BS EN 10226-2:2005 – Pipe threads where pressure tight joints are made on the threads — Part 2: Taper, external threads and taper internal threads — Dimensions, tolerances and designation

1 Scope
This European Standard specifies the requirements for thread form, dimensions, tolerances and designation for jointing pipe threads, sizes 1 /1 6 to 6 inclusive, for joints made pressure-tight by the mating of the threads. These threads are taper external and taper internal and are intended for use with pipes suitable for threading and for valves, fittings or other pipeline equipment interconnected by threaded joints.
An appropriate thread sealant or jointing compound should be used on the thread to ensure pressure-tight joints.
NOTE 1 Threaded joints using taper external threads and parallel internal threads are detailed in EN 1 0226-1 .
NOTE 2 The requirements for taper external threads are identical in EN 1 0226-1 and EN 1 0226-2.
NOTE 3 For pipe threads where pressure-tight joints are not made on the threads see EN ISO 228-1 .
NOTE 4 EN 1 0226-3 gives details of recommended gauging systems for the verification of thread dimensions and thread form.
2 Normative references
The following referenced documents are indispensable for the application of this European Standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 1 0226-3, Pipe threads where pressure-tight joints are made on the threads — Part 3: Verification by means of limit gauges
3 Terms and definitions
For the purposes of this European Standard, the following terms and definitions apply (see also Figures 2 and 3).
NOTE For consistency and clarity, common terms and definitions have been adopted for EN 1 0226-1 and EN 1 0226-2.
Consequently some definitions may include terms that seem inappropriate to this document.
3.1
gauge diameter
major diameter of the thread, whether external or internal, at the gauge plane
3.2
major cone
imaginary cone, which just touches the crests of a taper external thread or the roots of a taper internal thread
3.3
gauge plane
plane, perpendicular to the axis of the taper thread, at which the major cone has the gauge diameter
NOTE 1 For external threads the gauge plane is located at a distance equal to the gauge length from the small end of the thread.
NOTE 2 For taper internal threads; the gauge plane is located at a distance of half pitch behind the face of the threaded work piece. This distance has been agreed so that the position of the gauge plane on taper internal threads is consistent with parallel internal threads in EN 1 0226-1 .
3.4
gauge length
on an external thread, the distance from the gauge plane to the small end of the thread, measured parallel to the axis
BS EN 10226-2:2005 – Pipe threads where pressure tight joints are made on the threads — Part 2: Taper, external threads and taper internal threads — Dimensions, tolerances and designation