PMC 30：API 521

舒适圈

FIRE CASE

Wetted Area Calculations

All the possible fire scenarios shall be considered. A fire scenario consists of a potential fire area of typically 300 m2 where a pool fire due to hydrocarbon accumulation is likely to occur; a circle of about 10 m radius (as per API 521, 3.19.2.2) centred on the equipment protected by the relevant PSV should be considered: all equipment inside this circle protected by the same PSV contribute to determine the total wetted area.  To take into account of layout uncertainties, where necessary, a length of 20 m shall be considered for involved piping.  An height of flame of 8 m shall be considered for the wetted area calculations (API 521, 3.15.1.1).

Air-cooled exchangers are subjected to the same height limitations as other equipment. The so-called chimney effect where hot combustion products are pulled into air-cooled exchanger plenums, will not occur when the surrounding air is heated above temperatures in exchanger (API 521, 3.15.7.1).

To calculate the wetted area in the vessels, liquid at NLL shall be assumed (API 521, 3.15.1.1 table 4) when continuous liquid discharge is provided; for not continuous liquid discharge (on-off valves) the liquid at HLL should be considered.  For involved piping the wetted area shall be assumed proportional to the liquid fraction of the relevant stream at operating conditions (this area should be at least 10 % of wetted vessel area).

火灾工况

湿面积计算

应考虑所有可能的火灾情况。火灾场景包括一个潜在的火灾区域，面积通常为300平方米，其中可能发生由油气聚集引起的池火灾；应考虑以相关PSV保护的设备为中心，半径约为10米(按API 521, 3.19.2.2)的圆：该圆内的所有设备均受相同PSV保护，以确定总浸湿面积。为了考虑到布局的不确定性，在必要的情况下，所涉及的管道长度应考虑为20米。在计算润湿面积时，应考虑火焰高度为8米(API 521, 3.15.1.1)。

风冷式换热器与其他设备一样，也有相同的高度限制。所谓的烟囱效应，即热的燃烧产物被吸入空气冷却的热交换器中，当周围的空气在热交换器中被加热到高于温度时不会发生(API 521, 3.15.7.1)。

为了计算容器内的润湿面积，在提供连续的液体排放时，假定NLL处为液体(API 521, 3.15.1.1表4);对于不连续的液体排放(开关阀)，应考虑HLL处的液体。对于所涉及的管道，在运行条件下，湿面积应与相关流体的液体分数成比例(该面积应至少为湿容器面积的10%)。

More will be coming. . .

【食盐强标mandatory code】

GB 2721-2015 食品安全国家标准 食用盐  于2015年09月22日发布，2016年09月22日实施，新标准没有说原GB 5461（卫生标准）取消。