ASME B30.9 specifies the minimum design factor for alloy steel chain slings as

• A. 3
• B. 5
• C. 4
• D. 6

Answer: (C)

ASME B30.9 uses a design factor of four to one for alloy steel chain slings. This design factor is the safety margin built into the sling’s strength: the working load limit (WLL) you can lift is the sling’s minimum breaking strength (MBS) divided by four. In practice, this means the chain sling is designed to carry much less than its breaking strength to account for shocks, wear, and real-world conditions. For example, if a chain sling has an MBS of 40,000 pounds, its WLL would be 10,000 pounds. The factor is there to keep loads well within the rope’s or chain’s capabilities during dynamic lifting, angle effects, and wear over time. Other numerical options do not reflect the standard used for alloy steel chain slings in this code.