Welding safety

This is not a comprehensive guide. There are many ways in which welding can damage your health. The main points are:

  • Protect all skin from UV light
  • Closing your eyes for a few sneaky tacks will not prevent arc eye
  • Work in a well ventilated area (extraction fans not blowing fans as those would blow your shielding gas away).
  • Wear a vapour mask if your extraction isn’t great.
  • Be careful not to have flammable stuff nearby. Welding and grinding sparks can travel a long distance.

Welding arc eye

The light generated by MIG welding is extremely bright. Looking directly at a welding arc even for a short time causes arc eye when the bright flash from the arc burns the cornea. The cornea is very sensitive to sun burn. Expect to be awake all night with the sensation that someone is sticking pins in your eye.

For sensible people wearing a full face welding mask it tends to be the reflected light that causes arc eye. Welding all day in a room with white painted walls can be enough. Welders caps aren’t just to stop sparks.

Be very careful to warn anyone else in the area when you are about to start welding, and use a welding screen if welding in an area where there might be passers by. Be especially careful with pets and children – they can be as daft as a brush.

welding mask

Metal vapor and your lungs, kidneys, brain etc.

MIG welding and angle grinding results in metal vapors.

Aluminium alloy vapour and fumes from zinc coatings are poisonous. Exposure can result in heavy metal poisoning (welding shivers) – flu like symptoms that can persist for a few days. The zinc coating should be removed from galvanised steel before welding, and wear a proper charcoal welding mask when you go anywhere near zinc.

It doesn’t stop there – the fumes from flux cored gasless wire and ARC welding are nasty. Stainless gives off chromium, MIG and TIG arcs give off ozone. Welding should be carried out in a well ventilated area.

This stuff is cumulative. Professional workshops normally have extraction systems. A DIY approach might be to leave the garage door open when welding. For prolonged welding It’s a good idea to wear a vapour mask.

metal vapor and lungs

Protection from UV light and molten metal

The light from MIG welding has a strong ultraviolet content and causes sunburn. I’ve welded in a T-shirt in the past and the burns from an afternoon of thick metal were very painful. Full coverering of arms and legs is essential. If it’s hot wear thin clothes in preference to stripping to exposed skin.

Although the weld is also likely to spit small blobs of metal out. Welding gauntlets protect the hands and wrists, and it is sensible to wear cotton overalls or clothing. Take care not to leave gaps in your clothing or shoes where a blob of metal could enter. Blobs of molten metal can burn through any thin clothing and cause small but painful burns.

The metal you weld stays hot for a good while. Most of my burns have been caused by forgetting this and picking up a hot piece of metal in my bare hands.

welding gloves (gauntlets)

Fire safety

Molten metal can spit several feet from a weld. Grinding sparks are even worse. Do a risk assessment on your surroundings – though you could wait until you’ve had a few destructive fires like I did. Any sawdust, paper or plastic bags in the area can smolder and catch fire so keep a tidy area for welding. You think you’ll notice flames but flames aren’t bright when looking through a shade 10 visor.

Keep a fire extinguisher beside the exit door from your workshop. CO2 is the best type for welding. A bucket of sand is also a good idea – it could save the expense of having the fire extinguisher refilled.

The photo shows a foam extinguisher (it contains water so it’s not safe for use near electrical equipment like …err… electric welders). It’s since been replaced by a 2kg CO2 extinguisher. Don’t squirt water or foam extinguishers anywhere near electricity for obvious reasons.

My extinguisher sits ready to use with the plastic tie removed. You’d be amazed how long it takes to figure out how to remove the plastic tie when you really need to. Fires spread quickly and you will be in a panic (been there)!

fire extinguisher

Angle grinding

Workshop tools are noisy and will damage hearing. I was lucky enough to be given some good advice by an almost completely deaf mechanic at the start of my career. He shouted “always wear ear protection when using a grinder, a hammer or even a drill”. Don’t use cheap ones like the daft frog in the photo – you can pick up nice Peltor ones from Screwfix for £10.

Eye protection is important for grinding. Make sure you buy decent goggles with impact resistant lenses and without direct air breathing holes. The cheaper ones just let sparks in. Also always make sure the sparks are directed away from you as you grind.

Keep fire in mind again when using a grinder. I’ve never started a fire when welding, but have done a couple of times by not paying attention to where grinding sparks were landing. Clear up grinding dust too – aluminium dust mixed with steel dust burns so well it’s actually used as a welding power source (thermite).

angle grinding protection

Common sense (a disclaimer)

Use your common sense when welding. This page may not be comprehensive. Take advice from your welding supplier and experienced welders before starting to weld. See the more detailed disclaimer too.

Weklding helmets and safety equipment A range of welding helmets and other safety equipment are available in the shop on this website.

