Gas Train Equipment: How Direct Gas Fire Heat Treating Works

When Gulf Coast Combustion shows up on a job site, the equipment setup is what the industry calls gas train equipment. It’s the core of direct gas fire combustion heat treating — the method GCC has specialized in since 2014. Here’s a breakdown of what each component is, what it does, and why it matters for on-site PWHT.

The Blower

The blower provides the air needed for combustion. It forces air at approximately 1 psi into the burner, where it mixes with fuel to produce the high-velocity flame. The pressure from the hot gases leaving the burner can project heat up to 60 feet into the vessel — which is what makes this method effective for large-diameter, long-run pressure vessels that need even heat distribution across significant internal volume.

The Control Console

The control console manages fuel flow and monitors the burner. It contains the gas regulator and ignition transformer, verifies correct fuel pressure, and monitors the flame continuously. If flame loss occurs, an alarm sounds and fuel supply shuts down automatically.

The gas regulator reduces incoming gas pressure to 1–2 psi for use with the control train. It’s adjustable, which allows for a controlled low-temperature start-up — important for code-compliant heat-up rates on thick-walled vessels.

The ignition transformer provides 8,000–10,000 volts to the spark electrode to light the burner. It’s designed for intermittent use, not continuous operation.

High-Velocity Gas Burners

GCC uses three burner sizes depending on job requirements: 3 million BTU/hr, 6 million BTU/hr, and up to 10 million BTU/hr. The 6–10 million BTU burner is used most often on large vessel firings where significant heat output and air volume are required.

All are nozzle-mix burners — meaning gas and air mix at the burner tip rather than upstream, which provides precise control over the combustion process. The 6–10 million BTU unit is stainless steel with an 8-inch air inlet and a standard 2-inch gas hose connection.

The Vaporizer

A vaporizer is required when the fuel source is in liquid state — most commonly when using LPG on job sites without a natural gas supply. LPG is stored and transported as a liquid under pressure. Before it can be combusted, it has to undergo a phase change from liquid to vapor. The vaporizer handles that conversion.

When a client has a natural gas supply at their facility, GCC can connect directly to it — no vaporizer needed, and typically a meaningful cost savings for the client.

How Gas Train Equipment Works on a Job

On a pressure vessel PWHT job, the gas train is positioned outside or adjacent to the vessel. Burners are installed through available nozzles and manways. The vessel, wrapped in insulation, becomes its own furnace. High-velocity combustion drives heat throughout the interior, and Type K thermocouples attached directly to the vessel surface monitor temperature in real time on a strip chart recorder. The result is a controlled, documented heat cycle that meets ASME Section VIII requirements from heat-up through cool-down.

Read how GCC executes a complete on-site PWHT from start to finish with our Complete Guide to Pressure Vessel PWHT.

Gulf Coast Combustion deploys this equipment throughout the Gulf Coast, mobilizing directly to your facility for on-site PWHT. For a full overview of our services, visit our services page.

For the full picture of how direct gas fire fits into on-site PWHT, read: What Is Direct Gas Fire Heat Treating — and Why Does It Matter for High-Pressure Vessels?