ASTM F1947-21a

Standard Practice for Installation of Folded Poly(Vinyl Chloride) (PVC) Pipe into Existing Sewers and Conduits

SIGNIFICANCE AND USE
4.1 This practice is for use by designers and specifiers, regulatory agencies, owners, and inspection organizations who are involved in the rehabilitation of non-pressure sewers and conduits.
SCOPE
1.1 This practice describes the procedures for the rehabilitation of sewer lines and conduits with nominal diameters between 4 in. and 30 in. (100 mm and 750 mm) by the insertion of folded PVC pipe, which is heated, pressurized, and expanded against the interior surface of the existing pipe with either a mechanical rounding device or steam pressure. The finished formed PVC pipe will be continuous and conform to the existing pipe. This rehabilitation process can be used in a variety of non–pressure applications, such as: sanitary sewers, storm sewers, and process piping.  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Jul-2021
• ICS: 23.040.20 - Plastics pipes
• ICS: 83.080.20 - Thermoplastic materials
• Technical Committee: F17 - Plastic Piping Systems
• Drafting Committee: F17.67 - Trenchless Plastic Pipeline Technology

Relations

• Refers: ASTM F412-20 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Apr-2020
• Refers: ASTM F1417-11a(2019) - Standard Practice for Installation Acceptance of Plastic Non-pressure Sewer Lines Using Low-Pressure Air
• Effective Date: 01-Aug-2019
• Refers: ASTM F1417-11A(2019)e1 - Standard Practice for Installation Acceptance of Plastic Non-pressure Sewer Lines Using Low-Pressure Air
• Effective Date: 01-Aug-2019
• Refers: ASTM F412-19 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Jan-2019
• Refers: ASTM D1600-18 - Standard Terminology for Abbreviated Terms Relating to Plastics (Withdrawn 2024)
• Effective Date: 01-Jan-2018
• Refers: ASTM F412-17a - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Aug-2017
• Refers: ASTM D790-17 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 01-Jul-2017
• Refers: ASTM F412-17 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Feb-2017
• Refers: ASTM F412-16a - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 15-Nov-2016
• Refers: ASTM F412-16 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Aug-2016
• Refers: ASTM D790-15e1 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 01-Dec-2015
• Refers: ASTM D790-15 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 01-Dec-2015
• Refers: ASTM F1417-11a(2015) - Standard Practice for Installation Acceptance of Plastic Non-pressure Sewer Lines Using Low-Pressure Air
• Effective Date: 01-Aug-2015
• Refers: ASTM F412-15 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Jun-2015
• Refers: ASTM D2122-15 - Standard Test Method for Determining Dimensions of Thermoplastic Pipe and Fittings
• Effective Date: 15-Mar-2015

Overview

ASTM F1947-21a is the internationally recognized standard practice for the installation of folded Poly(Vinyl Chloride) (PVC) pipe into existing sewers and conduits. Developed by ASTM International, this practice provides detailed procedures for rehabilitating gravity-flow, non-pressure pipelines-such as sanitary and storm sewers-with nominal diameters ranging from 100 mm (4 in.) to 750 mm (30 in.). Utilizing a trenchless technology approach, this method allows for the renewal of aging, deteriorated, or structurally compromised pipelines by inserting a folded PVC pipe, which is then expanded and formed to fit the host conduit.

This standard is a critical resource for designers, specifiers, regulatory agencies, owners, and inspection organizations engaged in sewer and pipeline rehabilitation. It supports efficient asset management, extends service life, and minimizes environmental disruption during installation.

Key Topics

• Scope of Application: Focused on non-pressurized pipelines, including sanitary sewers, storm sewers, and industrial process lines.
• Installation Procedures: Outlines the sequential steps for cleaning, inspection, insertion, expansion, and final connection in pipeline rehabilitation using folded PVC pipe technologies.
• Material Requirements: Specifies the use of folded PVC pipe conforming to ASTM F1504 requirements and, where applicable, the use of elastomeric containment tubes.
• Preparation & Inspection: Details procedures for pipeline cleaning, internal inspection (often via closed-circuit television), and obstruction removal to ensure proper installation.
• Expansion Process: Describes the use of heat, pressure, and optional mechanical rounding devices to expand and form the PVC liner against the host pipe wall.
• Leakage and Quality Control Testing: Covers practices for post-installation testing, including water exfiltration and low-pressure air testing as per ASTM F1417, and the preparation of rounded field samples for dimensional and flexural property checks.
• Safety and Compliance: Emphasizes user responsibility for safety, regulatory, and environmental compliance during all stages of the installation process.

