2-Lug Vs 4-Lug Couplings

All Chicago style couplings are 2-lug through 1 inch.  All 2-lug couplings, regardless of the NPT size (or hose size) will interchange.  All couplings over 1 inch will have a 4-lug design.  4-Lug couplings will not interchange with 2-lug couplings, they are too big and have 2 extra lugs.  If you have a coupling that is greater than 1 inch pipe thread or hose shank, and it has 2-lugs instead of 4, then it is either:

  • A sandblast coupling
  • A different type of interchange, typically from EU or Asian manufacturers 
  • or it has been reduced using pipe fittings or other adapters, look closely and see if there are any adapters threaded into the coupling.

4 Lug couplings have the same pressure rating and application recommendations, but are larger and have two extra lugs to create a secure leak-free connection for larger diameter hose lines.

For additional information and detail, please see this blog post on coupling dimensions.

Please contact us if you need identify a coupling that does not match anything shown on this site.




Bryan FeldmanCapital Rubber