3D Model — Orbit & Inspect
Anatomy of a Dee Shackle
Body (Bow)
The U-shaped forged steel body that bears the load. The narrow “D” shape restricts the load to an in-line direction, preventing side-loading. WLL is stamped on the body.
Pin (Bolt)
The removable cross-member that closes the shackle. Can be a screw pin (hand-tightened) or a safety bolt (bolt, nut, and split pin for permanent connections).
Ears (Lugs)
The two flat sections at the top of the body where the pin passes through. The pin hole must be unworn and round — elongation indicates overloading.
Cotter Pin / Split Pin
Used with safety bolt pins to prevent the nut from vibrating loose. Required for all permanent rigging and standing connections where the shackle cannot be regularly inspected.
Dee Shackle vs Bow Shackle
| Feature | Dee Shackle | Bow Shackle |
|---|---|---|
| Shape | Narrow “D” | Wide “Ω” |
| Best for | Single in-line loads | Multi-leg slings |
| Side loading | NOT permitted | Tolerates angular loads |
| Typical use | Chain end links, turnbuckles, wire rope eyes | Connecting 2, 3, or 4 leg sling assemblies |
| Pin rotation risk | Low (narrow body) | Higher (wider body allows movement) |
Selection Rule
Use a dee shackle for straight, in-line pulls. Use a bow shackle when multiple sling legs converge at one point.
Working Load Limits (WLL)
WLL is stamped on the shackle body and must be legible. Common grade S dee shackle sizes:
| Pin Dia. | WLL | Proof Load |
|---|---|---|
| 10 mm | 1.0 t | 2.0 t |
| 12 mm | 2.0 t | 4.0 t |
| 14 mm | 3.2 t | 6.4 t |
| 16 mm | 4.7 t | 9.4 t |
| 19 mm | 6.5 t | 13.0 t |
| 22 mm | 9.5 t | 19.0 t |
| 25 mm | 12.0 t | 24.0 t |
Proof load = 2 × WLL. Never exceed the stamped WLL. Shackles that have been loaded beyond proof load must be removed from service.
Pin Types
- Screw Pin: Threaded pin tightened by hand into the ear. Tighten fully, then back off ¼ turn so the pin can be removed after loading. Used for temporary rigging where the shackle is regularly connected and disconnected.
- Safety Bolt (Bolt/Nut/Split Pin): A bolt passes through the ears, secured with a nut and cotter/split pin. Used for permanent or semi-permanent rigging where the connection must not come undone (e.g., crane pendants, standing rigging).
- Round Pin: Smooth pin retained by a cotter pin only. Less common. Used where quick connection/disconnection is needed but with a safety retention device.
Critical Pin Rules
- Never replace a shackle pin with a bolt, rod, or wire — only use the original rated pin
- Never hammer a pin tight — hand-tight only for screw pins
- Screw pin must always be fully threaded into the ear — if it won’t seat, the shackle is damaged
- Never load the shackle on the pin — load must always bear on the body (bow)
Inspection & Rejection Criteria
Inspect shackles before every use. Remove from service if ANY of the following are found:
Reject Immediately If
- Worn pin: visible wear, reduced diameter, or thread damage
- Elongated body: the “D” shape has stretched — indicates overloading
- Cracks or bends: any visible crack, twist, or deformation in body or ears
- Missing markings: WLL, grade, or manufacturer stamp illegible or absent
- Wrong pin fitted: pin from a different shackle, non-original replacement, or makeshift bolt
- Corrosion: significant pitting, rust, or material loss
- Visible deformation: opening has widened (evidence of overloading)
- Missing cotter/split pin: on safety bolt type — nut will vibrate loose
- Ear hole elongation: pin holes are no longer round — shackle has been shock-loaded
Good Condition Indicators
- Body retains original “D” shape with no distortion
- Pin threads cleanly into ears and seats fully
- WLL and grade markings clearly legible
- No cracks, corrosion, or surface defects
- Pin diameter matches ear holes (no slop or play)
- Cotter/split pin intact on safety bolt types
Safe Use Rules
- Never side-load a dee shackle — the load must always pull in line with the body. Side loads can reduce capacity by up to 50% and cause the pin to bend or the body to distort.
- Always load on the body (bow), never on the pin. The pin is the weakest point.
- Pin must be fully seated in both ears before any load is applied.
- For screw pins: tighten hand-tight, then back off ¼ turn to allow removal after loading.
- Never use a shackle as a permanent anchor point unless it has a safety bolt pin with cotter pin.
- Never weld, heat-treat, or modify a shackle — this destroys the manufacturer’s heat treatment and voids the WLL rating.
- Select the shackle size so the sling eye sits freely in the body — do not force oversized fittings into undersized shackles.
- Tag and quarantine any shackle that has been shock-loaded, dropped from height, or suspected of overloading.
Storage & Handling
- Store in a dry, covered area — never on the ground in mud or standing water
- Keep pins in shackles during storage to prevent loss and mismatching
- Lightly oil threads on screw pins to prevent seizing
- Do not throw shackles — dropping from height can cause micro-cracks invisible to the naked eye
- Separate different sizes and grades to prevent mismatching
- Remove from service and tag for re-inspection if a shackle has been in storage for an extended period
- Store away from chemicals, acids, and salt spray