Parting wires - Parting wires
Initial Report
Outline:
Three reports that all relate to wires parting in service.
What the reporter told us (1):
The vessel had berthed safely, and the deck crew was instructed to deploy the starboard accommodation ladder. When the crew started lowering the ladder, the wire rope parted about two metres from its inboard thimble eye, in way of the outrigger’s outboard guide sheave. The gangway fell and hung vertically down the ship’s side. Fortunately, no one was injured. The ladder was recovered and secured, and the portable wharf gangway was deployed and used at the port.
Further Dialogue (1):
The company operated a maintenance programme that called for wires to be end-for-ended after 30 months and renewed every 5 years. The parted wire had only been installed 29 months earlier. The maintenance programme also called for the accommodation ladder to be thoroughly inspected every six months, however no specific instructions or guidance were provided for determining the condition of the wire. On board records showed that the last inspection of the accommodation ladder took place 2 weeks prior to the wire failure, at which time no defects were reported, the wire had been greased and all rollers and moving fittings were free to turn with no signs of defects. Subsequently the company amended their maintenance programme to include monthly inspections and maintenance requirements for the wires. Accommodation ladder wires constructed of galvanized wire rope must be renewed after 24 months.
What the reporter told us (2):
During mooring operations on arrival one of the ship’s forward mooring wires parted at the eye whilst being heaved tight. The damaged wire was released from the shore bollard and replaced with a soft mooring line. The mooring operation was completed safely without further incident.
Further Dialogue (2):
According to the ship’s records, the wire in question had been greased three days before arrival in port. A periodic inspection of the wire had been carried out less than 3 months before the failure, at which time the wire was assessed as acceptable. However, the records also showed that the wire had been in service for 5.7 years. No records of cutbacks, re-termination or periodic load tests were available. Spare mooring wires were available onboard.
What the reporter told us (3):
During routine discharge operations, 4 out of 6 strands of the inner breast mooring wire parted at a position 35-40 metres from the eye. The terminal was immediately informed, and permission was granted for the replacement of the damaged wire. The mooring wire was replaced and the discharge operation was completed without further incident.
Further Dialogue (3):
The wire in question had only been in service for 15 months. Records showed that an inspection one week before the vessel arrived in port had assessed the condition of the wire as ‘very good’. The wire had been lubricated 3 weeks before arriving in port. Furthermore, vessel records also showed that the last brake holding capacity test for the mooring winch was performed less than three months before the failure. Spare wires were available on board. At the time of the failure, the breast lines were not equally tensioned, and the mooring brake of the parted wire had not slipped.
A company investigation concluded that the wire failed due to:
- Unequal tensions in the mooring lines and/or improper adjustment of the mooring brake and/or
- a hidden defect in the wire, although its general condition was very good
CHIRP comment:
Wire rope maintenance on board ships can be a major issue. Not all ships carry pressure lubricators for the wire ropes, while bigger ships mean bigger and heavier mooring wires being handled by smaller crews. Few ships have the capability to run a wire off the mooring winch drum for routine maintenance. Consequently, for many wires, surface dressing with a suitable wire rope lubricant (or simple grease) whilst still on the drum, is the best that can be hoped for.
From the very first time the mooring wire dips into the water, insidious saltwater corrosion begins to weaken the wire from the heart out. CHIRP would suggest that no mooring wire should be considered fit for purpose and ‘acceptable’ beyond 5 years.
The smaller wires used on an accommodation ladder may never go into the water, but their location at the ship’s side is very exposed and renders the wire liable to constant attack from saltwater spray. The wires are also exposed to sunlight and, potentially, tropical heat and dust, which is not ideal.
The first report is a perfect example of why combination pilot boarding arrangements , where the pilot ladder is secured directly to the accommodation ladder platform, are just inherently unsafe and wrong and should never be allowed.
In the first report, CHIRP commends the company who moved away from a 30-month end-for-ending and 5-year renewal policy to a straightforward 2-year renewal policy. One also has to question the wisdom of SOLAS permitting lifeboat fall wires to remain in place for up to 5 years. A simple 2-year renewal policy would have been so much easier and safer – surely?