ASTM D2837-04
(Test Method)Standard Test Method for Obtaining Hydrostatic Design Basis for Thermoplastic Pipe Materials or Pressure Design Basis for Thermoplastic Pipe Products
Standard Test Method for Obtaining Hydrostatic Design Basis for Thermoplastic Pipe Materials or Pressure Design Basis for Thermoplastic Pipe Products
SCOPE
1.1 This test method describes two essentially equivalent procedures: one for obtaining a long-term hydrostatic strength category based on stress, referred to herein as the hydrostatic design basis (HDB); and the other for obtaining a long-term hydrostatic strength category based on pressure, referred to herein as the pressure design basis (PDB). The HDB is based on the material's long-term hydrostatic strength (LTHS),and the PDB is based on the product's long-term hydrostatic pressure-strength (LTHSΡ). The HDB is a material property and is obtained by evaluating stress rupture data derived from testing pipe made from the subject material. The PDB is a product specific property that reflects not only the properties of the material(s) from which the product is made, but also the influence on product strength by product design, geometry, and dimensions and by the specific method of manufacture. The PDB is obtained by evaluating pressure rupture data. The LTHS is determined by analyzing stress versus time-to-rupture (that is, stress-rupture) test data that cover a testing period of not less than 10 000 h and that are derived from sustained pressure testing of pipe made from the subject material. The data are analyzed by linear regression to yield a best-fit log-stress versus log time-to-fail straight-line equation. Using this equation, the material's mean strength at the 100 000-h intercept (LTHS) is determined by extrapolation. The resultant value of the LTHS determines the HDB strength category to which the material is assigned. The LTHSΡ is similarly determined except that the determination is based on pressure versus time data that are derived from a particular product. The categorized value of the LTHSΡ is the PDB. An HDB/PDB is one of a series of preferred long-term strength values. This test method is applicable to all known types of thermoplastic pipe materials and thermoplastic piping products. It is also applicable for any practical temperature and medium that yields stress-rupture data that exhibit an essentially straight-line relationship when plotted on log stress (pound-force per square inch) or log pressure (pound-force per square in. gage) versus log time-to-fail (hours) coordinates, and for which this straight-line relationship is expected to continue uninterrupted through at least 100 000 h.
1.2 Unless the experimentally obtained data approximate a straight line, when calculated using log-log coordinates, it is not possible to assign an HDB/PDB to the material. Data that exhibit high scatter or a "knee" (a downward shift, resulting in a subsequently steeper stress-rupture slope than indicated by the earlier data) but which meet the requirements of this test method tend to give a lower forecast of LTHS/LTHSΡ. In the case of data that exhibit excessive scatter or a pronounced "knee," the lower confidence limit requirements of this test method are not met and the data are classified as unsuitable for analysis.
1.3 A fundamental premise of this test method is that when the experimental data define a straight-line relationship in accordance with this test method's requirements, this straight line may be assumed to continue beyond the experimental period, through at least 100 000 h (the time intercept at which the material's LTHS/LTHSΡ is determined). In the case of polyethylene piping materials, this test method includes a supplemental requirement for the "validating" of this assumption. No such validation requirements are included for other materials (see Note 1). Therefore, in all these other cases, it is up to the user of this test method to determine based on outside information whether this test method is satisfactory for the forecasting of a material's LTHS/LTHSΡ for each particular combination of internal/external environments and temperature.
Note 1—Extensive long-term data that have been obtained on commercial pressure pipe grades of polyvinyl chloride (PVC), polybutlene (PB), and cross l...
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An American National Standard
Designation:D2837–04
Standard Test Method for
Obtaining Hydrostatic Design Basis for Thermoplastic Pipe
Materials or Pressure Design Basis for Thermoplastic Pipe
1
Products
This standard is issued under the fixed designation D2837; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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. Scope materials and thermoplastic piping products. It is also appli-
cable for any practical temperature and medium that yields
1.1 This test method describes two essentially equivalent
stress-rupture data that exhibit an essentially straight-line
procedures: one for obtaining a long-term hydrostatic strength
relationshipwhenplottedonlogstress(pound-forcepersquare
category based on stress, referred to herein as the hydrostatic
inch) or log pressure (pound-force per square in. gage) versus
design basis (HDB); and the other for obtaining a long-term
logtime-to-fail(hours)coordinates,andforwhichthisstraight-
hydrostatic strength category based on pressure, referred to
line relationship is expected to continue uninterrupted through
herein as the pressure design basis (PDB). The HDB is based
at least 100000 h.
on the material’s long-term hydrostatic strength (LTHS),and
1.2 Unless the experimentally obtained data approximate a
the PDB is based on the product’s long-term hydrostatic
straight line, when calculated using log-log coordinates, it is
pressure-strength (LTHS ). The HDB is a material property
P
not possible to assign an HDB/PDB to the material. Data that
and is obtained by evaluating stress rupture data derived from
exhibit high scatter or a “knee” (a downward shift, resulting in
testing pipe made from the subject material. The PDB is a
a subsequently steeper stress-rupture slope than indicated by
productspecificpropertythatreflectsnotonlythepropertiesof
the earlier data) but which meet the requirements of this test
the material(s) from which the product is made, but also the
method tend to give a lower forecast of LTHS/LTHS.Inthe
P
influenceonproductstrengthbyproductdesign,geometry,and
case of data that exhibit excessive scatter or a pronounced
dimensions and by the specific method of manufacture. The
“knee,” the lower confidence limit requirements of this test
PDB is obtained by evaluating pressure rupture data. The
methodarenotmetandthedataareclassifiedasunsuitablefor
LTHS is determined by analyzing stress versus time-to-rupture
analysis.
(that is, stress-rupture) test data that cover a testing period of
1.3 Afundamental premise of this test method is that when
not less than 10000 h and that are derived from sustained
the experimental data define a straight-line relationship in
pressure testing of pipe made from the subject material. The
accordance with this test method’s requirements, this straight
data are analyzed by linear regression to yield a best-fit
line may be assumed to continue beyond the experimental
log-stress versus log time-to-fail straight-line equation. Using
period, through at least 100000 h (the time intercept at which
this equation, the material’s mean strength at the 100000-h
the material’s LTHS/LTHS is determined). In the case of
intercept (LTHS) is determined by extrapolation. The resultant P
polyethylene piping materials, this test method includes a
value of the LTHS determines the HDB strength category to
supplemental requirement for the “validating” of this assump-
which the material is assigned. The LTHS is similarly
P
tion. No such validation requirements are included for other
determined except that the determination is based on pressure
materials (see Note 1). Therefore, in all these other cases, it is
versustimedatathatarederivedfromaparticularproduct.The
uptotheuserofthistestmethodtodeterminebasedonoutside
categorized value of the LTHS is the PDB. An HDB/PDB is
P
information whether this test method is satisfactory for the
oneofaseriesofpreferredlong-termstrengthvalues.Thistest
forecasting of a material’s LTHS/LTHS for each particular
P
method is applicable to all known types of thermoplastic pipe
combination of internal/external environments and tempera-
ture.
1
This test method is under the jurisdiction ofASTM Committee F17 on Plastics
NOTE 1—Extensive long-term data that have been obtained on com-
Piping Systems and is the direct responsibility of Subcommittee F17.40 on Test
mercial pressure pipe grades of polyvinyl chloride (PVC), polybutlene
Methods.
(PB), and cross linked polyethlene (PEX) materials have shown that this
CurrenteditionapprovedJune1,2004.PublishedJuly2004.Original
...
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