kSIST FprEN 17151-2:2026

• Abstract:

  This document specifies a test method for determining the creep behaviour under compression of boxes made of thermoplastic materials intended for use in a modular system for non-pressure underground conveyance and storage of surface water.

• Status: Not Published
• Public Enquiry End Date: 04-Mar-2026
• ICS: 23.040.01 - Pipeline components and pipelines in general
• ICS: 23.040.03 - Pipeline and its parts for external water conveyance systems
• Technical Committee: PCV - Plastic pipes, fittings and valves
• Current Stage: 5020 - Formal vote (FV) (Adopted Project)
• Start Date: 26-Oct-2026
• Due Date: 14-Dec-2026
• Completion Date: 27-Oct-2026
• Ref Project: FprEN 17151-2 - Plastics piping systems for non-pressure underground conveyance and storage of surface water - Part 2: Test method for determination of creep behaviour of boxes under compression

kSIST FprEN 17151-2:2026 is a draft European Standard published by SIST for a compression creep test on boxes made of thermoplastic materials. It specifies how to determine creep behaviour under constant compressive load for boxes intended for modular systems used in non-pressure underground conveyance and storage of surface water. Engineers, laboratories and product assessors use it to measure deformation over time and to derive a creep factor for design and comparison.

What does kSIST FprEN 17151-2:2026 specify?

kSIST FprEN 17151-2:2026 specifies a test method, not a product specification. It is Part 2 of the prEN 17151 series, and Part 1 covers long-term compression strength of boxes.

The document is organized into Scope, Normative references, Terms and definitions, Symbols and units, Apparatus, Test sample, Test procedure, Analysis, Test report, and a normative Annex A for regression analysis. In practice, that means the standard tells a lab what to test, how to load the sample, how to record deformation, how to calculate results, and what must be reported.

What are the key requirements of kSIST FprEN 17151-2:2026?

kSIST FprEN 17151-2:2026 focuses on a constant-load compression creep test on box units that represent the weakest entity of the final construction. The main requirements are in Clauses 5 to 9 and Annex A.

Sample, conditioning and test loads

The test sample is a box with integral components, tested in the vertical installation direction unless otherwise specified. Homogeneous extruded boxes are cut so the sample remains representative, with a minimum vertical length of 0.5 m and a horizontal-to-vertical ratio below 1.0.

One sample is used per test load unless the referring standard says otherwise. Samples must be at least 21 days old and conditioned in air at the test temperature for at least 24 h before testing. A minimum of three loads should be used, chosen so failure does not occur during the test, with the document giving examples based on short-term compression strength from EN 17150.

Apparatus and measurement

The compression machine applies a constant load through stiff plates. The plates must be flat, smooth and clean, and the load must act perpendicular to the sample within 90° ± 1°. If a force multiplication device is used, the resulting load is verified with a calibrated load cell.

The measuring devices need defined accuracies for time, dimensions, displacement, weighing and load. In practice, this ensures the deformation data are trustworthy enough to support extrapolation and design decisions.

Test procedure and recording

Unless otherwise specified, the test temperature is 23 °C ± 2 °C. Each sample is first given a pre-load between 5 kPa and 10 kPa, then loaded to the full test load and held constant for the duration of the test, with the load not varying by more than ±2 %.

The standard requires deformation to be recorded over time, either at fixed intervals or by displacement-triggered intervals. The first hour needs dense recording, and later readings must still be frequent enough for log-time analysis. The test duration is chosen to support the intended extrapolation, and the document notes that extrapolating to 50 years requires at least 4 380 h of test duration.

Analysis and reporting

Clause 8 requires strain to be plotted against log time. Strain is calculated from deflection and the height after preload, and compressive stress is calculated from the applied force and the sample area. The linear creep region is then extrapolated using regression analysis, with Annex A giving the fitting method and a suitability check based on the squared correlation coefficient r.

The creep factor is the extrapolated strain divided by the strain at 0.05 h after full load, and the report must declare the creep factor for each stress level. The report also includes the sample identification, test configuration, dates, stress levels, plots, extrapolated strain, and any factors that may have affected the result.

