TIG Welding Guide

What Is TIG Welding and How Does It Work?

TIG welding (Tungsten Inert Gas welding, also known as Gas Tungsten Arc Welding or GTAW) is a precision arc welding process that uses a non-consumable tungsten electrode to create the weld, while an inert shielding gas (almost always argon) protects the weld pool from contamination by the surrounding air.

Unlike processes that feed a consumable wire electrode through the torch, the tungsten electrode in TIG welding never melts into the weld. Instead, it generates the arc that heats the base metal until it forms a molten puddle. If filler metal is needed, the welder feeds a separate filler rod into the puddle by hand, while controlling the torch with the other hand and often using a foot pedal to manage amperage in real time. This separation of heat control and filler addition is what gives TIG its trademark precision: a skilled welder can vary penetration and bead shape far more finely than with processes when heat and filler arrive together.

The basic equipment needed for TIG welding includes:

• A constant-current TIG power source (AC/DC inverter machines are now the industry standard); browse our TIG welders in stock here.
• A torch fitted with a non-consumable tungsten electrode
• A shielding gas supply, typically pure argon (sometimes an argon/helium blend for thicker material)
• Filler rod, where additional material is needed
• A foot pedal or thumb control for live amperage adjustment

How Does TIG Welding Compare to MIG and Stick Welding?

The three processes solve the same basic problem: joining metal with a fused weld in different ways, and each suits different jobs:

• TIG vs MIG: MIG welding (Metal Inert Gas, or Gas Metal Arc Welding) feeds a continuous consumable wire electrode that melts and becomes part of the weld, acting almost like a hot adhesive between the two pieces of metal. This makes MIG considerably faster and easier to learn than TIG, and well-suited to production environments and general fabrication. TIG, by contrast, actually fuses the base materials themselves, giving the welder finer control over heat input, penetration, and finish. The trade-off is speed: TIG is a slower, more manual process that demands more operator skill.
• TIG vs Stick (MMA/SMAW): Stick welding uses a flux-coated consumable electrode and is prized for its portability and tolerance of harsh, outdoor, or on-site conditions. It’s a practical choice for heavy site work where TIG’s sensitivity to wind and surface contamination would cause problems. TIG, in a controlled workshop environment, produces a cleaner, higher-quality weld with a narrower heat-affected zone. It does, however, need a stable, sheltered setup to do it.

In short: choose MIG for speed and production volume, Stick for portability and rough conditions, and TIG when weld quality, appearance, and precise control matter most. Particularly on stainless steel, aluminium, and other materials, where the integrity of the finished weld is critical.

For a fuller side-by-side comparison of all three processes, see our Arc Welding Processes Guide.

Is TIG Welding Strong Enough for Heavy or Structural Steel?

Yes. When performed correctly, following a qualified welding procedure specification (WPS) by a competent welder, TIG welding poses no issue with mechanical integrity on carbon steel, regardless of material thickness. TIG is one of the highest-quality arc welding processes available, and its low current, low voltage, and low overall heat input produce a narrower heat-affected zone (HAZ) in the base material than many other processes. A genuine mechanical advantage on structural work where distortion and grain coarsening matter.

The reason TIG sometimes gets questioned on heavy steel isn’t weld integrity; it’s practicality. TIG is a more expensive and slower process than alternatives like Stick or submerged arc welding, which is why it isn’t the default choice for high-volume heavy construction. The cost and time difference, not weld strength, is usually what rules TIG out of large structural jobs in favour of Stick electrodes such as 7018, particularly where preheat and post-weld heat treatment are already part of the procedure for heavy-wall pipe or plate.

How Strong Is a TIG Weld Compared to a MIG Weld?

There’s no simple answer that applies across every job, because weld strength depends on filler metal, joint design, and welder skill at least as much as it depends on process. That said, a few points consistently come up in this comparison:

Is TIG Welding Good for Thick Metal and Structural Applications?

