Ground Joint Couplings are primarily used in steam and high pressure air applications – both of which generate high heat. The only recommended hose attachments are Campbell’s Interlocking U-Bolt Clamps or Crimpnology Long Ferrules. Generally, the ½” thru 1” size range is used for steam and the 1-1/2” thru 4” are used for high pressure air. All Campbell ground joint couplings utilize a hand-tight, leak-free, metal-to-metal connection backed up by a Viton o-ring.