English to Chinese Tech/Engineering Petroleum Eng/Sci about oil tanks

In the case of viscous oils, such as cutback and penetration-grade asphalts, where the danger of tank collapse resulting from sticking pallets or from plugging of flame arresters is greater than the possibility of flame transmission into the tank, open vents may be used as an exception to the requirements of Sections 4.4.1.2 and 4.4.1.3 for PV valves or flame-arresting devices.