, spatters, and produces poor fusion.

Each of these levers is a variable a procedure must lock down. Change the shielding gas, the polarity, or the electrode classification, and you have arguably created a new procedure—one that may require fresh qualification. That is why AWS D1.1 treats them as essential variables rather than shop-floor preferences. Standards bodies even publish pre-qualified standard welding procedure specifications to shortcut that work.

Next time an inspector asks why a specific gas or polarity is stamped on the form, the answer is physics. The process used to qualify that procedure is the subject of the sections ahead.

The WPS Step by Step: Every Variable You Must Document

A welding procedure specification is not a suggestion sheet—it is a contract with the code. Every line exists to lock down a variable that, if it drifts, changes the metallurgy, the strength, or the soundness of the finished joint. A WPS typically includes the welding process, joint design, base metals, filler metals, shielding, preheat, position, electrical characteristics, technique, and post-weld heat treatment. Let’s walk the document block by block.

The Header Block: Identification, Revision, and Date

The top of the form carries your company name, a unique WPS number, the revision level, and the date. That revision line matters more than people think: when a procedure changes, the revision bumps, and old work must be traceable to the version actually used. The header also references supporting documents. A WPS may be supported by one or more PQRs, and a single PQR may support one or more WPSs—one test coupon can legally back several related procedures stored under different WPS numbers.

Process, Type, and Position

Next comes the welding process—SMAW, GMAW, FCAW, SAW, or GTAW—and the degree of automation: manual, semi-automatic, mechanized, or automatic. A hand-held stick electrode and a robotic arc are not interchangeable, and the code treats them differently. Position (1G through 6G) and vertical progression (uphill or downhill) get their own lines, because gravity changes how the puddle freezes and how much heat the joint absorbs.

The Joint, the Metals, and the Filler

Here you document joint design (groove type, included angle, root gap, backing), the base metal specification and qualified thickness range, and the filler metal classification plus diameter. Listing “ASTM A572 Grade 50” is not enough—the WPS states the thickness band the procedure was tested on, since cooling rates shift with section size.

Shielding, Thermal Control, and Technique

Shielding gas mix and flow rate—or flux type—sit alongside preheat and interpass temperature limits. Then the electrical characteristics: current type, polarity, amperage and voltage ranges, and travel speed. Finally, technique: stringer or weave beads, number of passes, and electrode angle. Polarity alone can flip penetration, which is why getting it right on a flux core procedure matters as much as on a critical GTAW root—the same DCEN-versus-DCEP logic that governs TIG welding polarity applies here. Many procedures finish with a post-weld heat treatment clause, or a firm “none required.”

Essential, Nonessential, and Supplementary Variables

This is where requalification lives. Change an essential variable and you must requalify the procedure with new testing. Essential variables move mechanical properties: filler metal classification, base metal grouping, preheat, and heat input among them. Nonessential variables—travel speed ranges, electrode brand, or the number of passes—can be changed with a simple revision; no new coupon needed. Supplementary essential variables only activate when notch toughness is specified, typically triggering impact testing and tightening heat-input windows.

Quick Note: Under AWS D1.1, “prequalified” WPSs that meet stipulated conditions do not require procedure qualification testing—but a written WPS is still required. D1.1 covers the prequalified requirements in Clause 5 and qualification in Clause 6 (2025 edition).

Note: AWS also publishes Standard Welding Procedure Specifications (SWPS) that a shop can adopt without developing its own; see the AWS B2 committee’s SWPS resources.

A Real Groove Weld Example

Say you qualify a single-V groove on 1/2-inch A572 Grade 50 to the same steel. A shop-floor WPS line might read: SMAW, E7018, 1/8 in., DCEP, 110–130 A, 22–26 V, travel 4–6 in./min, 60° included angle, 3/32 in. root gap, 50°F minimum preheat, 400°F maximum interpass, three stringer passes, no PWHT. Every range is a tested window, not a guess.

How to Read a WPS on the Shop Floor

Read ranges, not single numbers—they are the legal window you weld inside. Check polarity and amperage first, confirm the position matches yours, then verify filler classification and diameter against the spool or rod you picked up. If anything is missing or unclear, stop and ask; a good welding practice habit is treating the WPS as the authority over habit or memory.

