ASTM F3288/F3288M-20

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:F3288/F3288M −20 An American National Standard
Standard Specification for
MRS-Rated Metric- and Inch-sized Crosslinked Polyethylene
(PEX) Pressure Pipe
ThisstandardisissuedunderthefixeddesignationF3288/F3288M;thenumberimmediatelyfollowingthedesignationindicatestheyear
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 system shall be used independently of the other, and values
from the two systems shall not be combined.
1.1 This specification covers crosslinked polyethylene
1.4.1 For consistency with ISO 9080, MRS values are only
(PEX) pipe that is outside diameter controlled in metric pipe
in MPa and degrees Centigrade for conversion to the pipe
sizes (DN 16 to 1000) and inch pipe sizes (NPS 3 to 54), and
materialdesignationcode(forexamplePEXpipewithanMRS
pressure rated (see Appendix X1) using the MRS rating
of 8 MPa is called a PEX 80.
system. This Specification is intended for PEX pipe made by
1.5 This standard does not purport to address all of the
various processes, as long as the PEX pipe made by that
safety concerns, if any, associated with its use. It is the
process meets all the requirements of this Specification. In-
responsibility of the user of this standard to establish appro-
cluded are requirements and test methods for material,
priate safety, health, and environmental practices and deter-
workmanship, UV protection, dimensions, hydrostatic sus-
mine the applicability of regulatory limitations prior to use.
tained pressure, environmental stress cracking, stabilizer
1.6 This international standard was developed in accor-
functionality,bent-pipehydrostaticpressure,oxidativestability
dance with internationally recognized principles on standard-
in potable chlorinated water, minimum operating temperature,
ization established in the Decision on Principles for the
degreeofcrosslinking,andhydrostaticburstpressure.Require-
Development of International Standards, Guides and Recom-
ments for pipe markings are also given. The pipe covered by
mendations issued by the World Trade Organization Technical
this specification is intended for pressure piping applications
Barriers to Trade (TBT) Committee.
suchas,industrialandgeneral-purposepipelines,potablewater
pipelines, fire – extinguishing pipelines, oil and gas producing
2. Referenced Documents
applications to convey fluids such as oil, dry or wet gas, gas
gathering, multiphase fluids, and non-potable oilfield water,
2.1 ASTM Standards:
and chemical pipelines. It is not intended for municipal natural
D618 Practice for Conditioning Plastics for Testing
gas distribution.
D792 Test Methods for Density and Specific Gravity (Rela-
tive Density) of Plastics by Displacement
1.2 This specification also includes requirements for quali-
D1505 Test Method for Density of Plastics by the Density-
fying joints made using polyethylene electrofusion fittings and
Gradient Technique
PEX pipe. Installation considerations are in X3.2.
D1598 Test Method for Time-to-Failure of Plastic Pipe
NOTE 1—NPS fittings should not be used for DN sized pipe, and DN
Under Constant Internal Pressure
sized fittings should not be used for NPS pipe.
D1599 Test Method for Resistance to Short-Time Hydraulic
1.3 Thetextofthisspecificationreferencesnotes,footnotes,
Pressure of Plastic Pipe, Tubing, and Fittings
and appendixes, which provide explanatory material. These
D1600 TerminologyforAbbreviatedTermsRelatingtoPlas-
notes and footnotes (excluding those in tables and figures)
tics
should not be considered as requirements of the specification.
D1603 Test Method for Carbon Black Content in Olefin
1.4 Units—The values stated in either SI units or inch- Plastics
pound units are to be regarded separately as standard. The D2122 Test Method for Determining Dimensions of Ther-
values stated in each system are not necessarily exact equiva- moplastic Pipe and Fittings
lents; therefore, to ensure conformance with the standard, each D2290 Test Method for Apparent Hoop Tensile Strength of
Plastic or Reinforced Plastic Pipe
This specification is under the jurisdiction ofASTM Committee F17 on Plastic
Piping Systems and is the direct responsibility of Subcommittee F17.26 on Olefin For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Based Pipe. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Aug. 1, 2020. Published August 2020. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
F3288–20 the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3288/F3288M−20
D2565 Practice for Xenon-Arc Exposure of Plastics In- gaseous fuels — Metric series — Specifications — Part 1:
tended for Outdoor Applications Pipes
D2765 Test Methods for Determination of Gel Content and ISO 18553 Method for the assessment of the degree of
Swell Ratio of Crosslinked Ethylene Plastics pigment or carbon black dispersion in polyolefin pipes,
D4218 Test Method for Determination of Carbon Black fittings and compounds.