What terms does kSIST FprEN 17151-2:2026 define?

• creep - increase in strain with time when a constant force is applied.
• creep factor - strain ratio for a given applied stress and time.
• EN 17150 - the referenced test method for short-term compression strength of boxes, used here to help choose suitable loads.
• prEN 17151-1 - the companion part covering long-term compression strength of boxes.
• EN ISO 7500-1:2018 - the calibration and verification standard for the force-measuring system of the compression testing machine.
• r - the squared coefficient of correlation used in Annex A to judge whether the regression data are suitable for analysis.

Who uses kSIST FprEN 17151-2:2026?

kSIST FprEN 17151-2:2026 is used by manufacturers of thermoplastic boxes, testing laboratories, product certifiers, and engineers responsible for modular surface-water systems. It is also relevant to quality managers and buyers who need a common test method for comparing products or checking declared performance. In practice, it supports product development, type testing, conformity assessment and technical specification work.

Which standards are used with kSIST FprEN 17151-2:2026?

• EN 17150 - provides the short-term compression strength reference used when selecting test loads.
• prEN 17151-1 - supplies related terminology and the companion test method for long-term compression strength.
• EN ISO 7500-1:2018 - sets the calibration and verification requirements for the force-measuring system used in the test machine.

What does the kSIST FprEN 17151-2:2026 document contain?

kSIST FprEN 17151-2:2026 contains three key figures and three calculation formulas that support the test method. Figure 1 identifies the preferred test direction, Figure 2 shows strain versus log time with extrapolation, and Figure 3 shows the isochronous strain-versus-stress plot.

The document also includes formulas for strain, stress and creep factor, plus the normative regression method in Annex A. Annex A gives the least-squares line fit with time as the independent variable, including the data-suitability check and the equations used to calculate the fit parameters.

The report clause turns the test into a documented result package for design, testing and assessment. It captures the sample identity, test conditions, stress levels, plots, extrapolated values and any test events that could have influenced the outcome.

SLOVENSKI STANDARD
oSIST prEN 17151-2:2026
01-marec-2026
Cevni sistemi iz polimernih materialov, ki delujejo po težnostnem principu in so
položeni v zemljo, za transport in shranjevanje površinske vode - 2. del:
Preskusna metoda za ugotavljanje leznih lastnosti zabojev
Plastics piping systems for non-pressure underground conveyance and storage of
surface water - Part 2: Test method for determination of creep behaviour of boxes
Kunststoff-Rohrleitungssysteme für die drucklose unterirdische Entwässerung für Nicht-
Trinkwasser - Teil 2: Prüfverfahren zur Bestimmung des Kriechverhaltens von
Versickerungsblöcken
Systèmes de canalisations en plastique pour le transport et le stockage souterrains sans
pression des eaux de surface - Partie 2 : Méthode d’essai pour la détermination du
comportement au fluage des structures alvéolaires ultra-légères
Ta slovenski standard je istoveten z: prEN 17151-2
ICS:
23.040.03 Cevovodi za zunanje sisteme Pipeline and its parts for
transporta vode in njihovi deli external water conveyance
systems
oSIST prEN 17151-2:2026 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 17151-2:2026
oSIST prEN 17151-2:2026
DRAFT
EUROPEAN STANDARD
prEN 17151-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2025
ICS 23.040.01
English Version
Plastics piping systems for non-pressure underground
conveyance and storage of surface water - Part 2: Test
method for determination of creep behaviour of boxes
Systèmes de canalisations en plastique pour le Kunststoff-Rohrleitungssysteme für die drucklose
transport et le stockage souterrains sans pression des unterirdische Entwässerung für Nicht-Trinkwasser -
eaux de surface - Partie 2 : Méthode d'essai pour la Teil 2: Prüfverfahren zur Bestimmung des
détermination du comportement au fluage des Kriechverhaltens von Versickerungsblöcken
structures alvéolaires ultra-légères
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 155.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 17151-2:2025 E
worldwide for CEN national Members.