Procedure Qualification Records (PQR): Testing a Weld Before You Trust It

When a foreman hands you a Welding Procedure Specification (WPS), that document only holds weight because it was proven. A WPS becomes “qualified” by welding a test coupon under the exact parameters listed, subjecting it to destructive and nondestructive tests, and recording the results in a Procedure Qualification Record (PQR). Think of the coupon as the receipt: if it passes, the procedure is valid. If it fails, the numbers go back to the drawing board. This is the backbone of code-quality work across structural, pressure, and fabrication jobs.

Turning a Coupon Into Proof

The qualification process begins with a test weld. For a groove weld on plate, a welder or welding operator will deposit metal onto a prepared joint exactly as the proposed WPS states. Once cooled, that coupon is sectioned into specimens for testing. According to AWS B2.1, tension and guided-bend specimens are required for groove-weld procedure qualification, with notch-toughness tests added when required by the referencing code. These results are logged on the PQR and become the boundary for what that WPS can cover.

The Tests That Separate Acceptable From Unacceptable

Not every job calls for every test, but a few are staples. Tensile testing pulls a specimen until it breaks to confirm the weld is at least as strong as the base metal. Guided bend tests (face and root) stress the fusion line to reveal cracks or lack of fusion. A nick-break test does a similar job for certain materials and processes. For fillet welds, fillet weld soundness tests and macroetch expose internal discontinuities by cutting and etching a cross-section. Lastly, radiographic (RT) or ultrasonic (UT) examination can verify soundness without destroying the entire coupon. For performance, a welder or welding operator may be qualified by volumetric NDE of a test coupon or by bend tests taken from the coupon.

Quick Note: Acceptance criteria vary by code. A small, tight indication may be allowed under AWS D1.1, but rejected under ASME Section IX. Always check the governing code for your job.

Thickness Ranges, Diameters, and Essential Variables

A qualified procedure is not a free pass for any thickness. The thickness of the test coupon sets the range the WPS can cover. For example, qualifying on 1/2 inch plate allows a certain range up and down, but qualifying on 1-1/2 in (38 mm) or more removes the upper thickness limit for many materials under ASME Section IX. Diameter ranges follow similar logic for pipe. These boundaries only hold if the essential variables stay within limits. Changes to process, base metal group, filler metal, shielding gas, preheat, post-weld heat treatment, or electrical variables can all trigger requalification. This is why shops practice strict parameter control before testing.

Procedure Qualification vs. Welder Qualification

One of the most common mix-ups is PQR versus WPQ (Welder Performance Qualification). A PQR qualifies the procedure: it proves the method can produce sound welds. A WPQ qualifies the welder: it proves that individual can execute that method. Performance qualification covers process, position, thickness range, and vertical progression (uphill or downhill) for the test. Under AWS D1.1, a welder’s qualification remains in effect indefinitely unless the welder has not used a given process for longer than 6 months. This separation keeps accountability clear between method and skill.

A Practical Example

Consider a structural shop qualifying a shielded metal arc procedure for 1/2 inch A36 plate. They weld a single-V groove coupon per their proposed WPS, then cut it for two tensile specimens, four guided bends (two face, two root), and a macroetch. After passing all acceptance criteria, the test results are recorded on the PQR. From there, the WPS can be written with a qualified thickness range for that joint. The welder who ran the coupon may also earn a WPQ for that process and position. Safety remains non-negotiable throughout, from protective eyewear to proper NIOSH-recommended ventilation.

Ultimately, the PQR is not paperwork for paperwork’s sake. It is proof earned by fire, force, and precision. By testing before you trust, a qualified electric arc welding procedure keeps welds sound, workers safe, and structures standing for years to come.

Electrical Parameters That Make or Break a Procedure: Amps, Volts, Polarity, and Heat Input

Every number printed on a WPS traces back to one thing: electricity. The welding machine feeds current through the electrode, the arc converts that current into heat, and the heat decides how the metal melts, mixes, and cools. Change one electrical variable and you change penetration, bead shape, deposition rate, and the final mechanical properties. That is why the electrical section of a procedure is not negotiable.

