ASTM D2992-96e1
(Practice)Standard Practice for Obtaining Hydrostatic or Pressure Design Basis for "Fiberglass" (Glass-Fiber-Reinforced Thermosetting-Resin) Pipe and Fittings
Standard Practice for Obtaining Hydrostatic or Pressure Design Basis for "Fiberglass" (Glass-Fiber-Reinforced Thermosetting-Resin) Pipe and Fittings
SCOPE
1.1 This practice establishes two procedures, Procedure A (cyclic) and Procedure B (static), for obtaining a hydrostatic design basis (HDB) or a pressure design basis (PDB) for fiberglass piping products, by evaluating strength-regression data derived from testing pipe or fittings, or both, of the same materials and construction, either separately or in assemblies. Both glass-fiber-reinforced thermosetting-resin pipe (RTRP) and glass-fiber-reinforced polymer mortar pipe (RPMP) are fiberglass pipe.
Note 1—For the purposes of this standard, polymer does not include natural polymers.
1.2 This practice can be used for the HDB determination for fiberglass pipe where the ratio of outside diameter to wall thickness is 10:1 or more.
Note 2—This limitation, based on thin-wall pipe design theory, serves further to limit the application of this practice to internal pressures which, by the hoop-stress equation, are approximately 20 % of the derived hydrostatic design stress (HDS). For example, if HDS is 5000 psi (34 500 kPa), the pipe is limited to about 1000-psig (6900-kPa) internal pressure, regardless of diameter.
1.3 This practice provides a PDB for complex-shaped products or systems where complex stress fields seriously inhibit the use of hoop stress.
1.4 Specimen end closures in the underlying test methods may be either restrained or free, leading to certain limitations.
1.4.1 Restrained Ends—Specimens are stressed by internal pressure only in the hoop direction, and the HDB is applicable for stresses developed only in the hoop direction.
1.4.2 Free Ends—Specimens are stressed by internal pressure in both hoop and longitudinal directions, such that the hoop stress is twice as large as the longitudinal stress. This practice may not be applicable for evaluating stresses induced by loadings where the longitudinal stress exceeds 50 % of the HDS.
1.5 The values stated in inch-pound units are to be regarded as the standard. The values in parentheses are given for information purposes only.
Note 3—There is no similar or equivalent ISO standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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e1
Designation: D 2992 – 96 An American National Standard
Standard Practice for
Obtaining Hydrostatic or Pressure Design Basis for
“Fiberglass” (Glass-Fiber-Reinforced Thermosetting-Resin)
1,2
Pipe and Fittings
This standard is issued under the fixed designation D 2992; 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.
e NOTE—Editorial corrections were made to Equations A1.17 and A1.19 in September 1999.
1. Scope information purposes only.
1.1 This practice establishes two procedures, Procedure A
NOTE 2—There is no similar or equivalent ISO standard.
(cyclic) and Procedure B (static), for obtaining a hydrostatic
1.6 This standard does not purport to address all of the
design basis (HDB) or a pressure design basis (PDB) for
safety concerns, if any, associated with its use. It is the
fiberglass piping products, by evaluating strength-regression
responsibility of the user of this standard to establish appro-
data derived from testing pipe or fittings, or both, of the same
priate safety and health practices and determine the applica-
materials and construction, either separately or in assemblies.
bility of regulatory limitations prior to use.
Both glass-fiber-reinforced thermosetting-resin pipe (RTRP)
and glass-fiber-reinforced plastic mortar pipe (RPMP) are
2. Referenced Documents
fiberglass pipe.
2.1 ASTM Standards:
1.2 This practice can be used for the HDB determination for
D 618 Practice for Conditioning Plastics and Electrical
fiberglass pipe where the ratio of outside diameter to wall
Insulating Materials for Testing
thickness is 10:1 or more.
