🔩 Determination of tensile properties of thermoplastics pipes — general test method: test pieces of specified shape cut (die-cut) or machined in the longitudinal direction of the pipe, pulled in a testing machine according to ISO 5893 with self-tightening grips and a load indicator accurate to 1 %; stress at yield σy (MPa) and elongation at break εb (%), details for PVC in Part 2, for polyolefins in Part 3, PN-EN ISO 6259-1

Materials and NDT PN-EN ISO 6259-1

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN ISO 6259-1:2015-05 (Polish version), in full (our translation): “This International Standard specifies a method for determining the mechanical properties in tension of thermoplastics pipes, including in particular the following properties: - stress at yield, - elongation at break. This part of ISO 6259 applies to all types of thermoplastics pipes, regardless of their intended use”. We read the text of the standard in the preview of ISO 6259-1:2015 from the cover to 5.3 (page 3, load indicator); we do not have 5.4 or Clauses 6–11 (test pieces, conditioning, speed, procedure, results, test report) — we only know their titles from the table of contents.

ACCORDING TO THE TEXT OF ISO 6259-1:2015 (foreword, introduction, Clauses 1–5.3, table of contents). The standard was prepared by ISO/TC 138/SC 5; the second edition replaces ISO 6259-1:1997 after technical revision. Series: Part 1 — general test method, Part 2 — pipes of PVC-U, PVC-C and PVC-HI, Part 3 — polyolefin pipes. Introduction: it is a short-term tensile test; it can provide data for further testing and development; it is not significant where the force is applied considerably differently than in this test (impact, creep, fatigue); it is principally a test of material in the form of pipe — results can serve as a process control test but are not a quantitative assessment of long-term pipe performance; the series is based on ISO 527, which applies to material in sheet form, whereas ISO 6259 applies to material in pipe form; pipes are tested as supplied, without reducing the thickness, and the wall can exceed 50 mm, hence changes in the test pieces: thin-walled pipes — die-cut test pieces, thick ones — only machined; requirements for materials are in informative annexes of the respective parts. Scope (1): stress at yield and elongation at break; Part 1 — for all types of thermoplastics pipes, regardless of intended use. References (2): ISO 1167-1:2006, ISO 2602, ISO 5893, ISO 6259-2:1997, ISO 6259-3:2015. Terms (3): gauge length at break L; initial cross-section A = b·h (mm²); initial gauge length L₀ (the values from ISO 527 are maximum gauge lengths); nominal outside diameter dn, nominal size DN/OD; nominal wall thickness en (equal to the specified minimum wall thickness at any point); thickness h and width b of the central part of the test piece; elongation at break εb (%), calculated from the gauge length at break; force at yield F (N); stress at yield σy (MPa); yield — transition from elastic to plastic deformation, usually seen as a decrease or shoulder in the stress–strain curve. Principle (4): test pieces of given shape and dimensions are taken from the pipe in the longitudinal direction by cutting or machining and pulled in a testing machine under specified conditions. Apparatus (5): tensile testing machine according to ISO 5893 (computer-controlled machines according to ISO 527-1:2012 allowed); grips keeping the axis of the test piece in the direction of pull (e.g. centring pins), limiting slip, with pressure increasing with the force, not causing premature fracture at the grips — pre-stressing for alignment allowed; load indicator free from inertia lag at the test speed, accurate to within 1 % of the actual value (ISO 5893, ISO 7500-1). From the table of contents: type of test piece, sampling from the pipe and selection of test pieces, checking of test pieces, conditioning, test speed, results — stress at yield, elongation at break, statistical parameters and retests.

STATUS (PKN catalogue cards as of 02.10.2026). The card of PN-EN ISO 6259-1:2015-05 (Polish version, published 27-12-2016, 16 pages, price group H) has no “Withdrawn” header: Chemistry Sector, KT 140 Plastic Pipes, Fittings and Valves, ICS 23.040.20 and 23.040.45, “Introduces: EN ISO 6259-1:2015 [IDT], ISO 6259-1:2015 [IDT]”, “Replaces: PN-EN ISO 6259-1:2003 – Polish version”. The PKN search for “PN-EN ISO 6259-1” (02.10.2026) also shows PN-EN ISO 6259-1:2002 (English version), PN-EN ISO 6259-1:2003 and the English version of the 2015-05 edition. The EVS catalogue (read 02.10.2026) lists ISO 6259-1:2015 as valid from 26.03.2015.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read 02.10.2026). The number 6259-1 appears in 7 records at 7 laboratories: AB 005, AB 023, AB 041, AB 163, AB 237, AB 414, AB 1256. In the current scopes on the PCA website (read 02.10.2026, issues from 16.07.2025 to 20.07.2026) the 2015-05 edition is given by AB 005, AB 163, AB 237, AB 414 and AB 1256, the number without a year — by AB 023 and AB 041; five laboratories also cite Part 3 (PN-EN ISO 6259-3:2015-08), two — also Part 2 (PN-EN ISO 6259-2:2021-03). The “Laboratories” tab searches for entries STARTING WITH “PN-EN ISO 6259-1” and shows 6 laboratories; at AB 005 the database entry starts with standards of the PN-EN ISO 527 series, so it does not appear in this tab — checked with the tab query on the production server labcoda.pl on 02.10.2026.

