Aluminum Pipe Fittings and Manifolds - 195
Aluminum pipe fittings are used only in specialty applications where their uses and limitations are understood. They are not designed for use in general shop water or air plumbing layouts (refer to traditional metals like brass, steel/malleable iron, stainless steel, plastics, etc. for general plumbing applications). Aluminum to aluminum pipe threads are not designed to be removed or re-tightened as they will bind very quickly and easily (ie. the friction of threading together will cause the aluminum to bond to itself - PTFE sealants, pastes, or tapes can lessen the effect but will not prevent it). Therefore, once aluminum to aluminum threads are threaded together, it is considered permanent and leak paths would be difficult to eliminate (butt weld aluminum fittings are available, N205WD, N210WD, N225WD, etc). As a general guide, they can be used for vacuum or maximum 150 psi at ambient temperatures, but they can be welded and tested for other pressure ratings in certain applications. If using aluminum in combination with other metals, users must understand electrolysis and galvanic corrosion (especially with copper or steel with aluminum) as water, salt water, and other elements will degrade the metals. When attaching caps or plugs to aluminum tanks, it is better practice to use stainless steel caps or plugs (or plastic/nylon/poly) so they can be removed. Most "Cast Aluminum" pipe fittings are made of A356.2 alloy, and "Couplings, Nipples, and Sch 40 Butt Weld fittings" are made of 6061-T6 alloy. Threads conform to ASME B1.20.1.