Content in Polyethylene Compounds by the Muffle-
2.6 PPI Standards:
Furnace Technique
PPI TN-17 Crosslinked Polyethylene (PEX) Tubing
D5596 Test Method for Microscopic Evaluation of the
PPI TR-3 HDB/HDS/PDB/SDB/MRS/CRS Policies - Poli-
Dispersion of Carbon Black in Polyolefin Geosynthetics
cies and Procedures for Developing Hydrostatic Design
F412 Terminology Relating to Plastic Piping Systems
Basis (HDB), Hydrostatic Design Stresses (HDS), Pres-
F2023 Test Method for Evaluating the Oxidative Resistance
sure Design Basis (PDB), Strength Design Basis (SDB),
of Crosslinked Polyethylene (PEX) Pipe, Tubing and
Minimum Required Strength (MRS), and Categorized
Systems to Hot Chlorinated Water
Required Strength (CRS) Ratings for Thermoplastic Pip-
F2657 Test Method for Outdoor Weathering Exposure of
ing Materials or Pipe
Crosslinked Polyethylene (PEX) Tubing
PPI TR-4 HDB/HDS/SDB/PDB/MRS/CRS
F3203 Test Method for Determination of Gel Content of
Listed Materials, PPI Listing of Hydrostatic Design Basis
Crosslinked Polyethylene (PEX) Pipes and Tubing
(HDB), Hydrostatic Design Stress (HDS), Strength De-
F3373 Specification for Polyethylene (PE) Electrofusion
sign Basis (SDB), Pressure Design Basis (PDB), Mini-
Fittings for Outside Diameter Controlled Crosslinked
mum Required Strength (MRS), Categorized Required
Polyethylene (PEX) Pipe
Strength (CRS) Ratings for Thermoplastic Piping Materi-
2.2 Federal Standard:
als or Pipe
FED-STD-123 Marking for Shipment (Civil Agencies)
3. Terminology
2.3 Military Standard:
MIL-STD-129 Marking for Shipment and Storage
3.1 Definitions—Unless otherwise specified, definitions, ab-
2.4 NSF Standards:
breviations and initials are in accordance with Terminology
NSF/ANSI 14 for Plastic Piping Components and Related
F412 and Terminology D1600.
Materials
3.2 Definitions of Terms Specific to This Standard:
NSF/ANSI 61 for Drinking Water System Components-
3.2.1 minimum required strength (MRS)—seeISO12162for
Health Effects
MRS definition.
2.5 ISO Standards:
3.2.1.1 Discussion—MRS is determined only at 20 °C and
ISO 1167 Thermoplastics pipes, fittings and assemblies for
50years.Foradesigntemperatureotherthan20 °Coradesign
the conveyance of fluids — Determination of the resis-
time other than 50 years, CRS is used in place of MRS, as
tance to internal pressure — Part 1: General method
discussed in 3.2.2.
ISO 3126 Plastics piping systems – Plastics components –
3.2.2 categorized required strength (CRS) or CRS(θ,t),
Determination of dimensions
n—see ISO 12162 for CRS definition.
ISO 9080 Plastics piping and ducting systems—
3.2.2.1 Discussion—TheMRSofacompoundisdetermined
Determination of the long-term hydrostatic strength of
beforeaCRScanbedetermined.CRSisusedforadesigntime
thermoplastics materials in pipe form by extrapolation
other than 50 years or a design temperature other than 20 °C.
ISO 12162 Thermoplastics materials for pipes and fittings
An example of the use of CRS is provided in Appendix X2.
for pressure applications—Classification and
designation— Overall service (design) coefficient 3.2.3 nominal diameter, DN, adj— a designation for SI unit
outside diameter controlled pipe sizes.
