NPS thread stands for National Pipe Straight thread, a standard type of straight thread used on pipes typically ranging from 1/8 inch to 12 inches in nominal size. These threads are designed to create a mechanical seal when joined, though they are generally not suitable for high-pressure applications without additional sealing methods.
Here's a breakdown of NPS threads:
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Definition: NPS threads are a set of U.S. national standard straight pipe threads.
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Purpose: They provide a mechanical connection for pipes, fittings, and valves.
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Sealing: While NPS threads create a tight connection, they generally require a sealant compound or gasket for leak-proof joints, especially in fluid or gas systems. This is because the threads themselves do not form a pressure-tight seal like tapered threads (such as NPT).
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Size Range: Commonly used for pipe sizes ranging from 1/8 inch to 12 inches in nominal diameter.
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Application: NPS threads are commonly used in low-pressure applications like drain lines, garden hose connections, and mechanical connections where a tight seal isn't critically needed solely from the thread engagement.
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Distinction from NPT: It is crucial to distinguish NPS (National Pipe Straight) from NPT (National Pipe Tapered) threads. NPT threads are tapered and designed to create a pressure-tight seal as the threads are tightened. NPS threads are straight and require a sealant or gasket to achieve a reliable seal. Mating an NPS thread with an NPT thread can lead to leakage and damage.
In summary, NPS threads provide a straight, mechanical connection for pipes and fittings, typically requiring a sealant or gasket to ensure a leak-proof seal, particularly in fluid or gas systems.
