Boss Ground Joint Hose CouplingGround Joint Interlock Hose Couplings or Boss Couplings, are designed for medium to high pressure applications in air as well as fluid and steam service. This coupling system offers a secure threaded connection with the ability to quickly 'hammer' the wing nut swivel to easily loosen or tighten. They are often found on 'Bull' air hose and steam hose assemblies. Sizes range from small diameter up to 6 inch hose.

Ground joint female couplings have a metal-to-polymer seal with no separate gasket. This allows for better chemical compatibility and eliminates potential leakage or downtime from lost gaskets. The female coupling has a large wing nut swivel with unique female thread. A spud adapter threads into this hammer swivel (female NPT is standard, double spud and male thread adapters are also available). The spud adapter can be attached to a male NPT boss interlock hose coupling, or to an NPT outlet on the compressor or air manifold system. Ground Joint hose couplings have an interlocking ridge to fit the notches on a bolted clamp for added shank retention (see boss clamp photo below).

Boss Ground Joint Spud Adapters

Sizes Range from 1/4" to 6" Hose ID

Available in Malleable Iron, Plated Steel, Brass, Stainless Steel

Additional Products include: Male NPT Spud, Double male boss thread spud, Interlocking Hose Mender, Wing Nut Caps

4-bolt boss hose clamp

Ground joint coupling hose shanks feature a serrated lip specially designed to mate with interlocking bolt clamps

Interlocking hose clamps have 2, 4, or 6 bolts depending on the hose diameter

Please view our informative blog on bull compressed air hose configurations


Ground joint wing nut thread is not NPT, a spud adapter is required to connect these couplings to any NPT coupling or pipe (included in the complete female hose coupling)

A gasketed version of this system is available, however it is less common and is not interchangeable. The polymer-seat ground joint style coupling is recommended unless mating to an existing older system.

™ Boss is a trademarked property of Dixon Valve & Coupling Company, all rights reserved


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  • Per Section 1417 of the Safe Drinking Water Act (SDWA) use Lead free parts in all consumable water applications.  Lead free refers to the wetted surface of pipes, fittings and fixtures in potable water systems that have a weighted average lead content = 0.25%. Source: California Health & Safety Code (116875). Vermont Act 193*171NLF
    Please contact us for a limited assortment of lead-free products