ISO 13477 Thermoplastics pipes for the conveyance of
fluids — Determination of resistance to rapid crack
3.2.4 nominal pipe size, NPS, adj—a designation for inch-
propagation (RCP) — Small-scale steady-state test (S4
pound unit outside diameter controlled pipe sizes.
test)
3.2.5 overall design coeffıcient (C), n—a factor with a value
ISO 13760 Plastics pipes for the conveyance of fluids under
greater than 1, which takes into consideration material proper-
pressure — Miner’s rule ~ Calculation method for cumu-
ties (C ) and application service conditions (C ), as well as
M A
lative damage
properties of the components of a piping system other than
ISO 14531-1 Plastics pipes and fittings — Crosslinked
those represented in the lower predictive limit. Minimum
polyethylene (PEX) pipe systems for the conveyance of
overall design coefficients (C ) are specified in ISO 12162
min
for various plastic piping materials. For PEX, C is 1.25 as
min
specified in ISO 12162. See Appendix X1 for further discus-
Available from DLA Document Services, Building 4/D, 700 Robbins Ave.,
sion on design coefficients.
Philadelphia, PA 19111-5094, http://quicksearch.dla.mil.
Available from NSF International, P.O. Box 130140, 789 N. Dixboro Rd.,Ann
Arbor, MI 48105, http://www.nsf.org.
Available from International Organization for Standardization (ISO), ISO
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Available from Plastics Pipe Institute (PPI), 105 Decker Court, Suite 825,
Geneva, Switzerland, http://www.iso.org. Irving, TX 75062, http://www.plasticpipe.org.
F3288/F3288M−20
TABLE 1 Outside Diameters and Tolerances for DN size PEX Pipe
C 5 C 3 C 5 1.25 3 C or (1)
M A A
DN Size Minimum outside Maximum Maximum of
C 5 1.25 3 C 3 C 3 diameter outside diameter absolute out–of-
A1 A2
A
(mm) (mm) roundness
(mm)
...if there are multiple applications design coefficients
16 16.0 16.3 1.2
20 20.0 20.3 1.2
Discussion—design coefficients are sometimes referred to
25 25.0 25.3 1.2
as reduction factors.
32 32.0 32.3 1.3
40 40.0 40.4 1.4
3.2.5.1 material design coeffıcient (C ), n—factor that takes
M
50 50.0 50.4 1.4
intoaccountthepropertiesoftheplasticmaterial.ForPEX,the
63 63.0 63.4 1.5
material coefficient (C ) is 1.25, as specified in ISO 12162. 75 75.0 75.5 1.6
M
90 90.0 90.6 1.8
3.2.5.2 application design coeffıcient (C ), n—a factor that
110 110.0 110.7 2.2
A
125 125.0 125.8 2.5
takes into account various aspects of the installation or the
140 140.0 140.9 2.8
application that the plastic pipe is used for. The application
160 160.0 161.0 3.2
coefficient is left to the design engineer to incorporate via
180 180.0 181.1 3.6
200 200.0 201.2 4.0
appropriate design codes and national regulations and should
225 225.0 226.4 4.5
be dependent on the location of the pipeline, on the
250 250.0 251.5 5.0
temperature, on the type of fluid being conveyed, and on the
280 280.0 281.7 9.8
315 315.0 316.9 11.1
installation method.
355 355.0 357.2 12.5
3.2.6 design stress (σ ), n—stress equal to the MRS or CRS 400 400.0 402.4 14.0
S
450 450.0 452.7 15.6
divided by the overall design coefficient (C).
500 500.0 503.0 17.5
560 560.0 563.4 19.6
σ 5 ~MRS or CRS !⁄C (2)
S
630 630.0 633.8 22.1
710 710.0 716.4 24.9
3.2.7 maximum operating pressure (MOP), n—the esti-
800 800.0 817.2 28.0
mated maximum pressure the pipe is capable of withstanding
900 900.0 908.1 31.5
continuously with a high degree of certainty that failure of the
1000 1000.0 1009.0 35.0
pipe will not occur, as shown in the following equations that
A
Values are consistent with ISO 14531-1.
areusedinthisspecificationtorelatedimensions,designstress,
and maximum operating pressure.
