Why Is Hatch Cover Maintenance Important For Offshore Assets?

11 Nov

Why Is Hatch Cover Maintenance Important For Offshore Assets?

Development of hatch covers over the years

The ideal hull on a ship would be a hollow, watertight chamber. At the same time, it can provide access. They were originally fitted with cargo hatch covers consisting of wooden hatch boards. Steel beams will be fitted in to support the hatch opening.

In sailing vessels, the cargo hatches used to be small to preserve the integrity of the hull. Decks are often awash during ocean passages and the smaller the opening, the smaller the risk of flooding the holds.

Bigger ships and smaller crews led to the invention of the mechanically folding steel hatch cover. This is commonly known as MacGregor hatches. It consists of interlocking steel panels with rubber packing fitted inside the edges of the steel panels. A steel compression bar will be fitted onto the hatch coaming. In this way, the ship is deemed to be cargo-worthy by achieving its weathertight conditions.

Why hatch cover leak and what can it lead to?

Hatches leak for a variety of reasons, but mainly because of poor maintenance or failure to close them properly. When hatch covers show signs of leaking, the rubber gaskets are the first to gain attention. Ship crews may be able to change the gaskets themselves. However, some owners limit hatch cover attention to replacing the gaskets when worn out. In doing so, they miss out on many of the finer points of hatch cover maintenance.

Most hatch covers have movable parts like hinges, hydraulic cylinders, wheels, etc are all exposed to wear and tear over time and have an influence on how well the hatch covers work. At the same time, corrosion and physical wear of fixed parts of hatch coamings, hatch panels, storage racks, etc., may lead to leaking hatch covers.

Leaking hatch cover could lead to more serious consequences than wet cargo. This includes flooding, accelerated corrosion, or even loss of the ship. It is crucial for safety at sea and protection of the environment to maintain hatch cover weather-tightness and strength. The lack of hatch cover maintenance for hatch covers has shown to be the primary cause of water ingress into the cargo holds. Thus, this is how it leads to cargo damage.

Shipowners are obligated to deliver the cargo in the same condition as it was loaded onboard upon a contract of carriage of goods by sea. Cargo, which has been wet by seawater, will result in financial loss. Recovery claims will be filed against the shipowner carrier by the Cargo consignees and their cargo insurers. These claims can be very substantial depending upon the nature of the cargo and the amount of water ingress.

What is the test taken to check for hatch cover Watertight Integrity?

1) Hose Tests

The ability of the most used hatch covers to prevent water ingress depends upon the existence of a watertight seal between sections of rubber packing and steel compression bars.

The hose test involves playing a jet of water along the cross joints and perimeter seals of the hatch cover at a certain minimum pressure and distance from the structure. It requires a minimum of two people to carry it out. One to operate the hose and one to observe from within the hold to see whether water is gaining access.

2) Ultrasonic Tests

The use of ultrasonic equipment is a modern, viable means of testing for watertight integrity of hatch covers, access hatches, doors, ventilators, etc. It is preferable to use Class-approved equipment operated by qualified personnel and to follow approved test procedures.

The test involves placing an electronic signal generator within the cargo hold (laden or not) and using the receiving sensor to first take a reading at the access or booby hatch with the main hatch cover closed.

What are the basic procedures to maintain hatch cover for offshore assets?

Only qualified personnel should operate the hatch covers. They should be well-trained and be fully aware of the manufacturer’s procedures for the safe operation of the hatch covers. A proper risk assessment needs to be carried out and this needs to be reviewed regularly and ship crews are briefed and trained.

Special care and attention should be paid to the opening and closing of the hatch covers when the ship has an excessive trim or list. This is due to the possibility of the covers “running away” when in motion.

It is not recommended to open the hatch covers whilst at sea to carry out maintenance and repairs but there will be times when it is necessary. In such cases, it must be carefully considered, considering crew safety and the anticipated weather and sea conditions. It may be necessary to take extra measures to secure the hatch covers in the open position to prevent them from moving when the ship is moving.