How To Measure Pipe Thread. Measure top diameter of thread at b; Similarly, a thread that measures 1 is actually a 3/4 bsp thread.
Thread dimensions are based on the id of the pipe. You will need a string, ruler, marker, and your piece of pipe. Measure the outside diameter (od) of your pipe or pipe fitting:
For pvc pipe measure the outer diameter, for the fittings measure the inner diameter.
Find figure nearest this dimension in column 1 or 2 of chart. Look at the conversation chart to find the nominal diameter (a ll. Measure top diameter of thread at b; Use a caliper, measuring tape, or ruler to measure the thread diameter of a male thread or female thread.