The recommended maximum time for which a mooring rope product can be stored under specified conditions while also the defined quality remains with no loss of its properties, is called Shelf Life.
Synthetic mooring fiber ropes are made from various materials such as Polypropylene, Polyester, Polyamide, HMPE which have different properties and can be affected by many factors when in storage:
🌡️ Heat Generating Sources
When exposed to heat, all synthetic materials are affected and may lose mechanical properties such as tensile strength. Depending on the temperature exposure and the rope material, the degradation of the rope may vary.
💧 Ambient Moisture
While most synthetic ropes are not affected by moisture, Polyamide (Nylon) ropes absorb water particles and their strength may be significantly reduced. This process is irreversible even in small moisture levels.
☀️ Sunlight Exposure
Sunlight can cause depolymerization of the rope’s material. The extent of the damage on the mechanical properties depends on the size of exposure (direct or diffused sunlight, time period of exposure and UV stabilization of the material).
🧪 Chemical Exposure
Many cases of rope storage conditions on-board vessels include contact with various chemicals (paints, acids, cleaning products etc.) that can cause severe damage to the molecular structure of the rope. This leads to further degradation of material strength and may be a cause for rope retirement.
Proper Storage of Mooring Ropes Includes:
- Dry conditions
- Room temperatures
- No exposure to sunlight
- Zero exposure to chemicals
Ropes stored on-board vessels under these conditions in packaging as received by manufacturer may reach many years without loss of the initial defined quality.
⌛ The Shelf Life of any rope product will be a maximum of 7 years (when stored properly as explained above) retaining 100% of its break strength, but this Shelf Life is terminated by the date that the item is used for service (operation) or subjected to disposal action.
⏲️ At 10 years of proper storage, minimum strength losses are expected (up to 5%), but the rope will be still safe and fit for use in mooring operations. After 10 years of proper storage the strength losses are undetermined and the user is recommended to check for residual strength. When a rope item is unpacked and introduced to operation, shelf-life management stops and service life begins.
