ASTM D2837-01ae1

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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An American National Standard
e1
Designation: D 2837 – 01a
Standard Test Method for
Obtaining Hydrostatic Design Basis for Thermoplastic Pipe
1
Materials
This standard is issued under the fixed designation D 2837; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1
e NOTE—The terms Hydrostatic Design Stress and Pressure Rating were editorially updated in June 2002.
1. Scope accordance with this test method’s requirements, this straight
line may be assumed to continue beyond the experimental
1.1 This test method describes a procedure for obtaining a
period, through at least 100 000 h (the time intercept at which
long-term hydrostatic strength category, referred to herein as
the material’s LTHS is determined). In the case of polyethylene
the hydrostatic design basis (HDB), for thermoplastic pipe
piping materials, this test method includes a supplemental
materials based on the material’s long-term hydrostatic
requirement for the “validating” of this assumption. No such
strength (LTHS). The LTHS is determined by analyzing stress
validation requirements are included for other materials (see
versus time-to-rupture (that is, stress-rupture) test data that
Note 1). Therefore, in all these other cases, it is up to the user
cover a testing period of not less than 10 000 h and that are
of this test method to determine based on outside information
derived from sustained pressure testing of pipe made from the
whether this test method is satisfactory for the forecasting of a
subject material. The data are analyzed by linear regression to
material’s LTHS for each particular combination of internal/
yield a best-fit log-stress versus log time-to-fail straight-line
external environments and temperature.
equation. Using this equation, the material’s mean strength at
the 100 000-h intercept (LTHS) is determined by extrapolation.
NOTE 1—Extensive long-term data that have been obtained on com-
The resultant value of the LTHS determines the HDB strength mercial pressure pipe grades of polyvinyl chloride (PVC), polybutlene
(PB), and cross linked polyethlene (PEX) materials have shown that this
category to which the material is assigned. An HDB is one of
assumption is appropriate for the establishing of HDB’s for these
a series of preferred long-term strength values. This test
materials for water and for ambient temperatures. Refer to Note 2 and
method is applicable to all known types of thermoplastic pipe
Appendix X1 for additional information.
materials, and for any practical temperature and medium that
1.4 The experimental procedure to obtain individual data
yields stress-rupture data that exhibit an essentially straight-
points shall be as described in Test Method D 1598, which
line relationship when plotted on log stress (pound-force per
forms a part of this test method. When any part of this test
square inch) versus log time-to-fail (hours) coordinates, and for
method is not in agreement with Test Method D 1598, the
which this straight-line relationship is expected to continue
provisions of this test method shall prevail.
uninterrupted through at least 100 000 h.
1.5 General references are included at the end of this test
1.2 Unless the experimentally obtained data approximate a
method.
straight line, when calculated using log-log coordinates, it is
1.6 This standard does not purport to address all of the
not possible to assign an HDB to the material. Data that exhibit
safety concerns, if any, associated with its use. It is the
high scatter or a “knee” (a downward shift, resulting in a
responsibility of the user of this standard to establish appro-
subsequently steeper stress-rupture slope than indicated by the
priate safety and health practices and determine the applica-
earlier data) but which meet the requirements of this test
bility of regulatory limitations prior to use.
method tend to give a lower forecast of LTHS. In the case of
1.7 The values stated in inch-pound units are to be regarded
data which exhibit excessive scatter or a pronounced “knee,”
as the standard. The values given in parentheses are for
the lower confidence limit requirements of this test method are
information only and are not considered the standard.
not met and the data are classified as unsuitable for analysis.
1.3 A fundamental premise of this test method is that when
NOTE 2—Over 3000 sets of data, obtained with thermoplastic pipe and
the experimental data define a straight-line relationship in
piping assemblies tested with water, natural gas, and compress
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