SEP-2100 Production Separator — Relief Valve Change Isolation
Pressure relief valve replacement on a three-phase production separator in sour service. Covers double block and bleed, depressurisation, H2S purge and the protection that must remain in service while the relief path is open.
How Setyr addresses Oil & Gas →
It refers to equipment that does not exist and illustrates the elements 29 CFR 1910.147(c)(4)(ii) requires a procedure to contain. It is not a document to adopt. Under (c)(4)(i) the employer must develop and document energy control procedures specific to their own machines, and under (c)(6) must inspect them at least annually.
11 points, in sequence
Separator inlet block valve, upstream of the double block pair.
Method: Close and lock. Confirm seat integrity by monitoring pressure between the block pair.
Caution: A single block on live production is not isolation. The bleed between the pair is what proves the seat.
Separator inlet block valve, downstream of the first block.
Method: Close and lock.
Caution: Both blocks must be locked. Locking one and closing the other leaves an unsecured device in the isolation.
Bleed valve between the inlet block pair. Proves the blocks are holding.
Method: Open the bleed to the flare header and lock open. A sustained zero reading proves the blocks. A rising pressure means a passing seat.
Caution: This is the verification, not a formality. Pressure recovering at the bleed means production is still reaching the vessel.
Gas outlet block valve to the compression suction header.
Method: Close and lock.
Caution: Compression suction can pull vessel contents backwards through an unblocked gas outlet.
Liquid outlet block valve to the production header.
Method: Close and lock. Confirm the level control valve is also closed and de-energised.
Caution: The level controller strokes the outlet valve on its own. Isolating the valve without the controller leaves an actuator that will try to move.
Vessel depressurisation valve to the flare header.
Method: Open to flare and lock open. Depressurise to atmospheric and hold. Confirm zero at two independent gauges before breaking containment.
Caution: Depressurising a sour vessel releases H2S to the flare. Confirm wind direction and that the flare is lit before opening.
Vessel low-point drain to the closed drain system.
Method: Open the drain and lock open. Drain to the closed system until flow ceases.
Caution: Residual sour liquid in the boot remains after gas depressurisation. Gas at zero does not mean the vessel is empty.
Nitrogen purge connection for sweetening the vessel before entry or hot work.
Method: Purge with nitrogen until H2S readings at the sample point are below the entry threshold on two consecutive tests.
Caution: Purging displaces H2S with an asphyxiant. The atmosphere can be sweet and still not breathable.
Spare relief path — the standby PSV on the twin-valve arrangement.
Method: Do NOT isolate. Confirm the standby PSV is lined up and its inlet block is car-sealed open before removing the duty valve.
Caution: Removing the duty relief valve without the standby in service leaves the vessel with no overpressure protection.
Emergency shutdown valve and its solenoid on the inlet line.
Method: Do NOT isolate. Confirm the ESD remains armed and will close on demand.
Caution: Defeating the ESD to make the job easier removes the last automatic protection on a live inlet.
Fixed H2S detection heads at the separator skid and the personal monitors carried by the crew.
Method: Do NOT isolate. Confirm fixed heads are in service and every crew member has a bump-tested personal monitor.
Caution: H2S deadens the sense of smell at concentrations well below lethal. Detection is the only warning available.
What your site must supply
This example is structurally complete and factually generic. The things below are the things only you can know — and they are exactly what makes a procedure yours.
- Your own asset and isolation-point tag numbers. The tags shown are illustrative and refer to equipment that does not exist.
- The actual location of every disconnect, valve and vent on your equipment.
- Measured stored-energy magnitudes and the dwell time required to dissipate them.
- Your verification method for each point, and who is authorised to perform it.
- Any additional energy sources present on your equipment and absent here.
Author this properly, once
Setyr holds procedures like this as living documents — bound to real isolation points, with lock registries, group lockout, person-in-charge custody and periodic review built in.