GB/T 24921.2-2010Sizing, se-lection and installation of pressure relieving valves for petrochemical industries -- Part 2: Installation (English PDF)

6.1 Installation requirements

6.1.1 The typical installation of the isolation valve on the inlet and discharge pipeline of the pressure relief valve is shown in Figures 10 ~ 13.See Appendix A for typical installation examples.

6.1.2 When installing the isolation valve on the inlet and discharge pipeline of the pressure relief valve, it shall not violate the requirements of national laws or regulations.

6.1.3 The isolation valve shall be properly installed and used; a locking device shall be provided to ensure that the safety of the system is not endangered. Appropriate control measures must be taken for the relevant potential hazards.

7.2 Installation method

7.2.1 Conventional pressure relief valves can be closed or open, without special exhaust requirements. The open valve cover is used for steam and is directly discharged to the atmosphere. The valve cover closed valve is discharged internally to the discharge side, the vent holes on the valve cover are usually sealed with screw plugs.

7.2.2 The valve cover of the bellows balanced pressure relief valve must always keep the vent hole in the vent state, to ensure the normal operation of the valve. The vent hole on the valve cover can also be used as a visual leak detection hole, to determine whether the bellows is broken. Ice, insects or other obstacles shall be prevented from blocking the vent hole.

7.2.3 For bellows balanced pressure relief valves with auxiliary balancing pistons, the

vent holes on the valve cover shall be connected to the atmosphere and allow part of the medium to flow out from the vent holes.

7.2.4 When the medium is flammable, toxic or corrosive, a pipe shall be installed to connect the valve cover vent holes to a safe location.

7.2.5 For pilot pressure relief valves, the pilot valve vent holes are usually connected to the atmosphere during installation. If discharge to the atmosphere is not allowed, the pilot valve can be connected to the discharge pipe or discharged to a safe place through the auxiliary pipe system.

7.2.6 For the design of the pilot valve vent hole, unless the pilot valve is a balanced design structure, back pressure shall be avoided as much as possible.

8.1 General requirements

In order to ensure the pressure, large displacement, action and sealing performance of the pressure relief valve of the pressure-bearing equipment system, meanwhile, to avoid the inconvenience caused by a single low-pressure and large-size pressure relief valve to the operation and maintenance of the equipment, multiple pressure relief valves with different set pressures are usually installed in the system, to achieve overpressure discharge, as shown in Figure 16.

8.2 Installation requirements

8.2.1 When the inlet pipelines of multiple pressure relief valves are shared pipelines, the flow channel area of the shared pipeline must be at least equal to the sum of the inlet areas of each pressure relief valve connected to it, as shown in Figure 16a).

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