According to the definition (see Article 2 paragraph 5 pressure accessory
means a device with an operational function and having an identifiable
pressure-bearing housing – i.e. the device has a function additional to that of
containing pressure.
The pressure accessory can be attached to other pressure equipment for
example by bolting, brazing, soldering or welding. A pressure accessory has a specific operational function (or functions), which could be for example:
measurement, change the mechanical characteristics of the fluid flow, taking a sample, removal of sediment or gas. A pressure accessory does not necessarily have moving parts.
Typical examples of pressure accessories are: valves, pressure regulators,
measurement chambers, pressure gauges, water gauge glasses, filters,
expansion joints and manifolds.
The following examples are not pressure accessories:
- safety valve (a safety accessory)
- cover, collar, gasket, flange, bolt (components of a pressure equipment)
- sight glass with its frames (components of a pressure equipment)
- Y-shape or similar fittings (piping components)