TABLE 2 Outside Diameters and Tolerances for NPS PEX Pipe
MOP=2σ ⁄ D ⁄ t 2 1 , or (3)
@~ ! #
S o
NPS Average Outside Tolerances for Maximum of
Diameter Average absolute out–of-
MOP=2σ ⁄~R-1!
S
A
Diameter (±) roundness
For MOP at a temperature other than 20 °C or a time other
in. in. in.
than 50 years:
3 3.500 0.016 0.07
MOP=2~CRS!⁄@~R-1!~C!#, (4)
4 4.500 0.020 0.09
5 5.563 0.025 0.11
MOP=2 CRS ⁄ R-1 C 3 C (5)
~ ! @~ !~ !#
M A
6 6.625 0.030 0.13
8 8.625 0.039 0.17
where:
10 10.750 0.048 0.22
12 12.750 0.057 0.26
σ = design stress, MPa
S
14 14.000 0.063 0.28
MOP = maximum operating pressure, MPa
16 16.000 0.072 0.40
D = average outside diameter, see Table 1(mm) or Table
o
18 18.000 0.081 0.54
2 (in.) 20 20.000 0.090 0.60
22 22.000 0.099 0.66
t = minimum wall thickness, see Table 3 (mm) or Table
24 24.000 0.108 0.72
4 (in.)
26 26.000 0.117 0.78
R = standard dimension ratio (SDR) or dimension ratio
28 28.000 0.126 0.98
30 30.000 0.135 1.05
(DR)
32 32.000 0.144 1.12
MRS = Minimum Required Strength, MPa
34 34.000 0.153 1.19
CRS = Categorized Required Strength, MPa
36 36.000 0.162 1.26
C = Overall Design Coefficient
42 42.000 0.189 1.47
48 48.000 0.216 1.68
54 54.000 0.243 1.89
3.2.7.1 Discussion—MOPis sometimes referred to as PN or
A
nominal pressure Values are consistent with ISO 14531-1
3.2.8 material designation, n—As used in this standard, the
material designation for PEX pipe shall consist of the abbre-
4. Pipe Classification
viation for the type of plastic (PEX) followed by two or three
Arabic digits, which are the MRS (in MPa only) times ten, as 4.1 General—This specification covers two PEX pipe ma-
shown in Table 5. terial designations – PEX 80 with an MRS of 8.0 MPa and
F3288/F3288M−20
TABLE 3 Minimum Wall Thicknesses for DN size PEX Pipe TABLE 5 Material Designation For PEX Pipe
A
All dimensions in mm Material Designation MRS (20 °C and 50 years)
MPa
DN DR 6 DR SDR 9 SDR DR DR SDR
Size 7.4 11 13.6 16.2 17 PEX 80 8.0
PEX 100 10.0
16 3.0 2.3 2.0 . . . .
20 3.4 3.0 2.3 2.0 . . .
25 4.2 3.5 3.0 2.3 2.0 . .
32 5.4 4.4 3.6 3.0 2.4 2.0 2.0
40 6.7 5.5 4.5 3.7 3.0 2.5 2.4
4.2 Operating Temperature Range—The determination of
50 8.3 6.9 5.6 4.6 3.7 3.1 2.9
the minimum operating temperature shall be in accordance
63 10.5 8.6 7.1 5.8 4.7 3.9 3.7
75 12.5 10.3 8.4 6.8 5.6 4.6 4.4
with6.10.Themaximumoperatingtemperatureisbasedonthe
90 15.0 12.3 10.1 8.2 6.7 5.6 5.3
maximum temperature at which a CRS is determined by the
110 18.3 15.1 12.3 10.0 8.1 6.8 6.5
pipe manufacturer or is listed in PPI TR-4, but not greater than
125 20.8 17.1 14.0 11.4 9.2 7.7 7.4
140 23.3 19.2 15.7 12.7 10.3 8.7 8.2
93 °C, as specified in 5.2. Operating temperatures higher than
160 26.6 21.9 17.9 14.6 11.8 9.9 9.4
93 °C require special design considerations – consult with the
180 29.9 24.6 20.1 16.4 13.3 11.1 10.6
manufacturer.
