Checklist for Process Gas Line Connection Selection

Process gas line connection selection looks simple yet is a common failure source. A checklist can push leaks, pressure drop, contamination, and maintenance issues into the design stage. Work through five layers: diameter — fitting — sealing — cleanliness — layout.

Layer one, diameter and pressure drop. Too small a line creates significant pressure drop at high flow; too large adds dead volume and purge time. Size the line from target flow and allowable drop, leaving margin for process variation.

Layer two, fitting type. VCR metal seals suit high-purity and fluorine-bearing gases; compression fittings suit conventional pressure and repeated assembly; flanges fit large bores or high pressure. Match fitting and tubing materials to avoid galvanic corrosion.

Layer three, sealing and leak control. Confirm seal material compatibility with media and temperature, follow torque specifications, and helium-leak-check high-purity systems to hold the specified leak rate. Sealing is where gas-train reliability most often fails.

Layer four, cleanliness: electropolished surfaces, particle and metal-ion release limits, and oil-free assembly. Layer five, layout: minimize dead zones, reserve purge and sensing ports, and keep components serviceable. Work through all five and most line hazards disappear at design time.