General

Application

The rules in this chapter apply to ships engaged in the transportation of compressed natural gases (CNG). For liquefied gas carriers reference is made to Ch.5.

The vessel must be accepted by the flag state and the respective port authorities.

Fundamental safety requirements

The overall safety with respect to life, property and environment shall be equivalent or better than comparable liquefied natural gas (LNG) vessels built and operated according to traditional ship rules and industry practices.

For new concepts a quantitative risk assessment (QRA) shall be submitted as a part of the classification documentation. The QRA shall comply with the principles for safety assessment outlined in e.g. IMO Report MSC 72/16. For new concepts or modifications to existing systems a hazard identification (HAZID)/hazard operability study (HAZOP) of the cargo tank, cargo piping, process system, operational procedures etc. shall be submitted for information. The fundamental safety requirements shall take into consideration safety targets for:

 — life (crew and third party personnel)

— property (damage to ship, off-hire)

— environment (oil pollution, gas release to the atmosphere).

The safety level on a LNG carrier represents the minimum acceptable safety level for a CNG vessel.

In addition, the as low as reasonably practicable (ALARP) principle shall be adopted as a safety philosophy to ensure:

— focused and continuous safety efforts

— that the overall (and absolute) targets are not misused to argue that sound safety measures are not implemented