Current Type and Polarity: DCEN, DCEP, and AC

Direct current (DC) flows one direction. When the electrode is negative (DCEN, or “straight polarity”), electrons bombard the workpiece and dump most of the heat into the base metal—deep penetration, narrow bead. When the electrode is positive (DCEP, or “reverse polarity”), more heat lands on the electrode, which melts faster and gives a cleaning action. You can see this trade-off clearly in TIG welding polarity, where DCEN handles steel and DCEP (or AC) tackles aluminium.

Alternating current (AC) switches direction constantly, splitting the difference: it gives a balance of penetration and cleaning, which is why AC still dominates stick welding on rusty steel and some aluminium work. DC welding aluminium behaves very differently, and flux-core wire has its own rules—see DCEN vs DCEP for flux core.

Constant Current vs Constant Voltage

Power sources are built around one of two behaviors. A constant-current (CC) machine holds amperage steady while voltage floats, which suits manual processes where arc length changes constantly—SMAW and GTAW. A constant-voltage (CV) machine holds voltage steady and lets current rise and fall with wire-feed speed, which is exactly what semiautomatic GMAW, FCAW, and SAW need.

Amperage, Voltage, Wire Feed Speed, Travel Speed, and CTWD

Amperage controls penetration depth and deposition rate—more amps, more metal melted. Voltage controls arc length and bead width; a wider arc flattens and widens the bead. Wire feed speed (WFS) sets how fast filler enters the arc, and it directly drives amperage on a CV machine. Travel speed is how quickly you move; too slow and the bead piles up and overheats. Contact-tip-to-work distance (CTWD) changes voltage readings—stretch it out and voltage rises and current drops, weakening penetration. Keep an eye on the consumable itself in our contact tip guide.

Heat Input: The Number That Protects the Metal

Heat input ties all of it together. The formula:

Heat input (kJ/in) = (Volts × Amps × 60) ÷ Travel speed (in/min)

Say your WPS lists 25 volts, 200 amps, and 8 in/min of travel. Heat input = (25 × 200 × 60) ÷ 8 = 37,500 J/in, or 37.5 kJ/in. Bump travel speed to 12 in/min and it drops to 25 kJ/in. That single lever—travel speed—can push you over a code limit without touching the dials at all.

Higher heat input means slower cooling, a wider heat-affected zone (HAZ), and softer, sometimes embrittled metal. Most WPSs cap the maximum permitted heat input for exactly this reason. Under ASME Section IX, a heat input increase (QW-409.1) is a supplementary essential variable that becomes a full essential variable when the construction code requires impact testing. Variable classification also depends on the process: a variable essential for SMAW (QW-253) may be nonessential for GTAW (QW-256).

GMAW Transfer Modes

Amperage ranges also decide the transfer mode in GMAW: short-circuiting at low current, globular in the middle, and spray at high current. The WPS names the mode because each one changes penetration and heat input—and deposition behavior you can sharpen with deliberate welding practice.

On the machine, amperage and voltage dials are calibrated in broad steps, and the wire-feed knob on a CV machine effectively sets the amperage. Confirm real values with a clamp meter or the digital display, then compare against the WPS. A dial position of “6” means nothing until it reads the amps the procedure calls for.

Quick Note: A machine dial reading is not a WPS value. Always verify it with a meter and match the procedure—never “turn it up till it sounds right” on code work.

Base Metals, Filler Metals, Joint Design, and Preheat: The Support Cast

A procedure is only as strong as the metals and geometry it describes. Two plates, one electrode, and a gap—get any one of these wrong and the strongest amps in the world won’t save the joint.

Base Metal Grouping: P-Numbers and AWS Groups

Codes cluster thousands of steels into families so you don’t qualify every alloy separately. ASME uses P-numbers, while AWS D1.1 organizes structural steels into groups with similar weldability. Within a group, one qualified procedure usually covers the rest. Cross a group boundary—say, from mild steel to quenched-and-tempered—and you need new testing. The AWS D1.1 Structural Welding Code also lists prequalified base metal–filler metal combinations in Clause 5, so some pairings are approved without fresh qualification.

