Typical Process Vent / Hydro Test Vent & Drain Assemblies

Classification of Vent Assembly:

Vent assemblies can be broadly classified as Process Vents and Hydrostatic Test Vents.

Process Vent:

During the process of a system, some vents needs to be operated very often (e.g start-up, shutdown and maintenance, etc.).  So there should be a proper venting assembly for the whole life cycle of the piping system.  This assembly should have valve so that after venting, the valve can be closed and continue the normal operation. Air must also be released from pipe to allow filling and admitted to permit draining or pumping out liquids. Selection of Process vent assembly is based on the piping class. Some of the typical Process Vent assemblies are shown below.

Process Vent Assembly-1 & 2

Process Vent Assembly-3 & 4

Process Vent Assembly-5 & 6

Hydro Test Vent:

During the Hydro Test of a piping system, the air inside the pipe will be trapped at higher elevations when supplying the water inside the pipe. This trapped air needs to be removed before testing. For these purpose Hydro Vents will be provided at each higher elevations of a piping system. Vents are needed to let air in and out of systems.  Some type of hydro test vent caps are seal welded after the testing. Typical Hydro Test Vent assemblies are shown below.

Hydro Test Vent Assembly-1 & 2

Hydro Test Vent Assembly- 3 & 4

Hydro Test Vent Assembly-5

Drain Assembly:

Normally drain assemblies are provided in a piping system to drain out the process liquid as well as the water after the hydro test. The Hydro test drains are used as process drains during the process cycle. Typical Drain assemblies are shown below.

Drain Assembly-1 & 2

Drain Assembly- 3 & 4

Drain Assembly- 5 & 6

Hydro Test Vent/Drain Assembly Locations:

PIDs show only Process vents such as vacuum breakers and process drains. Positions of the required vent and drain points are established on the piping drawings. Typical hydro test vent assembly and drain assembly locations are shown below for reference purpose.

Hydro Test Vent/Drain Assembly Locations

If you like the above post please click the Google +1 rating and share the vital info among other pipers. Please feel free to comment.