D 883 Terminology Relating to Plastics
NOTE 1—This limitation, based on thin-wall pipe design theory, serves D 1598 Test Method for Time-to-Failure of Plastic Pipe
further to limit the application of this practice to internal pressures which,
Under Constant Internal Pressure
by the hoop-stress equation, are approximately 20 % of the derived
D 1599 Test Method for Short-Time Hydraulic Failure Pres-
hydrostatic design stress (HDS). For example, if HDS is 5000 psi (34 500
sure of Plastic Pipe, Tubing, and Fittings
kPa), the pipe is limited to about 1000-psig (6900-kPa) internal pressure,
D 1600 Terminology for Abbreviated Terms Relating to
regardless of diameter.
Plastics
1.3 This practice provides a PDB for complex-shaped prod-
D 2143 Test Method for Cyclic Pressure Strength of Rein-
ucts or systems where complex stress fields seriously inhibit 4
forced Thermosetting Plastic Pipe
the use of hoop stress.
D 3567 Practice for Determining Dimensions of “Fiber-
1.4 Specimen end closures in the underlying test methods
glass” (Glass–Fiber–Reinforced Thermosetting Resin)
may be either restrained or free, leading to certain limitations. 4
Pipe and Fittings
1.4.1 Restrained Ends—Specimens are stressed by internal
F 412 Terminology Relating to Plastic Piping Systems
pressure only in the hoop direction, and the HDB is applicable
F 948 Test Method for Time-to-Failure of Plastic Piping
for stresses developed only in the hoop direction.
Systems and Components Under Constant Internal Pres-
1.4.2 Free Ends—Specimens are stressed by internal pres- 4
sure with Flow
sure in both hoop and longitudinal directions, such that the
2.2 ISO Standard:
hoop stress is twice as large as the longitudinal stress. This 5
3 Preferred Numbers—Series of Preferred Numbers
practice may not be applicable for evaluating stresses induced
by loadings where the longitudinal stress exceeds 50 % of the 3. Terminology
HDS.
3.1 Definitions:
1.5 The values stated in inch-pound units are to be regarded
3.1.1 General—Definitions are in accordance with Termi-
as the standard. The values in parentheses are given for
nologies D 883 and F 412, and abbreviations are in accordance
with Terminology D 1600, unless otherwise indicated.
This practice is under the jurisdiction of ASTM Committee D-20 on Plasticsand
is the direct responsibility of Subcommittee D20.23on Reinforced Plastic Piping
Systems and Chemical Equipment. Annual Book of ASTM Standards, Vol 08.01.
Current edition approved April 10, 1996. Published June 1996. Originally Annual Book of ASTM Standards, Vol 08.04.
published as D 2992 – 71. Last previous edition D 2992 – 91. Available from American National Standards Institute, 11 W. 42nd St., 13th
This revision incorporates a change in the data-analysis procedure. Floor, New York, NY 10036.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 2992
3.1.2 closure, free-end—a sealing device or mechanism cally, will cause failure of the pipe after a specified number of
fastened to the end of the test specimen so that internal pressure cycles by Procedure A or a specified number of hours by
produces longitudinal tensile stresses in addition to hoop and Procedure B.
radial stresses in the test specimen.
NOTE 5—The time for determination of LTHS or LTHP is specified by
3.1.3 closure, restrained-end—a sealing device or mecha- 6 6
the product standard. Typically, the time is 150 3 10 or 657 3 10 cycles
nism which relies on a rod through the test specimen or an
for Procedure A and 100 000 or 438 000 h for Procedure B.
external structure to resist the end thrust produced by internal
3.1.13 long-term hydrostatic pressure (LTHP)—the esti-
pressure, thereby limiting the stresses in (straight) specimens to
mated internal pressure of the piping product that, when
the hoop and radial directions only.
applied cyclically, will cause failure of the product after a
3.1.4 failure—the transmission of the test fluid through the
specified number of cycles by Procedure A or a specified
body of the specimen in any manner, whether it be a wall
number of hours by Procedure B.
