ASTM F3253-24

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: F3253 − 24 An American National Standard
Standard Specification for
Crosslinked Polyethylene (PEX) Tubing with Oxygen Barrier
for Hot- and Cold-Water Hydronic Distribution Systems
This standard is issued under the fixed designation F3253; 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* ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This specification covers requirements, test methods,
mendations issued by the World Trade Organization Technical
and marking requirements for crosslinked polyethylene (PEX)
Barriers to Trade (TBT) Committee.
tubing with a polymeric oxygen barrier layer, made in one
standard dimension ratio (SDR 9), and distribution system
2. Referenced Documents
components intended for hydronic heating and cooling appli-
2.1 ASTM Standards:
cations up to and including a maximum working temperature
D618 Practice for Conditioning Plastics for Testing
of 200 °F (93 °C).
D792 Test Methods for Density and Specific Gravity (Rela-
1.1.1 Components are comprised of tubing, fittings, valves,
tive Density) of Plastics by Displacement
and manifolds. Tubing made to this specification incorporates
D1505 Test Method for Density of Plastics by the Density-
a single outer or middle wall oxygen barrier layer intended for
Gradient Technique
inhibiting the transmission or permeation of oxygen through
D1598 Test Method for Time-to-Failure of Plastic Pipe
the tubing wall. Requirements and test methods are included
Under Constant Internal Pressure
for materials, workmanship, tubing dimensions and tolerances,
D1599 Test Method for Resistance to Short-Time Hydraulic
burst pressure, sustained pressure, excessive temperature and
Pressure of Plastic Pipe, Tubing, and Fittings
pressure, thermo-cycling, bent tube, oxidative resistance, layer
D1600 Terminology for Abbreviated Terms Relating to Plas-
adhesion, UV resistance, oxygen permeation, and fitting pull-
tics (Withdrawn 2024)
out strength tests. The components covered by this specifica-
D2122 Test Method for Determining Dimensions of Ther-
tion are intended for use in residential and commercial hy-
moplastic Pipe and Fittings
dronic heating and cooling systems. Requirements for potable
D2749 Symbols for Dimensions of Plastic Pipe Fittings
water applications are outside the scope of this specification.
D2765 Test Methods for Determination of Gel Content and
1.2 The text of this specification references notes, footnotes,
Swell Ratio of Crosslinked Ethylene Plastics
and appendixes which provide explanatory material. These
D2837 Test Method for Obtaining Hydrostatic Design Basis
notes and footnotes (excluding those in tables and figures) shall
for Thermoplastic Pipe Materials or Pressure Design Basis
not be considered as requirements of the specification.
for Thermoplastic Pipe Products
1.3 The values stated in inch-pound units are to be regarded
F412 Terminology Relating to Plastic Piping Systems
as standard. The values given in parentheses are mathematical
F876 Specification for Crosslinked Polyethylene (PEX) Tub-
conversions to SI units that are provided for information only
ing
and are not considered standard.
F877 Specification for Crosslinked Polyethylene (PEX) Hot-
and Cold-Water Distribution Systems
1.4 This standard does not purport to address all of the
F1281 Specification for Crosslinked Polyethylene/
safety concerns, if any, associated with its use. It is the
Aluminum/Crosslinked Polyethylene (PEX-AL-PEX)
responsibility of the user of this standard to establish appro-
Pressure Pipe
priate safety, health, and environmental practices and deter-
F1588 Test Method for Constant Tensile Load Joint Test
mine the applicability of regulatory limitations prior to use.
(CTLJT)
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This specification is under the jurisdiction of ASTM Committee F17 on Plastic contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Piping Systems and is the direct responsibility of Subcommittee F17.61 on Water. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Feb. 1, 2024. Published February 2024. Originally the ASTM website.
approved in 2017. Last previous edition approved in 2023 as F3253–23. DOI: The last approved version of this historical standard is referenced on
10.1520/F3253–24 www.astm.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
F3253 − 24
F1960 Specification for Cold Expansion Fittings with PEX ISO 13760 Plastics pipes for the conveyance of fluids under
Reinforcing Rings for Use with Cross-linked Polyethylene pressure -- Miner’s rule -- Calculation method for cumu-
(PEX) and Polyethylene of Raised Temperature (PE-RT) lative damage
Tubing ISO 17455 Plastics piping systems — Multilayer pipes —
F1807 Specification for Metal Insert Fittings Utilizing a Determination of the oxygen permeability of the barrier
Copper Crimp Ring, or Alternate Stainless Steel Clamps, pipe
for SDR9 Cross-linked Polyethylene (PEX) Tubing and ISO R161-1690 Pipes of Plastic Materials for the Transport
SDR9 Polyethylene of Raised Temperature (PE-RT) Tub- of Fluids (Outside Diameters and Nominal Pressures) Part
ing 1, Metric Series
F1865 Specification for Mechanical Cold Expansion Insert
2.5 Military Standard:
Fitting With Compression Sleeve for Cross-linked Poly-
MIL-STD-129 Marking for Shipment and Storage
ethylene (PEX) Tubing (Withdrawn 2018)
2.6 NSF Standard:
F2023 Test Method for Evaluating the Oxidative Resistance
NSF/ANSI Standard No. 14 for Plastic Piping Components
of Crosslinked Polyethylene (PEX) Pipe, Tubing and
and Related Materials
Systems to Hot Chlorinated Water
2.7 PPI Standard:
F2080 Specification for Cold-Expansion Fittings with Metal
PPI TR-3 Policies and Procedures for Developing Hydro-
Compression-Sleeves for Crosslinked Polyethylene (PEX)
static Design Basis (HDB), Hydrostatic Design Stresses
Pipe and SDR9 Polyethylene of Raised Temperature
(HDS), Pressure Design Basis (PDB), Strength Design
(PE-RT) Pipe
Basis (SDB), Minimum Required Strength (MRS)
F2159 Specification for Plastic Insert Fittings Utilizing a
Ratings, and Categorized Required Strength (CRS) for
Copper Crimp Ring, or Alternate Stainless Steel Clamps
Thermoplastic Piping Materials or Pipe
for SDR9 Crosslinked Polyethylene (PEX) Tubing and
PPI TR-4 PPI Listing of Hydrostatic Design Basis (HDB),
SDR9 Polyethylene of Raised Temperature (PE-RT) Tub-
Strength Design Basis (SDB), Pressure Design Basis
ing
(PDB) and Minimum Required Strength (MRS) Ratings
F2434 Specification for Metal Insert Fittings Utilizing a
for Thermoplastic Piping Materials or Pipe
Copper Crimp Ring for SDR9 Cross-linked Polyethylene
(PEX) Tubing and SDR9 Cross-linked Polyethylene/
3. Terminology
Aluminum/Cross-linked Polyethylene (PEX-AL-PEX)
3.1 The terminology used in this specification is in accor-
Tubing
dance with Terminology F412, Terminology D1600, and Sym-
F2657 Test Method for Outdoor Weathering Exposure of
bols D2749, unless otherwise specified. The abbreviation for
Crosslinked Polyethylene (PEX) Tubing
crosslinked polyethylene is PEX.