200 33.2 27.4 22.4 18.2 14.7 12.4 11.8
225 37.4 30.8 25.2 20.5 16.6 13.9 13.2
250 41.5 34.2 27.9 22.7 18.4 15.5 14.7
5. Material Requirements
280 46.5 38.3 31.3 25.4 20.6 17.3 16.5
315 52.3 43.1 35.2 28.6 23.2 19.5 18.5
5.1 General—Crosslinked polyethylene materials meeting
355 59.0 48.5 39.7 32.2 26.1 21.9 20.9
the requirements specified in Section 5, are primarily defined
400 . 54.7 44.7 36.3 29.4 24.7 23.5
by means of color, UV protection, density, degree of
450 . 61.5 50.3 40.9 33.1 27.8 26.5
500 . . 55.8 45.4 36.8 30.9 29.4 crosslinking, and long-term strength tests specified in Section
560 . . 62.5 50.8 41.2 34.6 32.9
6.
630 . . 70.3 57.2 46.3 38.9 37.0
710 . . 79.3 64.5 52.2 43.9 41.8
5.2 Material Performance and MRS/CRS Requirements:
800 . . 89.3 72.6 58.8 49.4 47.0
5.2.1 PEX pipe shall be made from polyethylene materials
900 . . . 81.7 66.2 56.6 52.9
meeting the MRS requirements of 4.1, which have been
1000 . . . 90.2 72.5 61.8 58.8
A crosslinked during the pipe manufacturing process, such that
Small pipe diameters have minimum wall thicknesses values greater than the
calculated value based on DR or SDR.
the pipe meets the performance requirements of Section 6.
5.2.2 To establish the maximum operating temperature, the
manufacturer shall determine the CRS at that temperature, as
TABLE 4 Minimum Wall Thicknesses for NPS PEX Pipe
discussed in Appendix X2. The PEX pipe shall have a 60 °C
A
All dimensions in inches
CRS at 50 years of at least 5.0 MPa.
NPS DR 7.3 DR SDR 9 SDR DR DR SDR SDR
NOTE 3—CRS times can range from 5 years to 100 years, and CRS
8.3 11 13.5 15.5 17 21
temperatures can range from 0 °C to 93 °C.
3 0.479 0.422 0.389 0.318 0.259 0.226 0.206 0.167
4 0.616 0.542 0.500 0.409 0.333 0.290 0.265 0.214
5.3 Color—Pipe made in accordance with this specification
5 0.762 0.670 0.618 0.506 0.412 0.359 0.327 0.265
is permitted to be colored using any commercially available
6 0.908 0.798 0.736 0.602 0.491 0.427 0.390 0.315
colorant. Pipe made in accordance with this specification is
8 1.182 1.039 0.958 0.784 0.639 0.556 0.507 0.411
10 1.473 1.295 1.194 0.977 0.796 0.694 0.632 0.512
also permitted to contain no colorant.
12 1.747 1.536 1.417 1.159 0.944 0.823 0.750 0.607
5.3.1 Pipe made in accordance with this specification is
14 1.918 1.687 1.556 1.273 1.037 0.903 0.824 0.667
16 2.192 1.928 1.778 1.455 1.185 1.032 0.941 0.762 permitted to have co-extruded PEX color stripes or PEX layers
18 2.466 2.169 2.000 1.636 1.333 1.161 1.059 0.857
of differing colors from the primary color of the PEX pipe.
20 . 2.409 2.222 1.818 1.481 1.290 1.176 0.952
These stripes or layers are on the OD of the pipe.
22 . . 2.444 2.000 1.630 1.419 1.294 1.048
24 . . 2.667 2.182 1.778 1.548 1.412 1.143 5.3.2 The PEX material used in the stripe or layer shall be
26 . . . 2.364 1.926 1.677 1.529 1.238
the same type material as specified in 5.2 for the PEX pipe. If
28 . . . 2.545 2.074 1.806 1.647 1.333
PEX pipe is to have colored stripes or colored layer, the MRS
30 . . . 2.727 2.222 1.935 1.765 1.429
testingspecifiedin5.2shallbeconductedonpipesampleswith
32 . . . 2.909 2.370 2.065 1.882 1.524
34 . . . 3.091 2.519 2.194 2.000 1.619
colored stripes or colored layer.
