ASTM D2837-08
(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
SIGNIFICANCE AND USE
The procedure for estimating long-term hydrostatic strength or pressure-strength is essentially an extrapolation with respect to time of a stress-time or pressure-time regression line based on data obtained in accordance with Test Method D 1598. Stress or pressure-failure time plots are obtained for the selected temperature and environment: the extrapolation is made in such a manner that the long-term hydrostatic strength or pressure strengthis estimated for these conditions.
Note 3—Test temperatures should preferably be selected from the following: 40°C; 50°C; 60°C; 80°C; 100°C. It is strongly recommended that data also be generated at 23°C for comparative purposes.
The hydrostatic or pressure design basis is determined by considering the following items and evaluating them in accordance with 5.4.
Long-term hydrostatic strength or hydrostatic pressure-strength at 100 000 h,
Long-term hydrostatic strength or hydrostatic pressure-strength at 50 years, and
Stress that will give 5 % expansion at 100 000 h.
The intent is to make allowance for the basic stress-strain characteristics of the material, as they relate to time.
Results obtained at one temperature cannot, with any certainty, be used to estimate values for other temperatures. Therefore, it is essential that hydrostatic or pressure design bases be determined for each specific kind and type of plastic compound and each temperature. Estimates of long-term strengths of materials can be made for a specific temperature provided that calculated values, based on experimental data, are available for temperatures both above and below the temperature of interest.
Hydrostatic design stresses are obtained by multiplying the hydrostatic design basis values by a service (design) factor.
Pressure ratings for pipe may be calculated from the hydrostatic design stress (HDS) value for the specific material used to make the pipe, and its dimensions using the equations in 3.1.11.
4.5.1 Pressure ratings...
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 (LTHSP). 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 LTHSP 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 LTHSP 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 applicabl...
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An American National Standard
Designation:D2837–08
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 (´) 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 method is applicable to all known types of thermoplastic pipe
materials and thermoplastic piping products. It is also appli-
1.1 This test method describes two essentially equivalent
cable for any practical temperature and medium that yields
procedures: one for obtaining a long-term hydrostatic strength
stress-rupture data that exhibit an essentially straight-line
category based on stress, referred to herein as the hydrostatic
relationshipwhenplottedonlogstress(pound-forcepersquare
design basis (HDB); and the other for obtaining a long-term
inch) or log pressure (pound-force per square in. gage) versus
hydrostatic strength category based on pressure, referred to
logtime-to-fail(hours)coordinates,andforwhichthisstraight-
herein as the pressure design basis (PDB). The HDB is based
line relationship is expected to continue uninterrupted through
on the material’s long-term hydrostatic strength (LTHS),and
at least 100000 h.
the PDB is based on the product’s long-term hydrostatic
1.2 Unless the experimentally obtained data approximate a
pressure-strength (LTHS ). The HDB is a material property
P
straight line, when calculated using log-log coordinates, it is
and is obtained by evaluating stress rupture data derived from
not possible to assign an HDB/PDB to the material. Data that
testing pipe made from the subject material. The PDB is a
exhibit high scatter or a “knee” (a downward shift, resulting in
productspecificpropertythatreflectsnotonlythepropertiesof
a subsequently steeper stress-rupture slope than indicated by
the material(s) from which the product is made, but also the
the earlier data) but which meet the requirements of this test
influenceonproductstrengthbyproductdesign,geometry,and
method tend to give a lower forecast of LTHS/LTHS.Inthe
P
dimensions and by the specific method of manufacture. The
case of data that exhibit excessive scatter or a pronounced
PDB is obtained by evaluating pressure rupture data. The
“knee,” the lower confidence limit requirements of this test
LTHS is determined by analyzing stress versus time-to-rupture
methodarenotmetandthedataareclassifiedasunsuitablefor
(that is, stress-rupture) test data that cover a testing period of
analysis.
not less than 10000 h and that are derived from sustained
1.3 Afundamental premise of this test method is that when
pressure testing of pipe made from the subject material. The
the experimental data define a straight-line relationship in
data are analyzed by linear regression to yield a best-fit
accordance with this test method’s requirements, this straight
log-stress versus log time-to-fail straight-line equation. Using
line may be assumed to continue beyond the experimental
this equation, the material’s mean strength at the 100000-h
period, through at least 100000 h (the time intercept at which
intercept (LTHS) is determined by extrapolation. The resultant
the material’s LTHS/LTHS is determined). In the case of
P
value of the LTHS determines the HDB strength category to
polyethylene piping materials, this test method includes a
which the material is assigned. The LTHS is similarly
P
supplemental requirement for the “validating” of this assump-
determined except that the determination is based on pressure
tion. No such validation requirements are included for other
versustimedatathatarederivedfromaparticularproduct.The
materials (see Note 1). Therefore, in all these other cases, it is
categorized value of the LTHS is the PDB. An HDB/PDB is
P
uptotheuserofthistestmethodtodeterminebasedonoutside
oneofaseriesofpreferredlong-termstrengthvalues.Thistest
information whether this test method is satisfactory for the
forecasting of a material’s LTHS/LTHS for each particular
P
1
This test method is under the jurisdiction ofASTM Committee F17 on Plastic
combination of internal/external environments and tempera-
Piping Systems and is the direct responsibility of Subcommittee F17.40 on Test
ture.
Methods.
Current edition approved May 1, 2008. Published June 2008. Originally
NOTE 1—Extensive long-term data that have been obtained on com-
´1
approved in 1969. Last previous edition approved in 2004 as D2837–04 . DOI:
mercial pressure pipe grades of polyvinyl chloride (P
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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.
An American National Standard
e1
Designation:D2837–04 Designation:D2837–08
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 (´) 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—Equation X4.5 was editorially corrected in November 2006.
1. 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
(LTHS ). The HDB is a material property and is obtained by evaluating stress rupture data derived from testing pipe made from
P
the subject material. The PDB is a product specific property that reflects not only the properties of the material(s) from which the
productismade,butalsotheinfluenceonproductstrengthbyproductdesign,geometry,anddimensionsandbythespecificmethod
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 10000 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-stressversuslogtime-to-failstraight-lineequation.Usingthisequation,thematerial’smeanstrengthatthe100000-hintercept
(LTHS) is determined by extrapolation. The resultant value of the LTHS determines the HDB strength category to which the
material is assigned. The LTHS is similarly determined except that the determination is based on pressure versus time data that
P
arederivedfromaparticularproduct.ThecategorizedvalueoftheLTHS isthePDB.AnHDB/PDBisoneofaseriesofpreferred
P
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 100000 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
tendtogivealowerforecastofLTHS/LTHS .Inthecaseofdatathatexhibitexcessivescatterorapronounced“knee,”thelower
P
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 100000 h (the time intercept at which the material’s LTHS/LTHS is determined). In the case of polyethylene
P
piping materials, this test method includes a supplemental requirement for the “validating” of this assumption. No such validation
requirementsareincludedforothermaterials(seeNote1).Therefore,inalltheseothercases,itisuptotheuserofthistestmethod
to determine based on outside information whether this test method is satisfactory for the forecasting of a material’s LTHS/LTHS
P 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
...
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