Planned Maintenance System:

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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 the maintenance is carried out as per the running hours like 4000 hrs, 8000 hrs etc., or by the calendar intervals like 6 monthly, yearly etc. of the machinery. The maintenance is carried out irrespective of the condition of the machinery. The parts have to be replaced if it is written in the schedule, even if they can be still used.
  • Corrective or Breakdown Maintenance: In this system the maintainence is carried out when the machinery breaks down. This is the reason it is known as the breakdown maintenance. This is not a suitable and good method as situations may occur wherein the machinery is required in 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 get costly as during breakdown several other parts may also get damaged.

Types of Maintenance Procedures (Contd) :

  • Condition Maintenance system: In this system the machinery parts are checked regularly. With the help of sensors etc. the condition of the machinery is accessed regularly and the maintenance is done 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 with 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 to maintain charter party speed and consumption requirements.
  • To avoid interruption and oversight of work by covering all of the work.
  • To make clear demarcation between onboard and shore maintenance work. Composition of “Planned Maintenance System” :

The system is composed of deck department and engine department. The deck department covers cargo related, radio related and catering related equipment.

a paper/software-based system which allows ship owners or operators to carry out maintenance in intervals according to manufacturers and class/Classification society requirements. The maintenance, primarily supervised by the onboard personnel, is then credited towards inspections required by periodic surveys. The planning and scheduling of the maintenance, as well as its documentation, must be made according to a system that is approved by classification societies

HATCH COVERS: 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 damped 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 internal structure of ship due to corrosion.

The various types or hatch covers that are 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 type are used on bulk carriers (to be specific side- rolling). Rolling type can be divided into end rolling, side rolling, and piggy back & 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 that is carried.

Folding type: hatch covers consists of two flat type topped panels which are operated via hydraulic arms. These may be fitted on both weather deck as well as tween deck. A major advantage in the design of folding type hatch covers is its large size which means less number of panels.

Rolling type hatch covers consists of two covers at the end of the hatchway. Wheels are fitted which help in the sliding of the panel either athwartship in case of side rolling or longitudinally in case of end rolling. These type of hatch covers are usually fitted on large ships. Hydraulic rams are required to raise them to rolling position as they are extremely heavy and have very large

Stacking cover type: These type of facility are used on ships having relatively smaller hatch cover. It consists of a hydraulically powered lifting crane facility whose purpose is to lift the covers longitudinally and stack it together at one end or over any empty stowage tank. It is relatively cheap and is used mostly in barges.

Operation of hatch covers

  1. 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 your hands should be dry when switching on to avoid pump getting a shock. In the case of hydraulic pumps ensure that there is sufficient oil in the hydraulic tank, prior to switching on the pump.
  • Ensure that there are no objections on the track way. 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 lead and snatch blocks should be such that the wire reaches the warping drum of the winch in the correct way 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 presence of paint, rust or loose cargo. So ensure that the compression bar is clean and undamaged. The rubber during operation of hatches. One operating the system and 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 any 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 si clear before operation starts.
  • Hatch pontoon wheels and rollers should rotate freely without any strain.
  • The drain channels are provided along the top of the hatch coaming and in 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 which 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 in case the vessel is rolling.
  • The locking bar should be applied when pontoons are stowed in the open position in the stowage area. This prevents accidental slipping of hatch cover when in open position. It should be removed prior to closing the hatch covers. The safety chain on single pull Macgregor type hatches does a similar job.
  • It is dangerous to keep folding or rolling type hatch covers partly or halfway open.
  • In the case of side rolling hatch covers, additional turnbuckle lashings may need to be taken when hatch covers are opened at sea for hatch cleaning purposes. They should never be opened in case the vessel is rolling. With single pull hatch covers pulled by chains – ensure that the length of the chain on each side of the coaming is the same and the length of the chain in between the hatch covers is also the same. This can be adjusted by means of a bottle screw provided at the end of each chain.
  • Frequently check for chain stretching by marking a length of about 2 meters by means of seizing wire when the chain is new. Chain should be renewed when stretched over 15%.

Maintenance of hatch covers

  1. General maintenance

Attention should be paid to the following points:

  • The manufacturer’s literature should be studied and fully understood regarding the operation and planned maintenance of the hatch cover system.
  • Coaming drain plugs to be kept clear at all times.
  • Before closing hatch covers great care should be taken to ensure that the hatch coamings, the compression bar and the cross-joints are thoroughly cleaned and scraped and any cargo removed.
  • Care should be taken to ensure that the quick acting cleats (QACs) and the top cleats on the hatch covers are properly lubricated. The steel nut used for adjusting at the bottom of the cleat should be kept greased at all times. Check the neoprene rubber washer for compression, wear and tear and elasticity.
  • Grease hatch fitting regularly – including the hatch cover wheels, grease points and moving parts.
  • It must be noted that no matter how well the hatch covers are secured in place, there is always a little movement of the covers relative to their coamings due to the movement of the ship in the seaway. As the main load of the hatch covers is taken by the resting pads on the hatch coamings, these pads must be regularly given a coat of grease so that their wear and team is minimized.
  • Over a period of time the rest pads could get worn down to such an extent that the hatch cover lip begins to touch the hatch coaming face plate. This could cause:
    • The hatch cover lip to make a groove in the hold coaming face plate.
    • The rubber packing to compress excessively, causing it to take on a permanent groove which can be in excess of 6 mm.