TIG is well-suited to structural and thick-section steel work, with two practical caveats worth planning around:

1. Material and joint preparation matter more than with other processes. TIG demands a clean, contaminant-free joint. This isn’t a process you can run over mill scale, rust, or oily surfaces the way you might with Stick or MIG.
2. The machine and torch specifications need to match the section thickness. On heavier steel, torch rating becomes the limiting factor as often as the power source itself. A torch rated below around 250 amps will struggle to sustain the amperage a thick-section weld needs. Through its full duty cycle, a water-cooled torch is recommended for better arc stability at higher amperages. As a practical guide, base metal over roughly 6mm (1/4 inch) thick typically needs a minimum of around 200 amps, with 250 amps the more comfortable working point.

If a TIG machine seems underpowered or trips out on heavier material, the cause is more often the electrical supply or torch spec than the welding process itself; see the troubleshooting note below.

Why Does My TIG Welder Trip Out or Lose Power on Heavy Steel?

A handful of causes account for most cases:

• Undersized or extended power supply. An electrical supply that’s underpowered for the machine, or a power cord that’s longer than necessary, even at the correct gauge, will cause a voltage drop that starves the machine under load. Have a qualified electrician check or expand the breaker supplying the unit.
• Undersized torch. A torch rated below the amperage required for the job will not sustain the arc through a full weld cycle on heavier material.
• Faulty or poor grounding. A hot ground cable during welding, a corroded ground clamp or connection, or corroded internal connectors between the ground cable and transformer can all cause power loss or instability. Check the ground cable, clamp, and the machine’s internal connections, and ensure any bolts and nuts at these points are clean.

If problems persist, it’s worth supplying the machine’s brand and model when seeking advice, since older or lower-powered machines often have specific known issues.

TIG Welding Safety and Common Mistakes

What Are the Most Important TIG Welding Safety Practices?

TIG welding carries the same core hazards as other arc welding processes: arc radiation, fume, heat, and electric shock. The right PPE and setup choices reduce all of them:

• Never weld without full PPE. This means a welding helmet, gloves, and flame-resistant protective clothing as standard. Wearing safety glasses under an auto-darkening helmet adds protection against stray UV rays that can otherwise reach the eyes around the edges of the lens.
• Plan for fume extraction. Use weld fume extraction wherever the job and workspace allow, particularly indoors or in any enclosed area. See our range of fume extractors for sale >
• Protect the weld from wind and draughts. TIG relies entirely on the shielding gas blanket to keep the weld pool free of atmospheric contamination. Windy or open-air conditions disturb that gas coverage and lead directly to pinholes and porosity in the finished weld. This is one of the main reasons TIG isn’t practical for general outdoor site work the way Stick welding is.
• Manage torch heat properly. Think about the angles you’ll be welding at before you start, and choose air or water cooling for the torch accordingly. A neglected or wrongly cooled torch is a common source of avoidable downtime and damage.

What Causes Flash Burn in Welding, and How Do You Avoid It?

Flash burn (sometimes called “welder’s flash” or arc eye) is a painful, temporary burn to the cornea caused by exposure to the intense UV radiation an arc produces. It’s avoided with the same basic discipline that prevents most TIG safety issues: never strike or view an arc without a properly rated welding helmet, and consider safety glasses underneath the helmet for additional protection against UV scatter. Particularly in workshops where multiple welders are working in proximity to each other’s arcs.

What Are the Most Common TIG Welding Mistakes?

Most TIG welding problems come down to a short list of avoidable habits:

