4.2　Arrangement Requirements for Piperacks

4.2.1　Air coolers may be arranged above the piperacks，and pumps（or pump houses），heat exchangers or other small equipment may be located under the piperacks，but shall meet the requirements specified in Article 5.3.6，5.5.3，5.9.7 and 5.9.8 of this Specification.

4.2.2　If the access beneath the piperacks is served as fire fighting road，the minimum overhead clearance from ground to piperacks shall not be less than 4.5m.

4.2.3　Piperacks may be arranged in single-level or multi-level，and the overhead clearance from ground to the lowest level of piperack shall be determined according to the elevation of equipment under the piperacks，the elevation of the piping connected to equipment and the height required by operation and maintenance accesses.

4.2.4　Where trusses are designed for piperacks，the overhead clearance of piperacks shall be calculated from ground to the bottom of trusses.

4.2.5　The width of piperacks shall comply with the following requirements：

1　Number，sizes and spacing of the pipes；

2　The width of instrument and electrical cable trays on piperacks；

3　The width required for the reserved pipes；

4　The size of support columns of air cooler structures，if air coolers are arranged above piperacks；

5　The size of pump baseplates and the width of access for operation and maintenance，if the pumps are arranged under the piperacks.

4.2.6　The distance between piperack columns shall be consistent with the span for most of pipes，and should be within 6m-9m.

4.2.7　The inter-level spacing of multi-level piperacks shall be determined according to the size of pipe and piperack structures，and should be within 1.2m to 2.4m.For large plant，the inter-level spacing may be within 2.5m to 3.0m.When the piperacks change direction or two piperacks perpendicularly intersect，piperacks should be staggered，and the height difference between the staggered piperacks should be within 0.6m to 1.2m.For large plant，the height difference between the staggered piperacks may be within 1.25m to 1.5m.

4.2.8　Concrete piperacks shall have full-length embedded parts installed on the top of beams，and the types of embedded parts shall conform to the national current relevant standard of the nation SH/T 3055.