To avoid this from happening, the rest pads need to be built up to the manufacturers recommended height by welding flat plates of the requisite thickness of the rest pads.

  • Care and maintenance of hydraulic jacks and motors must be carried out according to the manufacturer’s manual.
  • In single pull hatches, which are pulled by chains – regular inspection of chains should be carried out.
  • The lead blocks and snatch blocks should be overhauled according to the ship’s maintenance plan (usually, once in at least 6 months) and should be regularly inspected for cracks and other damages (if applicable).
  • The trackway should be regularly chipped and painted. Sometimes grease is applied on the trackway so that the pontoon rollers move smoothly. But this is not a good idea as grease, dust and cargo accumulates on the trackway obstructing the movement. It is better to keep the trackway dry and clean.
  • Hatch pontoon wheels should be overhauled according to the ship’s maintenance plan (usually, once in at least 6 months). Internal bearings of the wheels should be inspected and if damaged, should be replaced.

b)   Procedures for checking the weather-tightness of the hatch covers The weather tightness of the hatch covers can be checked in many ways.

  1. Hatch cover leaks
  • Some visual signs of hatch cover leaks to look out for
    • Water marks (seepage) on the inside of the hatch coamings.
    • Water lines or spots on top of the cargo on completion of a voyage.
    • Entry of daylight into a sealed hold with hatch covers closed and battened.
    • Slack marks or streaks of IG soot along the coaming flat bar (in case of OBOs and O/O carriers)

Emergency measures that can be taken in case of hatch cover leaks:

If hatch overs are found to be leaking the following measures can be taken:

  • Open the hatch cover, remove any debris or loose rust on the flat plate which might be the reason for poor sealing and close hatch cover again. Ensure the cross-joints of the two pontoons at the centre are flush against each other. Start cleating at the ends and work towards the centre. Tighten the cleat nuts at the areas where the leak was observed.
  • Ramnek tape can be used in places where leaking is suspected to ensure no water enters the hold. Although in the long run it is damaging to the hatch covers (the bond is so strong that it removes the paint when peeled off), it helps the ship to defend against cargo claims as it indicates that the ship has exercised due diligence and had taken all necessary precautions.
  • Some bulk cargoes and also some general cargoes can be covered with plastic sheeting with the top sheet overlapping the bottom sheet and any water due to leak or even due to condensation in the hold is collected on top of the sheet and removed prior to discharge.
  • Silicon sealant can be applied along the packing where leaks are found. This is only a temporary measure and should be applied to only very minor leaks.

During the inspection, pay particular attention to:

  • Hold ladders
  • Tank top
  • Cracks in plating, frames, web and other strengtheners
  • Leakage from top side tanks
  • Piping system in the hold
  • Shipside frames and transverse bulkheads
  • Connection of the bulkhead with upper stool shelf plate, especially at the swages end of the corrugation.
  • Connection of the bulkhead to topside sloping plate.
  • Corrugation bulkhead in entirety for buckling / distortion.
  • Connection of ballast trunk to shell plating, topside and hopper tank.
  • Connection of bulkhead with lower stool, lower stool shelf plate and shedder plate. Check shedder plate carefully for cracks in way of crossing of shedder plate in adjacent hold and for any cracks in the bulkheads.
  • Lower stool bulkhead and its connection to tank top and side hoppers.
  • Connection of curtain plate/diaphragm between corrugations with corrugated bulkheads.
  • Access ladders and platforms condition including handrails.
  • Manhole doors to lower stools for any leakage.
  • Welds – check for any decay or breakdown of welds.
  • Breakdown of paint coatings.
  • Structural damage
  • Hatch coamings and hatch end beams – pay particular attention to:
  • Check hatch coaming brackets/stays connection to the main deck for any cracks, especially stays close to centre line and at extreme ends of the coamings.
  • Check hatch coaming flats for any grooving in way of resting area of hatch covers, cracks in way of hatch cover wheel lifting plates and cut outs for cleats.
  • Check all hatch corners (inside) for cracks in the deck plating and in the coaming.
  • Check for cracks in main deck plating and top stool shelf plate in way of hatch entrances.
  • On hatch end beams, check for cracks in way of knuckles, grain filling holes, hatch end beam connection to top side tanks and end connection of hatch end beams to top side tank sloped plate.
  • Cross deck underside longitudinal brackets connections to hatch end beam and top stool vertical bulkhead.

Ultrasonic Hatch Cover Tester:

The principle for ultrasonic hatch cover testing is very simple. After the hatch covers are closed, a transmitter generating an ultrasonic signal is placed in the cargo hold (empty or loaded with cargo) emitting ultrasonic waves. The surveyor or operator then uses the ultrasonic receiver to ‘listen’ from the outside of the hold and detect any ultrasonic sounds that pass through holes in the hatch cover sealing system with pin-point accuracy.

The size of the leak can be established from the strength of the signal detected. The hatch cover leak detection system has three levels of emitters: upper, lower and vertical. This means that all the ultrasound is directed to the hatch covers, optimising its effectiveness. The diagram shows the dispersion pattern of the ultrasonic sound emanating from the Transmitter. The high sound pressure level is ample to fill the largest of holds enabling reliable and accurate readingsdimensions