Gas to Flare — No Vibration, No Noise, No Problem!

With oil and gas facilities operating under increasingly high demands, its severe service valves need to match the pace or risk slowing down a plant’s production, efficiency and reliability. Such a strict demand for reliability in the oil and gas industry is especially true in the gas to flare application. Often utilized in a process plant, gas to flare can be employed offshore or onshore. These valves come into use in emergency situations where high-pressure gas either in process vessels or in pipelines needs to be vented. However, due to environmental concerns, this gas can’t be vented into the atmosphere, so a flare is used to burn the gas before venting it.

Tight Shutoff

Under normal operating conditions, gas to flare valves are closed. While at first this may seem they would require less maintenance, the necessity for tight shutoff becomes more important than ever. The products that need to be flared are high cost items and even small continuous leakage can result in costly product loss.

Anytime after an emergency situation, a valve in this application needs to close again, repeating the same tight shutoff it had before, preventing leakage while it is closed until it has to re-open in the next emergency situation.

Velocity Control

High-pressure drop in the gas to flare application can result in high noise and vibration that in some instances not only cause vibration of the valve, but of the whole piping system, which can result in costly mechanical failure.

Although ideally the scenario would be multiple valves discharging simultaneously to a flare header, in reality one or two valves are usually open, with the worst-case scenario being only one opening and going to the flare header, resulting in a very low backpressure of the flare header and in turn a high pressure drop across the valve. Conventional valves in this situation will experience high noise and vibration due to uncontrolled trim exit velocity that can lead to premature failure of the trim with shortened life and high maintenance cost.

Reliability

Faced with the above challenges of both tight shutoff and velocity control, the third crucial element for a valve in the gas to flare application is reliability. If the control valve fails to open in an emergency situation, safety valves will have to open, which creates another high maintenance situation. When the safety valves are opened, they end up shutting down at least part of the plant which can have a significant cost impact, hence the reason they are only utilized as a last resort situation. This is why it is important that the gas to flare valves open when required, before shutting off tightly every time.

DRAG® Technology

CCI’s unique multistage pressure reducing DRAG® design eliminates the possibility of excessive noise and vibration. By incorporating this type of multi-passage trim in place of a standard, simple orifice-plug design, there can be a noise reduction of 20-40 dBA.

To further ensure proper operation and elimination of premature valve failure, computer analysis is used in applications where critical service valves require exceptional shutoff performance to withstand long periods of closure at high-pressure drops. For gas to flare valves, a minimum of Class V shutoff and frequently Class VI shutoff has been applied successfully for this application.

While many valves are marketed as being able to withstand the demanding challenges facing the oil and gas industry, few tend to provide the complete solution needed for the extreme conditions of severe service. With forty years of service, the CCI DRAG® valve has demonstrated to users that it is the intelligent choice for increased plant production through highly reliable valve performance in oil and gas applications.

Published in SOLUTIONS Winter 2001