Sch 1 para 11
(1) A manufacturer must, when designing a vessel, define the use to which it will be put, and select— (a) the minimum working temperature T min ; (b) the maximum working temperature T max ; and (c) the maximum working pressure PS. (2) Where a minimum working temperature exceeding - 10°C is selected, the qualities required of the materials must be satisfied at - 10°C.