ABSTRACT
By 33 CFR 154.828 regulation, a liquid seal must be installed on the inlet to vapor destruction unit in vapor control system. However, installation and maintenance of liquid seal are subject to many problems in ship environment. Therefore, US Coastguard, which is the governing body of the regulation, have granted exemptions from the liquid seal requirements on a case-by-case basis, provided that alternative safety devices to prevent and mitigate flashback are in place. In this paper, relevant regulation is reviewed, together with the requirements for exemption from liquid seal installation. Safety assessment results of a proposed alternative to liquid seal, composed of anti-flashback burner, differential pressure sensors and quick closing valves, are compared with liquid seal in order to prove that the proposed alternative is a viable solution for replacing liquid seal in marine vapor control system.
