Which sequence correctly describes a TIG welding machine shutdown?

• A. Close gas cylinder, turn off power, release regulator pressure
• B. Release regulator pressure, turn off power, close gas cylinder
• C. Turn off power, then close gas cylinder, then release regulator pressure
• D. Close gas cylinder only

Answer: (A)

Shut down safety first means cutting off energy and gas supplies in a careful order to reduce hazards. The best sequence starts by closing the shielding gas cylinder. This immediately stops the flow of argon or whichever gas you’re using, isolating the gas supply and preventing ongoing leakage or unwanted gas in the line while you handle other steps.

Next, switch the welding power off. Turning off the power removes electrical energy from the system, reducing the risk of arcing or shock while you complete the shutdown and disconnect components.

Finally, release the regulator pressure. Depressurizing the regulator and hose after the gas is cut off ensures there’s no stored pressure in the line when you store or service the equipment, keeping the system safe for the next use.

Other sequences are less safe because they either allow gas to vent under pressure while the line is still potentially energized or leave pressurized gas in the line after the power is already shut down, increasing the chance of leaks or hazards. Only closing the gas first, then powering down, and then relieving pressure provides a clean, safer shutdown.