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Pipe & Pneumatic Fittings · DIN 906 (taper thread) / DIN 908 (parallel thread with seal) · Application guide

What Are Hex Socket Pipe Plugs Used For?

Typical applications, the industries that specify hex socket pipe plugs, and how to choose the right size, material and finish for the joint.

Hex Socket Pipe Plugs are used for joining and sealing fluid or pneumatic lines. They are manufactured to DIN 906 (taper thread) / DIN 908 (parallel thread with seal), and selection is driven by the pipe thread size, the fit and tolerance the assembly requires, and the service environment.

Primary duty
Joining and sealing fluid or pneumatic lines
Governing standard
DIN 906 (taper thread) / DIN 908 (parallel thread with seal)
Pipe thread size range
DIN 906 to DIN 7604
Category
Pipe & Pneumatic Fittings

Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation.

What Are Hex Socket Pipe Plugs Used For? application image

The primary duty of Hex Socket Pipe Plugs is joining and sealing fluid or pneumatic lines. Below: the sectors that specify them in volume, the checklist used to select the right size and material for the application, installation notes, and the known limits of the type. Stocked across roughly 906 to 7604, they cover heavy and structural work.

Typical Applications for Hex Socket Pipe Plugs

The most common settings where these are specified:

  • Fabrication & metalwork: bench and on-site assembly of steel frames, enclosures and weldments.
  • Pneumatic systems: connecting air lines, cylinders and valves on automation rigs.
  • Hydraulic & fluid power: sealed, pressure-rated joints in fluid lines.
  • Process & plant piping: tapped connections on manifolds and equipment.
  • General machine building: fastening covers, brackets, motors and sub-assemblies on production equipment.

How to Specify Hex Socket Pipe Plugs for Your Application

  • Size: Match the nominal size to the mating thread or hole. This product spans 906–7604; check the full table below for the exact dimensions of each size.
  • Thread & pressure: Match the thread form (BSP/NPT/metric) and pressure rating to the line, and seal appropriately (tape, sealant or O-ring).
  • Environment: For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
  • Standard: This product is supplied to DIN 906 (taper thread) / DIN 908 (parallel thread with seal). Quoting the standard on your order guarantees interchangeable dimensions between suppliers.

Installation & Assembly Practice

  • Seal tapered threads with PTFE tape or anaerobic sealant applied clear of the first thread; parallel threads seal on a washer or O-ring, not on the thread.
  • Tighten to the fitting manufacturer's torque — over-tightening tapered threads splits female ports.

Common Selection Mistakes with Hex Socket Pipe Plugs

  • Mating BSP and NPT threads directly — the 55°/60° forms do not seal against each other.
  • Exceeding the pressure rating of the lowest-rated component in the line.

Where Hex Socket Pipe Plugs Are Not the Right Choice

Do not mix thread forms (BSP into NPT) without an adapter, and do not exceed the pressure rating of the lowest-rated component.

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Sends the selected values to the quote form below.

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The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.

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Specification
Business Information

Dimensions & Specifications (DIN 906 (taper thread) / DIN 908 (parallel thread with seal))

StandardThread formSeals onNeeds a washer
DIN 906taper (R / NPT)the thread flanksno
DIN 908parallel (G / M)the face under the headyes u2014 bonded or USIT ring
DIN 910parallel (G / M), hex headthe face under the headyes u2014 bonded or USIT ring
DIN 7604parallel (G / M), hex head, low profilethe face under the headyes u2014 bonded or USIT ring
Inside the plant

Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

  1. Wire rod feeding into a cold heading machine
    01

    Cold heading

    Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.

    Head dimensions and under-head radius checked at set-up and per shift.

  2. Thread rolling machine producing bolt threads
    02

    Thread rolling

    Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.

    Go / no-go ring gauges to ISO 965 tolerance class 6g.

  3. Baskets of bolts staged for heat treatment
    03

    Heat treatment

    Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.

    Core hardness and tensile tested per lot to ISO 898-1.

  4. Zinc plated bolts in a treatment basket
    04

    Surface treatment

    Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.

    Coating thickness and neutral salt spray hours to ISO 9227.

Frequently Asked Questions

How do I choose the right size of Hex Socket Pipe Plugs?

Match the nominal size to the mating thread or hole. This product is available from 906 to 7604; the full dimension table on this page lists each size.

Can I mix BSP and NPT Hex Socket Pipe Plugs?

Not directly — the thread forms differ in angle and taper. Use a dedicated BSP-to-NPT adapter, and seal with the method suited to the thread (tape, sealant or O-ring).

What material should Hex Socket Pipe Plugs be for outdoor use?

For damp, coastal or chemical environments specify A4 (316) stainless or a suitably coated steel. For indoor or dry use, A2 (304) stainless or zinc-plated steel is normally adequate.

Are Hex Socket Pipe Plugs made to a recognized standard?

Yes — they are manufactured to DIN 906 (taper thread) / DIN 908 (parallel thread with seal), so dimensions are interchangeable between suppliers when you quote the standard on your order.

Can I get a quote for Hex Socket Pipe Plugs in the size and material I need?

Yes. Use the technical drawing and quote form on this page to set the size and options, then send the exact configuration to our team for pricing and lead time.