Safety Devices

Pressure Vessel Safety

Awareness Tutorial

There are four types of over pressurization devices:

Rupture Disks -

Relief Valves -

Safety Relief Valves -

Safety Valves -

What should you expect on an over-pressurization device?

Every device must have a name tag. The name tag must have one of the following ASME symbols ‘UV’ [spring loaded over pressurization device] ‘UD’ [rupture disk]. The name tag will have the set pressure and capacity. The set pressure should never be greater than the pressure vessels MAWP [maximum allowable working pressure].

Here are some special rules to the set pressure-

1.) Relief Valves, Safety Relief Valves, and Safety Valves should be set at or below pressure vessel ASME nameplate MAWP.

2.) Rupture Disks should be set not higher than the PV [pressure vessel] nameplate. Under special circumstances the rupture disk can be set up to 110% of the MAWP. In addition to this special condition, whenever there is a possibility of internal fire in the pressure vessel the rupture disk can be set not higher than 160%, but a pressure vessel engineer will need to be consulted.

Remember There should never be a shut off valve between the PV and over pressurization device.

How should the over-pressurization device be installed?

1.) Always in an Upright installation.

2.) Installed the over pressurization device a few pipe diameters away from the PV, but consult the code and manufacture for maximum distance.

3.) Make sure the exhaust discharges safely away, so no one could be injured.