UNC, UNF and UNEF Threads

The Unified Thread Series was agreed on by the United States, Britain and Canada in 1949 to obtain interchangeability. Recently, modifications have been made to the original specifications for ease of use.

Unified National Threads (UNC/UNF/UNEF/UNS) are Imperial standard, typically consists of coarse (UNC), fine (UNF) and extra fine (UNEF) three graded thread series,much like metric thread series.

 

The female or male UNC, UNF, UNEF, UNS threads are parallel, also have the same 60° thread angle as the ISO metric thread.

Unified National Threads:

• UNC- Unified National Corase
• UNF- Unified National Fine
• UNEF- Unified National Extra Fine
• UNS- Unified Special

The unified threads are the main standard for bolts, nuts, and a wide variety of other threaded fasteners used in many countries.

In some of RELAB nozzles, we also use the unified national thread. The FA, FD, FE series Mist Nozzles are 10-24UNC-2A and 12-24UNC-2A thread, and the Oil Burner Nozzles use the 9/16"-24UNEF thread.