Choosing a welding process is not the same as choosing a welding machine. A welder must understand the system: the process, power source, electrode or filler metal, shielding method, polarity, work connection, joint condition and the instructions in the applicable Welding Procedure Specification (WPS).
This welding processes guide explains the practical differences between Shielded Metal Arc Welding (SMAW), Gas Metal Arc Welding (GMAW/MIG-MAG) and Gas Tungsten Arc Welding (GTAW/TIG). It also introduces basic oxy-fuel cutting awareness, common workshop tools, power-source controls and the checks a welder should make before starting work.
These are practical skills that may help technicians prepare for competency-based work and assessment. Saudi Skill Test is an independent preparation resource and is not affiliated with the Saudi government, Takamol or NSDC. Project requirements, an approved WPS, manufacturer instructions and site safety rules always take priority over general training guidance.
Safety first: Welding can expose workers to electric shock, ultraviolet and infrared radiation, hot metal, sparks, fire, fumes, gases and compressed-gas hazards. Do not start work until the task, work area, equipment and required controls have been checked. Saudi occupational-safety guidance should be followed at the worksite.
Welding Workshop Tools
A competent welder does more than strike an arc. Good welding starts with preparation, measurement and inspection.
Common workshop equipment may include:
- welding power source suitable for the process;
- electrode holder or welding torch;
- work lead and work clamp;
- wire feeder where required;
- shielding-gas cylinder, regulator and flow-control equipment where required;
- welding helmet and suitable eye, face, hand and body protection;
- chipping hammer and wire brush for processes that produce slag;
- angle grinder and suitable discs for preparation and cleaning;
- clamps, magnets, fixtures and strongbacks for fit-up where appropriate;
- steel rule, tape, square and gauges for dimensional checks;
- temperature-measuring equipment when a procedure requires temperature control;
- local exhaust or other ventilation controls where the hazard assessment requires them.
A grinder can remove contamination or prepare an edge, but it cannot correct an incorrect drawing dimension or replace WPS fit-up requirements.
Shielded Metal Arc Welding (SMAW)
Shielded Metal Arc Welding (SMAW), often called stick welding, uses a flux-coated consumable electrode. The arc melts the electrode and base metal. As the coating reacts, it helps protect the molten weld metal and normally leaves slag that must be removed as required between passes and after welding.
Why SMAW is widely used
SMAW equipment can be relatively simple and portable. This makes the process common in fabrication, maintenance, structural work and field conditions. It can be useful where access is difficult or where moving a gas cylinder and wire-feeding system would be inconvenient.
However, process suitability depends on much more than portability. The electrode classification, base metal, joint, welding position, polarity, current type, service requirements and WPS all matter.
Electrode selection
A stick electrode should never be selected only because its diameter “looks right.” Selection can depend on:
- base-metal type and properties;
- required weld-metal properties;
- welding position;
- power-source capability and polarity;
- joint design and fit-up;
- material thickness;
- project specification and WPS;
- service environment;
- storage and handling requirements.
Manufacturer technical data and the WPS are the correct places to confirm permitted current range, polarity and handling requirements. Some electrodes are particularly sensitive to moisture and must be stored and handled according to their specified conditions. A general article should not invent a universal storage temperature or exposure time.
Practical SMAW control
Arc length, travel speed, electrode angle and current all influence bead shape and weld quality. If the welder changes several variables at once, diagnosing a poor bead becomes difficult. A better approach is to check the WPS and setup, observe the result, and correct one identified cause rather than making random adjustments.
Gas Metal Arc Welding (GMAW / MIG-MAG)
Gas Metal Arc Welding (GMAW) uses a continuously fed consumable wire electrode and an externally supplied shielding gas or gas mixture. The terms MIG and MAG are commonly used in industry, depending on the shielding-gas concept, while GMAW is the broader process name.
A typical GMAW system includes:
- power source;
- wire feeder;
- welding gun;
- contact tip and liner;
- wire spool or other wire package;
- work lead and clamp;
- shielding-gas supply, regulator and hose system.
The relationship between voltage and wire feed
GMAW commonly uses a constant-voltage (CV) power source. Wire-feed speed, voltage and other machine controls interact with the arc. The correct settings depend on the wire, diameter, shielding gas, material, transfer mode, joint and procedure.
