Equipment Piping (Pumps, Exchangers, Vessels & Control Stations) Flashcards

What is the standard arrangement of a control valve station?

Answer: Block valves upstream and downstream with a globe bypass

Blocks and bypass allow isolating the control valve for maintenance while operating manually.

Which orifice tap orientation is typical for gas lines to avoid liquid in impulse lines?

Answer: Top

Top taps prevent condensate from collecting in the impulse tubing.

Why is straight pipe required upstream and downstream of an orifice meter?

Answer: To develop a stable flow profile for accurate measurement

Fittings and valves distort velocity profiles, so required run lengths depend on beta ratio.

What clearance is commonly maintained between the bottom of a control valve and grade?

Answer: Enough for removal of bottom flange or plug, typically at least about 12 inches

Maintenance access to the valve bottom and actuator requires working space.

Where should a flashing-service control valve be placed?

Answer: As close as practical to the downstream vessel, with downstream line sized for two-phase flow

Flashing generates vapor, so the downstream line must be larger and short to limit erosion and noise.

When the control valve is smaller than the line, which fittings are used?

Answer: Reducers and swages on each side

Reducers match the valve to line size and are usually installed with enough run to keep flow stable.

A fuel gas burner control valve typically has what failure position?

Answer: Fail closed

Failing closed cuts fuel to a burner during signal or air loss, which is the safe state.