oSIST prEN 17151-2:2026
prEN 17151-2:2025 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Symbols and units . 5
5 Apparatus . 6
5.1 Compression testing apparatus . 6
5.2 Measuring devices . 6
6 Test sample . 7
6.1 General. 7
6.2 Number . 7
6.3 Age and conditioning . 7
7 Test procedure . 8
7.1 Loads . 8
7.2 Test temperature . 8
7.3 Test procedure . 8
7.4 Test duration . 8
8 Analysis . 8
8.1 Plot strain vs time . 8
8.2 Creep factor . 10
8.2.1 Creep factor at test stress . 10
8.2.2 Strain at specific stress . 10
9 Test report . 10
Annex A (normative) Regression analysis with time as the independent variable . 12
A.1 Principle . 12
A.2 Regression with time as the independent variable . 12
A.2.1 General. 12
A.2.2 Suitability of data . 13
A.2.3 Functional relationships . 13
Bibliography . 14

oSIST prEN 17151-2:2026
prEN 17151-2:2025 (E)
European foreword
This document (prEN 17151-2:2025) has been prepared by Technical Committee CEN/TC 155 “Plastics
piping systems and ducting systems”, the secretariat of which is held by NEN.
This document is currently submitted to the CEN Enquiry.
prEN 17151 consists of the following parts under the general title Plastics piping systems for non-pressure
underground conveyance and storage of surface water:
— Part 1: Test method for determination of long-term compression strength of boxes
— Part 2: Test method for determination of creep behaviour of boxes (this document)

oSIST prEN 17151-2:2026
prEN 17151-2:2025 (E)
Introduction
The test described in this document determines the extent to which thermoplastic units will deform
permanently under the influence of constant compressive stress. Creep occurs as a function of time through
extended exposure to levels of stress that are below the yield strength of the material.
Creep tests are performed in compression at different load levels and the deflection over time is measured.
The load levels are selected to ensure that failure does not occur within the time frame of the test.
The creep tests are carried out by testing a series of samples placed between two stiff plates with different
constant compression loads applied. Deflection is recorded against time. The linear portion of the creep
strain plot can be extrapolated to predict the strain at a given time longer than the test period, normally
dictated by the application design. From these extrapolated curves a creep factor can be obtained.

oSIST prEN 17151-2:2026
prEN 17151-2:2025 (E)
1 Scope
This document specifies a test method for determining the compressive creep behaviour of boxes made of
thermoplastic materials intended for use in a modular system for non-pressure underground conveyance
and storage of surface water.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN 17150, Plastics piping systems for non-pressure underground conveyance and storage of non-potable
water — Test method for determination of short-term compression strength of boxes
prEN 17151-1, Plastics piping systems for non-pressure underground conveyance and storage of surface
water — Part 1: Test method for determination of long-term compression strength of boxes
EN ISO 7500-1:2018, Metallic materials — Calibration and verification of static uniaxial testing machines —
Part 1: Tension/compression testing machines — Calibration and verification of the force-measuring system
(ISO 7500-1:2018)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply in addition to the terms and
definitions in prEN 17151-1.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
creep
increase in strain with time when a constant force is applied
[SOURCE: EN ISO 899-1:2017] [1]
3.2
creep factor
strain ratio for a given applied stress and time
4 Symbols and units
For the purposes of this document, the following symbols and units apply.
b initial width of box mm
i
d deflection at time t mm
e e
F force applied kN
h initial height of box mm
i
h height of box after pre-load mm
l initial length of box mm
i
oSIST prEN 17151-2:2026
prEN 17151-2:2025 (E)
t time to which test results are extrapolated h
e
γ creep factor for stress level i at extrapolated time -
te,i
ε extrapolated strain at t %
e e
ε strain at extrapolated time for stress level i %
te,i
ε strain at 3 min (0,05 h) for stress level i %
t0,05,i
σ compressive s
...