Explosion-proof lighting for gas plants looks simpler than a refinery and is not, because the gas itself changes across the plot. Methane is group IIA with a high auto-ignition temperature, so a T3 fixture covers the inlet and the metering skid with margin; where the stream carries hydrogen sulphide the auto-ignition temperature drops to about 260 degrees and the temperature class becomes the deciding block. Add the cold of an LNG send-out, ice that forms on uninsulated steel and sites that are unmanned most of the week, and the specification writes itself: Ex db eb IIC T4 Gb, IP66, C5-M coating and a driver rated for the ambient you actually measured.
An inlet separator, a sweetening unit, a compressor house and an LNG send-out handle four different fluids, and the marking follows the fluid rather than the pipe rack it sits under.
Methane is group IIA. Hydrogen, present in treat gas and in some hydrogenation steps, is group IIC. Ask for the composition rather than the plant name: two gas plants in the same region can need two different groups.
Hydrogen sulphide auto-ignites near 260 degrees, which puts a T3 ceiling on the fixture and makes T4 the default we ship. On a sweet stream the same fixture is simply conservative, which is cheaper than maintaining two spare parts.
An LNG send-out holds a low ambient and forms ice on uninsulated steel, so the driver and the gasket have to be rated for it. Unmanned sites add a second constraint: the fixture has to hold its IP rating for years with nobody checking the seals.
The table is the starting point we use on a gas plant drawing. The licensor's zone drawing governs, and on a brownfield site the existing drawing is often older than the equipment standing under it.
| Area | Zone | Group and class | Fixture |
|---|---|---|---|
| Inlet and slug catcher | Zone 1 | IIA, T3 | AEL 100–150 W |
| Metering and regulating skid | Zone 1 | IIA, T3 | AELL linear 40 W |
| Compressor house | Zone 1 | IIA, T3 | AELL linear 40–80 W |
| Sour gas and amine unit | Zone 1 | IIB, T3 | AEL 100 W |
| Odorisation room | Zone 1 | IIB, T3 | AELL linear 20–40 W |
| LNG send-out and loading | Zone 2 | IIA, T3 | AEL 150 W, IP66/67 |
Ask for the gas composition before you accept a temperature class. On a sour stream it is the block that decides the order.
A gas plant is usually specified in two passes: the process areas first, where the zone drawing is fixed by the licensor, and the balance of plant afterwards, where a smaller fixture does the job. Both passes end with the same two shapes. Floodlights go on the skids and the send-out, where light has to travel. Linear fixtures go in the compressor house and along the pipe racks, where a floodlight would throw half its output into the sky.
A gas plant offer carries the same pack as a refinery one, plus the ambient derating: the client's engineer will want to see the driver curve at the temperature you measured on site, not the catalogue's 25 degrees. Where the site is unmanned, add the maintenance interval and the spare strategy, because those two numbers decide whether the plant is lit in year five.
Send the gas composition and the zone drawing. We return the marking per area, a fixture schedule and the ambient derating we applied to the driver.
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