Anchor chain needs regular inspection and maintenance cycle testing, and when necessary, the anchor chain can be refurbished and repaired by hot-dip galvanizing.

Anchor chain is one of the important mooring equipment of ships, and it bears the important responsibility of connecting anchors and hulls and fixing ship positions. It is exposed to seawater, wind and waves and friction all year round, and is one of the parts of the ship system that is most susceptible to corrosion and mechanical wear. Scientific maintenance of anchor chains can not only extend their service life, but also affect the safety of ship mooring. This article will systematically explain how to scientifically maintain anchor chains from the aspects of common damage, maintenance methods, maintenance cycles and inspection standards of anchor chains.

1.Common types of damage to anchor chains

Anchor chains used in marine environments face a variety of damage threats, mainly including the following types:

1. Corrosion

Anchor chains are immersed in seawater all year round and are high-risk areas for electrochemical corrosion of seawater. In particular, the anchor chain frequently contacts the seabed during the process of lifting and dropping anchors. The chloride ions in the seawater can easily penetrate the coating, causing the metal surface of the chain link to oxidize, forming rust, and gradually thinning the effective cross-section of the chain link. 

2. Mechanical wear

During use, the anchor chain will repeatedly contact and rub with the guide chain wheel, anchor chain barrel, anchor hole and other parts of the hull. Sand, corals, and metal fragments on the seabed may also scratch the surface of the chain links, causing local wear and even cracks.

3. Bending, deformation, and breakage

When the anchor chain is subjected to sudden strong pulling, impact in severe sea conditions, overload use, etc., the chain links may bend, twist, or even break. Such problems often occur in the chain links near the anchor ring or the connection with the anchor.

4. The anchor chain steel stamp is blurred or detached

Each section of the anchor chain is usually stamped or numbered to identify the manufacturing batch and service life. Once the steel stamp is blurred due to corrosion or wear, it will affect the subsequent management and traceability of the anchor chain.

2. Daily maintenance points of the anchor chain

Scientific anchor chain maintenance should start from daily operations, focusing on detail management and preventive maintenance:

1. Regular flushing and cleaning

After each use, the anchor chain should be rinsed with fresh water to remove salt and sediment on the surface. In particular, when recovering the anchor chain, it needs to be slowly recovered to avoid bringing sediment or gravel into the anchor chain compartment to prevent rust from accumulating between the chain links.

2. Coating protection

During maintenance, check whether the paint and coating on the surface of the anchor chain are intact. Anti-rust paint or grease should be applied to the exposed parts in time to prevent oxidation corrosion. Common anti-corrosion measures include epoxy paint, zinc coating and heavy anti-corrosion grease.

3. Prevent the anchor chain from tangling or overlapping

The anchor chain is prone to kinking, looping or chain jumping during the lowering or recovery process. These abnormal conditions may cause excessive force on the local chain links. The anchor chain should be released or reeled in smoothly as much as possible.

3. Regular inspection and maintenance cycle

1. Inspection frequency recommendation

Inspect after each voyage: Check whether there are obvious scratches, breaks or peeling rust on the surface of the chain links after anchoring;

Quarterly maintenance: Conduct a comprehensive inspection, including accessories such as swivels, shackles, and anchor chain barrels;

Semi-annual key inspection: Flip the entire anchor chain, check the numbering of each section, and thickness inspection;

2. Inspection method

Visual inspection: Check whether the chain links have obvious wear, cracks, corrosion, etc.;

Thickness gauge inspection: Use ultrasonic or magnetic thickness gauge to detect the thickness of the chain section to confirm whether it meets the standard;

Magnetic particle inspection or ultrasonic inspection: Perform inspection on high-risk parts (such as bends and welding points) to check whether there are internal cracks;

Load test: Perform a tensile test on the entire chain segment or a partial chain link to verify whether it still has a safe working load.

Visual inspection method is suitable for daily anchor chain maintenance inspection, and thickness gauge and magnetic particle and ultrasonic flaw detection load tests are common in anchor chain pre-delivery inspection.

4. Common anchor chain renovation and repair methods

1. Hot-dip galvanizing treatment

Hot-dip galvanizing is an anti-corrosion treatment method widely used in anchor chain renovation. The process is to form a uniform zinc layer on the surface of the chain link to prevent oxidation reaction and extend the service life. 

2. Replace damaged chain links

For broken or severely worn chain links, it is not recommended to repair welding. The entire chain link should be replaced according to the standard and the steel stamp number should be kept intact. Welding repairs often have strength risks and are not recommended for use in high-strength working chains.

3. Establish anchor chain management files

In order to maintain anchor chains more scientifically, it is recommended that ships or shipowners establish a complete set of anchor chain management files, including:

The factory number, manufacturer, and start time of use of each section of anchor chain;

Inspection and maintenance records, including inspection time, inspector, and test results;

Renovation or replacement records, including treatment methods and test conclusions;

Expected time for the next maintenance or renovation.

This archival management method helps to track the status of the anchor chain throughout the life cycle, and facilitates accountability and traceability in maintenance and emergencies.

5.Conclusion

Although the anchor chain is the "infrastructure" of ship equipment, its safety directly determines the stability and safety of the ship in wind and waves. Scientifically maintaining the anchor chain is not only responsible for the equipment, but also a guarantee of life and property. From daily cleaning to periodic inspections, from surface protection to structural inspections, every link cannot be ignored. I hope this article can provide reference and help for you who are engaged in ship operation, port operation and maritime management, so that each section of anchor chain is strong and reliable and can withstand the test of wind and waves.

Our anchor chains are all certified by classification societies.

Please feel free to contact us if you have any questions.