Q. a. Explain the factors that are considered in the development of the critical equipment & systems onboard ship.
b. Give your opinion on the importance of identifying critical equipment & systems onboard the ship.
Answer –
Critical Equipment: Equipment whose failure will result in a potential hazardous situation or an accident, thereby causing injury to the personnel or loss of life or damage to the marine environment or property.
1. Critical Equipment & Technical Systems can be identified by the critical assessment procedure.
2. For this process two things are determined:
a. Consequence Value which depends on the impact of equipment failure on:
i) Safety: Evaluation rely on failure of the equipment leading to potential injury situations. E.g.
(a) no injury = 0 value
(b) Near Miss/First Aid = 2 units.
(c) Serious Injury = 15 units.
(d) Safety Equipment = 50 units.
ii) Environment: Consequence value of the equipment failure on environment, assessing oil spill & release of the harmful substances. For e.g.
(a) No hazard = 0 value
(b) Small spills (1 M3) = 2 units
(c) Large oil spills needs full scale response = 25 units.
iii) Operational Impact: Consequence value of the equipment failure on operations. Failure will impact transportation, loading & discharge of the cargo, reduction or loss of propulsion. E.g.
(a) No operational impact = 0 units.
(b) Immediate loss of operations = 10 units.
iv) Repair Cost: Consequence value of the equipment failure evaluating cost for manpower, space, dry-dock, survey etc. e.g.
(1) Repair cost < USD 5000 = 1 unit.
(2) Like repair cost > USD 100,000 = 7 units.
Total consequence value = f(consequential value of the equipment failure to safety, environment, operations, repair)
b. Failure Probability: Depends on:
1. Equipment Reliability: Obtained from the manufacturer. For e.g.
i. Unlikely to fail or mean time between failure > 6 years = 1 unit.
ii. Very likely to fail or mean time between failures < 6 months = 8 units.
iii. Utilization Reliability: Consider the way the equipment will be operated. For e.g.
1. Duty / Standby (Inactive) = 1 unit.
2. Intermittent operation = 2 units.
3. Continuous operation = 4 units.
iv. Service/Exposure: To environment & weather conditions. For e.g.:
1. Mooring Equipment (Aft) = 1 unit.
2. Mooring Equipment (Fore) = 4 units.
Failure probability = S(i + ii + iii)
3. Numeric value will be given to the every equipment. Rating the consequence of the equipment failure on the above mentioned factors.
4. The consequence of the failure should be checked in most suitable condition. For e.g.
a. Steering Gear failure consequence should be checked when the vessel is entering or leaving the port. Failure will result in the collision or grounding with significant environmental & cargo damage.
b. Main engine starting failure should be checked when vessel is entering or leaving port, when operation of systems is most critical.
c. Emergency generator starting failure should be checked when there is no main power supply. Failure would have immediate operation impact & equipment will be classed as Safety Equipment.
5. Where the equipment is provided with 100 % redundancy, failure consequence should be assessed with back up of equipment available.
CRITICAL SCORE = CONSEQUENCE VALUE * FAILURE PROBABILITY
IF CRITICAL SCORE > 250 = CRITICAL EQUIPMENT
Based on above assessment, generic list of the critical equipment whose sudden failure will result in hazardous situations for large ocean going ship are for e.g.:
Additional factors for checking the Critical Equipment:
1. Subject to periodical review & risk assessment based on vessel type & design.
2. Additional may be included based on:
a. Work experience.
b. Basis information received from other sources like case studies/accidents etc.
c. Experience of the Chief Engineer/Master
d. Review by the Company.
3. Generally equipment with redundancy don’t fall into this category.
B)
1. It is essential to identify critical equipment so as to assure functional reliability or the use of back-up arrangements in case of a sudden operational failure.
2. Specific measures which include the regular testing of the stand-by equipment or technical systems can then be put in continuous use.
3. Further safeguards may be the following:
a. Regular testing of alarm functions.
b. Preventive maintenance of critical components
c. Alternate running of stand-by arrangements
d. Lubricating and fuel oil analysis
e. Filter cleaning
f. Inspections/surveys at appropriate intervals
g. Additional shipboard procedures to ensure redundancy during critical operations
4. The maintenance activities that promote the reliability of critical equipment can be integrated into the ship’s maintenance plan.
5. The list of the critical equipment can be periodically reviewed &, when needed, amended based on the outcome of SMS reviews, internal/external safety management audits & reported accidents.