F2735 Specification for Plastic Insert Fittings For SDR9
Cross-linked Polyethylene (PEX) and Polyethylene of 3.2 Definitions of Terms Specific to This Standard:
Raised Temperature (PE-RT) Tubing
3.2.1 barrier layer—a very thin polymeric film within the
F3347 Specification for Metal Press Insert Fittings with
tube wall or around the circumference of the tubing which
Factory Assembled Stainless Steel Press Sleeve for SDR9
provides a means for greatly reducing the transmission of
Cross-linked Polyethylene (PEX) Tubing and SDR9 Poly-
oxygen from the atmosphere and into the fluid within the tube.
ethylene of Raised Temperature (PE-RT) Tubing
3.2.2 hydrostatic design basis (HDB)—As defined by Ter-
F3348 Specification for Plastic Press Insert Fittings with
minology F412 is one of a series of established stress values
Factory Assembled Stainless Steel Press Sleeve for SDR9
(specified in Test Method D2837) for a plastic compound
Cross-linked Polyethylene (PEX) Tubing and SDR9 Poly-
obtained by categorizing the long-term hydrostatic strength
ethylene of Raised Temperature (PE-RT) Tubing
determined in accordance with Test Method D2837.
2.2 AWWA Standard: 3.2.2.1 Discussion—A voluntary listing of HDB, and HDS
Manual M-11, Steel Pipe Design and Installation
values are contained in PPI publication PPI TR-4.
2.3 Federal Standard: 3.2.3 hydrostatic design stress (HDS)—As defined by Ter-
FED-STD-123 Marking for Shipment (Civil Agencies)
minology F412 is the estimated maximum tensile stress the
material is capable of withstanding continuously with a high
2.4 ISO Standards:
degree of certainty that failure of the tube will not occur. This
ISO 1167 Thermoplastics pipes, fittings and assemblies for
stress is circumferential when internal hydrostatic water pres-
the conveyance of fluids -- Determination of the resistance
sure is applied. The HDS is equal to the hydrostatic design
to internal pressure -- Part 1: General method
basis (HDB) times the design factor (DF) for water; HDS
5HDB×DF. For this specification, the design factor is less than
or equal to 0.50.
Available from American Water Works Association (AWWA), 6666 W. Quincy
Ave., Denver, CO 80235, http://www.awwa.org.
DLA Document Services Building 4/D 700 Robbins Avenue Philadelphia, PA
19111-5094 http://quicksearch.dla.mil/ Available from NSF International, P.O. Box 130140, 789 N. Dixboro Rd., Ann
Available from International Organization for Standardization (ISO), ISO Arbor, MI 48113-0140, http://www.nsf.org.
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Plastics Pipe Institute (PPI), 105 Decker Court, Suite 825 Irving TX, 75062.
Geneva, Switzerland, http://www.iso.org. http://www.plasticpipe.org
F3253 − 24
3.2.4 hydrostatic strength equivalency (HSE)—a pressure 3.2.7 manifold—an appurtenance that has at least one inlet
testing evaluation methodology where hydrostatic testing is and multiple outlets
conducted on PEX tubing that is constructed with a barrier
3.2.8 standard dimension ratio (SDR)—the ratio of outside
layer or layers in the middle or outside wall of the tubing, and
diameter to wall thickness as defined by Terminology F412
is constructed with PEX material that has an established HDB.
except this standard uses the minimum total wall thickness,
HSE methodology is applied where the barrier layer or layers
inclusive of layers, to establish SDR. When the total wall
reduce the thickness of the HDB rated PEX material in the wall
thickness calculated by the given formula is less than 0.070 in.
such that the PEX wall thickness excluding the barrier layer(s)
(1.78 mm) then the total wall thickness is arbitrarily increased
is slightly less than that required for SDR 9.0.
to 0.070 in. except for NTS ⁄16 and smaller which are
3.2.4.1 Discussion—HSE testing is conducted to confirm
prescriptively assigned.
that the pressure rating of the PEX tubing having a barrier layer
3.2.9 standard thermoplastic tubing materials designation
or layers as described herein is at least equal to comparable
code—This material designation code consists of the abbrevia-
SDR 9.0 PEX tubing that does not have a barrier layer or
tion for the type of plastic (PEX) followed by four Arabic digits
layers. When PEX tubing has a barrier layer(s) that does not
that describe those properties in accordance with applicable
reduce the thickness of the HDB-rated PEX material below that
ASTM standards and as shown in Table 1. This material
required for SDR 9.0, it is not necessary to conduct HSE
designation code solely addresses the PEX material and does
testing because pressure rating is determined using the ISO
not address any other polymeric materials which might be used
equation (3.2.6).
in the construction of oxygen barrier tubing.
