PROPOSED DESIGN CRITERIA FOR A BILGE PUMPING SYSTEM: A CASE STUDY OF LARGE BULK CARRIER
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In this study, the bilge pumping performance was investigated using the actual bilge pumping arrangement of a 180K class bulk carrier, and it was assumed that the No. 1 cargo hold was fully flooded. As a result of the calculation, the mean water velocity at bilge main could not satisfy the 2m/s requirement while discharging all the accumulated water from the flooded No. 1 cargo hold with the actual arrangement installed on the 180K class bulk carrier. As a result of the calculation by modified arrangement, it was found that the 2 m/s requirement could be satisfied when a pipe smaller than the required internal diameter according to the rule requirements of classification societies was applied to the bilge main under the same pump conditions. In addition, it was found that the flow rate of the pump should be increased by at least 40% when piping acceptable for the rule requirements of classification societies was applied to the bilge main. The bilge pumping system of 180K bulk carriers may be similar for every ship, and in our opinion, urgent modifications and repair are necessary for consideration of the characteristics of bulk carriers with a relatively high risk of flooding. According to the GBS structure, the rule requirements of classification societies regarding bilge pumping system should comply with the intended purpose of SOLAS Regulation II-1/35-1. It is proposed to revise SOLAS Regulation II-1/35-1 by applying the concept of Performance-Based Standard (PBS) in order to secure the performance of the bilge pumping system by applying a pipe smaller than the required internal diameter according to the rule requirement of classification societies. In particular, it is proposed that SOALS Regulation II-1/35-1.3.9, the requirement for the required internal diameter of bilge main, should be deleted so that any size pipe can be used if the bilge pumping performance can satisfy the 2 m/s requirement. Finally, “2 m/s Criterion” is proposed only design criteria to fulfill the intended purpose of the 2 m/s requirement of SOLAS.