FprEN ISO 11295

SLOVENSKI STANDARD
oSIST prEN ISO 11295:2025
01-maj-2025
Cevni sistemi iz polimernih materialov za obnovo cevovodov - Razvrstitev in
pregled strateških, taktičnih in operativnih dejavnosti (ISO/DIS 11295:2025)
Plastics piping systems used for the rehabilitation of pipelines - Classification and
overview of strategic, tactical and operational activities (ISO/DIS 11295:2025)
Rohrleitungssysteme aus Kunststoff für die Sanierung von Rohrleitungen -
Klassifizierung und Überblick über strategische, taktische und operative Aktivitäten
(ISO/DIS 11295:2025)
Systèmes de canalisation en plastique destinés à la réhabilitation des réseaux enterrés -
Classification et vue d’ensemble des activités stratégiques, tactiques et opérationnelles
(ISO/DIS 11295:2025)
Ta slovenski standard je istoveten z: prEN ISO 11295
ICS:
23.040.01 Deli cevovodov in cevovodi Pipeline components and
na splošno pipelines in general
oSIST prEN ISO 11295:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN ISO 11295:2025
oSIST prEN ISO 11295:2025
DRAFT
International
Standard
ISO/DIS 11295
ISO/TC 138/SC 8
Plastics piping systems used for
Secretariat: JISC
the rehabilitation of pipelines —
Voting begins on:
Classification and overview of
2025-03-06
strategic, tactical and operational
Voting terminates on:
activities
2025-05-29
Systèmes de canalisation en plastique destinés à la réhabilitation
des réseaux enterrés — Classification et vue d’ensemble des
activités stratégiques, tactiques et opérationnelles
ICS: 23.040.20
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Reference number
ISO/DIS 11295:2025(en)
oSIST prEN ISO 11295:2025
DRAFT
ISO/DIS 11295:2025(en)
International
Standard
ISO/DIS 11295
ISO/TC 138/SC 8
Plastics piping systems used for
Secretariat: JISC
the rehabilitation of pipelines —
Voting begins on:
Classification and overview of
strategic, tactical and operational
Voting terminates on:
activities
Systèmes de canalisation en plastique destinés à la réhabilitation
des réseaux enterrés — Classification et vue d’ensemble des
activités stratégiques, tactiques et opérationnelles
ICS: 23.040.20
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
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Published in Switzerland Reference number
ISO/DIS 11295:2025(en)
ii
oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms .2
3.2 Terms related to techniques .3
3.3 Terms related to services conditions .5
4 Abbreviated terms . 5
5 Pipeline rehabilitation process . 6
6 Investigation and condition assessment of the existing pipeline . 7
6.1 Performance criteria .7
6.1.1 General .7
6.1.2 Hydraulic requirements .8
6.1.3 Structural requirements .8
6.1.4 Environmental requirement .8
6.1.5 Operational requirements .9
6.2 Investigation of performance .9
6.2.1 General .9
6.2.2 Hydraulic investigation .10
6.2.3 Structural investigation . .10
6.2.4 Environmental investigation . .11
6.2.5 Operational investigation .11
6.3 Condition assessment .11
6.4 Risk analysis . 12
6.5 Control measures . 12
7 Classification and characteristics of rehabilitation techniques .13
7.1 Overview . 13
7.2 Classification of renovation techniques . 15
7.2.1 General . 15
7.2.2 Lining with continuous pipes . 15
7.2.3 Lining with close-fit pipes .17
7.2.4 Lining with cured-in-place pipes . 20
7.2.5 Lining with discrete pipes .24
7.2.6 Lining with adhesive-backed hoses. 28
7.2.7 Lining with spirally-wound pipes . 29
7.2.8 Lining with pipe segments .32
7.2.9 Lining with a rigidly anchored plastics inner layer . 33
7.2.10 Lining with sprayed polymeric materials . . 35
7.2.11 Lining with inserted hoses .37
7.3 Classification of trenchless replacement techniques . 38
7.3.1 General . 38
7.3.2 Pipe bursting. 39
7.3.3 Pipe removal .41
7.3.4 Horizontal directional drilling (HDD) . 44
7.3.5 Impact moling .47
7.3.6 Pipe jacking . 49
8 Selection of rehabilitation techniques .52
8.1 General .52
8.2 Pipeline system layout .52
8.3 Hydraulic performance . 53
8.4 Structural performance . 54

