Seals & Fittings

O-rings and fluid-conveyance fittings — adapters, elbows, unions, tube-coupling nuts, and pipe plugs — are the components that seal and connect hydraulic, pneumatic, and other fluid-carrying lines. Like the fastener classes above, each is built to a Military Standard or Aerospace Standard number that fixes its dimensions and, for O-rings, its elastomer compound — the two properties that determine whether a given seal will hold under a given system’s pressure, temperature, and fluid type.

The identification path is the same one used across the catalog: an MS or AS number, or the NSN it resolves to, carries the part’s technical characteristics and manufacturer cross-references, so a buyer can confirm a fitting or seal’s exact specification before ordering rather than matching it by measurement or by eye. O-rings in particular are one of the highest-volume, most frequently reordered classes in this catalog, precisely because a system’s seals wear and are replaced on a schedule tied to the equipment, not the part.

Fittings and seals in this class turn up wherever a fluid system has a joint, a bend, or a port that needs to seal: hydraulic lines, pneumatic actuation systems, and fuel or lubrication circuits across airframes and ground equipment. Atlas Air Supply quotes this hardware to its governing specification under CAGE 224F0.

How do I find the right O-ring size or material for my application?

O-ring dimensions and elastomer compound are fixed by the MS or AS spec number called out on the drawing or bill of materials for that application — that number (or its NSN) resolves to the O-ring’s full technical record. Matching the number confirms both size and material; measuring a physical sample or matching by appearance alone can miss a compound difference that isn’t visible.

How is a hose or tube fitting identified by NSN?

A fitting’s NSN carries its federal record — type (adapter, elbow, union, plug), the tube or pipe size it’s built for, thread type, and manufacturer cross-references. Working from the NSN (or the MS/AS number stamped on the drawing) confirms the exact fitting rather than matching by physical shape.