Applications

This standard serves as a critical technical reference for:

• Sewer Rehabilitation: Restoring service life in deteriorated gravity sewers, reducing infiltration and inflow, and mitigating structural deficiencies without open-cut excavation.
• Storm Sewer Renewal: Providing a cost-effective solution for renewing aging stormwater infrastructure in municipal or industrial settings.
• Industrial Piping: Suitable for non-pressure process piping systems experiencing deformation, cracks, or corrosion.
• Trenchless Technology Projects: Supporting no-dig restoration techniques that help avoid major surface disruptions, thus reducing project timelines and minimizing community impact.
• Asset Management: Enhancing infrastructure resilience and sustainability by extending the operational lifespan of critical subsurface pipelines.

Related Standards

For comprehensive project specification and compliance, users should also consult these related standards:

• ASTM F1504: Specification for Folded Poly(Vinyl Chloride) (PVC) Pipe for Existing Sewer and Conduit Rehabilitation
• ASTM F1417: Practice for Installation Acceptance of Plastic Non-pressure Sewer Lines Using Low-Pressure Air
• ASTM D1784: Classification System and Basis for Specification for Rigid Poly(Vinyl Chloride) (PVC) Compounds
• ASTM D2122: Test Method for Determining Dimensions of Thermoplastic Pipe and Fittings
• ASTM D790: Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics
• ASTM F1216: Practice for Rehabilitation of Existing Pipelines and Conduits by the Inversion and Curing of a Resin-Impregnated Tube
• NASSCO Recommended Specifications: For Sewer Collection System Rehabilitation
• Uni-Bell UNI-B-5-89: For modulus of soil reaction and standardized terminology