36 . . . 3.273 2.667 2.323 2.118 1.714
42 . . . . . 2.710 2.471 2.000
NOTE 4—Choice of color for stripes or pipe is subject to the end use
48 . . . . . 3.097 2.824 2.286
application of the pipe.
54 . . . . . . 3.176 2.571
5.4 UV Protection:
A
Small pipe diameters have minimum wall thicknesses values greater than the
5.4.1 If the carbon black content in the pipe is less than
calculated value based on DR or SDR
2.0 %, the pipe shall be weathered in accordance with Test
MethodF2657,PracticeD2565orISO14531-1AnnexC.After
PEX pipe has been weathered, it shall meet the thermal
PEX 100 with an MRS of 10.0 MPa. The maximum operating
stability, 95 °C hydrostatic strength, and elongation at break
pressure(MOP)forPEXpipeisbasedontheMRSorCRSand
requirements of ISO 14531-1, Table 8.
shall be determined in accordance with the equations in 3.2.7.
NOTE 2—The CRS for PEX pipe is only determined after the MRS is NOTE 5—Generally, the acceleration factor for accelerated weathering
established. is between 3.75 to 4.4 times the number of test hours.
F3288/F3288M−20
5.4.2 The UV requirement of 5.4.1 is not applicable if the 6.4.1 The test pressure (P) is based on the following
content of well-dispersed carbon black, such as N110 or N550, equation:
is greater than 2.0 % and less than 3.0 % as measured by Test
P 52S⁄ D ⁄t 2 1 (6)
~ !
o
Method D1603 orTest Method D4218 (see ISO 14531-1Table
where:
8). To demonstrate good carbon black dispersion the PEX pipe
P = Test pressure, MPa
shall meet the ISO 14531-1 dispersion requirement of less than
S = Hoop stress per Table 7
or equal to grade 3 when measured in accordance with ISO
D = outside diameter per Table 1 or Table 2
18553, or in accordance with an equivalentASTM test method o
t = minimum wall thickness, per Table 3 or Table 4
for carbon black dispersion, such as Test Method D5596.
5.4.3 Pipe intended for chlorinated potable water
6.5 Environmental Stress Cracking—There shall be no loss
applications, shall first be weathered in accordance with 5.4.1
of pressure in the pipe when tested in accordance with 7.7.
using the complete requirements of Test Method F2657, and
6.6 Degree of Crosslinking:
then shall meet the requirements of 6.8.
6.6.1 When tested in accordance with 7.8, the degree of
5.5 Density—When determined in accordance with 7.5, the
crosslinking for PEX pipe shall meet the following specified
polyethylene compound prior to crosslinking shall have a
requirements before installation. The minimum percentage
minimum density of 0.926 g/cc.
crosslinking value shall be 65 % for PEX compounds cross-
linked using silanes or radiation, or 70 % for PEX compounds
6. Pipe Requirements
crosslinked using peroxides. The maximum degree of cross-
6.1 Workmanship—The materials, procedure for mixing, linking shall be 89 % for all PEX types.
and the pipe process for crosslinking shall result in a product 6.6.2 In addition, for pipe with a wall thickness greater than
with MRS values at 20 °C and 50 years as shown in Table 5, 0.5 in. or 12.7 mm, the degree of crosslinking shall be
when conditioned in accordance with 7.1 and determined in measured at four points separated by 90° in the middle of the
accordance with procedures no less restrictive than those of wall. For one of these points, measurements shall be taken at
ISO 9080 or PPI TR-3. Table 6 provides design stress values three points across the wall thickness. Fig. 1 shows the
locations where the gel content samples shall be collected
for each MRS pipe material designation using the minimum
overall design coefficient of 1.25 for water at 20 °C and 50 relative to each other. Collect shaving samples, about 0.10 mm
years. The design engineer shall also take into consideration thick, by drilling a hole in the axial pipe direction with a 3-mm
the effect of the environment on the overall design coefficient. drill bit to collect a 0.2 – 0.4 gram sample size.
