Healthy Venting

When pressure relief valves go off and you are standing next to it, you should have trust that the high pressure steam will blow through the vent piping as designed - especially if the discharge elbow is an open system.

An added level of safety, to help you stroll through the plant with confidence, is a bellows safety relief connector at the end of the discharge elbow.

Open system relies on draft

A common design for pressure relief valves is over- lapped piping with a drip pan. The larger piping has enough clearance to accommodate the thermal growth differences between the vessel and vent piping.

When the valve trips and releases high pressure steam, the high velocity will create a draft, or vacuum at the open drip pan. Hot condensate will then drip back down and collect in the drip pan.

Any obstructions in the vent piping can cause back pressure and potential blow-back of steam or hot water through the opening around the drip pan.

To at least reduce the hot water exposure risk, all drain pans on open systems should be connected to a drain line.

A sealed system is a safe system

Bellows safety valve connectors have been used for many years on pressure relief valves by utilities; they like the added security to personnel of a sealed vent line.

With a closed system at ground and walkway levels, there is no draft when a pressure relief valve trips; nor is there the potential of steam blow-back.

The bottom Line

Using bellows safety flex connectors on pressure relief valves seals the venting system and in return adds an additional level of protection in your plant - so you don't care where you are standing when the valve trips.

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