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8.4.1 General . 54
8.4.2 Non-pressure pipes . 54
8.4.3 Pressure pipes . 55
8.5 Environmental impact . 58
8.6 Construction constraints .59
8.7 Project specification .59
9 Implementation of rehabilitation techniques .60
9.1 Preconstruction activities . . 60
9.2 Assessment of conformity of products .61
9.3 Inspection, storage and handling of the materials on site .61
9.4 Application of rehabilitation technique .61
9.4.1 Preparatory work .61
9.4.2 Construction.62
9.5 Acceptance control .62
9.5.1 General .62
9.5.2 Inspection .62
9.5.3 Leak tightness testing .62
9.5.4 Sampling . 64
9.6 Completion of the work . 64
9.6.1 Finishing off the rehabilitation work . 64
9.6.2 Lateral reinstatement . 64
9.7 Documentation of the process . 64
Bibliography .65

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oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent
rights identified during the development of the document will be in the Introduction and/or on the ISO list of
patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by ISO/TC 138 Plastics pipes, fittings and valves for the transport of fluids,
Subcommittee SC 8, Rehabilitation of pipeline systems, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 155, Plastics piping systems and ducting systems, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 11295:2022), which has been amended
following the merging and renumbering of the system standards, referred to in this standard. There are no
technical changes compared to the third edition, apart from modifications of two existing definitions (3.1.12
and 3.2.2) and the addition of two new definitions (3.1.9, 3.1.10)
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

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oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
Introduction
Pipeline systems are continuously required to satisfy physical, chemical, biochemical and biological
demands. These demands depend on planning, material, construction, type and period of use.
When pipeline systems become operational, they constitute a valuable asset to the network owner, requiring
adequate management, including monitoring the performance of the pipeline system. For general guidelines
and requirements on asset management, ISO 55000, ISO 55001 and ISO 55002 are applicable.
For the specific case of pipelines for water supply and wastewater collection, detailed information on the
overall management of the networks is provided by ISO 24516-1 and ISO 24516-3.
In the case of loss of performance of a pipeline system, reactive measures initially focus on improving
regular maintenance procedures, including cleaning. In case of deterioration or other serious defects, more
stringent measures to rehabilitate the pipeline become necessary.
Rehabilitation is carried out when there is a need to restore or upgrade the performance of a pipeline system.
Rehabilitation can consist of repair, renovation or replacement. In recent years, the rehabilitation of pipeline
systems has become increasingly important and will continue to be so.
This document provides information on the design process when considering rehabilitation of an existing
pipeline, in order of sequence:
a) investigation and assessment of the deficiencies of current performance of the existing pipeline;
b) determination of viable options, based on performance criteria and process-related factors;
c) specification of the selected type of technique and the required pipe material;
d) the installation;
e) testing the performance.
The techniques used for the renovation and trenchless replacement of existing pipelines are classified in
technique families and the typical characteristics of each are described in general terms.

