IBV in Line Breather Valve

Cargo tank pressure/vacuum relief(by passvalve-In LineType)
For periodically nuattended machinery spaces in cargo ship, the administration shall give special consideration to maintaining fire intergrity of the machinery space, the location and centralization of the fire-extinguishing system controls, the requred shut-down arrangements(e.gventilation, fuel pumps, etc.) and may requrie additional fire-extingushing appliances and other fire-fighting equipment and breating apparatus.

Applied Basic Rule
SOLAS,2014 Consolidated Edition Reg.II-2/11.6.3.3

Relative Rules and Requirements
IMOMSC/Circ.677:1994