Working Load Limit (WLL) Calculation

The Working Load Limit (WLL) is the maximum load a tiedown can safely handle. § 393.100 requires total tiedown WLL ≥ 50% of cargo weight.

Manufacturer WLL

• Every chain, strap, hook, and tiedown component has a stated WLL
• WLL is the maximum continuous load
• Working margin: 1/2 to 1/4 of breaking load
• Stamped or labeled on the component

Common chain WLL examples

• 3/8" Grade 70 chain: WLL 6,600 lbs
• 3/8" Grade 80 chain: WLL 7,100 lbs
• 1/2" Grade 70 chain: WLL 11,300 lbs
• 5/8" Grade 70 chain: WLL 18,100 lbs

Common strap WLL examples

• 4" strap: WLL ~5,000 lbs
• 6" strap: WLL ~9,000-13,000 lbs

Deration factors

• Wear: damaged chains/straps are derated (lower WLL)
• Wet conditions: ratings may reduce
• Knots/folds: significantly reduce WLL
• Sharp edges: contact with cargo edges reduces WLL

Total tiedown WLL

• Sum of all tiedown WLLs on the load
• Must be ≥ 50% of cargo weight
• Example: 10,000 lb cargo requires ≥ 5,000 lb total WLL
• Distribute across multiple tiedowns

Common errors

• Assuming higher-rated tiedown without verification
• Counting damaged tiedowns (should be removed)
• Single high-WLL tiedown instead of multiple distributed
• Tiedown attachment point WLL not considered (must also be rated)

Anchor point WLL

• Trailer anchor points have their own WLL
• Total cargo tiedown limited by lowest WLL in the system
• Attachment to weak anchor = WLL limited by anchor, not tiedown

Compass cargo securement

• WLL calculator built-in
• Tiedown configuration scoring
• Alert if total WLL insufficient for cargo
• Common commodity ratings referenced

CFR citations

• 49 CFR § 393.100
• WLL Standard

How Compass surfaces this

Searchable in Compass Ask. Runs against carrier fleet data when invoked from the relevant tracker. Read-only; no actions without explicit user approval.

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