It cannot be more strongly emphasized that when using any heat-treatment salts (low-temperature or high-temperature salts) the utmost of care be taken, not only by the heat-treatment associate but by management in terms of safety lectures on the use of the salts, handling the salts and other safety issues.
Nitrate salts are generally comprised of a mixture of potassium nitrate and sodium nitrite. Both of these salts are oxygen suppliers, and one often finds them being used occasionally in the mixture of gunpowder. Extreme care needs to be applied when using not only the nitrate salts, but any heat-treatment salts.
If the salt bath is in need of repair and it necessitates a person going inside of the salt bath (empty of course), the event should and MUST be considered “confined-space entry.”
Everyone involved in the repair of the salt bath must fully understand each other’s function and the potential dangers of confined-space entry. This applies not only to heat-treatment salt baths. Any furnace that requires an entry into the process chamber or quench tank must be considered confined-space entry, and each person should sign off that they understand the confined-space-entry requirements.
When handling the salts (nitrate or otherwise), one should wear appropriate safety clothing. This safety clothing includes:
- Fire-resistant insulated long-sleeved jacket
- Fire-resistant insulated over-trousers
- Long-sleeved insulated gloves
- Shoe spats to prevent burning of the feet with liquid salt splashes
- Safety goggles for eye protection
- Safety full-face shield
- Head protection helmet
The nitrate salts are generally very easy to handle with an approximate working temperature range from 350-1000˚F. It should also be remembered that if the safety clothing is not worn and if the salt splashes (for whatever reason) onto the skin, it will keep on burning into the skin until the salt cools down to a solid. This can create very nasty burns that will take a long time to heal.