Water Works Threads: Keeping Communities Connected to This Resource

Water Works Threads: Keeping Communities Connected to This Resource

Between consumption, sanitation, and irrigation purposes, every community needs access to water in order to thrive. Besides water wells, water service laterals are one of the solutions that make this possible in the first place. However, that’s not to say it doesn’t take a multitude of parts and connections to get there.

Underground service line water works valves and fittings contain threads on the end connections. The purpose of threads is to either create a pressure tight seal utilizing thread sealant or to join two parts together (mechanical joint) with no thread sealant. Threads are located on both the inlet and outlet. There are many different types of threads, such as the following:
 

Straight Threads
Straight threads are commonly used on compression nut ends, meter ends (NPSM), flare ends, and ball valve end pieces, along with many other parts. There is no sealant required between threads for seal. Some water works specific threads are specified by the American Water Works Association (AWWA).

Straight mechanical threads
Straight mechanical threads require a gasket for proper sealant and are commonly used on compression nuts and meter nuts.

Flare Threads
Flare threads are used on flare nut and flare ends and are interchangeable in the water works industry. No thread sealant is required as the seal is made by compressing the flared copper tube between the body and the nut.

Tapered threads – NPT
National Pipe Tapered Thread (NPT) is very common and used frequently in the plumbing and water works industry. In the field, these threads are commonly fitted with thread tape or thread sealant to help ensure a good seal. NPT threads are both Male National Pipe Thread (MNPT) and Female National Pipe Thread (FNPT). Common water works applications include ball valves, saddles, and various adapters and fittings.

Tapered Threads – AWWA Corp
AWWA corp thread is a water works specific tapered thread that has a steeper tapered angle than an NPT thread and is interchangeable among manufacturers, as specified by the AWWA. This solution is used on saddles and corp stops (plug and ball style) and thread sealant is required.

Tapered Threads – British
British threads are similar to NPT threads but use a 55-degree thread form rather than a 60-degree thread form. However, they are not commonly used in the U.S. and thread sealant is required.

For more information on the topic, take the ‘Common Water Works Threads’ AYU course!