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When you need to cap off an unused port on a hydraulic manifold, air compressor, or fuel system, a protruding hex-head plug is the last thing you want. These male Allen socket pipe plugs let you drive the cap flush — or even recessed — using a standard hex key, leaving a clean, snag-free surface every time.
Machined from A2 304 stainless steel, each plug features a tapered male thread in either PT (British Standard Pipe Taper, 55°) or NPT (National Pipe Taper, 60°) and covers the full size range from 1/16" up to 2". The internal hex socket drive eliminates the need for a bulky wrench in tight spaces.
Ideal for blanking test ports on pneumatic lines, sealing unused inlets on water manifolds, or permanently capping threaded holes in industrial machinery — wherever a low-profile, corrosion-resistant pipe plug is required.
Blank off unused ports on manifolds and valve bodies with a flush, low-profile plug that won't interfere with adjacent fittings or hose runs.
Cap water lines, test ports, or unused inlets during rough-in or system modifications — available in NPT for North American residential plumbing.
Seal unused NPT ports on oil coolers, fuel rails, and coolant manifolds where a recessed plug keeps the engine bay tidy and leak-free.
Keep a range of PT and NPT sizes on hand for blanking test points, decommissioning lines, or sealing threaded holes during equipment overhauls.
| Product Type | Male Allen Socket Pipe Plug / Threaded End Cap |
|---|---|
| Material | A2 304 Stainless Steel |
| Thread Standards | PT (BSPT, 55°) and NPT (60°) |
| Size Range | 1/16", 1/8", 1/4", 3/8", 1/2", 3/4", 1", 1-1/4", 1-1/2", 2" |
| Drive Type | Internal Hex (Allen Socket) |
| Head Style | Flush / Countersunk (no external hex head) |
| Sealing Method | Tapered thread interference fit; PTFE tape recommended for high-pressure use |
| Finish | Natural stainless (uncoated) |
| Typical Applications | Hydraulic manifolds, pneumatic lines, fuel systems, water pipes, test ports, industrial blanking |
| Packing Options | 1, 2, 5, 6, or 10 pieces (see variant options) |
PT (BSPT) uses a 55° thread angle; NPT uses 60°. Both are tapered, but they are not interchangeable — mixing standards will cause leaks or thread damage. Always match the plug to the thread standard of your female port. Check your system documentation or use a thread gauge to confirm.
For low-pressure air or water (typically under 100 psi), the tapered threads alone may seal adequately. For higher pressures, fuel, oil, or any critical fluid system, apply 3–5 wraps of PTFE tape or a quality pipe thread sealant. Tighten hand-snug plus approximately 1/4 turn — avoid over-tightening, which can crack the mating fitting.
304 stainless offers good general corrosion resistance but can pit under prolonged saltwater exposure. For marine applications, 316 stainless is generally recommended. For freshwater, industrial fluids, and outdoor non-salt environments, 304 performs well and significantly outlasts plated carbon steel.
Pipe thread sizes refer to the nominal bore of the pipe, not the actual thread outer diameter. A 1/4" NPT plug, for example, has threads that measure approximately 0.54" in outer diameter. The easiest approach is to match the size stamped on your existing fitting or valve body. If unsure, a thread pitch gauge will confirm both size and standard.
Yes — that is a key advantage of the Allen socket design. With no external hex head, you can drive the plug until its face sits flush with or slightly below the mating surface. This is particularly useful on manifolds, valve bodies, and any assembly where protruding hardware would interfere with adjacent components or covers.
The required hex key size varies by plug diameter — smaller sizes (1/16"–1/4") typically use a 3–5 mm hex key, while larger sizes (1/2"–2") generally require 6–10 mm or larger. A standard metric or imperial hex key set will cover the full range. If you need the exact size for a specific variant, contact us to confirm.
Pressure ratings depend on size, thread engagement, and the mating material. Smaller sizes in 304 stainless typically handle several hundred psi in standard plumbing applications. For high-pressure hydraulic or pneumatic systems, always verify the rating against your system's working pressure and apply appropriate thread sealant. Contact us if you need guidance for a specific application.
