Valves, Fittings, and Pipe Materials Flashcards

A needle valve is best suited for applications requiring:

Answer: Precise flow metering and throttling

The needle valve's tapered stem and small orifice allow very fine, precise adjustments to flow rate.

When threading black steel pipe, the correct taper for NPT threads is:

Answer: 1/16 inch per inch

National Pipe Taper (NPT) threads have a standard taper of 1/16 inch per inch (3/4 inch per foot) of thread length.

Galvanized steel pipe should NOT be used for which of the following services?

Answer: High-temperature steam above 212°F

High temperatures cause the zinc coating to deteriorate and flake off, contaminating the system and weakening the pipe.

What is the function of a strainer installed upstream of a control valve?

Answer: Remove debris that could damage the valve seat

A strainer catches particulates and scale before they can score or damage the precision-machined surfaces of a control valve.

A full-port ball valve is specified instead of a standard-port ball valve when:

Answer: Minimum pressure drop and unrestricted flow are required

A full-port ball valve has a bore matching the pipe ID, providing virtually no restriction or pressure drop when fully open.

Which pipe material is most resistant to corrosion in seawater or highly corrosive chemical service?

Answer: Hastelloy or high-nickel alloy

Nickel alloys such as Hastelloy C provide exceptional corrosion resistance in aggressive chemical and marine environments where other metals fail.

A concentric reducer connects pipes of different sizes and is distinguished from an eccentric reducer because it:

Answer: Has both centerlines aligned on the same axis

A concentric reducer maintains a common centerline between both pipe sizes, making it suitable for vertical piping and non-critical horizontal runs.