DIN 906 specifies the dimensions and tolerances for hex socket pipe plugs. The full dimensional table is reproduced below, followed by the DIN, ISO and ASME parts that match or supersede it.
- Standard
- DIN 906
- Product
- Hex Socket Pipe Plugs
- Governing standards
- DIN 906 (taper thread) / DIN 908 (parallel thread with seal)
Equivalence between national standards is dimensional, not always metallurgical. Check the property class separately when substituting.
DIN 906 is the standard cited for hex socket pipe plugs. This page sets out what the standard controls for this part, reproduces the dimensional table supplied against it, and notes the related designations referenced on drawings.
DIN 906 — Scope
The table below lists the dimensions catalogued for hex socket pipe plugs under DIN 906. The scope of DIN 906 itself is not summarised here — where a figure matters, confirm it against the published document.
Tolerance & Product Grades
Product grade is a concept from dimensional fastener standards and does not apply to DIN 906. Tolerances for this part are the limits shown against each dimension in the table.
Dimensions Specified by DIN 906
| Standard | Thread form | Seals on | Needs a washer |
|---|
| DIN 906 | taper (R / NPT) | the thread flanks | no |
| DIN 908 | parallel (G / M) | the face under the head | yes — bonded or USIT ring |
| DIN 910 | parallel (G / M), hex head | the face under the head | yes — bonded or USIT ring |
| DIN 7604 | parallel (G / M), hex head, low profile | the face under the head | yes — bonded or USIT ring |
Companion Standards
A complete specification for hex socket pipe plugs normally cites several documents: one for the geometry, one for the material or mechanical properties, and one for the finish. DIN 906 is one of them, not all of them.
When to Specify DIN 906
DIN 906 is still widely used in European mechanical engineering and as a cross-reference on legacy drawings; its ISO equivalent is preferred for new designs.
Custom manufacturing · Made to drawing
Need a pipe & pneumatic fitting to this standard in a non-standard size?
Parts built to DIN 906 are already in the catalog, so a special is usually a variation on existing tooling rather than a new design — which is what keeps the cost down.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
Custom pipe & pneumatic fitting manufacturingSend a drawing
Applications & Industries
Where Hex Socket Pipe Plugs are used, and what decides the specification in each case. Stocked from DIN 906 to DIN 7604 (pipe thread size).
Industries that specify Hex Socket Pipe Plugs
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Hydraulics
Closing unused ports.
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Gearboxes and castings
Drain and fill plugs.
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Compressors
Port blanking.
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Machine building
Test and service ports.
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Pneumatics & automation
Air lines, cylinders and valve manifolds.
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Hydraulics & fluid power
Pressure-rated sealed connections.
Typical applications
- choosing DIN 906 where the thread itself must seal
- fitting a bonded or USIT ring under a parallel-thread plug
- matching the thread form before the thread size
- using a socket plug where the head must sit flush
- joining and sealing a fluid or air line
- adapting between thread forms on a manifold
Service conditions to specify against
- Marine and coastal
- Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
- Sealed joints
- Used where the fixing has to keep water or air out as well as hold — the elastomer, not the fastener, decides service life.
Where to use something else
- Do not fit a parallel-thread plug without its sealing washer; it tightens perfectly well and then weeps, and the plug gets blamed instead of the missing washer.
Full application guide: where Hex Socket Pipe Plugs are used, how to specify them, and the cases they are wrong for