A welder should avoid the habit of copying machine numbers from a different job. A setting that worked on another wire, plate thickness or gas mixture may not be appropriate for the current task.
Shielding gas matters
Shielding gas affects arc behavior, penetration profile, bead appearance, spatter and process stability. The correct gas must be compatible with the wire, base material, process requirements and WPS.
A gas cylinder label and approved documentation are more reliable than cylinder color alone. Gas identification practices can vary, so the welder should verify the actual product label and site system before connecting equipment.
Common GMAW setup checks
Before welding, check for issues such as:
- damaged or contaminated wire;
- incorrect drive-roll arrangement or excessive drive pressure;
- worn contact tip;
- damaged liner;
- restricted gas path;
- leaks at connections;
- poor work connection;
- unsuitable polarity;
- incorrect gas or wire for the WPS;
- excessive drafts that disturb shielding.
Gas Tungsten Arc Welding (GTAW / TIG)
Gas Tungsten Arc Welding (GTAW), commonly called TIG welding, uses a non-consumable tungsten electrode to produce the arc. Filler metal can be added separately when the procedure requires it. Shielding is supplied externally, commonly using an inert gas system appropriate to the procedure.
GTAW is valued where precise control and a clean weld profile are important. It is used in many high-quality fabrication applications and across a range of metals, but it generally requires good joint preparation, clean material and disciplined torch control.
What the tungsten does
The tungsten electrode carries the welding current and forms the arc. It is not intended to be consumed as filler metal. Electrode type, diameter, preparation and machine settings must suit the material, current and equipment.
For many DC TIG applications on steels, direct current electrode negative (DCEN) is commonly used, but this should not be turned into a universal rule for every metal and machine. AC is widely associated with aluminum welding, and modern equipment may use adjustable waveform and balance controls.
GTAW cleanliness
GTAW is sensitive to contamination. Practical checks can include:
- clean base metal;
- suitable filler metal kept clean;
- clean tungsten in good condition;
- gas system without leaks or restrictions;
- torch parts assembled correctly;
- suitable shielding coverage;
- avoiding contact between tungsten and the molten pool or filler when the procedure does not permit it.
If the tungsten becomes contaminated, continuing to weld without correcting the condition can affect arc stability and weld quality.
Basic Oxy-Fuel Cutting Awareness
Oxy-fuel cutting is a thermal cutting process and is not the same as arc welding. It uses fuel gas and oxygen equipment to heat and cut suitable materials. A system may include cylinders or another approved gas supply, regulators, hoses, check devices, torch and cutting tip.
This work introduces additional hazards involving fuel gas, oxygen, fire, hot metal and compressed-gas equipment. It should only be performed by trained personnel under the required hot-work controls.
Important awareness points include:
- inspect hoses, regulators and torch components before use;
- use components intended for the actual gas service;
- keep cylinders secured and protected from damage;
- keep ignition sources and combustible materials controlled;
- do not use oxygen as a substitute for ventilation, compressed air or clothing cleaning;
- never perform hot work on a container that may contain flammable or hazardous residue unless the responsible safety process has confirmed it is safe.
Exact operating pressures and tip selections are manufacturer-specific and should not be copied from a generic guide.
Power Source Controls
The front panel of a welding machine can be misleading if a welder treats every control as independent. Controls depend on process and machine design.
Constant current and constant voltage
A constant-current (CC) power source is commonly used for SMAW and GTAW because these processes rely on controlled welding current while the welder manually influences arc length.
A constant-voltage (CV) power source is commonly used for GMAW and flux-cored wire processes. The interaction between voltage and wire feed helps maintain the arc in continuously fed electrode systems.
Multi-process machines may provide both modes, but selecting the wrong process mode can result in poor arc behavior even if the displayed amperage or voltage appears reasonable.
Controls are not WPS values
The machine dial or display is only one part of the procedure. A WPS may also control items such as:
- process;
- base material;
- filler classification;
- electrode or wire size;
- current type and polarity;
- welding position;
- joint preparation;
- preheat or interpass requirements where applicable;
- shielding gas;
- travel or deposition requirements;
- number and sequence of passes.
