Pipefitter Valves, Fittings, and Pipe Materials 5

Question 1

A needle valve is best suited for applications requiring:

Accepted Answer

Precise flow metering and throttling

Answer

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

Question 2

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

Accepted Answer

1/16 inch per inch

Answer

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

Question 3

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

Accepted Answer

High-temperature steam above 212°F

Answer

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

Question 4

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

Accepted Answer

Remove debris that could damage the valve seat

Answer

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

Question 5

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

Accepted Answer

Minimum pressure drop and unrestricted flow are required

Answer

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

Certified Pipefitter Practice Test