fracture, localized leaking, or weeping at a distance greater
3.1.14 pressure design basis (PDB)—an internal pressure
than one diameter from the end closure.
developed for fiberglass piping product by this practice and
NOTE 3—For this practice, specimens which have not failed may be
multiplied by a service design factor to obtain an HDP.
included as failures under the specific conditions given in 6.3, 9.3, and
3.1.15 pressure rating (PR)—the estimated maximum pres-
12.2.
sure in the pipe or fitting that can be exerted continuously with
3.1.5 fiberglass pipe—a tubular product containing glass a high degree of certainty that failure of the piping component
fiber reinforcement embedded in or surrounded by cured
will not occur.
thermosetting-resin; the composite structure may contain ag- 3.1.16 service design factor—a number equal to 1.00 or less
gregate, granular or platelet fillers, thixotropic agents, pig- that takes into consideration all the variables and degree of
ments, or dyes; thermoplastic or thermosetting liners or coat-
safety involved in a fiberglass piping installation so that when
ings may be included. it is multiplied by the HDB, an HDS and corresponding
3.1.6 reinforced plastic mortar pipe—a fiberglass pipe with
pressure rating is obtained, or when it is multiplied by the PDB,
aggregate. a pressure rating is obtained directly, such that in either case a
3.1.7 reinforced thermosetting resin pipe—a fiberglass pipe
satisfactory and safe piping installation results when good
without aggregate. quality components are used and the installation is made
3.1.8 hoop stress—the tensile stress in the wall of the piping
properly.
product in the circumferential direction due to internal pres- 3.2 Definitions of Terms Specific to This Standard:
sure; hoop stress will be calculated by the ISO equation, as
3.2.1 average outside diameter—a measurement obtained
follows: in accordance with Practice D 3567 less any veil-reinforced
and nonreinforced exterior coating thicknesses.
S 5 P D 2 t /2t (1)
~ !
r r
3.2.2 minimum reinforced wall thickness—a measurement
where:
obtained in accordance with Practice D 3567, excluding veil-
S 5 hoop stress, psi (kPa),
reinforced and nonreinforced coating and lining thicknesses;
D 5 average reinforced outside diameter, in. (mm),
wall thickness of fittings is determined at the thinnest section of
P 5 internal pressure, psig (kPa), and
the fitting body.
t 5 minimum reinforced wall thickness, in. (mm).
r
4. Summary of Practice
NOTE 4—Hoop stress should only be determined on straight hollow
4.1 Procedure A consists of exposing a minimum of 18
cylindrical specimens. Product evaluation of more complex shapes may be
specimens of pipe or fittings, or both to cyclic internal
based on pressure.
pressures at a cycle rate of 25 cycles/min and at several
different pressures. Elevated test temperatures are obtained by
3.1.9 hydrostatic design basis (HDB)—a hoop stress devel-
oped for fiberglass pipe by this practice and multiplied by a circulating a hot liquid through the specimens or by testing in
an air environment where the temperature is controlled.
service design factor to obtain an HDS.
3.1.10 hydrostatic design pressure (HDP)—the estimated 4.1.1 The cyclic LTHS or cyclic LTHP of a pipe or fitting is
maximum internal hydrostatic pressure that can be applied obtained by an extrapolation of a log-log plot of the linear
cyclically (Procedure A) or continuously (Procedure B) to a regression line for hoop stress or internal pressure versus
piping component with a high degree of certainty that failure of cycles to failure.
the component will not occur. 4.1.2 The experimental basis for Procedure A shall be in
3.1.11 hydrostatic design stress (HDS)—the estimated accordance with Test Method D 2143, which forms a part of
maximum tensile stress in the wall of the pipe in the hoop this practice. When any part of the procedure is not in
direction due to internal hydrostatic pressure that can be agreement with Test Method D 2143, the provisions of this
applied cyclically (Procedure A) or continuously (Procedure B) practice shall be used.
