The new cargo tank loading limit requirements in the IMO gas carrier codes

Within the last decade IACS and SIGTTO have carried out a comprehensive study for improving the loading limit requirements of the IMO Gas Carrier Codes. The final step of this study was the development of guidelines for the assessment of the adequacy of the vent piping system of type C tanks. Establishing such guidelines was conditional for the acceptance by the IMO-BCH-Sub6Committee for the revised loading limit requirements for type C tanks. These guidelines, presented in this paper, allow the assessment of the static back pressure at the PRV outlet under two phase flow and fire conditions. Simplified calculations procedures have been compiled which describe with sufficient accuracy a complex fluid and thermodynamic process. The results obtained are on the safe side. The guidelines also permit more complex procedures for assessing the static back pressure