Planned Maintenance System:
Inspection and maintenance of the ship and equipment; purpose of PMS; types of PMS. Hatch Covers Types of hatch covers; operation and maintenance of hatch covers; side cleats and cross-joint wedge mechanism, weather tightness, and hose testing before loading, Ultrasonic testing of hatch covers.
Types of Maintenance Procedures
- Preventive or Scheduled Maintenance System: It is famously known as the PMS or Planned Maintenance System. In this type of system, maintenance is carried out according to running hours, such as 4000 hrs, 8000 hrs, etc., or calendar intervals like 6 months, yearly, etc., of the machinery. Maintenance is carried out irrespective of the condition of the machinery. Parts are replaced if scheduled, even if they can still be used.
- Corrective or Breakdown Maintenance: In this system, maintenance is carried out when the machinery breaks down. This is why it is known as breakdown maintenance. This method is not suitable as situations may arise where the machinery is required in an emergency. The only advantage of this system is that the working of machinery parts is used to its full life or until it breaks. This system might become costly as several other parts may also get damaged during a breakdown.
- Condition Maintenance System: In this system, machinery parts are regularly checked. Sensors and other tools are used to assess the condition of the machinery, and maintenance is performed accordingly. This system requires experience and knowledge as wrong interpretation may damage the machinery and lead to costly repairs, which may not be acceptable by the company.
The purpose of the Planned Maintenance System is:
- To ensure that all maintenance is carried out at adequate intervals and in accordance with the schedule in the planned maintenance system.
- To maintain and keep all engines, machinery, and technical components in good working order at all times to avoid stoppages and maintain charter party speed and consumption requirements.
- To avoid interruption and oversight of work by covering all of the work.
- To make a clear demarcation between onboard and shore maintenance work.
Composition of “Planned Maintenance System”:
The system is composed of the deck department and engine department. The deck department covers cargo-related, radio-related, and catering-related equipment. It is a paper/software-based system that allows ship owners or operators to carry out maintenance at intervals according to manufacturers’ and class/Classification society requirements. The maintenance, primarily supervised by onboard personnel, is then credited towards inspections required by periodic surveys. The planning, scheduling, and documentation of maintenance must be done according to a system approved by classification societies.
The major objective of hatch covers and coamings on ships is to prevent the ingress of water into the cargo hold and protect the goods from being dampened and damaged. Hatch covers also act as a barrier to the ship’s internal structure by enduring the green water loads in extreme weather, which can damage the ship’s internal structure due to corrosion.
The various types of hatch covers mainly used on board are as follows:
- Lifting type
- Rolling type
- Folding type
- Sliding type
- Roll stowing type
Lifting-type or lift-away-type hatch covers are generally used on container ships, whereas rolling types are used on bulk carriers (specifically side-rolling). Rolling types can be divided into end rolling, side rolling, and piggyback & telescopic. Folding-type hatch covers are basically used on general cargo ships. However, these may vary depending on the stowage space and the type of cargo carried.
Folding-type hatch covers consist of two flat-type topped panels operated via hydraulic arms. These may be fitted on both the weather deck and tween deck. A major advantage of the design of folding-type hatch covers is their large size, which means fewer panels.
Rolling-type hatch covers consist of two covers at the end of the hatchway. Wheels are fitted to help slide the panel either athwartship in the case of side rolling or longitudinally in the case of end rolling. These types of hatch covers are usually fitted on large ships. Hydraulic rams are required to raise them to the rolling position as they are extremely heavy and have very large dimensions.
Stacking cover type: This type of facility is used on ships with relatively smaller hatch covers. It consists of a hydraulically powered lifting crane facility whose purpose is to lift the covers longitudinally and stack them together at one end or over any empty stowage tank. It is relatively cheap and is mostly used in barges.
Operation of Hatch Covers
- Care, precautions, and safe practices to be followed when operating hatch covers:
Some points to note during the operation of hatch covers are:
- All personnel involved in operating hatch covers should be properly trained. Read and follow the manufacturer’s instructions.
- When operating hatch covers, ensure that all cleats are removed.
- Before turning on power, ensure that the correct switch for that particular hatch cover is switched on. Also, ensure that your hands are dry when switching on to avoid a shock from the pump. In the case of hydraulic pumps, ensure that there is sufficient oil in the hydraulic tank before switching on the pump.
- Ensure that there are no obstructions on the trackway. They should be clear of all loose cargo, garbage, and dunnage.
- Lifting appliances should be attached to hatch covers from a safe working position (if applicable and required).
- Ensure that the hauling wire (check wire) used on a single-pull hatch cover is in good condition and well lubricated. The position of the lead and snatch blocks should be such that the wire reaches the warping drum of the winch correctly and does not go over sharp edges or bends. The wires should not show any signs of rusting, fraying, compression, or damage.
- The rubber gasket packaging, resting firmly on the compression bar, provides weather tightness. The sealing properties will be lost if the bar is grooved or damaged due to the presence of paint, rust, or loose cargo. So ensure that the compression bar is clean and undamaged. There should be two personnel involved in the operation of hatches: one operating the system and the other watching the hatch covers from the opposite side to ensure smooth operation.
- Personnel handling wires should always wear leather gloves to protect hands from any injury due to snags in the wire.
- All persons should keep well clear of the hatches when closing or opening, and the hatch cover stowage area must be checked to ensure it is clear before operation starts.
- Hatch pontoon wheels and rollers should rotate freely without any strain.
- Drain channels are provided along the top of the hatch coaming and between hatch pontoons where they interlock. This is meant for draining out any water coming on the hatch cover and the coaming due to shipping seas or rain. The channel should be kept clear so that the water drains off instead of accumulating and finding its way into the cargo space through some place where the sealing is weak.
- When hatch covers are of the type that have to be raised hydraulically before being opened (like in the single-pull type), ensure that all the hydraulic jacks are fully raised prior to operating the “OPEN” lever.
- Attention should be paid to the trim of the ship when handling mechanical hatch covers. The trim should not exceed that given in the manufacturer’s instructions. As a general guideline, hatches should not be opened if the ship is heeled 5° or more or trimmed 1.5° or more. They should never be opened