Grouping saves enormous time. A36 and A572 Grade 50, for instance, share similar weldability, so one qualified WPS frequently covers both. Step up to a quenched-and-tempered plate and the rules change overnight—higher carbon equivalent means more preheat and slower cooling.

Reading a Filler Metal Classification

Every electrode code tells a story. Take E7018: E means electrode, 70 is 70,000 psi minimum tensile strength, 1 is any-position, and 8 signals a low-hydrogen iron-powder flux. ER70S-6 is a solid wire (ER) at 70 ksi with a “6” deoxidizer level. E71T-1, covered by AWS A5.20, is a carbon steel flux-cored electrode—the workhorse of gasless FCAW you’ll find in our gasless MIG welding guide. For solid-wire work, our guide to MIG welding wires breaks down how the S and deoxidizer digits affect performance.

Stronger isn’t always better. Matching filler to base strength works for most structural work, but undermatching (a slightly softer filler) can improve ductility and reduce cracking on high-strength or restrained joints. Overmatching can harden the heat-affected zone and invite trouble.

Joints, Grooves, and Fit-Up

Joint type and groove geometry decide penetration and distortion. The common arrangements are butt, T, lap, and corner; grooves come as V, bevel, J, or U. Root opening, root face, and groove angle all appear on the WPS because each one governs how the arc reaches the root. Backing bars support the root; back gouging removes it and re-welds from the far side for full penetration.

Root opening typically runs 1/16 to 1/8 in for a single-V butt on plate, while a 60-degree included angle gives the electrode room to reach the root without excessive fill. Fit-up is where most procedures quietly fail: a wider root opening than specified overheats the puddle and can burn through, while too tight a gap starves penetration.

Here’s the prequalified shortlist under D1.1:

Joint	Typical Groove	Process/Position
Butt	Single-V, double-V, square	SMAW/GMAW/FCAW, all
T	Fillet, single-bevel	All positions
Lap	Fillet	All positions
Corner	Square, bevel	All positions

Change a prequalified joint beyond these limits—thicker material, a different bevel—and qualification testing kicks in. Our lap weld joint guide shows how small fit-up errors translate into weak welds.

Preheat, Interpass, and Post-Weld Heat Treatment

Quick Note: Preheat isn’t about comfort—it slows cooling so hydrogen escapes and hard martensite never forms.

Thick sections and high-carbon steels cool fast, trapping hydrogen and forming brittle zones. D1.1 Clause 5 sets minimum preheat and interpass temperatures based on thickness and carbon equivalent. Post-weld heat treatment (PWHT) relieves residual stress and tempers the HAZ. Watch it closely: excessive heat input and slow cooling can actually degrade toughness, which is why impact-tested procedures control it tightly. Good welding practice treats temperature as a measurable variable, not a guess.

For impact-critical work, the WPS pins down exact PWHT temperature and hold time because toughness is easy to lose and hard to win back. ASME IX governs much of this testing for pressure equipment. Preheat is measured, logged, and verified—not assumed.

Safety Inside the Procedure: Fumes, Ventilation, UV Radiation, and PPE

A welding procedure is not just a recipe for a sound joint — it’s a promise the welder survives to make the next one. Every qualified WPS assumes certain conditions: fume control, eye protection, and shock prevention. Strip those away and the procedure stops being compliant, no matter how flawless the bead looks.

Fume and Gas Hazards: The Invisible Variable

Welding throws off a complex plume — manganese, chromium, nickel, zinc, carbon monoxide, and ozone among them. Manganese is the headline concern. NIOSH recommends a REL of 1 mg/m³ as a TWA, while ACGIH sets a stricter inhalable TLV of 0.1 mg/m³ and a respirable TLV of 0.02 mg/m³. Confined-space welding can push manganese exposure dramatically higher, which is why the space itself changes the procedure.

Chronic manganese overexposure attacks the nervous system and produces Parkinson’s-like symptoms: tremors, poor coordination, and mood changes. That’s a key reason fume control is a procedure variable, not a personal preference. The stakes rise for anyone welding while pregnant, since the same fumes reach a developing body.

