5.3　Corrosion Allowance

5.3.1　Unless otherwise specified，the corrosion allowance for each surface of component parts of the tray which is exposed to fluids shall be as specified in Table 5.3.1.

Table 5.3.1　Corrosion allowances for component parts of tray　（unit:mm）

5.3.2　Where the downcomer and seal pan are also served as main support beams for trays，corrosion allowance for every surface exposed to fluids should be considered.