3.1 Shackles: Types, Standards & Rating
Key Takeaways
- Dee shackles are normally used in line, while bow shackles provide more connection room; body shape alone does not authorise side loading.
- Screw and bolt-type pins are selected from the connection, movement and loosening risk; a bolt-type system is commonly used for longer-term or vibration-prone arrangements.
- Only the matching manufacturer-controlled pin belongs in the shackle assembly.
- BS EN 13889 Grade 6 shackles use a coefficient of utilisation of 5, while other shackle standards may impose different requirements.
- WLL, bearing geometry, side-load permission, temperature and multiple-eye arrangements must all match the documented product.
Shackles: Types, Standards and Rating
A shackle connects load-bearing components through a removable pin. Safe selection depends on body shape, pin system, material grade, standard, WLL, connection geometry and environment. Similar appearance is not proof that two shackles are interchangeable.
Body Shapes
A dee or chain shackle has a relatively narrow body and is normally selected for a predominantly in-line load. Its shape limits room for multiple sling eyes and makes side loading especially important to avoid unless the manufacturer expressly rates it.
A bow or anchor shackle has a wider rounded crown. It can accommodate more connection movement or multiple sling eyes, subject to crowding and manufacturer limits. The name “bow” does not itself authorise side loading. Some products publish side-load reductions; others prohibit it.
A wide-body shackle provides a larger bearing surface for a wire-rope or synthetic sling. It can reduce local bending compared with a small pin, but it has its own approved connection orientation and load chart. Do not assume that its large body permits every multi-leg arrangement.
Pin Systems
A screw pin is convenient for connections that are assembled and removed frequently. Tighten it as the manufacturer instructs and prevent circumstances that could rotate or loosen it. It is not automatically unsafe in every dynamic lift, but the risk assessment must address motion, vibration and contact with moving sling eyes.
A bolt-type pin uses a bolt, nut and retaining device such as a split pin. It is commonly selected where the connection remains in place, rotation or vibration could loosen a screw pin, or loss of the pin would be difficult to detect. The retaining device secures the nut; it is not intended to carry the primary load.
Other pin arrangements exist for specific products. Use only the correct manufacturer's replacement pin. A commercial bolt lacks the controlled dimensions, fit, material, heat treatment and traceability of the shackle assembly.
Standards and Markings
BS EN 13889 covers specified forged steel shackles for general lifting purposes, including Grade 6 products with a coefficient of utilisation of 5. Other shackles may be made to other national, offshore or manufacturer standards. A standard number must therefore be read with the product grade and scope.
The applicable standard determines required markings. Common information includes manufacturer identity, WLL, grade or traceability mark and product size. CE or UKCA marking and a declaration apply where the current product-supply legislation requires them; they are not substitutes for the shackle's WLL and traceability. Older equipment may have been lawfully placed on the market under earlier marking rules.
Confirm the certificate matches the physical body and pin. A body from one shackle and a pin from another do not become a certified assembly simply because they fit.
Rating and Connection Geometry
The WLL applies to the conditions stated by the manufacturer. Check:
- in-line or permitted side-load direction;
- temperature and corrosion limits;
- number and size of sling eyes in the bow;
- pin and crown bearing diameter;
- point loading or eccentric loading restrictions; and
- any reduction for angle, multiple connections or special service.
Connect the shackle so load bears through the intended centre of the pin and crown. Avoid forcing an eye against the threaded portion, placing a hook on the pin tip, or allowing a sling to pull on only one shackle leg. If two sling eyes share a bow, verify that they do not crowd, overlap or pry the body.
Spacers may be permitted to centre a connection, but they must not bend the shackle legs or obstruct full pin engagement. Use only an arrangement accepted by the manufacturer or an engineered plan.
Selection Example
A lift needs a connector between a two-leg sling and a lifting lug. Do not select only by the sling's total mass. Establish the force at the connector, lug thickness and hole diameter, sling-eye size, expected articulation, temperature and whether the pin can rotate. Then select a documented shackle whose WLL and geometry cover the actual arrangement.
The Foundation rule is: shape suggests purpose; markings and instructions establish permission.
Storage and Control
Store shackles assembled with their matching pins in a dry controlled location so threads and markings are protected. Do not leave pins loose in a communal box where sizes and manufacturers can be mixed. A colour-status system may help inspection control, but the physical marks and records remain necessary. When a shackle is issued for a planned lift, record any special side-load chart or temperature limit with the rigging selection so a later crew does not unknowingly reuse the same body in a different configuration.
Which shackle body is normally selected for a single predominantly in-line connection with limited room for multiple sling eyes?
When is a bolt-type shackle pin commonly preferred?
For a Grade 6 shackle within BS EN 13889 scope, what coefficient of utilisation is specified?