ASTM F1947-21a ensures reliable, safe, and effective folded PVC pipe installation for sewer and conduit rehabilitation projects, supporting modern infrastructure renewal with established best practices.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F1947 −21a
Standard Practice for
Installation of Folded Poly(Vinyl Chloride) (PVC) Pipe into
Existing Sewers and Conduits
This standard is issued under the fixed designation F1947; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* D1600 Terminology forAbbreviatedTerms Relating to Plas-
tics
1.1 This practice describes the procedures for the rehabili-
D2122 Test Method for Determining Dimensions of Ther-
tation of sewer lines and conduits with nominal diameters
moplastic Pipe and Fittings
between4 in.and30in.(100 mmand750mm)bytheinsertion
F412 Terminology Relating to Plastic Piping Systems
of folded PVC pipe, which is heated, pressurized, and ex-
F1417 Practice for Installation Acceptance of Plastic Non-
panded against the interior surface of the existing pipe with
pressure Sewer Lines Using Low-Pressure Air
either a mechanical rounding device or steam pressure. The
F1216 Practice for Rehabilitation of Existing Pipelines and
finished formed PVC pipe will be continuous and conform to
Conduits by the Inversion and Curing of a Resin-
the existing pipe. This rehabilitation process can be used in a
Impregnated Tube
variety of non–pressure applications, such as: sanitary sewers,
F1504 Specification for Folded Poly(Vinyl Chloride) (PVC)
storm sewers, and process piping.
Pipe for Existing Sewer and Conduit Rehabilitation
1.2 The values stated in inch-pound units are to be regarded
2.2 NASSCO Standard:
as standard. The values given in parentheses are mathematical
Recommended Specifications for Sewer Collection System
conversions to SI units that are provided for information only
Rehabilitation
and are not considered standard.
2.3 Uni-Bell Standard:
1.3 This standard does not purport to address all of the
UNI-B-5-89
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3. Terminology
priate safety, health, and environmental practices and deter-
3.1 Definitions—Terminology used in this practice is in
mine the applicability of regulatory limitations prior to use.
conformancewithTerminologyF412andabbreviationsusedin
1.4 This international standard was developed in accor-
this practice are in accordance with Terminology D1600,
dance with internationally recognized principles on standard-
unless otherwise indicated.
ization established in the Decision on Principles for the
3.2 Definitions of Terms Specific to This Standard:
Development of International Standards, Guides and Recom-
3.2.1 containment tube, n—an optional elastomeric material
mendations issued by the World Trade Organization Technical
placed between the folded pipe and the existing pipe to protect
Barriers to Trade (TBT) Committee.
the folded pipe during insertion, for containment of steam
during the installation process, and to provide a waterproof
2. Referenced Documents
barrieragainstinfiltration,inflow,andstandingwater.Thistube
2.1 ASTM Standards:
remains within the pipe but provides no structural support.
D790 Test Methods for Flexural Properties of Unreinforced
3.2.2 dimples (dimpling), n—where a side connection meets
and Reinforced Plastics and Electrical Insulating Materi-
the existing pipe, there is not existing pipe support for the
als
folded PVC pipe during expansion causing a point of thermo-
plastic pipe expansion slightly beyond the existing pipe wall.
This formation of an external departure from the formed pipe
This practice is under the jurisdiction of ASTM Committee F17 on Plastic
wall is termed dimpling.
Piping Systems and is the direct responsibility of Subcommittee F17.67 on
Trenchless Plastic Pipeline Technology. 3.2.3 folded pipe, n—pipe that has been manufactured in a
Current edition approved Aug. 1, 2021. Published August 2021 Last previous
folded shape or that is subsequently folded for use in existing
edition approved in 2021 as F1947 – 21. DOI: 10.1520/F1947-21A.
sewer and conduit rehabilitation (see Fig. 1).
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 11521 Cronridge Drive, Suite J Owings Mills, MD 21117. www.nassco.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1947 − 21a
NOTE 1—This figure is intended only for clarification of terms specific to this practice and shows a representative folded and formed pipe shapes. Other
folded pipe shapes can meet the requirements of this practice.
FIG. 1 Folded Pipe and Formed Pipe, Clarification of Terms
3.2.4 formed pipe, n—foldedpipethathasbeeninsertedinto 5.2 The folded pipe shall be spooled in a continuous length
an existing sewer or conduit and expanded with heat, pressure,
for storage and shipping to the job site. Handling and storing
and, if applicable, a rounding device to conform to and take the shall be in accordance with the manufacturer’s published
shape of the existing pipe (see Fig. 1).
recommendations.
3.2.5 insertion point, n—an existing manhole, existing ac-
5.3 The optional containment tube should be an elastomeric