with a high degree of certainty that failure of the pipe will not 4.1.3 Joints between pipe and fitting specimens shall be
occur. typical of those normally used for the kind of piping being
3.1.12 long-term hydrostatic strength (LTHS)— the esti- tested.
mated tensile stress in the wall of the pipe in the hoop direction 4.2 Procedure B consists of exposing a minimum of 18
due to internal hydrostatic pressure that, when applied cycli- specimens of pipe or fittings, or both, to constant internal
D 2992
hydrostatic pressures at differing pressure levels in a controlled process and material are used both for test specimens and the
environment and measuring the time to failure for each piping in question.
pressure level. Test temperatures are obtained by immersing 5.4 Pressure ratings at each temperature for components
the specimens in a controlled-temperature water bath, by other than straight hollow shapes may be calculated using the
testing in an air environment where the temperature is con- HDP determined by testing one size of piping provided that (1)
trolled, or by circulating a temperature-controlled fluid through the specific materials and manufacturing process used for the
the specimen. test specimens are used for the components, (2) for joints, the
4.2.1 The static LTHS or static LTHP of a pipe or fitting is joining materials and procedures used to prepare the test
specimens are used for field joining, and (3) scaling of critical
obtained by an extrapolation of a log-log linear regression line
for hoop stress or internal pressure versus time to failure. dimensions is related to diameter and pressure rating of the
component.
4.2.2 The experimental basis for Procedure B shall be in
accordance with either Test Method D 1598 or Test Method
NOTE 6—Scaling of fittings and joints should be further verified by
F 948, or both, which form a part of this practice. When any
short-time testing in accordance with Test Method D 1599.
part of this practice is not in agreement with the selected
5.5 Results obtained at one set of environmental conditions
method, the provisions of this practice shall be used.
should not be used for other conditions, except that higher
4.2.3 Joints between pipe and fitting specimens shall be
temperature data can be used for design basis assignment for
typical of those normally used for the kind of piping being
lower application temperatures. The design basis should be
tested.
determined for each specific piping product. Design and
4.3 The HDB category is obtained by categorizing the
processing can significantly affect the long-term performance
LTHS in accordance with Section 7 or Section 10.
of piping products, and therefore should be taken into consid-
4.4 The PDB category is obtained by categorizing the LTHP
eration during any evaluation.
in accordance with Section 8 or Section 11.
5.6 This practice is valid for a given pipe or fitting only so
4.5 Hydrostatic design stresses for pipe are obtained by
long as the specimens are truly representative of that material
multiplying the HDB values by a service design factor.
and manufacturing process.
4.6 Reconfirmation of HDB or PDB for Altered
5.6.1 Changes in materials or manufacturing processes will
Constructions—When a product already has an HDB or PDB
necessitate a reevaluation as described in Section 12.
determined in accordance with this practice and a change of
process or material is made, a reconfirmation of the original
PROCEDURE A
HDB or PDB may be attempted in accordance with Section 12.
At least six specimens must be tested and meet the specified 6. Long-Term Cyclic Hydrostatic Strength or Long-Term
criteria. Cyclic Hydrostatic Pressure
6.1 Select either free-end or restrained-end closures based
5. Significance and Use
on the tensile stresses induced by internal pressure and the type
5.1 This practice is useful for establishing the hoop stress or of joint in the intended piping system (see 1.4).
internal pressure versus time-to-failure relationships, under 6.2 Obtain a minimum of 18 failure stress-cycle points for
selected internal and external environments which simulate each selected temperature in accordance with Test Method
actual anticipated product end-use conditions, from which a D 2143 except as follows:
design basis for specific piping products and materials can be 6.2.1 Determine the average outside diameter and the mini-
obtained. This practice defines an HDB for material in straight, mum reinforced wall thickness in accordance with Practice
hollow cylindrical shapes where hoop stress can be easily D 3567.
calculated, and a PDB for fittings and joints where stresses are
NOTE 7—Because of the need to cut the spec
...
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