Answer MEP Question 38

Q. With reference to fire pumps.

A. Explain how and when fire pumps should be tested, what are the requirements as per SOLAS-74, as amended.

B. Describe the routine maintenance to be carried out on the various fittings on a fire line, giving testing pressure where appropriate.

C. Describe briefly how will you dismantle a fire pump for survey. Give details of factors which will decide replacing the parts.

Fire Pump-test and survey

How the fire pumps are tested:-

A. Main Fire pumps:

a. Remote/ automatic start methods are tested. Prior starting confirm that the fire line is ready, valves and hydrants are appropriately opened.

b. It is to be monitored that the pumps running efficiently, priming systems are working properly.

c. Pump must deliver correct hydrant pressures at the highest hydrant.

B. Emergency fire pump:

a. Separation from main pumps is achieved by an isolation valve located on main deck, satisfactory separation is to be checked.

b. Pump is to be test run by starting from remote power sources which is separated from machinery spaces.

c. Heating arrangements if provided should be checked satisfactory.

d. Fuel supply for the emergency fire pumps operation is to be adequate as required by the regulations.

e. Test that pump runs efficiently, priming systems work and  deliver correct hydrant pressure.

When the fire pumps are tested:-

a. Fire pumps along with the fixed fire fighting appliances are inspected, weekly during Saturday routine.

b. Fire pumps are often operated during the emergency drills, fire drills are conducted at least monthly.

c. Emergency fire pumps should be kept in good working condition and test run should be done weekly without any failure.

d. Fire pumps are test run during the safety equipment surveys, Initial survey, Renewal survey and CSM surveys.

SOLAS Requirements:-

Regulations for Main and Emergency Fire Pump

Fire pumps are located in engine room and emergency fire pump is located in forward or aft bottom part of the ship are important fire fighting equipments for class A fires.

A. The requirement for the number of fire pump

a. In Passenger Ship of 4000 gross tonnage and upwards should have at least three fire pump and less than 4000 gross tonnages should have at least two fire pump

b. In Cargo ship of 1000 gross tonnage and upwards should have at least two fire pump and less than 1,000 gross tonnages should have at least two power-driven pumps, one of which shall be independently driven.

B. Capacity of fire pumps.

a. Passenger ships:- not less than the 2/3 of the flow rate of the bilge pumps.

b. Cargo ships:- Not less than the 4/3 of the flow rate of the bilge pumps of a passenger ship with the same dimension. Total need not to be more than 180m3/hr.

c. Each of the required fire pumps (excluding emergency fire pump) shall have a capacity greater than equal to 80% of total required capacity divided by the minimum number of required fire pumps.

d. None of the pump may have a capacity less than 25m3/hr.

e. Each pump must be capable in every circumstances, of delivering the two water jets required.

C. Regulations for Emergency Fire Pump

All passenger ships of 1000 GRT and upwards and in cargo ships of 2000 GRT and upwards must have fixed emergency fire pump independently driven by a self-cooled compression ignition engine or an electric motor driven by electric power from the emergency generator Emergency fire pump must be located outside of the E/R room, in the steering flat, shaft tunnel or in the forward part of the ship.

No direct access between the engine room and emergency fire pump. If access provided, it should be through an airlock arrangement.

Emergency fire pump must have own suction, the total suction head should not exceed 4.5 meters under any conditions of list or trim of the ship.

The capacity of the pump not less than 40 % of the total required the capacity of the fire pumps but in any case not less than 25 m3 / hr.

Should be capable of delivering 2 jets of water with minimum pressure not less than 2.1 bar.

The prime mover engine at that unit must be hand started and able to start with one man.

If the pump is fitted above the water level, the self-priming arrangement must be fitted.

If it is diesel engine driven,

Easily started in cold condition (0°C by hand cranking),

Fuel tank for engine shall contain sufficient to run on full load for at least 3 hrs

Sufficient reserve fuel for 15 hrs, store outside the machinery space.

Diesel power source of pump started in cold condition of 0° C by hand or by the power at least 6 times within a period of 30 minutes and at least twice within 1st 10 minutes.

If motor driven: emergency power supply heating arrangement to be provided.

Tank to have sufficient fuel for at least 3 hours and reserve fuel outside main machinery space to allow the pump to run for additional 15 hours.

Isolation to allow the pump to run for additional 15 hours not more than 40 meters to pressure integrity of fire main system.(Diameter of fire main: sufficient for maximum discharge from 2 pumps operating simultaneously except for cargo ship the diameter need be sufficient for a discharge of 140 m3 / hour.

Maintenance carried out on the various fittings on a fire line.

Various fittings on a fire line are suction valves, fire pumps, Non-return type discharge valve, isolation valve on deck, fire hydrants, drain cock, relief valve and expansion arrangement.

