USCG关于ambient temperature的考虑

sextant · 发表于 2022-10-21 09:48

问题出处引用如下：
USCG $154.176 Longitudinal contiguous hull structure.
a) The longitudinal contiguous hull structure of a vessel having cargo containment systems without
secondary barriers must meet the standards of the American Bureau of Shipping published in “Rules for
Building and Classing Steel Vessels”, 1981.
(b) The longitudinal contiguous hull structure of a vessel having cargo containment systems with
secondary barriers must be designed for a temperature that is:

(1) Colder than the calculated temperature of this hull structure when:
(i) The temperature of the secondary barrier is the design temperature; and
(ii) For any waters in the world except Alaskan waters, the ambient cold condition of:
(A) Five knots air at −18 °C (0 °F); and
(B) Still sea water at 0 °C (32 °F); or
(iii) For Alaskan waters the ambient cold condition of:
(A) Five knots air at −29 °C (−20 °F); and
(B) Still sea water at −2 °C (28 °F); or

为什么USCG要求有次屏蔽的液化气船在非阿拉斯加海域的ambient temperature 是空气-18，海水0 ？
而IGC里并没有对有无次屏蔽做单独要求，并且从确定钢级的角度定为5度空气，0度海水。
问题1：如果是要求满足USCG的B型舱，是不是温度场要按照air-18, sea water 0来定边界，而不需要满足USCG满足IGC的B舱，只需5度air,0度water即可？
问题2：为什么USCG对有次屏蔽的液化气船，有严格的要求，原因是什么？

thanks