How does an Offshore Single Point Mooring (SPM) Operation Work?

A single point mooring (SPM) happens to be a floating jetty/buoy anchored offshore that allows tanker ships to handle liquid cargo like petroleum products. SPM is mostly employed in places where there isn’t a specialized ability for loading or unloading liquid form cargo. These single point mooring (SPM) facilities, which are located several kilometres from the shore and connected by sub-sea and sub-oil pipes, can handle vessels of large capacity such as VLCCs.

For loading and unloading liquid and gas cargo, single point mooring (SPM) provides a link between shore-facilities and tankers. The following are   primary advantages of adopting SPM:

  • Capacity to deal with extra-large vessels
  • It does not necessitate ships arriving at the port, saving both fuel and time.
  • Ships with large draughts can simply be moored.
  • Cargo of high quality can be easily handled.

How Does SPM (Single Point Mooring) Work?

The offshore-anchored loading buoy is separated into various sections, each with its own function.

The key components of the SPM are the mooring and anchoring system, buoy body, and product transfer system.

The SPM is secured to the seabed with a mooring system that includes anchors, anchor chains, and chain stoppers, among other things. The mooring system allows the buoy to move freely within predetermined limits, taking into account the effects of wind, waves, current, and tanker ship circumstances. Anchor chains (legs) are fastened to the anchor point (gravity based or piled) on the seafloor to secure the buoy to the seabed. To link the chains to the buoy, chain stoppers are utilized.

The floating above-water element of the Single Point Mooring System (buoy body) has a revolving section that links to the tanker. The tanker can get steady in its preferred position around the buoy thanks to the rotating portion. A hawser setup, which consists of polyester or nylon rope shacked to an integrated hook on the buoy deck, is commonly used to moor the tanker to the buoy. To prevent damage from tanker fairlead, chafe chains are linked at the tanker end of the hawser. The mooring systems utilized in such offshore activities adhere to the Oil Companies International Marine Forum’s guidelines (OCIMF).

The mooring buoy’s product transfer system is placed in the centre. From the Pipeline End and Manifold (PLEM) (geostatic position) on the seabed, the system transports products to the ship. The subsea pipelines are connected to the buoy’s product transfer system by risers, which are flexible hoses. Breakaway couplings (A specific form of coupling having a breakpoint that will break at a predefined break load, activating internal valves that will automatically seal at both ends and prevent further release of products.) are used to attach the buoy to the tankers to prevent oil spills.

An overview of the single point mooring (SPM) system’s operation.

For cargo loading and unloading, the tanker ship is anchored to the buoy.

A boat landing spot on the buoy deck allows access to the buoy for securing the ship and setting up the connections.

Fenders protect the buoy from the ship’s unexpected movement caused by bad weather.

The buoy’s lifting and handling equipment makes it possible to handle hose connections and safety gadgets.

Valves are controlled from the electrical substation once the connections have been completed.

As a safety measure, necessary alarm systems and navigational aids are given.

The product transfer system of the single point mooring system is used to transport liquid cargo from the floating hose repair in Malaysia to the tanker.

Additional Sources

Maintenance and Operation Guide for Single Point Moorings

The Single Point Mooring Maintenance and Operations Guide provides a framework and set of procedures for operators of SPM terminals, based on the considerable expertise of numerous organizations.