3.2.5 HSE-SDR 9—an identifying term for the tubing where
3.2.9.1 Discussion—The first digit is for chlorine resistance.
the minimum PEX wall thickness falls outside the calculated
Since this standard is specific to hydronic distribution systems,
SDR 9 values yet the tubing as constructed meets the pressure
chlorine resistance is not a mandatory requirement of this
rating requirements of this standard as demonstrated by HSE
application and the default “0” is used if oxidative stability is
evaluation testing.
evaluated only per 6.1.9.1 (stabilizer functionality). If oxida-
3.2.6 ISO equation and pressure rating (PR)—The relation-
tive stability is evaluated per 6.1.9.2 (chlorine resistance), this
ship between dimensions, hydrostatic design basis, hydrostatic
digit is defined by Specification F876 as follows:
design stress, and pressure rating as defined by Terminology
(1) A digit “0” indicates that the PEX tubing either has not been tested for
F412 is illustrated as follows specific to this specification.
chlorine resistance or that the PEX tubing does not meet the minimum
requirement for chlorine resistance.
The following is commonly referred to as the ISO equation
(2) A digit “1” indicates the PEX tubing has been tested and meets the
(See ISO R161-1690.) :
requirement of 6.1.9.2 for minimum chlorine resistance at the end use
condition of 25 % at 140 °F (60 °C) and 75% at 73 °F (23 °C).
S 5 P~OD 2 t!⁄2t ~For outside diameter controlled pipe! (1)
(3) A digit “2” is reserved for future application.
(4) A digit “3” indicates that the PEX tubing has been tested and meets the
where:
requirement of 6.1.9.2 for minimum chlorine resistance at end use
S = hoop stress,
condition of 50 % at 140 °F and 50% at 73 °F.
(5) A digit “4” is reserved for future application.
P = pressure,
(6) A digit “5” indicates that the PEX tubing has been tested and meets the
OD = average outside diameter,
requirement of 6.1.9.2 for minimum chlorine resistance at end use
t = minimum wall thickness
conditions of 100 % of the time at 140 °F.
The pressure rating (PR) and HDS/HDB are related by the
3.2.9.2 Discussion—The second digit is for demonstrated
following equation:
UV resistance of PEX material when tested in accordance with
PR 5 2~HBD!~DF!⁄~SDR 2 1! 5 2~HDS!⁄~SDR 2 1! (2) Test Method F2657. For this specification it is one of the
(being specific to this specification with DF=0.50 and SDR
classification digits listed in Table 1 for the Nominal Exposure
9)
Time Period from Table 1 in Test Method F2657 where the
PR 5 2~HDB!~0.50!⁄~9 2 1! 5 2~HDS!⁄8 (3) decreased average failure time from 10.3 of Test Method
Example: PEX with HDB of 800 PSI at 180 °F made ac-
F2657 is less than or equal to 21%. Alternately, the second digit
cording to this specification to SDR 9
may be one of the classification digits from Table 1 for the
PR 5 2 800 0.50 ⁄ 9 2 1 5 100 PSI (4) Nominal Exposure Time Period from Table 1 of Test Method
~ !~ ! ~ !
TABLE 1 Material Designation Code Cells
Property Standard 0 1 2 3 4 5 6 7 8 9
Chlorine F2023 Not tested (See Specifi- Reserved (See Specifica- (See Specifi- (See Specifi- . . . .
Resistance or rated cation F876) tion F876) cation F876) cation F876)
25 % at 50 % at 140 °F Reserved 100 % at
140 °F 50 % at 73 °F 140 °F
75 % at 73 °F
Minimum UV F2657 Not tested 1 month 3 months 6 months . . . . . .
Resistance or rated
HDS . . . . . . . 630 . 800 .
for water at
73 °F
F3253 − 24
F2657 where the UV-exposed samples meet the requirement of than the minimum wall thickness calculated for SDR 9.0 is
7.2.10 Stabilizer Functionality. pressure rated as SDR 9.0 using the ISO equation (3.2.6), and
(1) The 21% pass/fail criteria originates from the statistical is marked “SDR 9”. Tubing having barrier layer(s) that has
analysis of an aggregate of data sets generated using Test PEX material minimum wall thickness that is less than the
Method F2023 and represents the mean Lower Predictive Limit minimum wall thickness calculated for SDR 9.0 is pressure
(95% two sided) compared to the expected failure times based rated using hydrostatic strength equivalency (HSE) testing
on three stress levels at each of three temperatures. Thus, this (7.3.13), and is marked “HSE-SDR 9”.
value represents the limit for statistical differentiation in failure
4.2 Fittings—This specification classifies fittings including
times using Test Method F2023 at the 95% confidence level (2
manifolds with integral fittings and valves, and valves with
sided). This research was conducted for the Plastics Pipe
integral fittings, intended for use in systems with PEX tubing,
Institute in 2005. The UV resistance of the PEX material is
by a maximum continuous use temperature that shall be 200 °F
demonstrated on representative pipe samples for the original
(93 °C) and by nominal sizes from NTS ⁄8 through NTS 6 on
validation of pipe made from a particular PEX material
the basis of resistance to hydrostatic burst pressure, hydrostatic
formulation, that material formulation being the combination
sustained pressure, excessive temperature/pressure capability,
of PEX base resin and its respective additives.
thermocycling, and by pull-out strength. Fittings shall be
3.2.9.3 Discussion—The last two digits are the hydrostatic
compatible with tubing made to the requirements of this
design stress for water at 73 °F (23 °C) in units of 100 psi with
specification.