Ventilation: What OSHA Actually Requires

OSHA 29 CFR 1910.252 requires mechanical ventilation at a minimum rate of 2,000 cubic feet (57 m³) per minute per welder in certain spaces, except where local exhaust or approved airline respirators are provided. OSHA also directs that local exhaust or general ventilation keep toxic fumes, gases, and dust below the maximum allowable concentration in 29 CFR 1910.1000.

Quick Note: 2,000 CFM is a floor, not a target. Local exhaust hoods capture fumes at the source, and approved airline respirators can substitute where ventilation can’t keep up.

Local exhaust hoods that capture fumes at the source
General mechanical ventilation for open shop areas
Approved respirators when engineering controls fall short
Air sampling to confirm exposures stay below limits

Where engineering controls can’t hit the numbers, a powered air-purifying respirator or supplied-air system becomes part of the procedure — standard practice for stainless and hardfacing work, where chromium and nickel join the plume.

In tight or confined spaces, ventilation is non-negotiable. Fumes pool, oxygen shifts, and concentrations climb fast — the same job that’s routine on an open floor becomes dangerous in a tank. A well-planned shop layout with ducted exhaust and gas monitoring turns that risk into a managed variable. Monitoring with a calibrated detector before entry is standard.

Arc Radiation, PPE, and Electrical Safety

The arc is blinding by design — it emits intense UV and infrared light. Proper shade numbers, a welding helmet, and protective eyewear shield your eyes, while flame-resistant clothing and leathers cover exposed skin. Shade numbers typically run 10 to 13 for arc welding — darker for high-current work, lighter for low-amp TIG. Screens protect nearby workers from arc flash, and routine welding practice builds the habits that keep PPE second nature.

Beyond the hood, a leather jacket, gauntlets, apron, flame-resistant cap, and hearing protection complete the kit. Portable screens keep the arc flash off coworkers’ eyes.

Electrical shock prevention starts with good habits: inspect electrode holders and welding lead connectors for damage, never change electrodes with wet gloves, and keep the work clamp solidly grounded. In wet areas, reduce open-circuit voltage and use an automatic voltage-reduction device. Hot work near flammables demands a permit, a fire watch, and a clear combustible-free zone. Flammable atmospheres must be tested and cleared before the first spark.

Note: A qualified WPS never excuses unsafe conditions. The procedure assumes ventilation, PPE, and shock protection are in place — if they aren’t, stop and fix them before striking an arc.

Common Mistakes, Weld Defects, and How to Troubleshoot a Procedure

Almost every defect you chase traces back to a number on that WPS page nobody followed. Here’s the uncomfortable truth: most “welder problems” are procedure problems wearing a welder’s jacket. Wrong polarity, a hot or cold setting, dirty steel—each one writes its own signature into the bead. That’s why AWS D1.1 devotes Clause 6 to inspection, defining the visual and NDT acceptance criteria every production weld must pass. Learn the signatures and you can troubleshoot in minutes instead of guessing.

The Procedure Mistake → Weld Defect Map

Procedure Mistake	Defect It Produces
Wrong polarity (e.g., DCEP where DCEN is called for)	Porosity, poor arc stability, lack of fusion
Amperage too low	Lack of fusion, incomplete penetration
Amperage/voltage too high	Undercut, burn-through, excess spatter
Heat input too low	Cold lap, lack of fusion, cracking
Heat input too high	Distortion, coarse grain, low toughness
Wrong filler metal	Cracking, mismatched strength
Contaminated base metal (oil, paint, galvanizing)	Porosity, hydrogen cracking
Poor fit-up / wrong joint geometry	Incomplete penetration, lack of fusion
Travel angle or speed errors	Undercut, overlap, slag inclusions
Skipping preheat	Hydrogen (cold) cracking

Lack of fusion and incomplete penetration are the heavyweights—cold, fast, or badly fitted joints that never melt into the sidewall. Porosity is gas trapped by contamination, moisture, or a shielding breakdown; a worn contact tip or wrong gas flow will do it. Overlap is different: molten metal rolls over unmelted base metal without fusing, leaving a stress riser you can usually spot visually. Undercut cuts a notch along the toe, and slag inclusions hide in multi-pass work where cleaning was skipped between passes. Cracking splits into hot (solidification, often from high sulfur or poor shape) and cold (hydrogen, from moisture and no preheat).

