Exam 24: Pipe Threads

The thread specification on a drawing should include:

When taper is shown on a drawing of a tapered pipe thread, it is usually exaggerated to provide clarity.

Pipe threads are used in applications where a pressure-tight joint or mechanical connection is required.

All pipe threads are tapered.

The thread form for straight pipe threads is the same as the American National Standard taper pipe thread.

Straight pipe threads have a thread angle of 60 degrees, and a taper of 0.50 inches per foot.

The type of joint that is assembled without a sealer, and is used in automotive, aircraft, and marine applications is a dryseal pressure-tight joint.

For tapered pipe threads, the taper is not normally shown on a drawing unless needed.

The designation for a tapered pipe thread used for a dryseal application, if extra clearance is required is:

The designation for a tapered pipe thread used for a pressure-tight joint, using a sealer, is:

The designation for a tapered pipe thread used for a rigid joint is:

The designation for a straight pipe thread used for a low-pressure-tight joint is:

The designation for a straight pipe thread used for a loose fitting mechanical joint where no internal pressures exist is:

The two types of pipe threads approved as American National Standard are tapered and straight.

The designation for a straight pipe thread used for a dryseal joint in soft or ductile material is:

NPT threads:

Mechanical joints are not pressure-tight; they may be rigid or loose.