cess shaft, or an excavated pit that serves as the point of
material capable of containing the steam required to process
entrance for the folded pipe into the existing pipe.
the folded pipe and serve as a protective waterproofing barrier.
3.2.6 rounded pipe sample, n—a folded pipe that has been
The containment tube shall be compatible with the PVC
inserted into a pipe mold and expanded with heat and pressure
compound, the folded pipe installation process, and the exist-
to conform to the mold, intended for testing purposes.
ing pipe so as not to effect the properties of the finished pipe.
3.2.7 rounding device, n—a flexible, bullet-shaped device,
whichmaybeusedtounfoldandexpandthefoldedpipetightly 6. Installation Recommendations
against the wall of the existing pipe.
6.1 Cleaning and Inspection:
3.2.8 termination point, n—an existing manhole, existing
6.1.1 Prep Work—Prior to entering access areas such as
access shaft, or an excavated pit that serves as the point of exit
manholes, and performing inspection or cleaning operations,
of the folded pipe from the existing pipe.
an evaluation of the atmosphere to determine the presence of
4. Significance and Use toxic or flammable vapors or lack of oxygen must be under-
taken in accordance with local, state, or federal safety regula-
4.1 This practice is for use by designers and specifiers,
tions.
regulatory agencies, owners, and inspection organizations who
6.1.2 Cleaning of Pipeline—Internal debris shall be re-
are involved in the rehabilitation of non-pressure sewers and
moved from the existing pipeline. The pipeline should be
conduits.
cleaned with hydraulically-powered equipment, high-velocity
5. Materials
jet cleaners, or mechanically-powered equipment in accor-
dance with NASSCO Recommended Specifications for Sewer
5.1 The folded poly(vinyl chloride) (PVC) pipe shall be in
accordance with Specification F1504. Collection System Rehabilitation.
F1947 − 21a
6.1.3 Inspection of Pipelines—Inspection of pipelines shall and pulled, with a power winch unit and the cable, directly
be performed by experienced personnel trained in locating from the spool, through the insertion point, through the
breaks, obstacles, and service connections by closed circuit containment tube (if utilized), and within the existing pipe into
television. The interior of the pipeline shall be inspected the terminating manhole.Adynamometer shall be provided on
carefully to determine the location of any conditions that may the winch or cable to monitor the pulling force. Pulling forces
prevent proper installation of the folded pipe, such as protrud- shall be monitored so as not to exceed the axial strain limits of
ing service taps, collapsed or crushed pipe, out-of-roundness, the folded pipe as recommended by the manufacturer.
significant line sags, and deflected joints. These conditions 6.3.4 After insertion is complete, the winch cable shall be
should be noted and corrected prior to installation. secured at the termination end, and the folded pipe shall be cut
off at the insertion point and secured.
6.1.4 Pipeline Obstructions—The existing pipeline shall be
clear of obstructions that will prevent the proper insertion and
6.4 Expansion:
full expansion of the folded pipeline such as offset joints of
6.4.1 To check that adequate temperatures are being
more than 12.5 % of inside pipe diameter, service connections
achieved prior to expansion, suitable monitors to gage tem-
that protrude into the pipeline more than 12.5 % of the inside
perature shall be placed at the insertion and termination ends.
pipe diameter or 1 in. (25 mm), whichever is less; and, other
6.4.2 Through the use of heat and pressure or heat, pressure,
reductions in cross-sectional area of more than 16 % based on
and a rounding device, the folded pipe shall be expanded fully.
the inside diameter of the existing pipe. If inspection reveals an
Expansion pressures shall be sufficient to unfold the folded
obstruction that cannot be removed by conventional
pipe, press it against the wall of the existing pipe, and form
equipment, then a point repair excavation shall be made to
dimples at service connections. The installer shall take care to
uncover and remove or repair the obstruction. Typically, bends
avoid over-expansion of the folded pipe and shall ensure that
along the existing pipe length in excess of 30° and changes in
the minimum resulting wall thickness of the formed pipe is not
pipe size cannot be accommodated along an insertion length of
less than those specified in Table 1.
the folded pipe. Such conditions require access at these points
NOTE 4—Folded pipe expansion pressures typically are in the range of
for termination and start of a new insertion.
8 psi to 10 psi (55 kPa to 69 kPa) but can vary based on field conditions.
NOTE 1—Some processes may accommodate larger obstructions. Con-
6.4.3 If a rounding device is used, it should be propelled at
sult the product manufacturer for applications which exceed these typical
a controlled rate within the folded pipe, expanding the folded