The welder’s job is to follow the applicable procedure, not to replace it with personal preference.
Electrodes, Wire and Filler Metal
Consumables affect weld chemistry, mechanical properties and usability. Three terms should remain separate:
- SMAW electrode: a consumable flux-coated rod that carries current and supplies filler metal.
- GMAW wire electrode: a continuously fed consumable wire that carries current and supplies filler metal.
- GTAW filler rod/wire: filler added separately from the non-consumable tungsten electrode when required.
Before use, verify the consumable identification against the WPS or job specification. Check condition, contamination, damage and storage history where relevant. Do not assume two fillers are interchangeable because they are the same diameter.
Shielding Gas
Shielding gas protects the arc and molten weld region from unwanted atmospheric interaction. The required gas depends on the process and application.
A practical gas-system inspection asks:
- Is this the correct gas identified on the cylinder or supply system?
- Is the regulator or flow-control equipment suitable for the service?
- Are hoses and fittings in serviceable condition?
- Are connections leak-free?
- Is the gas path open and unobstructed?
- Is the work area protected from excessive air movement where shielding could be disturbed?
- Does the setup match the WPS and manufacturer instructions?
Polarity
Polarity describes the electrical relationship between the electrode and work in a direct-current welding circuit.
- DCEN: direct current electrode negative.
- DCEP: direct current electrode positive.
Polarity can affect arc characteristics, electrode behavior and weld result. Typical process tendencies are useful for understanding, but the electrode classification, WPS and manufacturer data are the controlling references.
For example, many carbon-steel TIG applications use DCEN, while many common GMAW and SMAW applications use DCEP. But “SMAW always uses DCEP” would be incorrect because electrode requirements vary. A welder should verify the specific consumable rather than memorize an oversimplified rule.
Selecting a Process for the Task
The best welding process is the one that satisfies the technical, quality, access, productivity and safety needs of the actual job.
| Decision factor | SMAW | GMAW / MIG-MAG | GTAW / TIG |
|---|---|---|---|
| Equipment mobility | Often strong for field work | Requires wire-feed system and usually gas | Requires gas and careful torch setup |
| Deposition/productivity | Moderate; electrode changes required | Often high with continuous wire | Generally lower deposition, high control |
| Surface cleanliness | Tolerant in some applications, but preparation still matters | Clean material and good shielding important | Cleanliness is especially important |
| Wind sensitivity | No external shielding gas for standard SMAW | Shielding gas can be disturbed by drafts | Shielding gas can be disturbed by drafts |
| Precision/control | Good with skilled technique | Strong production capability | Excellent manual control for precision work |
| Slag | Usually present | Normally no flux slag in solid-wire GMAW | No flux slag in standard GTAW |
| Main consumable | Flux-coated electrode | Continuous wire electrode | Tungsten plus separate filler if required |
This table is a learning aid, not a procedure-selection authority. The approved project documentation determines which process is permitted.
Pre-Use Equipment Inspection
Before starting, use a consistent inspection sequence.
1. Confirm the job
- drawing or work instruction available;
- correct WPS identified where required;
- base material and joint identified;
- welding position understood;
- inspection hold points understood.
2. Check the power source
- correct process selected;
- cables and connectors serviceable;
- covers and controls intact;
- machine positioned safely;
- ventilation openings not blocked.
3. Check the welding circuit
- electrode holder or torch in good condition;
- work lead and clamp in good condition;
- work connection placed on clean, suitable metal;
- leads routed to reduce trip, heat and damage hazards.
4. Check consumables
- correct classification and size;
- clean and dry as required;
- storage requirements satisfied;
- no obvious damage or contamination.
5. Check gas equipment where used
- correct gas verified by label;
- cylinder secured;
- regulator and hose suitable and undamaged;
- no suspected leaks;
- torch gas path in good condition.
6. Check the work area
- combustible hazards controlled;
- screens or barriers used where others may be exposed to arc radiation;
- ventilation suitable for the task;
- hot metal and sparks controlled;
- access and housekeeping acceptable.
Common Setup Errors
Wrong polarity
Possible effects include unstable arc behavior, poor bead shape, excessive spatter or electrode problems. Confirm the consumable and procedure requirements before changing machine settings.