Periodic inspection as per ships Plan maintenance system:-

1. Monthly inspection

a. General cleanliness of fire pumps, valves, line, hoses, hydrants and surrounding area.

b. Check the hoses and Nozzles are properly stored and ready to use.

c. Check the fire main general condition is good. Free from corrosion and any physical damage. Valves are operating freely and in open condition.

d. Test run of fire pump to be conducted, keeping required number of hydrants open. check any leakage from the fire main. monitor the pressure and flow of pump. Also monitor the motor for the any abnormal vibration or Noise. After the test the System should render ready for operation in emergency situations.

2. Quarterly inspection

a. Bearing lubrication of pump.

b. Check the condition of gland packing, check leakage and renew if required.

3. Yearly

a. Fire pumps are dismantled mechanical seal (if fitted) is checked for mating surface. Inspect the conditions of shaft, sleeve, impeller, casing, wear ring and  coupling bolts. O-rings are to be renewed.

b. Fire main are tested for leakage at maximum service pressure. Isolation valves are overhauled, maintained and working is tested.

C. Hydrants/hoses are checked for general condition. They are also checked for  correct lengths/diameters. Hydrants are accessible, properly maintained and in working condition.

D. Nozzle size/type are correct, maintained and working.

4. 5-yearly

In fire Pumps, renew ball bearing and Mechanical seal. Check shaft trueness.

Dismantle a fire pump for survey:-

Considering the fire pump is a centrifugal pump. Ensure pump is stopped, shut the suction and discharge valve. Isolate the motor electrically by control room circuit breaker. Put Man at work tag. Electric isolation permit obtained. Local panel breaker put off. Check via purging cock that the line has no pressure.

Place the dismantled part on a clean surface. When separating fit and flange faces, use jack bolts and wooden hammers, and never apply force with chisels or drivers. When removing the rotating element, take care to avoid flaw on sliding faces and machined surfaces. Particularly, never damage the mechanical seal mating faces. When removing rotating parts from the shaft, draw off each one carefully after removing the locking device. Handle the long sized-parts such as shaft carefully so that it may not bend. At overhauling, put suitable match marks as many as possible to avoid mistakes when reassembling.

Dismantling:- 

1. Remove the distant piece, fitted between the pump and motor coupling after removing both motor and pump side coupling bolts and discs.

2. Remove cooling connections to mechanical seal.

3.Remove casing top cover bolts. Once casing cover bolts are removed, pump assembly is free to remove from place along with shaft, bearing housing, bearing, mechanical seal, impeller and impeller shaft with sleeve.

4. On removing the pump assembly, slacken impeller lock nut and remove the impeller from the shaft Remove shaft key. Care should be taken for not loosing the shaft key.

5. Remove distance ring.

6. Slacken the holding screw and remove mechanical seal's rotating part

7. Slacken bearing housing bolts fitted on casing cover.

8. Remove casing cover from the shaft.

9. Remove shaft sleeve from shaft.

10. Remove bearing housing cover

11. Remove bearing retaining circlip.

12. Remove bearing housing along with bearing.

Factors which will decide replacing the parts.

The parts are to be renewed as per the manufacturers recommended period of service such as bearings and mechanical seals.

In addition to that every time upon dismantling a pump few consumable items are required to be replaced such as washers, seal rings, O-rings etc.

Further, during its inspections as per the PMS and surveys, parts are checked inspected and tested. If they are not found in satisfactory condition, must be replaced.

Cleaning and Inspection of parts:

1. Remove bearing from housing for inspection.

2. Clean impeller, bearing , shaft sleeve , casing and the shaft. Inspect and evaluate each parts for any damages, deformation, wear and tears.

3. Measure the clearance between impeller and wear rings for top as well as bottom near rings. If clearance is more than the maker's

recommendation, renew it.

4. Inspect shaft sleeve for any wear down. If sleeve found worn out , renew the same.

5. Check the condition of bearing. If found not good, renew the same.

6. Check the conditions of mechanical seal's rotary and stationary parts. If found damaged, renew it.

7. Check bearing bush at the casing bottom and confirm any wear down. If worn out beyond acceptable limits, renew It.

Assembling the pump:

Assembly

Carry out assembly, by reversing the order of disassembly and paying attention as follows.

a. Remove dust and stain from each part by washing it thoroughly with kerosene. Repair it if flaw is found.

b. Fit the locking device perfectly in each rotating part if necessary.

c. When fitting the parts with match marks, be sure no follow them.

d. Install the mechanical seal carefully and confirm its movement by hand after installation.

e. Insert each packing ring in good order softly one by one from the bottom, staggering each joint by 90° or 180°

f. Check up alignment.

g. Turn the shaft by band to see whether it tums smoothly.