limitations.
pipe in a sequential manner. The rounding device shall be
6.2 Bypassing—If flow can not be interrupted for the nec-
flexible and inflated with continual pressure so that is pressur-
essary duration, bypassing of the flow is required around the
izes the formed pipe against the existing pipe wall while
sections of the existing pipe designated for rehabilitation. The
bypass should be made by plugging the pipeline at a point
upstream of the pipe to be reconstructed and pumping the flow
to a downstream point or adjacent system. The pump and
TABLE 1 Rounded Pipe Sample Dimensions
bypass lines shall be of adequate capacity and size to handle
Inch/Pound Units
any extreme flows expected during the installation period.
Formed Pipe
Minimum Wall Thickness, in.
Nominal
Services within the rehabilitation area will be out of service
Outside
temporarily.
Diameter,
DR 66 DR 50 DR 41 DR 35 4
NPS
NOTE 2—Public advisory services will be required to notify all parties
4 . . . 0.114
whose service laterals will be out of commission and to advise against
6 . . 0.146 0.171
water usage until the mainline is back in service.
8 . 0.160 0.195 0.229
9 . 0.180 0.219 0.257
6.3 Insertion:
10 . 0.200 0.243 0.286
12 . 0.240 0.292 0.343
6.3.1 The spool of folded pipe shall be positioned near the
15 . 0.300 0.365 0.429
insertion point and contained in a heating chamber. The
18 0.273 0.360 . .
temperature recommended by the manufacturer shall be main-
24 0.363 0.480 . .
tained in the heating chamber for a minimum of1hto fully 30 0.454 0.600 . .
SI (Metric) Units
heat the length of folded pipe to be inserted. Shorter insertion
Formed Pipe
lengths may be fully heated over a shorter time period as Minimum Wall Thickness, mm
Nominal
Outside
recommended by the manufacturer.
Diameter,
DR 66 DR 50 DR 41 DR 35
6.3.2 A containment tube then may be pulled through the
DN
existing conduit, secured at both ends, and inflated with air at 100 . . . 2.9
150 . . 3.7 4.3
low pressure.
200 . 4.1 5.0 5.8
225 . 4.6 5.6 6.5
NOTE3—Thecontainmenttubeallowsforthoroughandevenheatingof
250 . 5.1 6.2 7.3
the folded pipe by providing a barrier between the folded pipe and
300 . 6.1 7.4 8.7
infiltration or standing wat
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F1947 − 21 F1947 − 21a
Standard Practice for
Installation of Folded Poly (Vinyl Poly(Vinyl Chloride) (PVC)
Pipe into Existing Sewers and Conduits
This standard is issued under the fixed designation F1947; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This practice describes the procedures for the rehabilitation of sewer lines and conduits (4 to 15 in. diameter) with nominal
diameters between 4 in. and 30 in. (100 mm and 750 mm) by the insertion of a folded PVC pipe, which is heated, pressurized, and
expanded against the interior surface of anthe existing pipe with either a mechanical rounding device or steam pressure. The
finished formed PVC pipe will be continuous and conform to the existing conduit.pipe. This rehabilitation process can be used in
a variety of non–pressure applications, such as: sanitary sewers, storm sewers, and process piping.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D790 Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
D1600 Terminology for Abbreviated Terms Relating to Plastics
D1784 Classification System and Basis for Specification for Rigid Poly(Vinyl Chloride) (PVC) Compounds and Chlorinated
Poly(Vinyl Chloride) (CPVC) Compounds
D2122 Test Method for Determining Dimensions of Thermoplastic Pipe and Fittings
F412 Terminology Relating to Plastic Piping Systems
F1417 Practice for Installation Acceptance of Plastic Non-pressure Sewer Lines Using Low-Pressure Air
F1216 Practice for Rehabilitation of Existing Pipelines and Conduits by the Inversion and Curing of a Resin-Impregnated Tube
F1504 Specification for Folded Poly(Vinyl Chloride) (PVC) Pipe for Existing Sewer and Conduit Rehabilitation
2.2 NASSCO Standard:
Recommended Specifications for Sewer Collection System Rehabilitation
This practice is under the jurisdiction of ASTM Committee F17 on Plastic Piping Systems and is the direct responsibility of Subcommittee F17.67 on Trenchless Plastic
Pipeline Technology.
Current edition approved March 1, 2021Aug. 1, 2021. Published March 2021August 2021 Last previous edition approved in 20102021 as F1947 – 10 which was withdrawn
February 2019 and reinstated in March 2021. DOI: 10.1520/F1947-21.21. DOI: 10.1520/F1947-21A.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
11521 Cronridge Drive, Suite J Owings Mills, MD 21117. www.nassco.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1947 − 21a
2.3 Uni-Bell Standard:
UNI-B-5-89
3. Terminology
3.1 Definitions—Terminology used in this practice is in conformance with Terminology F412 and abbreviations used in this
practice are in accordance with Terminology D1600, unless otherwise indicated.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 containment tube, n—an optional elastomeric material placed between the folded pipe and the existing pipe to protect the
