The first time you watch a foundry pour, you understand why ordinary safety boots aren't enough. Molten iron at around 1,400°C doesn't care about a 200 joule toe cap. If it lands on your boot, it either runs straight off, or it burns through and sits there. EN ISO 20349 is the standard that decides which one happens.
It's a niche standard, but not an obscure one. Foundries, steel works, casting shops and heavy fabrication all rely on it, and plenty of buyers don't realise their usual S3 boot doesn't cover it. If you're kitting out anyone who works near molten metal or welding sparks, this one's for you. At Colbrook we sell both standard safety boots and foundry-spec footwear, so we see the confusion regularly.
What EN ISO 20349 covers
EN ISO 20349 is the standard for footwear that protects against the risks found in foundries and welding. It comes in two parts, and the difference between them matters.
EN ISO 20349-1 covers foundry work: splash from molten iron and molten aluminium, plus the heat that comes with it. EN ISO 20349-2 covers welding and allied processes: sparks, small splashes of molten metal and contact heat.
Here's the bit people get wrong. 20349 doesn't replace EN ISO 20345, the main safety footwear standard. It builds on it. A boot certified to 20349 also meets the relevant 20345 requirements, which is why the label usually shows both: the S1P or S3 code you already recognise, plus the 20349 marking for the heat side. If you need a refresher on what SB, S1, S2 and S3 actually mean, our guide to EN ISO 20345 safety footwear covers the full breakdown.
What the testing actually involves
This isn't a paperwork standard. To certify foundry footwear to Part 1, the test pours molten metal over the boot. For iron, the test metal is around 1,400°C; for aluminium it's lower, but still hot enough to ruin your day. The boot passes only if the metal runs off without sticking or burning through, and the temperature inside stays within a set limit. The sole is tested against contact heat, and the upper against flame.
Those tests explain why foundry boots look the way they do. Smooth leather uppers with fewer seams, so molten metal has nowhere to pool. Covered or minimal lacing, because a splash sitting in a lace is how you end up with hot metal inside the boot. Heat resistant rubber soles that don't soften when you stand on a hot floor. Some designs add metatarsal protection, since the top of the foot takes the brunt of a splash.
There's a trade-off. That smooth, heat-treated leather is stiff when new and less breathable than a standard work boot. It's the price of not burning your feet off, and anyone who wears foundry boots all shift will tell you the same.
Fe, Al and the codes that follow
Foundry-spec boots carry markings you won't see on a normal S3. Fe means the boot was tested against molten iron splash. Al means molten aluminium. The splash tests are metal specific, so if your process only involves one metal, check the boot was tested against that one. The FC48 foundry boot we supply covers both, which is why its full name reads Fe Al.
Welding boots work to Part 2 instead. Welding throws off sparks and small droplets rather than full pours, so the protection is lighter, but those droplets are still hot enough to melt through a standard boot upper if they sit there.
You'll also see familiar codes from EN ISO 20345 on these boots. HRO means the outsole resists contact heat, HI means heat insulation, CI covers cold insulation, FO is fuel and oil resistance, SR is slip resistance. They matter as much as the splash test when someone stands on hot floors all day.
Do your people actually need 20349?
Not every hot job needs this standard, and you shouldn't buy foundry boots just because someone works near heat. Match the boot to the real risk.
- Pouring, casting, tapping or handling molten metal means Part 1 foundry footwear, matched to the metal involved.
- Welding, cutting or grinding where sparks and slag fly means Part 2.
- Working on hot surfaces with no realistic splash risk means a good S3 boot with HRO and HI is usually enough, and it'll be lighter, cheaper and more comfortable.
Under the PPE Regulations you have to assess the risk and provide protection that matches it. If the assessment says molten metal splash is possible, the footwear has to be up to the job, and you need the paperwork to prove it. A genuine 20349 boot comes with an EU type examination certificate and a declaration of conformity. Ask the supplier for both before you order. If they can't produce them, treat the claim with suspicion.
Expect to pay for the difference. Foundry-spec boots start at roughly £85 ex VAT, against basic S3 boots we sell from under £40. The FC48, for example, sits at £84. When you're protecting someone from molten metal, that gap is easy to justify.
If you're not sure which standard applies to your site, ask before you spend. The wrong boot is a false economy, and checking the certificate takes two minutes. Call Colbrook on +44(0)1236 755544 or browse our safety boots range and PPE category online. Tell us what the job actually involves and we'll point you at the right spec.
REF: EN-ISO-20349-FOUNDRY-WELDING-FOOTWEAR