Poor work connection
A loose, dirty or badly placed work clamp can create unstable welding conditions and overheating at the connection. The return path should be sound and appropriate for the job.
Wrong consumable
A wire or electrode that fits the holder or feeder is not necessarily acceptable for the job. Verify classification, diameter and procedure compatibility.
Contaminated material
Oil, paint, rust, moisture, coatings and other contaminants can contribute to welding problems and may create hazardous fumes. Preparation must follow the job procedure and hazard controls.
Gas problems
Porosity or discoloration can involve several possible causes: incorrect gas, leaks, drafts, contaminated surfaces, restricted flow or technique. Diagnose the system instead of immediately increasing flow.
Random machine adjustment
Changing voltage, wire feed, current, travel speed and torch angle at the same time prevents controlled diagnosis. Return to the WPS baseline, identify the symptom, then correct the most likely verified cause.
A Practical Process-Selection Checklist
Before choosing or setting up a process, ask:
- What process does the WPS permit?
- What is the base material?
- What joint and welding position are required?
- Which filler or electrode classification is specified?
- What polarity and current type are required?
- Is external shielding gas required?
- Can shielding be maintained in the work environment?
- Are preheat or interpass controls required?
- What quality and inspection criteria apply?
- What hazards and permits apply to this location?
If any controlled variable is unknown, stop guessing and obtain the correct procedure or technical information.
What to Study Next
Understanding the process is only the first layer of welding competence. Continue with:
- W2 — Weld Joint Preparation, Welding Positions and WPS Basics for fit-up and procedure reading;
- W3 — Common Welding Defects and Visual Inspection for quality diagnosis;
- W4 — Welding Safety, Hot Work and Gas Cylinder Handling for worksite controls;
- the Welder practice tests for original practice questions based on occupational skills.
Key Takeaways
- A welding process, machine and consumable are related but not interchangeable concepts.
- SMAW uses a flux-coated consumable electrode; GMAW uses continuously fed wire with external shielding; GTAW uses a non-consumable tungsten electrode and separate filler when required.
- CC power sources are commonly associated with SMAW/GTAW, while CV is commonly associated with GMAW-type wire processes.
- Polarity must be verified from the electrode, WPS and manufacturer information rather than assumed.
- Shielding gas, wire and electrodes must match the actual procedure and material.
- A professional setup begins with the job documents, then equipment, circuit, consumables, gas system and work area.
- Safety and quality are part of the process selection, not checks added after welding begins.
Technical References
- ISO 4063:2023 — Welding, brazing, soldering and cutting — Nomenclature of processes and reference numbers — https://www.iso.org/standard/75108.html
- ISO 15607:2019 — Specification and qualification of welding procedures for metallic materials — General rules — https://www.iso.org/standard/71495.html
- ISO 9606-1:2012 — Qualification testing of welders — Fusion welding — Part 1: Steels — https://www.iso.org/standard/54936.html
- National Council for Occupational Safety and Health (Saudi Arabia), Occupational Safety and Health Industrial Hazards guidance — https://ncosh.gov.sa/en/knowledge-center/rules-regulations/administrative-systems/
- Miller Electric, Understanding Common Welding Terms — https://www.millerwelds.com/en-US/resources/knowledge-hub/welding-basics/understanding-common-welding-terms-a-guide-for-beginners
- Miller Electric, Factors for Selecting the Right Stick Electrode — https://www.millerwelds.com/en-US/resources/knowledge-hub/stick-welding/factors-for-selecting-the-right-stick-electrode
- Miller Electric, Guide to TIG Welding Basics — https://www.millerwelds.com/en-US/resources/knowledge-hub/tig-welding/how-to/guide-to-tig-welding-basics
- OSHA, Welding, Cutting and Brazing — Hazards and Solutions (supplemental technical safety reference; not Saudi law) — https://www.osha.gov/welding-cutting-brazing/hazards-solutions
Editorial note: All numeric settings, gas-flow values, electrode handling temperatures, preheat values and acceptance limits are intentionally excluded unless they can be tied to a specific WPS, standard or manufacturer document. This prevents a generic training guide from being mistaken for a job-specific procedure.