folded pipe during insertion, for containment of steam during the installation process, and to provide a waterproof barrier against
infiltration, inflow, and standing water. This tube remains within the pipe but provides no structural support.
3.2.2 dimples (dimpling), n—Wherewhere a side connection meets the existing pipe, there is not existing pipe support for the
folded PVC pipe during expansion causing a point of thermoplastic pipe expansion slightly beyond the existing pipe wall. This
formation of an external departure from the formed pipe wall is termed dimpling.
3.2.3 folded pipe, n—PVC pipe that has been manufactured in a folded shape or that is subsequently folded for use in existing
pipeline sewer and conduit rehabilitation (see Fig. 1).
3.2.4 formed pipe, n—folded pipe that has been inserted into an existing sewer or conduit and expanded with heat, pressure, and,
if applicable, a rounding device to conform to and take the shape of the existing pipe (see Fig. 1).
3.2.5 insertion point, n—an existing manhole, existing access shaft, or an excavated pit that serves as the point of entrance for the
folded pipe into the existing pipe.
NOTE 1—This figure is intended only for clarification of terms specific to this practice and shows a representative folded and formed pipe shape.shapes.
Other folded pipe shapes maycan meet the requirements of this practice.
FIG. 1 Folded Pipe and Formed Pipe, Clarification of Terms
F1947 − 21a
3.2.6 rounded fieldpipe sample, n—a rounded field sample is formed when the folded pipe folded pipe that has been inserted into
a mold pipe mold and expanded with heat and pressure to conform to the mold pipe.mold, intended for testing purposes.
3.2.7 rounding device, n—a flexible, bullet-shaped device, which may be used to unfold and expand the folded pipe tightly against
the wall of the existing pipe.
3.2.8 termination point, n—an existing manhole, existing access shaft, or an excavated pit that serves as the point of exit of the
folded pipe from the existing pipe.
4. Significance and Use
4.1 This practice is for use by designers and specifiers, regulatory agencies, owners, and inspection organizations who are involved
in the rehabilitation of non-pressure sewers and conduits.
5. Materials
5.1 The folded poly (vinyl poly(vinyl chloride) (PVC) pipe shall be in accordance with Specification F1504.
5.2 The folded pipe shall be spooled in a continuous length for storage and shipping to the job site. Handling and storing shall
be in accordance with the manufacturer’s published recommendations.
5.3 The optional containment tube should be an elastomeric material capable of containing the steam required to process the folded
pipe and serve as a protective waterproofing barrier. The containment tube shall be compatible with the PVC compound, the folded
pipe installation process, and the existing pipe so as not to effect the properties of the finished pipe.
6. Installation Recommendations
6.1 Cleaning and Inspection:
6.1.1 Prep Work—Prior to entering access areas such as manholes, and performing inspection or cleaning operations, an evaluation
of the atmosphere to determine the presence of toxic or flammable vapors or lack of oxygen must be undertaken in accordance
with local, state, or federal safety regulations.
6.1.2 Cleaning of Pipeline—Internal debris shall be removed from the existing pipeline. The pipeline should be cleaned with
hydraulically-powered equipment, high-velocity jet cleaners, or mechanically-powered equipment in accordance with NASSCO
Recommended Specifications for Sewer Collection System Rehabilitation.
6.1.3 Inspection of Pipelines—Inspection of pipelines shall be performed by experienced personnel trained in locating breaks,
obstacles, and service connections by closed circuit television. The interior of the pipeline shall be inspected carefully to determine
the location of any conditions that may prevent proper installation of the folded pipe, such as protruding service taps, collapsed
or crushed pipe, out-of-roundness, significant line sags, and deflected joints. These conditions should be noted and corrected prior
to installation.
6.1.4 LinePipeline Obstructions—The existing pipeline shall be clear of obstructions that will prevent the proper insertion and full
expansion of the folded pipepipeline such as offset joints of more than 12.5 % of inside pipe diameter, service connections that
protrude into the pipepipeline more than 12.5 % of the inside pipe diameter or 1 in. (25 mm), whichever is less; and, other
reductions in cross-sectional area of more than 16 % based on the inside diameter of the existing pipe. If inspection reveals an
obstruction that cannot be removed by conventional equipment, then a point repair excavation shall be made to uncover and
remove or repair the obstruction. Typically, bends along the existing pipe length in excess of 30° and changes in pipe size cannot
be accommodated along an insertion length of the folded pipe. Such conditions require access at these points for termination and
start of a new insertion.
