ASTM F690-86(1994)
(Practice)Standard Practice for Underground Installation of Thermoplastic Pressure Piping Irrigation Systems
Standard Practice for Underground Installation of Thermoplastic Pressure Piping Irrigation Systems
SCOPE
1.1 This practice covers general and basic procedures related to the proper installation of thermoplastic, flexible, pressure piping, 36 in. nominal size and smaller, for underground irrigation systems. Because there is considerable variability in end-use requirements, soil conditions, and thermoplastic piping characteristics, it is the intent of this practice to outline general objectives and basics of proper installation and to provide pertinent references, rather than to prescribe detailed installation procedures.
1.2 This practice should not be used for installing thermoplastic underground sewer, drain, potable water, conduit or gas service piping.
1.3 The values stated in inch-pound units are to be regarded as the standard. Values in parentheses are given for information only.
1.4 This standard does not purport to address all of the safety problems, 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.
General Information
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Standards Content (Sample)
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Designation: F 690 – 86 (Reapproved 1994) An American National Standard
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Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Practice for
Underground Installation of Thermoplastic Pressure Piping
Irrigation Systems
This standard is issued under the fixed designation F 690; 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.
1. Scope not damage the pipe and shall be recommended for use at the
design pressure for the pipeline. Consult the manufacturer for
1.1 This practice covers general and basic procedures re-
design and installation recommendations and refer to Practice
lated to the proper installation of thermoplastic, flexible,
F 402.
pressure piping, 36 in. nominal size and smaller, for under-
3.3 When steel or other metallic joining materials, subject to
ground irrigation systems. Because there is considerable vari-
corrosion, are used in the line, they shall be adequately
ability in end-use requirements, soil conditions, and thermo-
protected by wrapping or coating with high quality corrosion
plastic piping characteristics, it is the intent of this practice to
preventatives. Wrapping or coatings that are applied on metal-
outline general objectives and basics of proper installation and
lic surfaces should not be applied on plastic pipes and fittings
to provide pertinent references, rather than to prescribe detailed
unless it is first established by consulting the piping manufac-
installation procedures.
turer that they have no detrimental effect on the plastic.
1.2 This practice should not be used for installing thermo-
3.4 Joining specifications are listed under 2.1.3.
plastic underground sewer, drain, potable water, conduit or gas
3.5 Manufacturers of joining materials should be consulted
service piping.
for specific assembly instructions not covered by existing
1.3 The values stated in inch-pound units are to be regarded
specifications. When requesting information, the intended ser-
as the standard. Values in parentheses are given for information
vice application should be defined.
only.
1.4 This standard does not purport to address all of the
4. Trench Preparation
safety problems, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4.1 Trench Depth—In stable granular soils which tend to be
priate safety and health practices and determine the applica-
relatively smooth, and free of all rocks and debris larger than
bility of regulatory limitations prior to use.
⁄2 in. (13 mm) in sizes, excavation may proceed directly to
final grade. Where rocks of other protrusions are encountered
2. Referenced Documents
which may cause point loading on the pipe, the trench bottom
2.1 ASTM Standards:
should be overexcavated to permit installation of proper
D 2487 Test Method for Classification of Soils for Engi-
bedding (see Section 5).
neering Purposes
4.2 Trench Width—The width of the trench at any point
D 2488 Practice for Description and Identification of Soils
below the top of the pipe should be established with attention
(Visual-Manual Procedure)
given to these considerations:
F 402 Practice for Safe Handling of Solvent Cements,
4.2.1 The wider the trench at the top of the pipe, the greater
Primers, and Cleaners Used for Joining Thermoplastic Pipe
the earth load imposed on the pipe until the prism load has been
and Fittings
achieved.
4.2.2 Trench width should allow sufficient and safe working
3. Joints and Connections
room for proper alignment and assembly of the joints. Gener-
3.1 Joints and connections shall be assembled to withstand
ally, a trench width at the top of the pipe of about 2 ft (600 mm)
the design working pressure for the pipeline without leakage,
wider than the pipe diameter is adequate. However, for pipe
internal restriction or obstruction, which could reduce line
with an 18-in. (457-mm) diameter and larger in a vertical-
capacity below design requirements.
walled trench, a clearance of 3 ft (1 m) wider than the nominal
3.2 All joining materials shall be of composition that will
pipe size may be needed. For sloped trenches, a minimum of an
18-in. (457-mm) greater trench bottom width than the pipe
diameter allows sufficient width. If a wider trench becomes
This practice is under the jurisdiction of ASTM Committee F-17 on Plastic
Piping Systems and is the direct responsibility of Subcommittee F17.61 on Water.
necessary, the enlargement should be restricted as much as
Current edition approved Sept. 11, 1986. Published October 1986. Last previous
possible to only that section above the top of the pipe.
edition F 690 – 80.
4.2.3 Trench width should allow adequate room for snaking
Annual Book of ASTM Standards, Vol 04.08.
