Are you often troubled with different threads? G3/8?1/4NPT? R1/8? UNF? KF16? Then below let me introduce different threads and tell you how to distinguish!
International Metric Thread System : Chinese standard CNS adopts this kind of thread.Thread top is flat,and easy to lathe, thread bottom is round so as to enhance the strength of threads. Thread angle is 60°,Specification is shown in M.Metric thread are of two kind: coarse thread and fine thread.Shown as M8*1.25(M is code, 8: nominal diameter, 1.25: thread distance)
American Standard Thread: Top and bottom are both flat, with good strength.Thread angle is 60°，specification is shown as "how many threads every inch".It is classified as NC, NF, NEF shown as 1/2-10 NC.(1/2：outer diameter; 10:number of threads every inch; NC: code)
Unified Thread：Edited by America,England,and Canada，and currently recognized as inch screw thread. Thread angle is also 60°.Specification is shown as "how many threads every inch". It can be classified as UNC, UNF and UNEF. Writen as 1/2-10UNC(1/2: outer diameter;10: number of threads every inch;UNC:code)
Sharp V thread:Top and bottom of thread are both sharp,and the strength is relatively weak,and easy to be broken, so not often used. Thread angle is also 60°.
Whitworth Thread: The standard is adopted by England.Thread angle is 55°,shown in code "W".Applicable for rolling process. Written as W1/2-10.(1/2:outer diameter; 10:number of threads every inch; W: code)
Knuckle Thread:Specified by German DIN,and application for bulb, rubber hoses.Mark code is"Rd"
Pipe Thread:The thread used for preventing the leakage, commonly used for the pipe connection of gas or liquid.Straight pipe thread is"P.S,N.P.S" and inclined pipe code"N.P.T", and tapered degree: 1:16, that is 3/4".