• Welding onto a dirty or contaminated surface. TIG is far less forgiving of surface contamination than MIG or Stick. Clean the weld joint thoroughly before starting; this single step prevents a large share of weld defects.
• Neglecting tungsten preparation. Dress or grind the tungsten electrode to a clean point, similar to a sharpened pencil, before welding. A poorly prepared tip leads to an unstable arc and inconsistent welds.
• Skipping the gas lens. A gas lens helps hold the tungsten securely in place while maintaining good electrical contact for current transfer. It improves both shielding gas coverage and weld joint accessibility. Leaving it out is a common, easily fixed oversight.
• Getting torch gas settings wrong on aluminium. Using too much torch gas when AC welding aluminium wastes gas without improving the weld. Gas flow should be set appropriately for the joint and current, not simply turned up.
• Not researching welding parameters before starting. Amperage requirements vary by tungsten size, and guessing rather than checking leads to a weak or unstable arc.
• Over-welding the joint. Adding more weld than the joint needs, or overcompensating for a perceived weakness, increases welding time and wastes shielding gas and filler metal for no structural benefit. Efficient preparation reduces the temptation to over-weld.
• Working without an inverter power source. Modern inverter machines convert AC to DC and back at high speed, producing a smoother, more stable arc than older transformer-based machines. Worth factoring in when a “mistake” turns out to be working with an outdated machine rather than poor technique.

TIG Welding Quick Tips

A few additional habits are worth building into routine TIG work:

1. Use a foot pedal to control amperage in real time, increasing or decreasing heat into the weld puddle as the joint demands.
2. When TIG welding aluminium, mix a small amount of helium into the argon shielding gas; a 50/50 blend is a useful starting point for thicker aluminium or magnesium.
3. TIG’s versatility across materials is one of its biggest advantages. Make the most of a TIG machine by using it across the full range of metals it’s suited to, rather than defaulting to other processes out of habit.

TIG Welding Aluminium

TIG is the process of choice for welding aluminium where weld quality and appearance matter, but aluminium welding has its own specific demands around current type (AC vs DC), gas mixes, and heat control that go beyond general TIG technique.

This guide focuses on TIG welding as a general process. For aluminium-specific setup, including why AC is the industry standard for aluminium TIG welding, when DC can be used instead, and how to manage heat input on thinner sections, see our dedicated Aluminium Welding Guide.

Choosing the Right TIG Welder

This guide covers the TIG process itself. If you’re at the equipment-selection stage (comparing AC/DC vs DC-only machines, brands, power output, duty cycle, and portability), see our Which TIG Welder? Buying Guide for a full breakdown built around the right machine for your application.

Frequently Asked Questions

Is TIG welding the strongest type of weld?

TIG is often regarded as producing the strongest and highest-quality weld of the common arc processes, thanks to its precise heat control and narrow heat-affected zone. However, weld strength ultimately depends on filler metal, joint design, and welder skill as much as the process itself. A poorly executed TIG weld will not outperform a well-executed MIG or Stick weld.

Can TIG welding be used on thick or structural steel?

Yes. Provided a qualified procedure is followed by a competent welder, TIG poses no risk to mechanical integrity on carbon steel of any thickness. The main limiting factors on heavy steel are practical rather than structural: TIG is slower and more expensive than alternatives like Stick welding, and the torch and machine need to be correctly specified for the section thickness.

What’s the difference between TIG, MIG, and Stick welding?

TIG uses a non-consumable tungsten electrode and a separate filler rod for precise, high-quality welds, but it is slower and needs a clean, sheltered environment. MIG feeds a continuous consumable wire for faster, easier welding suited to production work. Stick (MMA) welding uses a flux-coated consumable electrode and tolerates outdoor and on-site conditions better than either TIG or MIG, at the cost of finish quality.

Why does my TIG welder keep tripping out or losing power?

This is usually caused by an undersized or extended power supply (causing a voltage drop), a torch that’s underrated for the amperage the job needs, or a faulty or corroded ground connection. Check the electrical supply and breaker first, then the torch rating, then the grounding.

What PPE do I need for TIG welding?

A welding helmet, gloves, and flame-resistant protective clothing are essential, along with fume extraction wherever practical. Safety glasses worn under an auto-darkening helmet add protection against stray UV exposure.

What causes porosity or pinholes in a TIG weld?

The most common cause is loss of shielding gas coverage, often from welding in windy or draughty conditions, which disturbs the inert gas blanket protecting the weld pool. Surface contamination on the joint and incorrect gas flow settings are the other frequent culprits.