In steel conduit fittings, various thread types and sizes are commonly used. The most common thread types include National Pipe Thread (NPT) and National Pipe Straight Mechanical (NPSM). Here are some details about these thread types:
National Pipe Thread (NPT):
NPT threads are tapered threads widely used in the United States for pipe and conduit fittings.
The taper of the threads allows for a tight seal when the male and female threads are connected.
Common NPT sizes include 1/2", 3/4", 1", 1-1/4", 1-1/2", 2", 2-1/2", 3", 3-1/2", 4", 5", 6", 8", 10", and 12".
National Pipe Straight Mechanical (NPSM):
NPSM threads are straight threads used for mechanical joints and fittings.
Unlike NPT threads, NPSM threads are not tapered, and they rely on a gasket or washer to create a seal.
Common NPSM sizes include 1/2", 3/4", 1", 1-1/4", 1-1/2", 2", 2-1/2", 3", 3-1/2", 4", 5", 6", 8", 10", and 12".
When working with steel conduit fittings, it's important to ensure that the threads on the fittings match the threads on the conduit and other connected components. Using the wrong thread type or size can result in improper connections, leaks, or difficulty in assembly.