any decimal figures dropped. Where the hydrostatic design
stress code contains less than two figures, a zero is used before
5. Materials
the number. Thus, a complete material designation code for
5.1 General—PEX oxygen barrier tubing systems shall use
PEX tubing consists of the three letters “PEX” and four digits.
crosslinked polyethylene tubing as described in this specifica-
See Fig. 1. For example ASTM F3253 PEX tubing marked
tion.
with the material designation code of PEX 0106 is a PEX
5.2 Tubing Materials:
tubing meeting the minimum stabilizer functionality
5.2.1 PEX tubing, exclusive of oxygen barrier and bonding
requirement, having a UV resistance of 1 month, and having an
layers, shall be made from polyethylene compounds which
HDS for water of 630 psi at 73 °F (HDB of 1250 psi).
have been crosslinked by peroxides, or silane compounds in
3.2.10 system components—tubing, fittings, valves and
extrusion, or by electron beam after extrusion, or by other
manifolds
means such that the tubing meets the performance require-
ments of Section 6. For the use temperatures that the tubing
4. Classification
will be marked for, the materials, procedure for mixing, and the
4.1 Tubing:
process for crosslinking shall result in a product with long term
4.1.1 General:
hydrostatic stress ratings equal to or better than those shown in
4.1.1.1 This specification covers one PEX tubing material
Table 2, when determined in accordance with Test Method
having pressure ratings for water at three temperatures. The
D2837 and procedures no less restrictive than those of PPI
pressure ratings decrease as the temperature is increased.
TR-3. Tubing inclusive of layers shall also meet the require-
4.1.1.2 This specification covers PEX tubing in one stan-
ments of PPI TR-3. See Appendix X1 for additional infor-
dard dimension ratio (SDR 9) for nominal diameters NTS ⁄8
mation on PPI hydrostatic stress ratings.
and larger, and with specified wall thicknesses for smaller
5.2.2 The oxygen barrier layer shall be specified by the
diameters. Tubing pressure ratings are uniform for all nominal
tubing manufacturer.
tubing sizes.
NOTE 1—Typically the oxygen barrier layer is made from EVOH
(1) All tubing sizes in this standard are dimensionally
(Ethylene vinyl alcohol). EVOH copolymer is defined by the mole %
compatible with PEX fittings that comply with 6.2.2.
ethylene content: lower ethylene content grades have higher oxygen
(2) All oxygen barrier tubing sizes in this standard are
pressure rated equivalent to SDR 9.0 PEX tubing. Tubing that
has PEX material minimum wall thickness equal to or greater
PPI Technical Report TR-3, PPI Policies and Procedures for Developing
Hydrostatic Design Basis (HDB), Hydrostatic Design Stresses (HDS), Pressure
Design Basis (PDB), Strength Design Basis (SDB), Minimum Required Strength
(MRS) Ratings, and Categorized Required Strength (CRS) for Thermoplastic Piping
PPI Technical Literature, Final Report – Proposal for the Evaluation of the
Materials or Pipe.
Chlorine Resistance of UV Exposed PEX Pipe.
FIG. 1 Standard Thermoplastic Tubing Materials Designation Code
F3253 − 24
TABLE 2 Hydrostatic Design Stresses and Pressure Ratings for
6.1.3.1 Outside Diameters—The outside diameters and tol-
SDR 9 PEX Tubing for Water at Different Temperatures
erances of the tubing inclusive of layers shall be per Table 3,
Hydrostatic Design Pressure Rating for
when measured in accordance with 7.3.3.1.
Rated Temperature
Stress Water
°F (°C) psi (MPa) psi (MPa)
6.1.3.2 Total Wall Thickness—The total wall thickness and
73 (23) 630 (4.34) 160 (1.10)
tolerances shall be per Table 4, when measured in accordance
180 (82) 400 (2.76) 100 (0.69)
with 7.3.3.2.
200 (93) 315 (2.17) 80 (0.55)
(1) Layers—Tubing made according to this specification
incorporating an oxygen barrier layer shall meet the total wall
thickness and tolerances requirements as specified in Table 4.
In addition, the oxygen barrier layer(s) shall not result in the
barrier properties. Polymeric oxygen barrier layer material other than
EVOH shall be acceptable provided that they are compatible with the PEX
reduction of the PEX material wall(s) below that specified in
material and the bonding/tie layer(s) and also meets all of the requirements
Table 5. In the case of tubing with a middle layer, the base PEX
of this specification.
material wall thickness shall be the sum of the inner and outer
5.2.3 Bonding or tie layer(s) material (if present) shall be
base PEX material wall thicknesses exclusive of barrier and
compatible with both PEX and the barrier layer providing for
bonding/tie layers. For tubing where the base PEX wall
permanent bonding between layers to meet layer adhesion
thickness falls below the dimensions given in Table 4 and also
requirements of this specification. The bonding/tie layer(s)
results in a calculated SDR greater than 9.0, the tubing
containing a colorant shall be acceptable.
manufacturer shall demonstrate hydrostatic strength equiva-
5.2.4 Tubing Material Designation—Tubing meeting the
lency (HSE) between the reduced PEX wall oxygen barrier
requirements of this specification shall be designated
tube and a non-barrier tube made from the same PEX formu-
5.3 Fitting and manifold materials, including fittings and
lation. HSE evaluation shall not be required on sizes smaller
manifolds with integral valves, shall meet the applicable
than ⁄2 nominal tubing size (NTS) as wall thickness minimums
material requirements of at least one of the Specifications
are not a function of SDR as the calculated SDR is less than 9.0
F1807, F1960, F2080, F2159, F2434, F2735, F3347, or F3348.
for ⁄8 NTS and smaller sizes even when using the minimum
PEX wall dimensions given in Table 5. HSE evaluation shall
6. Requirements
be conducted in accordance with 7.3.13. Tubing requiring HSE
6.1 Tubing:
evaluation shall be marked in accordance with 10.2.5 specifi-
6.1.1 Workmanship—The tubing shall be free of visible
cally stating “HSE-SDR 9”.
cracks, holes, foreign inclusions, or other defects. The pipe
6.1.4 Density—When determined in accordance with 7.3.4,
shall be as uniform as commercially practicable in color,
the PEX tubing material (exclusive of barrier and bonding/tie
opacity, density, and other physical properties.
layers) shall have a minimum density of 0.926 g/cm .
