02 October 2007

Health and Safety

OSHA inspected the shop shortly before I was hired, and apparently we met their standards. We run a pretty clean, safe shop, so I'm not surprised. That doesn't mean I'm feeling 100% secure about my health at work, though.

Tungsten Inert Gas (TIG) welding uses a tungsten or tungsten-alloy electrode (about the size of the graphite in a standard pencil) to carry electricity to the metal. The industry standard in the USA is 2% thoriated tungsten. It's been used for years, it's the least expensive type of tungsten electrode on the market... and it's radioactive.

Okay, it's not stirring-your-coffee-with-a-uranium-spoon radioactive, but it does put off enough alpha particles to cause concern. When the electrode is just sitting there, it's fairly harmless because the radioactive thorium is sort of encased in the tungsten. When it's being sharpened, however, the radiation is released in the dust and can cause lung damage.

The pdf version of the MSDS for 2% thoriated tungsten electrodes seems to be missing a snippet that shows up if you view the document as html:

Several studies carried out on thoriated tungsten electrodes have shown that due to the type of radiation generated, external radiation risks during storage, welding, or disposal of residues are negligible under normal conditions of use. On the contrary, during the grinding of electrode tips there is generation of radiation of radioactive dust, with the risk of internal exposure. Consequently, it is necessary to use local exhaust ventilation to control the dust at the source, complemented by respiratory protection equipment. The risk of internal exposure during welding is considered negligible since the electrode is consumed at a very slow rate. Precautions must be taken to control any risk of exposure during the disposal of dust from the grinding divices.

We don't have local ventilation for the belt sander we sharpen our tungstens with. Edit: the sander does have its own dust-collection system. We don't take any special precautions when disposing of the dust... it goes in the trash with everything else. I don't think any of the guys in the shop even realize that they're dealing with radioactive material. It's just another piece of metal to them.

Welding is dangerous. If I hadn't accepted that fact, I wouldn't be in this trade. I know I'm going to get burnt and electrocuted, I know my lungs will never be clean again, and I'm not too worried about that. On the other hand, with so many other types of (non-radioactive) tungsten electrodes on the market, it seems like an unnecessary risk to continue using thoriated tungsten. It's been banned or strictly regulated in the rest of the world, but we continue to use it as if it were completely harmless.

I always get Chuck to sharpen my electrodes for me.

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