Here’s the trap: a welder can have flawless hands and still fail inspection because the WPS handed to them was wrong. A travel speed that worked on 1/4-inch plate can cause incomplete penetration on 1-inch steel; a filler selected for mild steel will crack on high-carbon or hardened steel; a missing preheat turns a sound joint into a delayed-crack statistic overnight. The document—not the hand—sets the ceiling.

Inspection: Finding What the Eye Can’t

Inspection starts with visual testing (VT)—cheap, immediate, and able to catch undercut, overlap, and surface porosity. Dye penetrant flags surface-breaking cracks on non-porous metals; magnetic particle finds surface and near-surface cracks in ferrous steel. Ultrasonic and radiographic testing peer inside for subsurface lack of fusion, cracks, and slag. Under AWS D1.1, acceptance criteria for macroetch testing were updated in the 2025 edition, and guided-bend testing remains the gold standard for revealing both surface and subsurface discontinuities that VT alone misses.

Acceptance criteria live in the code you’re welding to—Clause 6 for D1.1, or a comparable standard like AWS B2.1 for procedure qualification.

Note: When a defect repeats, stop blaming the welder and audit the procedure first. Wrong polarity, dirty material, or a skipped preheat is a WPS and workmanship problem—not a technique problem. Fix the document and the defect usually disappears.

Troubleshooting: Read the Bead, Fix the Procedure

Rope-like or convex bead: too little heat—raise amperage or slow travel.
Wide, flat, spattered bead: voltage too high—trim it down.
Undercut at the toes: too much heat or too fast a travel speed.
Porosity scattered through the bead: contamination, moisture, or a gas-flow issue.
Cracks appearing hours later: hydrogen—add preheat and control cooling.
Excessive spatter and a wandering arc: check polarity and work-lead connections—quick-connect leads and ground clamps cause more grief than most welders admit.
Incomplete penetration at the root: increase root gap or amperage, or switch to the joint design on the WPS.

Get the fundamentals right and defects shrink fast—solid welding practice, the correct polarity for the process (see TIG polarity or flux-core polarity), careful fit-up, and the cleaning the WPS demands. When in doubt, stop, read the procedure, and verify every variable before you strike another arc.

Process Comparison and Real-World Choices: SMAW vs GMAW vs FCAW vs SAW

The same half-inch T-joint can be legally welded five different ways. That’s the heart of procedure comparison: the drawing defines the weld, not the process. Deposition rate, applicable positions, equipment cost, shielding, portability, and typical applications all shift the answer. Understanding what each arc process brings is how a fabricator picks the procedure that is cheapest to qualify, easiest to run, and safest to stand behind.

SMAW (Stick): The Portable Workhorse

Shielded metal arc welding needs no shielding gas, runs off engine drives, and shrugs off wind and dirty steel. Deposition is low and slag must be chipped, but for structural repair and field work it is hard to beat. A 3/16 E7018 rod remains a field staple.

GMAW (MIG) and FCAW (Flux-Cored)

GMAW delivers high deposition with a continuously fed wire and shielding gas—clean, fast, and ideal for production benches. FCAW swaps gas for a flux core (or uses both), tolerating wind and thicker metal; it is the go-to for structural steel. See why flux core is not the same as MIG, and watch your contact-tip wear during GMAW.

GTAW (TIG): Precision Over Speed

GTAW is slow but gives unmatched control for thin gauge, root passes, and exotic alloys. Polarity matters—DCEN for steel, AC for aluminum; the DCEN/DCEP/AC tradeoff changes the procedure entirely.

SAW: Heavy Deposition, Automatic

Submerged arc welding is a high-deposition automatic or semi-automatic process where the arc is buried under granular flux. It dominates heavy fabrication and pipe, and robotic SAW pushes deposition higher still—making automation for heavy-duty welding a procedure of its own.