WHAT THE LABORATORIES TEST (PCA entries). Thermoplastics pipes — “mechanical properties in tension”: elongation at break (AB 041, AB 1256 — also elongation at yield), yield point (AB 237); thermoplastics — elongation at break, tensile strength and yield point, machine up to 10 kN (AB 414); in broader entries covering plastics, composites and rubber — tensile test up to 300 kN and 800 % elongation (AB 005, together with PN-EN ISO 527-1…5 and PN-ISO 37) and maximum load 100 kN (AB 163); “mechanical properties in tension” in a flexible scope (AB 023).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Test piece: test pieces are taken from the pipe in the LONGITUDINAL direction and without reducing the thickness — a test piece thinner than the wall or taken in another direction is not a test piece of this standard; thin-walled pipes can be die-cut, thick-walled ones only machined. Material: Part 1 gives general conditions, while the type of test piece, speed and conditions for a specific plastic are in Part 2 (PVC) or 3 (polyolefins) — citing Part 1 alone does not define the whole procedure. Machine: the grips must prevent slip as far as possible and must not cause premature fracture of the test piece at the grip (5.2); the force must be indicated to within 1 % (5.3). Interpretation: this is a short-term test — the result serves process control and is not a quantitative assessment of long-term pipe performance (introduction). Name of the quantity: the standard determines stress at yield and elongation at break; “tensile strength” in some PCA entries is a different quantity name from the scope of the standard.

WHAT WE DO NOT STATE. We do not have 5.4 or Clauses 6–11: types and dimensions of test pieces, number of test pieces, conditioning, test speed, formulae for σy and εb, statistical parameters or rules for retests — we therefore give none of these figures.

Method principle

Test pieces are cut or machined from the pipe in the longitudinal direction, without reducing the wall thickness, and pulled in a tensile testing machine with self-tightening grips; the stress at yield (MPa) and elongation at break (%) are determined from the curve.

Applications

• Thermoplastics pipes (PVC, PE, PP and others) — 7 laboratories in PCA scopes
• Process control in pipe production — stress at yield and elongation at break
• Tests according to product standard requirements (material details in PN-EN ISO 6259-2 and PN-EN ISO 6259-3)

Key parameters

Standard

Standard number

PN-EN ISO 6259-1:2015-05 (wersja polska; EN ISO 6259-1:2015 IDT, ISO 6259-1:2015 IDT)

Title (PL)

Rury z tworzyw termoplastycznych — Oznaczanie właściwości przy rozciąganiu — Część 1: Ogólna metoda badań

Title (EN)

Thermoplastics pipes — Determination of tensile properties — Part 1: General test method

Step-by-step procedure

1. Taking test pieces

   From the pipe in the longitudinal direction, by die-cutting or machining, without reducing the wall thickness; type and number according to Clause 6 and Part 2 or 3. PN-EN ISO 6259-1:2015-05 current (PKN cards as of 02.10.2026).

2. Conditioning and speed

   According to Clauses 7 and 8 and the material part (outside the part we read).

3. Tensile test

   Test piece in the grips in the axis of pull, pre-stress if needed; pulling to fracture with recording of force (accuracy 1 %) and elongation.

4. Results

   Stress at yield σy and elongation at break εb; statistical parameters and retests according to Clause 10 (we do not have the formulae).

Required equipment and apparatus

Health and safety (OHS)

• The standard contains no safety warnings in the part we read; when pulling to fracture the laboratory sets the safety rules for working with the machine
• TECHNICAL NOTE: the result of a short-term test is not an assessment of long-term pipe performance; test pieces only in the longitudinal direction and without reducing thickness

Frequently asked questions