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Introduction
Welding is the process of permanently joining two or more metal parts, by melting both materials. The molten materials quickly cool, and the two metals are permanently bonded. Spot welding and seam welding are two very popular methods used for sheet metal parts.Spot welding is primarily used for joining parts that normally upto 3 mm (0.125 in) thickness.

Spot-weld diameters range from 3 mm to 12.5 mm (0.125 to 0.5 in) in diameter.

Materials
  • Low carbon steel is most suitable for spot welding. Higher carbon content or alloy steels tend to form hard welds that are brittle and could crack. This tendency can be reduced by tempering.
  • Austenitic Stainless steels in the 300 series can be spot welded as also the Ferritic stainless steels. Martensitic stainless steels are not suitable since they are very hard.
  • Aluminums can be welded using high power and very clean oxide free surfaces. Cleaning the surface to be oxide-free, adds extra costs (that can be avoided with low carbon steel).

  • Dissimilar materials cannot be spot welded due to different melt properties and thermal conductivities. Plated steel welding takes on the characteristics of the coating. Nickel and chrome plated steels are relatively easy to spot weld, whereas aluminum, tin and zinc need special preparation inherent to the coating metals.
Manufacturing Considerations
  • Thickness of the parts to be welded should be equal or the ratio of thicknesses should be less than 3:1.
  • Spacing of welds
    • Min. Weld to weld spacing = 10 x Stock thickness.
    • Center of weld to edge distance = 2 x weld diameter, minimum.
    • Weld to form distance = Bend Radius + 1 weld diameter, minimum.
  • Adequate access for spot welding should be considered. Small flanges in U channels for example may restrict the electrode from entering the part.
  • Flat surfaces are easier to spot weld due to easy access. Multiple bends impose access restrictions, and special fixtures may have to be designed to handle the parts, if access is not a problem.
  • Prior to finishing, the spot welds have to be sanded or ground to blend the welds with the rest of the surface.
  • It is best to choose the same spot weld size, to minimize setups and increase throughput.
  • Plating of spot welded assemblies can cause problems when the sheet metal is overlapped. This can cause plating salts to be trapped-requiring special cleaning, or potential long-term corrosion problems. By carefully designing the assembly to allow easy draining of plating solutions this can be avoided.
  • The mating parts can be self-jigged for easy location prior to welding. This can be done by lancing one part and locating in a corresponding slot in the other part; or by boss type extrusion, weld buttons, in part locating to a slot in the other. This type of design can often eliminate the need for external fixtures.

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TIG Welding Tutorial

This tutorial is intended to offer practical advice to complete beginner TIG welders but should also be useful to intermediate welders.

There’s no single ‘learn to TIG’ page, instead each page demonstrates aspects of the technique using different joint types. As usual the tutorial is not a substitute for a college course or time with a professional, but it should cover the basics. Feel free to ask on the forum if you get stuck.

Set Up

Just enough information to get the machine set up for the tutorials.

The page details how to grind the tungsten, how far the tungsten should stick out from the shroud, gas flow and machine settings.

Setting up a TIG welder

TIG Amp Chart

Learning to TIG weld is tricky enough without having to guess the amps. We’ve written down the amps, tungsten size and filler rod diameter that we would choose for different joints, materials and thicknesses. You can print them out and stick them to your welder.

There is no definitive chart for this sort of thing – the choice of amps depends a lot on technique and travel speed, but it’s handy to have a starting point.

TIG Amp Chart

TIG Welding Technique

TIG is a very precise process, much more so than MIG or Arc, so if you are moving from those processes pay attention to the tips on how to set up your body position to achieve the necessary precision.

We’ve produced a few videos to illustrate how to TIG weld. The page covers the technique itself and what to aim for.

TIG Welding Technique

Butt Weld and Tacking

Don’t spend too much time laying TIG beads – when you get the hang of moving the weld pool along it’s much more fun and informative to try a joint.

We’ve also covered tacking in this section.

Butt Welding and Tacking

Fillet Welds

Fillet welds are an excellent test of technique. Once you have clicked with fillets all of your other TIG welding should be good.

The earlier pages talk about things like the arc gap and how the filler rod affects the weld. Fillets will force good technique in these areas.

TIG Fillet Welds

Lap Joints

We’ve covered the main techniques so for completeness it’s worth offering some advice on the other types of joint you might want to do. Lap joints are very much like fillet joints, just you are welding end-on rather than side-on to the sheet on top.

The lap joint page covers the trouble that involves.

TIG Lap Joints

Outside Corner Weld

Outside corner joints introduce gas issues as well as positioning issues. That makes them a great way to finish off the technique section of the tutorial.

An inside corner (fillet) will demand more amps and will cope with a smaller shroud than butt welds. An outside corner is the opposite – the gas is not contained by the joint, and there is nowhere for the heat to go so amps need to be reduced.

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