어느 회사의 매뉴얼 내용중에 Seal Drum Design pressure 관련하여

다음과 같은 내용이 있습니다.

A design pressure of 50 psig (345 kPa) at the highest possible operating temperature of the entering vapors

resulting from a single contingency.  For those hydrocarbons typically  encountered in  refinery  operations, 

this  design  pressure should adequately protect the drum against an internal explosion. 

This design pressure must also be applied to the flare stack and the water outlet seal loop. 

However, for those locations which may flare streams containing more than 75% by volume ethylene,

a design pressure of 150 psig (1035 kPa) should be used.

 

Ethylene이 많은 경우는 특별히 Design Pressure를 높게 잡으라고 하는데, 이유가 무엇일까요?