§ 393.108 How is the working load limit of a tiedown, or the load restraining value of a friction mat, determined?
Wording in the annual edition revised as of Oct. 1, 2006, superseded November 18, 2024.
(a) The working load limit (WLL) of a tiedown, associated connector or attachment mechanism is the lowest working load limit of any of its components (including tensioner), or the working load limit of the anchor points to which it is attached, whichever is less.
(b) The working load limits of tiedowns may be determined by using either the tiedown manufacturer's markings or by using the tables in this section. The working load limits listed in the tables are to be used when the tiedown material is not marked by the manufacturer with the working load limit. Tiedown materials which are marked by the manufacturer with working load limits that differ from the tables, shall be considered to have a working load limit equal to the value for which they are marked.
(c) Synthetic cordage (e.g., nylon, polypropylene, polyester) which is not marked or labeled to enable identification of its composition or working load limit shall be considered to have a working load limit equal to that for polypropylene fiber rope.
(d) Welded steel chain which is not marked or labeled to enable identification of its grade or working load limit shall be considered to have a working load limit equal to that for grade 30 proof coil chain.
(e)(1) Wire rope which is not marked by the manufacturer with a working load limit shall be considered to have a working load limit equal to one-fourth of the nominal strength listed in the Wire Rope Users Manual.
(2) Wire which is not marked or labeled to enable identification of its construction type shall be considered to have a working load limit equal to that for 6 × 37, fiber core wire rope.
(f) Manila rope which is not marked by the manufacturer with a working load limit shall be considered to have a working load limit based on its diameter as provided in the tables of working load limits.
(g) Friction mats which are not marked or rated by the manufacturer shall be considered to provide resistance to horizontal movement equal to 50 percent of the weight placed on the mat.
| Size mm (inches) | WLL in kg (pounds) | ||||
|---|---|---|---|---|---|
| Grade 30 proof coil | Grade 43 high test | Grade 70 transport | Grade 80 alloy | Grade 100 alloy | |
| 1. 7 (1/4) | 580 (1,300) | 1,180 (2,600) | 1,430 (3,150) | 1,570 (3,500) | 1,950 (4,300) |
| 2. 8 (5/16) | 860 (1,900) | 1,770 (3,900) | 2,130 (4,700) | 2,000 (4,500) | 2,600 (5,700) |
| 3. 10 (3/8) | 1,200 (2,650) | 2,450 (5,400) | 2,990 (6,600) | 3,200 (7,100) | 4,000 (8,800) |
| 4. 11 (7/16) | 1,680 (3,700) | 3,270 (7,200) | 3,970 (8,750) | ||
| 5. 13 (1/2) | 2,030 (4,500) | 4,170 (9,200) | 5,130 (11,300) | 5,400 (12,000) | 6,800 (15,000) |
| 6. 16 (5/8) | 3,130 (6,900) | 5,910 (13,000) | 7,170 (15,800) | 8,200 (18,100) | 10,300 (22,600) |
| Chain Mark Examples: | |||||
| Example 1 | 3 | 4 | 7 | 8 | 10 |
| Example 2 | 30 | 43 | 70 | 80 | 100 |
| Example 3 | 300 | 430 | 700 | 800 | 1000 |
| Width mm (inches) | WLL kg (pounds) |
|---|---|
| 45 (13/4) | 790 (1,750) |
| 50 (2) | 910 (2,000) |
| 75 (3) | 1,360 (3,000) |
| 100 (4) | 1,810 (4,000) |
| Diameter mm (inches) | WLL kg (pounds) |
|---|---|
| 7 (1/4) | 640 (1,400) |
| 8 (5/16) | 950 (2,100) |
| 10 (3/8) | 1,360 (3,000) |
| 11 (7/16) | 1,860 (4,100) |
| 13 (1/2) | 2,400 (5,300) |
| 16 (5/8) | 3,770 (8,300) |
| 20 (3/4) | 4,940 (10,900) |
| 22 (7/8) | 7,300 (16,100) |
| 25 (1) | 9,480 (20,900) |
| Diameter mm (inches) | WLL kg (pounds) |
|---|---|
| 10 (3/8) | 90 (205) |
| 11 (7/16) | 120 (265) |
| 13 (1/2) | 150 (315) |
| 16 (5/8) | 210 (465) |
| 20 (3/4) | 290 (640) |
| 25 (1) | 480 (1,050) |
| Diameter mm (inches) | WLL kg (pounds) |
|---|---|
| 10 (3/8) | 180 (400) |
| 11 (7/16) | 240 (525) |
| 13 (1/2) | 280 (625) |
| 16 (5/8) | 420 (925) |
| 20 (3/4) | 580 (1,275) |
| 25 (1) | 950 (2,100) |
| Diameter mm (inches) | WLL kg (pounds) |
|---|---|
| 10 (3/8) | 250 (555) |
| 11 (7/16) | 340 (750) |
| 13 (1/2) | 440 (960) |
| 16 (5/8) | 680 (1,500) |
| 20 (3/4) | 850 (1,880) |
| 25 (1) | 1,500 (3,300) |
| Diameter mm (inches) | WLL kg (pounds) |
|---|---|
| 10 (3/8) | 130 (278) |
| 11 (7/16) | 190 (410) |
| 13 (1/2) | 240 (525) |
| 16 (5/8) | 420 (935) |
| 20 (3/4) | 640 (1,420) |
| 25 (1) | 1,140 (2,520) |
| Diameter mm (inches) | WLL kg (pounds) |
|---|---|
| 10 (3/8) | 150 (336) |
| 11 (7/16) | 230 (502) |
| 13 (1/2) | 300 (655) |
| 16 (5/8) | 510 (1,130) |
| 20 (3/4) | 830 (1,840) |
| 25 (1) | 1,470 (3,250) |
| Width × thickness mm (inches) | WLL kg (pounds) |
|---|---|
| 31.7 × .74 (11/4 × 0.029) | 540 (1,190) |
| 31.7 × .79 (11/4 × 0.031) | 540 (1,190) |
| 31.7 × .89 (11/4 × 0.035) | 540 (1,190) |
| 31.7 × 1.12 (11/4 × 0.044) | 770 (1,690) |
| 31.7 × 1.27 (11/4 × 0.05) | 770 (1,690) |
| 31.7 × 1.5 (11/4 × 0.057) | 870 (1,925) |
| 50.8 × 1.12 (2 × 0.044) | 1,200 (2,650) |
| 50.8 × 1.27 (2 × 0.05) | 1,200 (2,650) |
Amendment history
4 distinct wordings on file since Oct. 1, 2002- Oct. 1, 2002 → Oct. 1, 2003annual edition 2002
A new entry appears whenever the regulatory words change between government snapshots. Day-precise from the eCFR (2017 onward); before that, one snapshot per annual CFR edition (revised as of October 1). Bracketed citations are the Federal Register history printed with the section.