NOTE 1—Some processes may accommodate larger obstructions. Consult the product manufacturer for applications which exceed these typical limitations.
6.2 Bypassing—If flow can not be interrupted for the necessary duration, bypassing of the flow is required around the sections of
F1947 − 21a
the existing pipe designated for rehabilitation. The bypass should be made by plugging the linepipeline at a point upstream of the
pipe to be reconstructed and pumping the flow to a downstream point or adjacent system. The pump and bypass lines shall be of
adequate capacity and size to handle any extreme flows expected during the installation period. Services within the rehabilitation
area will be out of service temporarily.
NOTE 2—Public advisory services will be required to notify all parties whose service laterals will be out of commission and to advise against water usage
until the mainline is back in service.
6.3 Insertion:
6.3.1 The spool of folded pipe shall be positioned near the insertion point and contained in a heating chamber. A temperature, as
The temperature recommended by the manufacturer,manufacturer shall be maintained in the heating chamber for a minimum of
1 h to fully heat the length of folded pipe to be inserted. Shorter insertion lengths may be fully heated over a shorter time period
as recommended by the manufacturer.
6.3.2 A containment tube then may be pulled through the existing conduit, secured at both ends, and inflated with air at low
pressure.
NOTE 3—The containment tube allows for thorough and even heating of the folded pipe by providing a barrier between the folded pipe and infiltration
or standing water in the existing pipeline.
6.3.3 A cable shall be strung through the existing conduitpipeline (and containment tube, if applicable) and attached to the folded
pipe. The folded pipe shall be heated along the entire length and pulled, with a power winch unit and the cable, directly from the
spool, through the insertion point, through the containment tube (if utilized), and within the existing pipe into the terminating
manhole. A dynamometer shall be provided on the winch or cable to monitor the pulling force. Pulling forces shall be monitored
so as not to exceed the axial strain limits of the folded pipe material as recommended by the manufacturer.
6.3.4 After insertion is complete, the winch cable shall be secured at the termination end, and the folded pipe shall be cut off at
the insertion point and secured.
6.4 Expansion:
6.4.1 To check that adequate temperatures are being achieved prior to expansion, suitable monitors to gage temperature shall be
placed at the insertion and termination ends.
6.4.2 Through the use of heat and pressure or heat, pressure, and a rounding device, the folded pipe shall be expanded fully.
Expansion pressures shall be sufficient to unfold the PVCfolded pipe, press it against the wall of the existing conduit,pipe, and form
dimples at service connections. The installer shall take care to avoid over-expansion of the folded pipe and shall ensure that the
minimum resulting wall thickness of the formed pipe is not less than those specified in Table 1.
NOTE 4—Folded pipe expansion pressures typically are in the range of 8 psi to 10 psi (55(55 kPa to 69 kPa) but maycan vary based on field conditions.
6.4.3 If a rounding device is used, it should be propelled at a controlled rate within the folded pipe, expanding the folded pipe
in a sequential manner. The rounding device shall be flexible and inflated with continual pressure so that is pressurizes the formed
pipe against the existing pipe wall while pushing water ahead of the expansion process. The expansion rate (or rounding device
speed) shall not exceed 5 ft/s (1.52(1.5 m/s).
6.4.4 Once the rounding device has reached the termination point, the expansion pressure shall be maintained for a minimum
period of 2 min to ensure the complete expansion of the folded pipe at local deformities and to allow for complete dimpling at
side connections.
6.5 Cool Down—The formed pipe shall be cooled to a temperature below 100 °F (38 °C) before relieving the pressure required
to hold the PVC pipe against the existing pipe wall.
NOTE 5—Shrinkage of the formed pipe during cool-down typically is minimal due to the friction provided where the formed pipe conforms to existing
pipeline irregularities, such as offset joints.
F1947 − 21a
6.6 End Trimming—After the formed pipe has cooled down, the terminating ends shall be trimmed to a minimum of 3 in. (76.2(75
mm) beyond the existing pipe as allowance for possible shrinkage during cooling to ground temperature.
6.7 Service Connections—After the formed pipe has been installed, and leakage tested, if applicable, the existing active service
connections shall be reconnected. This should be done without excavation from the interior of the pipeline by means of a television
camera and a remote control cutting device unless otherwise specified by the owner.
NOTE 6—In many cases, a good seal is provided where the formed pipe dimples at service connections; however, this
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