6.1.2 Out-of Roundness—The maximum out-of roundness
6.1.5 Hydrostatic Sustained Pressure Strength—The tubing
requirements, shown in Table 3 for tubing, apply to the
shall not fail, balloon, burst, or weep as defined in Test Method
average, measured diameter. Tubing shall be measured prior to
D1598, at the test pressures shown in Table 6 when tested in
coiling.
6.1.3 Dimensions and Tolerances: accordance with 7.3.5.
TABLE 3 Outside Diameters and Tolerances for Oxygen Barrier Tubing
Nominal Tubing Average Outside
A
Tolerances for Average Diameter Out-of-Roundness
Size Diameter
NTS in. (mm in. mm in. mm
⁄8 0.250 (6.35) ±0.003 (±0.08) 0.008 (0.20)
⁄4 0.375 (9.52) ±0.003 (±0.08) 0.008 (0.20)
⁄16 0.430 (10.92) ±0.003 (±0.08) 0.008 (0.20)
⁄8 0.500 (12.70) ±0.003 (±0.08) 0.012 (0.32)
⁄2 0.625 (15.88) ±0.004 (±0.10) 0.016 (0.40)
⁄8 0.750 (19.05) ±0.004 (±0.10) 0.016 (0.40)
⁄4 0.875 (22.22) ±0.004 (±0.10) 0.016 (0.40)
1 1.125 (28.58) ±0.005 (±0.12) 0.020 (0.48)
1 ⁄4 1.375 (34.92) ±0.005 (±0.12) 0.020 (0.48)
1 ⁄2 1.625 (41.28) ±0.006 (±0.16) 0.024 (0.60)
2 2.125 (53.98) ±0.006 (±0.16) 0.030 ( 0.76)
2 ⁄2 2.625 (66.68) ±0.007 (±0.18) 0.038 (0.95)
3 3.125 (79.38) ±0.008 (±0.20) 0.045 (1.14)
3 ⁄2 3.625 (92.08) ±0.008 (±0.20) 0.046 (1.16)
4 4.125 (104.78) ±0.009 (±0.23) 0.052 (1.32)
4 ⁄2 4.625 (117.48) ±0.009 (±0.23) 0.059 (1.49)
5 5.125 (130.18) ±0.010 (±0.25) 0.065 (1.65)
6 6.125 (155.58) ±0.011 (±0.28) 0.072 (1.83)
A
The Out-of-Roundness specification applies only to tubing prior to coiling.
F3253 − 24
A
TABLE 4 Wall Thickness and Tolerances for Nominal PEX SDR 9
6.1.8 Degree of Crosslinking—When tested in accordance
Oxygen Barrier Tubing
with 7.3.8, the degree of crosslinking for PEX tubing material
Nominal Tubing
Minimum Wall Thickness Tolerance shall be within the range from 65 to 89 % inclusive. Depending
Size
on the process used, the following minimum percentage
NTS in. (mm) in. (mm)
crosslinking values shall be achieved: 70 % by peroxides, 65 %
B B
⁄8 0.047 (1.19) +0.007 (+0.18)
B B
⁄4 0.062 (1.57) +0.010 (+0.25) by electron beam, or 65 % by silane compounds. For this
⁄16 0.064 (1.63) +0.010 (+0.25)
specification, the degree of cross-linking of the PEX material
B B
⁄8 0.070 (1.78) +0.010 (+0.25)
B B excluding the layer(s) shall be tested in accordance with 7.3.8.
⁄2 0.070 (1.78) +0.010 (+0.25)
6.1.9 Oxidative Stability—Tubing made according to this
⁄8 0.083 (2.12) +0.010 (+0.25)
⁄4 0.097 (2.47) +0.010 (+0.25)
specification shall demonstrate sufficient oxidative stability
1 0.125 (3.18) +0.013 (+0.33)
against the deleterious effects of long-term thermal degradation
1 ⁄4 0.153 (3.88) +0.015 (+0.38)
1 ⁄2 0.181 (4.59) +0.019 (+0.48) such as those encountered in hydronic heating systems. There-
2 0.236 (6.00) +0.024 (+0.61)
fore tubing shall meet the performance requirements of either
2 ⁄2 0.292 (7.41) +0.030 (+0.76)
the Stabilizer Functionality Test or the Oxidative Stability
3 0.347 (8.82) +0.033 (+0.84)
3 ⁄2 0.403 (10.23) +0.035 (+0.89) (Chlorine) Test in accordance with 6.1.9.1 or 6.1.9.2:
4 0.458 (11.64) +0.040 (+1.02)
6.1.9.1 Stabilizer Functionality—Stabilizer Functionality
4 ⁄2 0.514 13.05) +0.045 (+1.14)
shall be tested in accordance with 7.3.10.
5 0.569 (14.46) +0.050 (+1.27)
6 0.681 (17.29) +0.060 (+1.52)
6.1.9.2 Oxidative Stability in Hot-Chlorinated Water—
A
Tubing shall have a minimum extrapolated time-to-failure of
The minimum is the lowest wall thickness of the pipe at any cross section. The
maximum permitted wall thickness, at any cross section, is the minimum wall
50 years when tested and evaluated in accordance with 7.3.9. If
thickness plus the stated tolerance. All tolerances are on the plus side of the
this method is used to evaluate oxidative stability of the tubing,
minimum requirement.