vi
oSIST prEN ISO 11295:2025
DRAFT International Standard ISO/DIS 11295:2025(en)
Plastics piping systems used for the rehabilitation of
pipelines — Classification and overview of strategic, tactical
and operational activities
1 Scope
This document specifies the steps of the overall process of pipeline rehabilitation, comprising:
— information on strategic and tactical activities:
a) investigation and condition assessment of the existing pipeline;
b) pipeline rehabilitation planning.
— information on and requirements for operational activities:
c) project specification;
d) applications of techniques;
e) documentation of the design and application process.
Definitions and classification of families of renovation and trenchless replacement techniques are provided,
and their respective features described. Areas of application covered include underground drains and
sewers and underground water and gas supply networks.
The following aspects are not covered by the scope of this document:
— new construction provided as network extensions;
— calculation methods to determine, for each viable technique, the characteristics of lining or replacement
pipe material needed to secure the desired performance of the rehabilitated pipeline;
— techniques providing non-structural pressure pipe liners;
— techniques for local repair.
It is the responsibility of the designer to choose and design the renovation or trenchless replacement
pipeline system.
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.
ISO 1043-1, Plastics — Symbols and abbreviated terms — Part 1: Basic polymers and their special characteristics
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1043-1 and the following apply.
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

oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 General terms
3.1.1
assessment
process, or result of this process, comparing a specified subject matter to relevant references
3.1.2
design working life
assumed period for which a structure or part of it is to be used for its intended purpose with anticipated
repair (3.1.9) and maintenance (3.1.13) but without renovation (3.1.8) or replacement (3.1.10) being necessary
3.1.3
hazard
condition of water, or biological, chemical, physical or radiological agent with the potential to cause harm to
public health
Note 1 to entry: Condition includes quantity.
[SOURCE: EN 15975-1:2011+A1:2015, 2.6; modified]
3.1.4
pipeline system
interconnecting pipe network for the conveyance of fluids
[SOURCE: ISO/DIS 11300-1:2025, 3.1.1]
3.1.5
drain
conduit which conveys wastewater, surface water or other unwanted liquids, including its connections to
lateral pipes, manholes, gullies and other network components
[SOURCE: ISO 6707-1:2020, 3.3.4.38, modified to include connections as stated]
3.1.6
sewer
pipeline which conveys unwanted liquids, including its connections to lateral pipes, manholes, access
chambers and other network components
[SOURCE: ISO 6707-1:2020, 3.3.4.41, modified to include connections as stated]
3.1.7
rehabilitation
measures for restoring or upgrading the performance of existing pipeline systems (3.1.4), including renovation
(3.1.8), repair (3.1.9) and replacement (3.1.10)
3.1.8
renovation
work incorporating all or part of the original fabric of the pipeline, by means of which its current performance
is improved
3.1.9
repair
rectification of local damage
3.1.10
replacement
construction of a new pipeline, on or off the line of an existing pipeline, where the function of the new pipeline
system (3.1.4) incorporates that of the old

oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
3.1.11
network extension
new construction off the line of a pipeline or a network with the aim to expand the total capacity of the network
3.1.12
trenchless replacement
replacement (3.1.10) without opening trenches other than small excavations to provide access for the
particular technique and for service and lateral connections
3.1.13
maintenance
routine work undertaken to ensure the continuing performance of a pipeline system (3.1.4)
3.1.14
independent pressure pipe liner
liner (3.2.3) capable on its own of resisting without failure all applicable internal loads throughout its design life
3.1.15
interactive pressure pipe liner
liner (3.2.3) which relies on the existing pipeline for radial support in order to resist without failure all
applicable internal loads throughout its design life
3.1.16
fully structural renovation
use of an independent pressure pipe liner (3.1.14) which is capable of resisting all external loads irrespective
of the condition of the existing pipeline
3.1.17
semi-structural renovation
use of an interactive pressure pipe liner (3.1.15) which is capable of long-term hole and gap spanning at
operational pressure
3.1.18
non-structural renovation
use of an interactive pressure pipe liner (3.1.15) which is not capable of long-term hole and gap spanning at
operational pressure
3.1.19
flow diversion
temporary isolation of the section of pipeline to be rehabilitated by the use of a temporary bypass or other means
3.2 Terms related to techniques
3.2.1
technique family
grouping of renovation (3.1.8) or trenchless replacement (3.1.12) techniques which are considered to have
common characteristics for standardization purposes
3.2.2
lining pipe
pipe inserted for renovation (3.1.8) purposes prior to any site processing
3.2.3
liner
lining pipe (3.2.2) after installation
3.2.4
lining system
lining pipe (3.2.2) and all relevant fittings inserted into an existing pipeline for the purposes of renovation (3.1.8)

oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
3.2.5
lining with continuous pipes
lining with pipe made continuous prior to insertion, where the diameter of the lining pipe (3.2.2) remains
unchanged
3.2.6
lining with close-fit pipes
lining with a continuous pipe for which the cross-section is reduced to facilitate installation and reverted
after installation to provide a close fit to the existing pipe
3.2.7
lining with cured-in-place pipes
lining with a flexible tube impregnated with a thermosetting resin, which produces a pipe after resin cure
3.2.8
lining with discrete pipes
lining with short lengths of pipe which are jointed to form a continuous pipe one by one during insertion
3.2.9
lining with adhesive-backed hoses
lining with a reinforced hose which relies on an adhesive bond to the host pipe to provide resistance to
collapse
3.2.10
lining with spirally-wound pipes
lining with a profiled strip, spirally wound to form a continuous pipe after installation
3.2.11
lining with sprayed polymeric materials
lining with a sprayed two-part polymeric resin material that forms a continuous pipe after resin cure
3.2.12
lining with inserted hoses
lining with a reinforced hose which is either permanently shaped or re-rounded after installation by the
application of an internal pressure
3.2.13
lining with a rigidly anchored plastics inner layer
lining with a single rigid annulus of structural cementitious grout formed between a plastics layer and the
host pipe, where the plastics layer is permanently anchored in the grout
3.2.14
lining with pipe segments
lining with prefabricated segments bonded to the existing pipe, which either have longitudinal joints and
cover the whole of the pipe circumference, or cover only part of the circumference
3.2.15
pipe bursting
on-the-line replacement (3.1.10) method in which an existing pipe is broken by longitudinal splitting or
brittle fracture, using a mechanically applied force from within, where the pipe fragments are forced into
the surrounding ground and a new pipe of the same, smaller or larger diameter, is simultaneously pulled in
3.2.16
pipe removal
on-the-line replacement (3.1.10) method, in which the existing pipe is removed by pipe eating (3.2.17) or pipe
extraction (3.2.18) and a new pipe is installed
3.2.17
pipe eating
type of pipe removal (3.2.16), where the existing pipe is progressively broken up and removed along with an
annulus of the ground immediately surrounding the existing pipe

oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
3.2.18
pipe extraction
type of pipe removal (3.2.16), where the existing pipe is extracted by pulling or pushing and replaced with a
new one, either simultaneously or as a separate step
3.2.19
horizontal directional drilling
off-the-line trenchless replacement (3.1.12) method in which a pilot bore is drilled using a steerable drilling
head connected to flexible rods and then the bore is enlarged by reamers up to the diameter required for the
pipe or pipes subsequently pulled/pushed into place
3.2.20
impact moling
off-the-line trenchless replacement (3.1.12) method in which pipes are pulled in behind a pneumatic powered
soil displacement hammer
3.2.21
pipe jacking
off-the-line trenchless replacement (3.1.12) method in which pipes are pushed through the ground, and the
soil inside removed either manually, mechanically or using a slurry system
3.2.22
auger boring
type of pipe jacking (3.2.21), where the bore is excavated by a rotating cutting head attached to an auger
which continuously removes the spoil, and the pipeline is pushed independently from the auger
3.2.23
microtunnelling
type of pipe jacking (3.2.21) where pipes are pushed behind a steerable, small scale tunnelling machine,
remotely controlled from the surface
3.2.24
grout system
cement-based grout including any fillers, reinforcement or other additives or admixtures, in specified
proportions
3.3 Terms related to services conditions
3.3.1
internal pressure resistance
ability to withstand internal fluid pressurization
3.3.2
allowable operating pressure
PFA
maximum hydrostatic pressure that a component is capable of withstanding continuously in service.
1)
Note 1 to entry: It is expressed in bars .
4 Abbreviated terms
For the purposes of this document, the abbreviated terms given in ISO 1043-1 and the following apply.
2 5 2
1) 1 bar =0,1 MPa = 0,1 N/mm = 10 N/m .

oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
CCTV closed circuit television
DN nominal diameter
HDD horizontal directional drilling
EP epoxy resin
GRP glass-reinforced thermosetting plastics
PA-U unplasticized polyamide
PE polyethylene
PFA allowable operating pressure
PP polypropylene
PRC polyester resin concrete
PUR polyurethane
PVC-U unplasticized poly(vinyl chloride)
RFC resin fibre composite
UP unsaturated polyester resin
VE vinyl ester resin
5 Pipeline rehabilitation process
The overall process of pipeline rehabilitation involves several sequential steps, for which this document
provides information and requirements as follows:
1) investigation of functional performance of the existing pipeline


2) condition assessment of performance against set requirements
Clause 6


3) measures to control risks / pipeline rehabilitation

4) pre-selection of suitable types of rehabilitation techniques } Clause 7
5) project specification

Clause 8

6) selection of technique / installer

7) application of rehabilitation technique

Clause 9

8) acceptance control

9) documentation of the rehabilitation process } 9.7
A substantial part of this document (Clause 7) is dedicated to the classification of families of techniques for
pipeline rehabilitation, covering both renovation and trenchless replacement. Key features, including typical
product characteristics, areas of application and process related factors are described for each technique family.
NOTE Guidance on the whole process of integrated management of drains and sewers is presented in EN 752.

oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
6 Investigation and condition assessment of the existing pipeline
6.1 Performance criteria
6.1.1 General
For every pipeline system certain objectives apply, depending on their intended functionality.
These are the basis for the performance requirements of a pipeline system. The pipeline system objectives
that impact on the performance requirements of the individual pipeline, shall be identified.
For drinking water distribution networks and wastewater collection networks, detailed guidance and
requirements are provided by ISO 24516-1 and ISO 24516-3 respectively. The items detailed below
specifically relate to the rehabilitation process of the pipeline systems in these networks, as well as in gas
supply networks.
Pipeline system objectives include at least the following:
— health and safety;
— environmental protection;
— sustainable operation.
Health and safety encompasses (depending on the function of the pipeline):
— provision of access to safe and good-quality drinking water;
— preventing spread of disease by safe disposal of wastewater;
— meeting user’s needs and expectations;
— minimizing occupational health and safety risks;
— maintaining pipeline system integrity.
Environmental protection includes:
— preventing pollution and minimizing generation of pollutants;
— minimizing energy consumption;
— avoiding nuisance in construction, operation and maintenance.
Sustainable operation includes:
— providing service over many years: economic, social, environmental;
— monitoring the quality of water (sampling, surveillance, maintenance);
— minimizing mains failures and leakages.
The objectives shall be transformed to performance requirements and the resulting design criteria that
ensure functionality of the pipeline system, such as: structural integrity, design working life, leak tightness,
prevention of pollution, sustainability and maintenance of flow.
Objectives can be split into the following categories:
— hydraulic requirements;
— structural requirements;
— environmental requirements;
oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
— operational requirements.
NOTE 1 In ISO 24512 ‘performance requirements’ are recommended to be clearly specified in objective, verifiable
‘Performance Indicators (PIs)’, allowing for a clear comparison with the targeted objectives.
NOTE 2 In EN 752, ‘performance requirements’ are for the status quo. When any predicted changes in time are
taken into account, they become ‘design criteria’.
6.1.2 Hydraulic requirements
The following hydraulic requirements shall be considered:
a) sufficient capacity, allowing for foreseeable increases in flow over the design working life of the
pipeline system;
b) ensuring operation of the pipeline system to be safe and economically efficient;
c) leak tightness in accordance with national or local testing requirements;
d) in the case of water supply pipelines, national or local regulations can additionally require:
— safeguarding of water quality;
— sufficient pressure, flow rate and continuity of supply;
— prevention of back flow (via valves and wash outs);
— minimization of stagnation to avoid possible deterioration of water quality;
— requirements for firefighting (hydrants) to follow requirements of national legislation;
— prevention of contamination at pumping stations.
e) in the case of non-pressure drains and sewers,
— national or local regulations or the relevant authority can specify requirements for limitation of
surcharge or flooding.
6.1.3 Structural requirements
The following shall apply:
a) structural integrity over the design working life of the pipeline system;
The pipeline system shall be able to withstand the loads without defects which can:
— lead to risk of loss of structural integrity;
— impair the function of the pipeline system.
6.1.4 Environmental requirement
The following shall apply:
a) protection of groundwater;
b) sustainable use of products and potential re-use through recycling;
c) minimization of the use of energy over the design working life of the pipeline system;
d) prevention of odours and toxic, explosive and corrosive gases.

oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
6.1.5 Operational requirements
The following shall apply:
a) trouble-free operation of the pipeline system, without interruptions of service;
b) minimization of the risk of failures: collapses (non-pressure pipelines) or bursts (pressure pipelines);
c) maintenance to be carried out safely and without risks to the health of personnel;
d) adequate access and working space;
e) prevention of noise and vibration;
f) not endangering adjacent structures and utility services.
6.2 Investigation of performance
6.2.1 General
Prior to the actual investigation, the following basic information about the existing pipeline shall be
collected:
a) location;
b) pipe material;
c) actual internal diameter or other non-circular section dimensions;
d) wall thickness (especially in the case of pressure pipelines where interactive lining is considered);
e) fluid transported;
f) accessibility and section lengths between access points;
g) frequency and location of any lateral connections, branches and/or valves;
h) depth of cover;
i) height of ground water table (both mean long-term and peak short-term);
j) flow quantity;
k) failure and repair records;
l) historical operating pressure regimes;
m) traffic or other surface loads;
n) proximity of adjacent buried services and structures.
NOTE 1 Some of this information can be ascertained from records and plans.
If available, the following additional information shall be acquired additionally:
— year of installation;
— pipe class (e.g. crushing strength, stiffness or pressure class);
— joint type;
— bedding and backfill of the original construction.
Methods for determining the condition of the existing pipeline affecting functional performance differ in some
respects for non-pressure and pressure applications and as a function of material, section size and shape.

oSIST prEN ISO 11295:2025
ISO/DIS 11295:2025(en)
In the case of non-pressure pipelines, the initial investigation shall be carried out by visual inspection in
the form of a CCTV survey and/or profiling equipment and/or by person-entry, and should be recorded
systematically such that the exact location of each feature, condition and defect is known and an assessment
of its severity can be made.
In the case of pressure pipelines, the initial investigation shall be carried out by non-flow-interrupting
techniques, such as via sonar/acoustic sensors, tracer gas leak detection and ground penetrating radar
measurements, in a second step possibly to be followed by a CCTV survey and testing on leak tightness (see
also 9.5.3.2).
In both cases, further investigation shall be carried out by checking exposed pipe sections and/or by
extraction and evaluation of pipe samples.
Where a substantial pipeline network shall be investigated, priorities shall be assigned, using the already
available information. Those pipelines likely to have the most serious problems, or those where the cost of
investigation is best justified, shall be investigated first.
Prior to inspection, in particular in the case of non-pressure drains and sewers, the pipelines should be
cleaned thoroughly (removing sediments, etc.).
NO
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