Standard Compliant Cast Double Bitt Mooring Bollards

Standard Compliant Cast Double Bitt Mooring Bollards

A batch of high-performance cast double bitt mooring bollards has completed factory inspection and is ready for export to overseas port terminals. This twin-post integrated bollard is one of the most widely adopted mooring fittings for commercial ports, engineered and manufactured in compliance with mainstream international port and marine equipment standards.

Relevant Industry Standards & Specifications

This double bitt bollard follows BS 6349-4 (Maritime Works – Design of fendering and mooring systems) for onshore quay mooring equipment design, the core British/European code for port mooring infrastructure, which defines load assumptions, installation requirements and safety factors for bollards on berthsBSI Knowle  For material, casting and load verification, production also references ISO 13795:2020 (Ships and marine technology — Mooring and towing fittings) and common classification society acceptance rules. Per standard requirements, the mandatory proof load test shall be executed at 1.5 times the Safe Working Load (SWL) and held for a specified duration without permanent deformation, crack or displacement; NDT inspection is applied on critical casting sections to eliminate internal shrinkage, porosity and inclusion defects. Marking of SWL, casting batch and traceability code must be permanently cast onto the body as required by the specifications.

Production Process

The double bitt bollard adopts one-piece sand casting with ductile iron or cast steel as raw material.

1. Pattern & mould preparation: Precision resin patterns are produced according to certified engineering drawings. Sand moulds are assembled for integral casting, avoiding welded joints which are common on fabricated bollards.

2. Melting and pouring: Molten metal is smelted and poured under strictly controlled temperature parameters to minimise casting defects such as slag inclusions and cold shut.

3. Shakeout, fettling and stress-relief heat treatment: After cooling, risers and flash are removed, then the casting goes through annealing treatment to release internal casting stress, improving impact resistance and fatigue performance under cyclic mooring tension.

4. Machining: Foundation bolt holes and base seating surface are precision machined to guarantee flat contact and accurate bolt positioning for quay installation.

5. Coating, inspection and load testing: Anti-corrosion epoxy primer (red paint) is applied for long-term protection against salt spray in coastal environments. Every production batch undergoes dimensional check, visual inspection, material certificate review and the mandatory 1.5×SWL static proof load test before packing and shipment.

Dockside Application

Fixed to quay slabs, jetties and dolphins via anchor bolts, double bitt bollards serve as primary fixed points to secure mooring lines for container vessels, bulk carriers, general cargo ships and barges. Its dual-post layout enables mooring crews to arrange bow lines, stern lines and spring lines on separate posts. When vessels move under combined loads of tide, wind and wave action, ropes can be wrapped and crossed between the two horns to distribute tension. It is especially preferred for busy multi-purpose berths and terminals with large tidal ranges, where frequent vessel movement and multi-line mooring are required.

Advantages Compared with Single Bollards, Cruciform Bollards & Staghorn Bollards

1. Multi-line load distribution: Unlike single bollards that stack multiple ropes on one horn and create concentrated overload, the double bitt design separates mooring lines onto two independent posts, distributing tension evenly and lowering the risk of sudden rope slip or local structural failure.

2. Superior anti-slip geometry: Top and middle retaining flanges prevent synthetic or steel mooring ropes from jumping off the bollard during vessel surging, delivering higher operational safety than plain cylindrical single bollards.

3. Space-saving integrated base: One shared foundation plate carries two posts. Compared with installing two separate single bollards, it reduces quay footprint, cuts foundation reinforcement work and simplifies on-site alignment and installation.

4. Broader adaptability for mixed vessel fleets: The same double bitt unit can accommodate mooring of small feeder vessels up to large bulk carriers, bringing flexibility for terminals handling diverse ship types.

5. Better fatigue performance: The monolithic cast structure eliminates welding seams, which are typical failure points for fabricated welded bollards. It performs better under repeated cyclic tension loads at exposed coastal terminals.