B
the standard thermoplastic tubing materials designation code
For nominal tubing sizes of ⁄2 and below, wall thickness minimums are not
functions of SDR.
for the 1st digit shall be a minimum of “1”, or optionally “3”,
or “5” per the requirements of Specification F876. (See 3.2.9.)
6.1.10 Oxygen Permeation—Tubing made according to this
A
TABLE 5 Minimum PEX Wall Thickness
specification shall meet the oxygen permeation requirements of
Nominal Tubing Size Minimum PEX Wall Thickness
-4
this standard. Oxygen permeation shall be less than 4.588x10
NTS in. (mm)
2 2
grains/(ft *day) at 104 °F (0.32 mg/(m *day) at 40 °C) when
B B
⁄8 0.042 (1.07)
tested in accordance with ISO 17455 using either the dynamic
B B
⁄4 0.057 (1.45)
B B
(Method I) or static (Method II) methods. Testing at tempera-
⁄16 0.059 (1.50)
B B
⁄8 0.065 (1.65)
tures higher or lower than 40 ºC is optional for the purposes of
C C
⁄2 0.065 (1.65)
this specification. Samples shall be conditioned in accordance
C C
⁄8 0.078 (1.98)
C C
⁄4 0.092 (2.34) with 7.3.11.
C C
1 0.120 (3.05)
6.1.11 Adhesion Test—Tubing that incorporates an optional
1 C C
1 ⁄4 0.148 (3.76)
C C middle or outer layer shall not show any delamination when
1 ⁄2 0.176 (4.47)
C C
2 0.231 (5.87) tested in accordance with the adhesion test of Specification
C C
2 ⁄2 0.287 (7.29)
F1281.
C C
3 0.342 (8.69)
C C 6.1.12 Bent Tube Hydrostatic Sustained Pressure Strength:
3 ⁄2 0.398 (10.11)
C C
4 0.453 (11.51) 6.1.12.1 General—PEX oxygen barrier tubing, up to and
C C
4 ⁄2 0.509 (12.93)
including NTS 1, can be installed cold-bent provided that
C C
5 0.564 (14.33)
C C 6.1.12.2 requirements are met.
6 0.676 (17.17)
A
The minimum PEX wall is the lowest measured wall thickness of the pipe,
NOTE 2—PEX tubing, larger than NTS 1 nominal diameter, is typically
excluding any non-PEX layers, at any cross section. The maximum permitted wall
installed as main distribution lines and is installed in straight runs. Fittings
thickness on the PEX wall is only limited by the dimensions stated in Table 4.
are used when a change in direction of 90° or greater and a bend radius of
B
For these sizes the minimum PEX walls are not functions of SDR and are not
6 times the outside diameter is needed. The test procedures in 6.1.12.2 are
subject to HSE evaluation testing as the calculated SDR is less than 9.0.
intended to evaluate PEX tubing installed in tight bend applications in
C
HSE evaluation testing shall be conducted for these sizes to confirm that tubing
accordance with the installation procedure in X2.3.4. This application
pressure ratings are equal to or greater than the pressure ratings established in
applies to tubing up to and including 1 in nominal diameter only. This
this standard for SDR 9.0 tubing. Tube constructions evaluated per the HSE
method shall be appropriately marked per section 10.2.4 specifically stating specification, unlike other PEX standards such as Specification F876, does
“HSE-SDR 9”
not require hot-bent hydrostatic sustained pressure testing as it is not a
practice recommended for oxygen barrier PEX tubing because of a high
likelihood of damage to the oxygen barrier layer such as tearing,
bunching, and loss of adhesion, after bending.
6.1.12.2 Cold-bent tubing, with a radius of 6 times the
6.1.6 Hydrostatic Burst Pressure—The minimum burst outside diameter and consisting of a continuous bend length
pressure for PEX oxygen barrier tubing shall be as shown in inducing not less than 90° angle, shall meet the minimum
Table 7, when determined in accordance with 7.3.6. hydrostatic sustained pressure strength requirements for 180 °F
6.1.7 Environmental Stress Cracking Resistance (ESCR)— as shown in Table 6 when tested in accordance with 7.3.5. The
There shall be no loss of pressure in the tubing, when tested in bend length and bend angle is kept throughout the testing
accordance with 7.3.7. period by rigid secures immediately outside the bend.
F3253 − 24
TABLE 6 Minimum Hydrostatic Sustained Pressure Requirements for PEX Nominal SDR 9 Tubing
Nominal Pressure Required for Test
A
Tubing Size psi , MPA
NTS 73 °F (23 °C) 180 °F (82 °C) 200 °F (93 °C)
⁄8 595 (4.10) 355 (2.45) 300 (2.07)
⁄4 515 (3.55) 305 (2.10) 260 (1.79)
⁄16 455 (3.13) 270 (1.86) 225 (1.55)
⁄8 425 (2.93) 250 (1.72) 210 (1.45)
⁄2 330 (2.27) 195 (1.34) 165 (1.14)
⁄8 and larger 325 (2.24) 190 (1.31) 165 (1.14)
A
The fiber stress for SDR9 PEX tubing used to derive this test pressure is:
at 73.4 °F (23 °C) 1300 psi (8.96 MPa).
at 180 °F (82 °C) 770 psi (5.31 MPa).
at 200 °F (93 °C) 650 psi (4.48 MPa).
