Differences between NPT, PT, G, ZG, RC, and M threads
Thread Content
1. Metric thread M (60°): A metric thread, also known as a standard thread, is a commonly used type of thread in China. The standard pitch values for metric threads are arranged in a segmented arithmetic sequence. The thread profile of metric threads is 60 degrees, and the pitch refers to the distance between two thread peaks. Metric threads – Thread specifications are for threads defined in metric units (millimeters), denoted as M + the nominal diameter of the thread X the pitch. 2. British imperial unsealed pipe thread G (55°) – commonly referred to as pipe thread – is a 55-degree unsealed pipe thread that belongs to the Whitworth thread family. The 1/4, 1/2, 1/8 designations in threads refer to the diameter of the thread size, measured in inches. Those in the industry usually refer to thread sizes in \"points\"; 1 inch equals 8 points, 1/4 inch equals 2 points, and so on. 3. General sealed pipe threads ZG (R, R1 or R2, RC) (55°). ZG is a notation used in China’s old mechanical drawing standards; it has now been replaced by R/R1/R2 for external threads and RC for internal threads. 4. American thread NPT (60°). NPT is an abbreviation for National (American) Pipe Thread; it represents a 60° general-purpose sealing pipe thread according to American standards, and is used in North America, with a taper of 1:16. The 1/4, 1/2, 1/8 designations in threads refer to the diameter of the thread size, also measured in inches. 5. Imperial thread PT (55°): The Pt thread is an imperial tapered pipe thread with a 1:16 taper. Imperial threads were the first to be invented, but after World War II, American threads gradually drove them out of the market; today, imperial threads are most commonly used in Korea and Japan. Summary: Unsealed pipe threads have no taper and are therefore cylindrical; such threads cannot achieve good sealing on their own. A sealing material (such as tape, packing tape, hemp rope, etc.) must be added to the threads in order to achieve a sealing effect. Sealed pipe threads (also known as self-sealing pipe threads) achieve self-sealing through the mutual compression of the thread teeth on a 1:16 taper, without the need for any sealing material. (However, in some tapered pipe threads, due to manufacturing issues, it is still common practice to wrap some sealing material around the cone-shaped screw as a precaution.)
Study hard*, make progress every day:victory:
Thank you for sharing, :handshake
Study hard*, understand things thoroughly, and keep making progress every day.
NPT (National Pipe Thread): NPT is a standard tapered pipe thread in the United States, used for sealing connections of pipes and fittings. It has a certain taper (usually 1:16), which allows for a tight seal to be formed when two NPT components are screwed together. It is typically used in pipeline systems that require airtight or watertight sealing. PT (Pipe Thread): PT usually refers to BSPT (British Standard Pipe Taper), that is, the British standard tapered pipe thread. Similar to NPT, it also has a tapered thread, but the pitch and thread angle are different; therefore, NPT and BSPT cannot be used interchangeably. It is mainly used in imperial and some international piping systems. G (Parallel Pipe Thread): G stands for BSPP (British Standard Parallel Pipe), which refers to the British standard for parallel pipe threads. This thread is non-tapered, meaning its diameter remains constant throughout its length. G-thread usually requires additional seals such as O-rings or tape to ensure a tight seal. ZG (Chinese National Standard Taper Pipe Thread): ZG is China’s **standard tapered pipe thread, similar to NPT but in accordance with China’s **standards. It also has a certain taper, which is used to achieve a sealing effect. RC (Right Cone, Right Hand Thread) and M (Metric Thread): RC usually refers to a conical right-hand thread, but this designation is not widely used; it may denote a type of thread specific to certain manufacturers or applications. M stands for Metric threads, one of the most commonly used thread standards; it includes external and internal threads, and defines parameters such as pitch and diameter. Metric threads are widely used in various mechanical and engineering fields around the world, as they are based on metric units, making them easy to calculate and manufacture.