Process	Deposition	Positions	Equipment Cost	Shielding	Portability	Typical Use
SMAW	Low	All	Low	Flux/slag	Excellent	Repair, field, pipe
GMAW	High	All (flat best)	Medium	Gas	Good	Production, sheet
FCAW	High	All	Medium	Flux ± gas	Good	Structural steel
GTAW	Low	All	Medium–High	Gas	Fair	Thin/root, aerospace
SAW	Very high	Flat/horizontal	High	Granular flux	Poor	Heavy fab, pipe

Why One Joint Can Have Many Valid Procedures

Because codes qualify a combination of variables, not one “best” process, the same joint often carries several approved WPSs. A bridge girder groove weld might be SAW in the shop and FCAW in the field. Shops weigh deposition rate, position limits, rework risk, and qualification cost—then pick the cheapest path that still passes inspection. AWS D1.1 is not automatically law, but contracts, project specifications, and regulators frequently adopt it, so once it is invoked, compliance is mandatory.

Equipment cost often decides the winner. SMAW needs only a machine and leads; GMAW and FCAW add a wire feeder and gas; SAW demands a carriage, flux handling, and often a positioner. For a one-off repair, that capital cost rarely justifies SAW, while a shop running miles of seam will amortize it in weeks.

How Automation Rewrites the Procedure

Automation changes the math. Robotic cells convert many technique variables into programmed parameters, so amperage, travel speed, and torch angle become fixed numbers that must be documented precisely. A robot’s procedure is, literally, its program. Every tweak a human would make instinctively must instead be written into the code and requalified if it crosses an essential variable.

Quick Note: A hobbyist welding a gate in the garage can adjust settings freely by feel. But once a project falls under a code, an AWS Standard Welding Procedure Specification—published under ANSI consensus rules and meeting AWS B2.1—plus a welder tested to it, is not optional.

When Informal Settings Are Fine—and When They Are Not

For a backyard bench or a decorative gate, dialing in amps by feel is normal, and practice builds that judgment. The rules change the moment a weld is structural, pressurized, or covered by a contract. There, informal settings cannot substitute for a qualified procedure, no matter how pretty the bead looks. Confirm the requirement before you strike an arc.

Building Your Own Procedure: Practical Tips, Steps, and Conclusion

After learning the variables that shape an electric arc welding procedure, the final task is turning that knowledge into a document you can trust. The numbers on a WPS are not guesses, but the product of discipline. Whether you are working in a small shop or a fabrication yard, the following path will help you create repeatable quality for any job.

Know When to Build, Borrow, or Bring in Help

Not every job requires a full qualification from scratch. For non-code fabrication, you can write a basic WPS and prove it with your own testing. When working to major codes such as AWS D1.1, ASME Section IX, or NAVSEA requirements, consider adopting prequalified Standard Welding Procedure Specifications that are supported by PQRs meeting AWS B2.1.

Quick Note: A WPS can be written by a Certified Welding Inspector (CWI) or other qualified individual. For high-risk work, hire a CWI or an accredited testing lab to avoid costly rework.

A Practical Workflow to Follow

Define the joint and materials: Record base metals, thickness, joint type, and fit-up. These factors will dictate preheat and will limit your range of variables.
Select the process and filler: Match your equipment to the job. For wire-fed work, use resources like our MIG Welding Wires guide or compare processes with Is Flux Core the Same as MIG? to make an informed choice.
Set electrical parameters from manufacturer data: Pull recommended amps, volts, polarity, and wire feed speed from datasheets. Reference specific settings, such as 3/16 E7018 amperage, to avoid guessing.
Weld a test coupon: Replicate shop conditions on a coupon. Focus on technique, travel speed, and cleanliness while adhering to safety standards like OSHA 1910.252 for arc welding and cutting.
Inspect it: Conduct visual inspection first, then any required destructive or NDT tests. Use this stage to spot defects and compare your results to good and bad MIG welds.
Document everything: Record all variables, test results, and photos on a PQR and its corresponding WPS. Be explicit, as small omissions can invalidate the entire procedure.
Qualify welders: Only qualified welders can use the procedure. Welding Practice will help them meet the required standard with confidence.

