Difference between ZG1/2" and G1/2"
Thread Content
Both ZG1/2\" and G1/2\" denote imperial threads. I’m not sure what the “Z” prefix means – could you please explain? :handshake
ZG1/2” denotes tapered pipe threads, while G1/2” refers to parallel threads. ZG1/2” provides better sealing performance than G1/2”. In some standards, when ZG1/2” is used, the internal thread is denoted as Rc1/2” and the external thread as R21/2”
ZG1/2": 1/2 inch tapered thread； G1/2": 1/2 inch pipe thread.
ZG tapered pipe thread, G pipe thread, parallel thread
Thank you, Dayou – I’ve learned something and gained a little more knowledge
G threads are used primarily for connection purposes; the inner diameter remains constant throughout the effective threaded section. Their sealing performance is poor after connection, so they cannot be used in applications where sealing is required. Due to its structural characteristics, ZG threads have unequal diameters within the effective threaded section; the tighter they are tightened during connection, the better the sealing performance, and they are primarily used in applications where high sealing standards are required. Understanding their uses allows one to choose them correctly for use.
Question: Is ZG1/2 or G1/2 commonly used for air supply ball valves? In the past, when galvanized pipes were used, the thread size was G1/2; now that stainless steel pipes are used for air supply, what is the thread specification for the butt-welded straight-through terminal fittings?
ZG1/2\" is the old standard designation for pipe threads; the current notation is R1/2 for external threads and Rc1/2 for internal threads, referring to tapered pipe threads with a thread angle of 55°. G1/2\" pipe thread; G1/2\"----4 threads, outer diameter 20.96mm, 1 inch/14 teeth.
For connections with pipes, ZG1/2 is used; for metric threads on ferrules, pipe threads are generally not used in the intermediate connectors
The new standard specifies: internal thread on the tapered tube: Rc, external thread on the tapered tube: R2；
ZG tapered pipe thread, G pipe thread. 1/2\" is 1/2 inch, which is 4 inches, with 1 inch equaling 8 inches.
Then if those threads aren’t used and welding is done directly, wouldn’t the sealing performance be better?
For the standard fittings available on the market, is the internal thread G1/2 or Rc1/2?