TABLE 7 Burst Pressure Requirements for Water at Different Temperatures for PEX SDR 9 Oxygen Barrier Tubing
Nominal Minimum Burst Pressures at
Tubing Size Different Temperatures
A
psi, MPa
NTS 73 °F (23 °C) 180 °F (82 °C) 200 °F (93 °C)
⁄8 870 (5.99) 390 (2.69) 330 (2.27)
⁄4 752 (5.18) 336 (2.32) 285 (1.96)
⁄16 665 (4.58) 300 (2.07) 250 (1.72)
⁄8 620 (4.27) 275 (1.89) 235 (1.62)
⁄2 480 (3.31) 215 (1.48) 185 (1.27)
⁄8 and larger 475 (3.27) 210 (1.45) 180 (1.24)
A
The fiber stress for SDR9 PEX tubing used to derive this test pressure is:
at 73 °F (23 °C) 1900 psi (13.10 MPa).
at 180 °F (82 °C) 850 psi (5.86 MPa).
at 200 °F (93 °C) 720 psi (4.96 MPa).
6.1.13 Excessive Temperature Pressure Capability: 6.2.4 Hydrostatic Burst:
6.1.13.1 In the event of water heating system malfunction, 6.2.4.1 Tubing and fittings (tested as assemblies) assembled
PEX oxygen barrier tubing shall have adequate strength to using the manufacturer’s instructions shall meet the minimum
accommodate short-term conditions of elevated temperature hydrostatic burst requirements shown in Table 7 when tested in
and pressure, 48 h of 210 °F (99 °C). 150 psi (1034 kPa) until accordance with 7.3.6.
repairs can be made. 6.2.4.2 Manifolds with integral shut-offs (valves) shall be
6.1.13.2 Excessive Temperature Hydrostatic Sustained tested with all ports in the full-open or unrestricted position.
Pressure—Tubing shall not fail as defined in Test Method (1) If the manifold has more than one connection size, the
D1598 in less than 30 days (720 h) when tested in accordance test pressure selected from Table 7 shall be based upon the
with 7.3.12. largest nominal PEX connection.
6.2.5 Hydrostatic Sustained Pressure Strength:
6.2 Fittings, including manifolds and valves with integral
6.2.5.1 Tubing and fittings (tested as assemblies) shall meet
fittings:
the minimum hydrostatic sustained pressure strength require-
6.2.1 Workmanship—Fittings and the materials that they are
ments shown in Table 8 when tested in accordance with 7.3.5.
made from shall be homogeneous throughout and free of
(1) Manifolds with integral shut-off (valves) shall be tested
visible cracks, holes, foreign inclusions, blisters, voids or other
with all ports in the full-open or unrestricted position.
defects that are visible to the naked eye that may affect fitting
6.2.6 Thermocycling:
integrity. All sealing surfaces shall be smooth and free of
foreign material.
TABLE 8 Minimum Hydrostatic Sustained Pressure Requirements
6.2.2 Dimensions and Tolerances—The dimensions and tol-
for SDR9 PEX Oxygen Barrier Tubing and System Component
erances of fittings shall meet the specific requirements con- A
, B
Assemblies
tained in Specifications F1807, F1960, F2080, F2159, F2434,
Nominal Tubing Size Pressure Required for Test, psi (MPa)
F2735, F3347, F3348 or other recognized PEX fitting approved
NTS 180 °F (82 °C)
⁄8 355 (2.45)
for use by the tubing manufacturer.
⁄4 305 (2.10)
6.2.3 Corrosion Resistance—Fittings shall be made from
⁄16 270 (1.86)
materials that are generally regarded as corrosion resistant. 3
⁄8 250 (1.72)
⁄2 195 (1.34)
6.2.3.1 Compliance with this specification requires that
⁄8 and larger 190 (1.31)
fittings defined in Specifications F1807, F1865, F1960, F2080,
A
The fiber stress for SDR9 PEX tubing used to derive this test pressure is: 770 psi
F2159, F2434, F2735, F3347, F3348 or other recognized PEX
(5.31 MPa) at 180 °F (82 °C).
fitting specification must meet the Performance requirements B
Test duration is 1000 h.
of this specification.
F3253 − 24
6.2.6.1 Fittings, assembled using the manufacturer’s The tolerance for out-of-roundness shall apply only to tubing
instructions, shall not leak after completion of 1000 cycles prior to shipment. Averaging micrometer or vernier caliper
between the temperatures of 60 °F (16 °C) and 180 °F (82 °C) measurements, four (4) maximum and minimum diameter
when tested in accordance with 7.4.3. measurements at any cross section, may be used for quality
(1) Manifolds with integral shut-offs (valves) shall be control checks if desired.
tested with all ports in the full open or unrestricted position.
7.3.3.2 Wall Thickness—Make micrometer measurements of
6.2.7 Excessive Temperature—Pressure Capability: the wall thickness in accordance with Test Method D2122 to
determine the maximum and minimum values. Measure the
NOTE 3—In the event of a water heating system malfunction, PEX
wall thickness at both ends of the tubing to the nearest 0.001 in.
tubing and system components shall have adequate strength to accommo-
date short-term conditions, 48 h of 210 °F (99 °C), 150 psi (1034 kPa) (0.025 mm).
until repairs can be made.
7.3.3.3 Barrier Layer and Bonding/Tie Layer(s)—Make
measurements of the layer or layers using either a video
6.2.7.1 Excessive Temperature Hydrostatic Sustained
microscope, a microscope with graduations or optical com-
Pressure—Tubing and system components, when tested as
parator to determine the maximum and minimum values.
assemblies, shall not fail as defined in Test Method D1598 in
Precision of layer measurements shall be at minimum 0.0005
less than 30 days (720 h) when tested in accordance with 7.4.5.
in (0.013 mm). Maximum and minimum barrier layer thick-
(1) Manifolds with integral shut-offs (valves) shall be
nesses inclusive of bonding/tie layer(s) shall be determined by
tested with all ports in the full open or unrestricted position.
two (2) or more equally spaced samplings around the pipe
6.2.8 Pull-Out Strength:
circumference. For the purposes of this standard the minimum
6.2.8.1 Fittings used with tubing meeting this specification
PEX wall shall be calculated as follows:
shall demonstrate sufficient strength to withstand the axial
(1) Minimum PEX wall thickness = Minimum total wall
(tensile) forces associated with installation and normal end-use
thickness in accordance with 7.3.3.2 minus the average of the
conditions encountered in hydronic systems. Conduct testing in
measured barrier and bonding/tie layer thicknesses in accor-
accordance with 7.4.6. Pass/Fail criteria shall be as defined in
dance with 7.3.3.3.
