Temperatures higher than which value can cause a permanent reduction in the rated load of a chain and its sling fittings?

• A. 250°F
• B. 500°F
• C. 750°F
• D. 1,000°F

Answer: (B)

When steel is exposed to high heat, its internal structure changes and its strength drops. The rating on a chain sling assumes normal service temperatures, so once the material is heated past a certain point, that rating can no longer be trusted. For carbon steel chain and sling fittings, heating above about 500°F causes a permanent reduction in the rated load because the steel softens (anneals) and its tensile and yield strengths decrease. If the chain or fittings have been heated beyond this threshold, they should not be used at their original rating and must be re-rated or replaced.

Temperatures at 750°F or 1000°F would only worsen the degradation, while 250°F is well below the threshold and does not cause a permanent loss of rating.