The pipe shall be homogeneous throughout and free of visible 6.6.3 The degree of crosslinking at each of the tested points
cracks, holes, foreign inclusions, or other defects. The pipe of all thick-wall pipe tested per 6.6.2 shall meet the require-
shall be as uniform as commercially practicable in color, ments specified in 6.6.1
opacity, density, and other physical properties.
6.7 Stabilizer Functionality—The functionality of a stabi-
6.2 Diameters and Tolerances: lizer in a specific PEX compound shall be verified by hydro-
6.2.1 Outside Diameters—The outside diameters and toler- static testing of pipe made from the compound when tested in
ances shall be as shown in Table 1 for DN sizes or Table 2 for accordance with 7.9.
NPS, when measured in accordance with 7.4 and 7.4.1.
6.8 Oxidative Stability in Chlorinated Water Applications—
6.2.2 Out-of Roundness—The out-of-roundness of pipe
PEX pipe intended for use in the transport of potable water
made in accordance with this specification shall be less than or
shall have a minimum extrapolated time-to-failure of 50 years
equal to the values specified in Table 1 or Table 2 when
when tested at one of three exposure conditions, in accordance
measuredinaccordancewithTestMethodD2122orISO3126.
with 7.10, to determine the chlorine resistance level – CR1,
6.3 Wall Thickness and Tolerances—The wall thickness for CR3 or CR5.
pipe made in accordance with this specification shall be as
6.9 Bent Pipe Hydrostatic Sustained Pressure Strength:
shown in Table 3 for DN sizes and in Table 4 for NPS, when
6.9.1 General—PEX pipe, up to and including DN 25, shall
measured in accordance with 7.4.2. The tolerance for all wall
meet the requirements of 6.9.2.
thicknesses is plus 12 %.
NOTE 7—PEX pipe larger than DN 25 is typically installed for main
NOTE 6—Small pipe diameters have minimum wall thicknesses values
distribution lines and is installed in straight runs. Fittings are used when
greater than the calculated value based on DR or SDR.
a change in direction of 90° or greater and a bend radius of <6 times the
6.4 Hydrostatic Sustained Pressure Strength—Pipe samples
tested in accordance with 7.6 shall not fail as defined in Test
TABLE 7 Hoop Stress Values for Hydrostatic Sustained Pressure
Method D1598.
Test
A
Temperature °C Material Designation for Hoop Stress
MPa
Pipe
TABLE 6 PEX Pipe Design Stress at 20°C
20 PEX 80 8.3
20 PEX 100 10.4
Material Designation Design Stress for Water
95 PEX 80 3.7
(MPa) (C = 1.25)
95 PEX 100 4.7
PEX 80 (MRS = 8 MPa) 6.4
A
PEX 100 (MRS = 10 MPa) 8.0
Hoop stress (MPa) values are consistent with ISO 14531-1
F3288/F3288M−20
6.12 Hydrostatic Burst Pressure/Apparent Tensile Strength:
6.12.1 The minimum burst hoop stress shall be 17.4 MPa
forPEXpipewithanMRSof8MPaor20.0MPaforPEXpipe
with an MRS of 10 MPa, when determined in accordance with
7.11. The minimum burst pressure is based on the equation in
6.4.1. For most of the pipe sizes, average OD/minimum wall is
equal to the DR or SDR. For the smaller pipe sizes, the
calculated value is slightly lower than the DR or SDR value,
and this will result in a slightly higher burst pressure.
6.12.2 For pipe sizes of DN 110 and larger or NPS 4 and
larger testing in accordance with 7.12 is permitted to replace
testing in accordance with 7.11.The minimum apparent tensile
strength at yield when determined in accordance with 7.12
shallbe17.4MPaforPEXpipewithanMRSof8MPaor20.0
MPa for PEX pipe with an MRS of 10 MPa.
6.13 Qualification of PEX Pipe for Use with Polyethylene
Electrofusion Joints—For PEX pipe that is deemed suitable by
the pipe manufacturer for joining to polyethylene (PE) elec-
trofusion fittings, the pipe manufacturer shall qualify the PEX
FIG. 1Sample Location For Degrees Of Crosslinking Test On
pipe by testing joints made with PE electrofusion fittings and
Thick-Wall Pipe
PEX pipe meeting this standard
...