Tuesday, March 4, 2008
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Rupture disc has been used in many application in protecting pressure containing part from overpressure. In some event as discussed in "Tube Rupture : Pressure Relief Valve (PSV) or Rupture Disk (RD) ?" and "Protective Measures against FIRE other than Pressure Relief Device (PRD)" rupture disc (RD) is preferred as compare to pressure relief valve. Nevertheless, in some application, designer would provide two (2) RDs in series with pressure gauge (PG) and pressure transmitter (PT) with high pressure alarm (PAH) and low pressure alarm (LAH) in between the ruptured discs.
Two (2) rupture discs (RDs) in series
The reasoning for 2 RDs in series is rather simple. Although RD is preferred in some event, however RD is prompt to fail prematurely and unintended due to corrosion, vibration, transient surge, fatigue, etc. ? In some critical services , designer would provide another RD in series in order to avoid inventory lose or flare gas backflow (during blowdown) to process system.
Pressure Gauge & Pressure Transmitter (with LAH) in between RDs
In the event of RD (1st RD expose to process fluid) is failed or leaked, pressure in between RDs will build quickly. Operator will be able to identify the failed RD during routine checking. Pressure transmitter (with high pressure alarm) would be triggered and initiate alarm in the control panel to alert operator.
Pressure Transmitter (with LAL) in between RDs
In some application, designer may provide low pressure alarm. The main reason is to identify the failure of second RD which expose to flare header. During normal operation, the section between RDs will be pressurized with inert gas to a preset pressure (i.e. 2 barg). In the event the RD (RD facing flare header) failed / leaked, the pressure in the section will lose quickly to flare header and low pressure alarm would be triggered to alert operator the failure of 2nd RD.
Thanks to Steven who has partly (80%) answered above queries.
What is the purpose of provides these kind of arrangement ?
Two (2) rupture discs (RDs) in series
The reasoning for 2 RDs in series is rather simple. Although RD is preferred in some event, however RD is prompt to fail prematurely and unintended due to corrosion, vibration, transient surge, fatigue, etc. ? In some critical services , designer would provide another RD in series in order to avoid inventory lose or flare gas backflow (during blowdown) to process system.
Pressure Gauge & Pressure Transmitter (with LAH) in between RDs
In the event of RD (1st RD expose to process fluid) is failed or leaked, pressure in between RDs will build quickly. Operator will be able to identify the failed RD during routine checking. Pressure transmitter (with high pressure alarm) would be triggered and initiate alarm in the control panel to alert operator.
Pressure Transmitter (with LAL) in between RDs
In some application, designer may provide low pressure alarm. The main reason is to identify the failure of second RD which expose to flare header. During normal operation, the section between RDs will be pressurized with inert gas to a preset pressure (i.e. 2 barg). In the event the RD (RD facing flare header) failed / leaked, the pressure in the section will lose quickly to flare header and low pressure alarm would be triggered to alert operator the failure of 2nd RD.
Thanks to Steven who has partly (80%) answered above queries.
Related Post
- Some Comments on Providing External Insulation as Protective Measure against FIRE
- Protective Measures against FIRE other than Pressure Relief Device (PRD)
- Design Temperature (Td) versus Maximum Allowable Working Temperature (MAWT)
- PSV for Shell-and-Tube HEX Tube Side Overpressure Protection against External Fire Attack ?
Labels: Overpressure Protection, Pressure Relief Device
posted by Webworm, 4:10 PM
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