An introduction to welding

Welding is a high heat process that melts the base metal with a filler material unlike soldering, which does not.

Types of welding

MIG (gas metal arc welding) is a type of arc welding with a small wire fed through a tube to get welded to the metal. It is faster, cheaper and easier than TIG welding and is commonly used for automotive and at-home DIY projects.

TIG (gas tungsten arc welding) requires the use of both hands and a foot (to operate the foot pedal). It is more costly, time-consuming and difficult and used to weld thick sections of stainless steel or non-ferrous material. This high-quality weld is generally used in the aerospace industry.

Plasma cutters use a high-energy beam to fuse the material together and requires expert control.

Preparing the steel for welding

A slight bevel on the edges you're welding will create a seam that offers more strength and durability than a welded seam done on straight edges. The most common ways to bevel steel include hand grinding, flame cutting and machining.

Welding safety

Welding is a tough skill to master and carelessness can easily cause injuries. These are a few key points about welding safety to keep in mind.

Noise

Noise levels above can be dangerous to your hearing. Examples of this include heavy traffic, trains, lawnmowers, or motorbikes. Flame cutting can produce over 100dB and puts you at risk of tinnitus, dizziness, and high blood pressure. Extended exposure to these noise levels can cause permanent hearing damage, and wearing earplugs can help you avoid this.

Electric shock

When dealing with live electrical circuits and molten metal the risk from a direct electrical shock or secondary shock is high. Always take the necessary precautions.

UV radiation

Arc-eye is a common, painful condition from exposure to the intense light emitted during welding. However, fumes, gases, sparks, dust or other particles can cause loss of vision when you don't wear a specialised welder's visor/helmet.

Gases

Invisible hazards can be very dangerous. Welding fumes contain various chemicals known to affect airways. Wearing a respirator mask will help filter the air.

While a welding career can be challenging, taking care of health and safety on the job can make it a wonderfully fulfilling career.

Learning and applying welding skills

Who are considered welders Tradesmen and women specialising in the fabrication of products by joining or fusing a variety of metal components together wear the proud title of welder. They are employed in a range of industries, including steel, construction, automotive manufacturing, shipbuilding, aerospace, mining, agriculture and more. The demand for welders is always high, and beyond solid skills, you will also need serious training.

For some employers, a matric certificate and a series of employer-based welding tests are sufficient, while others may require that welders have some form of formal welding certification or even a degree in welding from a recognised technical school, college or institution such as SAIW (Southern African Institute of Welding).

Welders also need physical strength and a certain amount of skill in order to manage hazardous and heavy welding equipment. They should be quick learners with excellent hand-eye coordination and manual dexterity and mathematically minded with problem-solving and strong communication skills.

Training as a welder can range from a few weeks of skills study and on-the-job training for low skilled positions to a few years of combined study and job training in the art of heating, joining and shaping metals.

Gaining welding experience and techniques through a welding apprenticeship with a company or through on-the-job training is a great asset for any welder, as work opportunities are greater for those with more expertise. Being educated in the latest technologies, methods and techniques through formalised welding learnership programmes include soldering, brazing, arc welding, casting and bronzing. Coursework may also include advanced mathematics, physical sciences, civil and mechanical technologies, metallurgy, blueprint reading, pipe layout, welding symbols and welding practicum. A trade test is often also required before practising as a qualified welder.

A practical, supervised internship for a specific period would include practising skills like shielded metal arc welding, gas tungsten arc welding, gas metal arc welding and oxyacetylene welding and cutting.

Possible careers include welding inspector, welding fabricator, welding supervisor, welding engineer or foreman, welding sales representative and welding educator.

Terminology

Parent metal

Metal to be joined by welding.

Filler metal

Metal added during welding.

Weld metal

All metal melted and retained in the weld.

Heat Affected Zone (HAZ)

The part of the parent metal affected by the weld but not melted.

Fusion line

Also known as a weld junction, the fusion line is the boundary between the weld metal and the HAZ.

Weld zone

The area containing the weld metal and the HAZ.

Weld face

The surface of a fusion weld on the side the weld was made.

Weld root

An area on the side of the first run furthest from the welder.

Weld toe

The boundary between a weld face and the parent metal or between runs. Weld toes are points of high stress concentration and can show the first signs of fatigue or cold cracks unless blended smoothly into the parent metal surface.

Excess weld metal

Weld metal lying outside the plane joining the toes.

Run (pass)

Metal deposited during a passage of an electrode.

Layer

Stratum of weld metal consisting of one or more runs.

Spot welding

Heat delivered between two electrodes and applied to a small area.

Seam welding

Similar to spot welding except it uses rotating wheels rather than electrodes to deliver a continuous leak-free weld.

Plug weld

Weld made by filling a hole in one component of a workpiece with filler metal to join it to the surface of an overlapping component exposed through the hole.

Slot weld

A joint between two overlapping components made by depositing a filler weld around the periphery of a hole in one component to join it to the surface of the other component exposed through the hole.

Lap joint

A connection between two overlapping parts making an angle to one another of 0-5° inclusive in the region of the weld.

Cruciform joint

A connection in which two flat plates or bars are welded to another flat plate at right angles and on the same axis.

Edge joint

A connection between the edges of two parts making an angle to one another of 0 to 30° inclusive in the region of the joint.

Corner joint

A connection between the ends of two parts making an angle to one another of more than 30 but less than 135° in the region of the joint.

Butt joint

A connection between the edges of two parts making an angle to one another of 135-180° inclusive in the region of the joint.

T-joint

A connection between the end of one part and the face of the other part, making an angle to one another of more than 5 up to and including 90° in the region of the joint.

Contact Tru-Butt for more information

For all your welding needs, including repairs, contact Tru-Butt today, for more information on their services.

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