How are G threads and NPT threads denoted respectively?
Thread Content
Does the G thread not require units? For example, a 1/4 inch G thread can be written as G 1/4, while an NPT thread needs to be written as 1/4" NPT. Is that correct?
The code for British imperial unsealed cylindrical threads is G, while the code for American standard sealed tapered pipe threads is NPT
NPT threads are British standard sealing pipe threads with a 60-degree angle, while American standard pipe threads are of the R type with a 55-degree angle; in China, the ZG standard is commonly used, also with a 55-degree angle.
Pipe threads are divided into sealed pipe threads and unsealed pipe threads. Pipe threads sealed with threads are denoted as: tapered male thread Rc1/2, cylindrical male thread Rp1/2, tapered female thread R1/2. Pipe threads that are not sealed with threads are denoted as: male thread G1/2, female thread G1/2A or B. NPT is a tapered pipe thread of general use in American thread standards, and is denoted as 1/2-14NPT. The thread pitch angle for pipe threads is 55°, while that for NPT threads is 60°.
It’s mainly because the tooth shapes and angles are different
The G thread is a cylindrical pipe thread with a thread angle of 55°; it can be denoted as G 1/4. The NPT thread is a tapered pipe thread with a thread angle of 60°, and it can be written as NPT1/4. In fact, for pipe threads, tapered threads, and tapered pipe threads, all one needs to do is include the thread designation along with the thread size.
Our company commonly uses NPT threads, but we still don’t know much about them. Is there a substitute?
No units are required; it can be written as G1/4 (-LH) NPT1/4 (-LH). The notation in parentheses indicates left-handed rotation; right-handed rotation does not require such notation