Page 41 - Sayı-08

FORMAL SAFETY ASSESSMENT OF OFFSHORE 39
SUPPORT VESSELS

 Human Error (Lack of training, oversleeping, no watch keeping etc.)
 Mooring/Anchoring Failures
 High Traffic Density
2. Fire and/or Explosion Sub-Categories
 Collision/Contact
 Welding/Cutting Work
 Human Error (Poor maintenance, bad operation etc.)
 Equipment/Machinery Failure (Deck) (Fractured FO valve, electrical spark, leaks etc.)
 Weather Effects
 Equipment/Machinery Failure (Engine Room)

Considering these sub-categories, they are well decided together expert group and keep
considering related historical data accordingly. Every sub-category is a reason which leads to a
hazard in the past. Therefore, it is now good to move Step 2; Risk Assessment.

Step 2 risk assessment aims to carry out an identification and an investigation for the causes and
results of the scenarios identified in previous step 1. To put it more clearly, risk assessment is a
step to understand how the hazard in step 1 develop and cause an accident. In order to obtain
possible outcomes, FTA, ETA and FMEA can be used. FTA distribution have been given in both
Fig. 5. In our case, after risk assessment, FTA has been carried out both to assess risks in this step
and in step 3 to understand cause-event chain items in order to proceed recommendations. In
accordance with IMO FSA Guidelines, at this step now we are using ranking in order to define
risks. See below Table 1 for detailed instructions of IMO FSA risk assessment. It is important to
rank and prioritize identified hazards in step 1 in order to have a judgement on them. With this
way, this gives an option to understand if identified hazard is minor or major. Deciding this, it is
possible to have a more efficient outcome and this eventually affects the decision making process.

Table 1. Severity Index, Frequency Index and Risk Index assessment from IMO guidelines.
SEVERITY INDEX

SI SEVERITY EFFECTS ON HUMAN EFFECTS ON SHIP S (Equivalent
SAFETY fatalities)

1 Minor Single of minor injuries Local equipment damage 0.01

2 Significant Multiple or severe injuries Non-severe ship damage 0.1

3 Severe Single fatality of multiple Severe damage 1
severe injuries

4 Catastrophic Multiple fatalities Total loss 10

FREQUENCY INDEX

FI FREQUENCY DEFINITION F (per ship year)

7 Frequent Likely to occur once per month on one ship 10
0.1
5 Reasonably probable Likely to occur one per year in a fleet of 10 ships, i.e.
Likely to occur few times during the ship's life

3 Remote Likely to occur once per year in a fleet of 1000 ships, i.e. 10-3
likely to occur in the total life of several similar ships

1 Extremely remote Likely to occur once in the lifetime (20 yers) of a world 10-5
fleet of 5000 ships

Sayı 6, 2016 GiDB|DERGi