7.4.6.
NOTE 5—It has been common practice to apply Merbromin (marketed
NOTE 4—Tests applicable to assemblies and bends are intended to be
as Mercurochrome trade name) or similar chemical die solution to the cut
performance qualification tests and not tests required of each fitting
end of the pipe in order to add a color tint to the otherwise clear EVOH
configuration.
layer.
7. Test Methods 7.3.4 Density—Determine the density of the PEX tubing
compound in accordance with Test Method D1505, or Test
7.1 Conditioning—Condition the specimens at 73 °F 6 4 °F
Methods D792, using three specimens.
(23 °C 6 2 °C) and 50 % 6 10% relative humidity for not less
7.3.5 Hydrostatic Sustained Pressure Test—Select the test
than 40 h prior to test in accordance with Procedure A of
specimens at random. Test individually with water at the three
Practice D618, for those tests where conditioning is required.
controlled temperatures and under the pressures given in Table
In cases of disagreement, the tolerances shall be 62 °F
6, 18 specimens of tubing, each specimen at least ten times the
(61 °C) and 62 % relative humidity.
nominal diameter in length, but not less than 10 in. (25.4 cm)
7.2 Test Conditions—Conduct the test in the standard labo-
or more than 3 ft (91.4 cm) between end closures and contain-
ratory atmosphere of 73 6 4 °F (23 6 2 °C) and 50 6 5 %
ing the permanent marking on the tubing. Test six specimens at
relative humidity, unless otherwise specified in the test meth-
each temperature. Condition the specimens for at least 2 h to
ods or in this specification. In cases of disagreement, the
within 6 4 °F (62 °C) of the specified test temperatures.
tolerances shall be 62 °F (61 °C) and 62 % relative humidity.
Maintain the specimens at the pressures indicated for the
appropriate temperatures for a period of 1000 h. Hold the
7.3 Tubing:
pressure as closely as possible, but within 6 10 psi (60.070
7.3.1 Sampling—A sufficient quantity of tubing, as agreed
MPa). Maintain the test temperatures within 6 4 °F (62 °C) of
upon by the purchaser and the seller, shall be selected and
the specified temperature. Test in accordance with Test Method
tested to determine conformance with this specification. In the
D1598 except maintain the pressure at the values given in
case of no prior agreement, random samples selected by the
Table 6 for 1000 h. Failure of two of the six specimens tested
testing laboratory shall be deemed adequate.
at either temperature constitutes failure in the test. Failure of
7.3.2 Test Specimens—Not less than 50 % of the test speci-
one of six specimens tested at either temperature is cause for
mens required for any pressure test shall have at least a part of
retest of six additional specimens at that temperature. Failure
the marking in their central sections. The central section is that
of one of six specimens tested at either temperature in retest
portion of tubing that is at least one tubing diameter away from
constitutes failure in the test. Failure of the tubing shall be
an end closure.
defined in accordance with Test Method D1598, namely:
7.3.3 Dimensions and Tolerances—Use any length of tubing
7.3.5.1 Failure—Any continuous loss of pressure resulting
to determine the dimensions. Measure in accordance with Test
Method D2122. from the transmission of the test liquid through the body of the
specimen under test.
7.3.3.1 Outside Diameter—Measure the outside diameter of
the tubing in accordance with Test Method D2122. The referee 7.3.5.2 Ballooning—Any abnormal localized expansion of a
method of measurement is to be by circumferential wrap tape. tubing specimen while under internal hydraulic pressure.
F3253 − 24
7.3.5.3 Bursting—Failure by a break in the tubing with specified in Table 6 for 200 °F (93 °C) and the tubing size.
immediate loss of test liquid and continued loss at essentially Testing shall be conducted in accordance with Test Method
no pressure. D1598 with the exceptions that the testing is not required to be
7.3.5.4 Seepage or Weeping—Failure that occurs through carried out until specimen failure as defined in Test Method
essentially microscopic breaks in the tubing wall, frequently D1598, and the specimen lengths are permitted to be shorter
only at or near the test pressure. than specified in Test Method D1598.
7.3.7.4 Visually evaluate any specimens that have lost
NOTE 6—At lower pressures, the pipe may carry liquids without
pressure during testing for ductile or brittle failure mode using
evidence of loss of liquids.
the definitions within Terminology F412. Any ductile failure
7.3.5.5 Delamination—Failure by separation of the layers
result(s) shall be discarded, and retest(s) performed.
visible to the unaided eye.
7.3.5.6 When testing in accordance with the requirements of NOTE 10—Failures, if they occur via environmental stress cracking,
should result in brittle failure which occurs via slow crack growth
6.1.12.2, only one cold bent specimen is required to be tested
emanating from the notch.
and the length of the specimen between end closures shall be
7.3.7.5 A mixed failure mode sometimes occurs in envi-
between 12 in. and 18 in. (305 mm and 457 mm).
ronmental stress cracking tests where the early stages of
7.3.6 Hydrostatic Burst Pressure—Determine the minimum
fracture are brittle and the final stages of failure are ductile;
burst pressure with at least five specimens in accordance with
these failures display slow crack growth characteristics just
Test Method D1599. The time of testing of each specimen shall
“outside” of the notch (that is, propagating radially
...