Paper Trail, Revisions, and Continuity

Procedure discipline does not end at approval. Revision control is critical: any change to an essential variable outside the qualified range requires requalification of the procedure. For personnel, documented welder continuity must be maintained, as failure to weld with a process for more than six months may require recertification under AWS D1.1. Keep these records in a secure, traceable system for the life of the project.

Looking Ahead: Digital Tools and Automation

The future of procedures is digital. Welding procedure management software, digital WPSs, and cloud-based approvals are streamlining compliance across shops. When paired with automation, such as robotic submerged arc welding, these systems ensure that the first weld and the thousandth weld share the same qualified parameters.

Note: While technology speeds up recordkeeping, it will never replace the expertise of a skilled welder or a qualified inspector.

Conclusion: Discipline Creates Repeatable Quality

From physics to paperwork, this guide has shown one truth: procedure discipline equals repeatable quality. You do not need to qualify everything on day one, but you do need to qualify what matters. Start small, document thoroughly, and seek help when code compliance is on the line. Whether you are a hobbyist or a veteran, take the first step today. Build a WPS, prove it, and protect the integrity of every weld you lay down.

Frequently Asked Questions

What is the difference between a WPS and a PQR?

A WPS (Welding Procedure Specification) is the written recipe that tells a welder how to make a production weld—base metal, filler, settings, position, and technique. A PQR (Procedure Qualification Record) is the proof behind it: it records the actual variables used to weld and test a coupon, plus the mechanical test results that show the procedure produces sound welds.

Do I need a qualified welding procedure for a home project?

For personal, non-structural, non-regulated projects you don’t legally need a code-qualified procedure, but following a written set of settings and technique improves consistency. The moment your work falls under a contract, building code, pressure-vessel code, or a client specification, a qualified WPS is generally mandatory.

What are essential variables in a welding procedure?

Essential variables are welding parameters that, if changed beyond the qualified range, affect the mechanical properties of the joint and require procedure requalification. Examples include welding process, base metal group, filler metal classification, thickness range, position, polarity, and heat input.

How is heat input calculated and why does it matter?

Heat input is calculated as voltage × amperage × 60 divided by travel speed, usually expressed in kilojoules per inch (kJ/in) or kilojoules per millimeter. It matters because too much heat input can degrade toughness in the heat-affected zone, while too little can cause lack of fusion, so procedures cap or control it closely.

How long does a welder’s qualification last?

Under AWS D1.1, a welder’s qualification remains in effect indefinitely as long as the welder keeps using that process and documented continuity is maintained. If the welder does not use a given process for more than 6 months, recertification may be required.

Can I use a prequalified WPS instead of testing a procedure?

Yes—if your joint, base metal, filler metal, process, position, and parameters all fall within the prequalified limits of the applicable code, such as AWS D1.1 Clause 5. You still must have a written WPS on file, but you avoid the cost and time of procedure qualification testing.

What tests are used to qualify a welding procedure?

Typical procedure qualification tests include tensile testing, guided bend tests (face and root), nick-break tests, fillet weld soundness tests, macroetch examination, and volumetric NDT such as radiographic or ultrasonic testing. Notch-toughness (Charpy) tests are added when the construction code requires impact properties.

Why does polarity matter in an arc welding procedure?

Polarity determines how heat is distributed between the electrode and the workpiece. DC electrode negative (DCEN) puts more heat into the work for deeper penetration, DC electrode positive (DCEP) puts more heat into the electrode for better cleaning and deposition, and AC balances the two—so the wrong polarity can cause defects even if everything else is correct.

Who is responsible for writing and approving a welding procedure?

The contractor, fabricator, or organization performing the work is responsible for developing, documenting, and approving welding procedures. A WPS can be written by a Certified Welding Inspector (CWI) or another qualified individual, but it must be approved and dated by the authorizing organization to be valid.

Does an automated or robotic arc welding procedure change the rules?

The core requirement stays the same—documented, qualified parameters—but automation shifts many technique variables into programmed settings, which makes precise documentation even more critical. Changes to programmed voltage, current, travel speed, or torch angle can fall outside the qualified range and trigger requalification, just as with manual welding.