Annual Book of ASTM Standards, Vol 08.04. when recommended by the manufacturer or as may be required
NOTICE:¬This¬standard¬has¬either¬been¬superceded¬and¬replaced¬by¬a¬new¬version¬or¬discontinued.¬
Contact¬ASTM¬International¬(www.astm.org)¬for¬the¬latest¬information.¬
F 690
to accommodate thermal expansion or contraction. joints to cool or solvent-cemented joints to cure for the
4.2.4 Narrower trench widths may be utilized by joining the minimum prescribed time before moving the pipe. While
moving larger diameter pipe lines, care should be taken to
pipe above ground and lowering it into the trench, provided
enough room is available in the trench for proper haunching. avoid excessive stressing of the joints.
Precautions outlined in 5.2 shall be followed. 5.3 Ensure that elastomeric seal joints are not installed so
4.3 Trench Depth—The trench depth shall be established they remain excessively deflected. Consult the pipe manufac-
turer for maximum permissible joint deflection limits.
with consideration given to requirements imposed by founda-
tion, bedding, pipe size, and cover. 5.4 Changes in the grade and line of direction of the pipe
shall be limited and shall be gradual enough so that the bending
4.4 Foundation—An adequate and stable foundation should
be present, or provided, for proper support at the total trench of the pipe will develop neither excessive diametrical expan-
sion nor excessive bending stresses. At no time should the pipe
load.
4.4.1 Foundation preparation is not necessary when smooth be blocked or braced to hold a bend. Excess curvature can
create stresses which could induce pipe failure under pressure.
stable trench bottoms are encountered.
4.4.2 Foundation preparation is necessary when unstable Consult the pipe manufacturer for recommended minimum
pipe bending radius.
trench bottom conditions are encountered. The designer should
specify the stabilizing method and materials which will satis- 5.5 When installing pipe with elastomeric seal, flanged
joints, or with any connector which protrudes beyond the pipe
factorily stabilize the encountered condition and provide ad-
equate and permanent support. diameter, bell holes should be excavated in the bedding
material or trench bottom to permit the pipe to be continuously
4.5 Bedding—The bedding material should consist of
supported. After pipe assembly and placement in the trench,
gravel, sand, silty sand, silty gravel, or clayey sand in granular
each bell hole should be filled with bedding material and
form and having a maximum particle size of ⁄4 in. (19 mm).
compacted if necessary to attain the same general density as the
4.5.1 Bedding shall be provided whenever rock, hard pan,
rest of the bedding.
boulders, or other materials that might damage the pipe are
5.6 It is advisable to permit newly installed pipe to cool to
encountered in the trench bottom at the established pipe grade.
approximately ground temperature prior to backfilling. This
4.5.2 When bedding is used, it shall be kept as nearly
will minimize the development of contraction stresses on the
uniform in depth as possible to minimize differential settle-
joints and, in the case of solvent-cemented connections, it will
ment.
prevent the possibility of joint separation due to contraction
4.6 Minimum Earth Cover—Protection from traffic loading
forces acting on an incompletely cured bond. Typically, pipe
or frost penetration, or both should be considered when
will cool adequately soon after being placed on a shaded-trench
establishing minimum earth cover requirements.
bottom.
4.6.1 For installations exposed to normal farm vehicle
5.7 Where differential settlement could create concentrated
traffic, the minimum total cover should not be less than:
1 loading on a pipe or joint, for example, at a point of connection
Pipe1to2 ⁄2 in. in diameter: 18 in. (450 mm)
Pipe 3 to 4 in. in diameter: 24 in. (600 mm) of a buried pipe to a rigid structure, such as a manhole,
Pipe 5 in. and larger in diameter: 30 in. (750 mm)
manufacturer’s recommendations should be followed to pre-
Pipe 5 to 18 in. in diameter: 30 in. (750 mm)
vent, or to properly relieve, damaging and shearing forces. One
Pipe 18 in. and larger in diameter: 36 in. (900 mm)
technique is to use extra care when compacting the foundation
4.6.2 The pipe line should be installed at sufficient depths to
and bedding under a rigid structure. Other techniques might
provide protection from traffic crossing, farming operations,
include construction of a supporting structure underneath the
and soil cracking. Load-bearing capabilities of installed pipe
joint and the pipe of about three diameters in cross section or
vary with type of pipe, type of backfill, soil conditions, and
the utilization of a flexible joint.
installation procedures. Consult the manufacturer for informa-
5.8 Special Installation—With certain pipes and in some
tion on product response to expected maximum earth loading.
soil conditions it is possible to install long lengths of pipe by
4.6.3 The trench depth shall be sufficient to ensure place-
the plowing-in technique. Consult the manufacturer for recom-
ment of the top of the pipe at least 10 in. (250 mm) below the
mendations.
known frost line. When conditions and design requirements
prevent satisfaction of this requirement, system design and 6. Thrust Blocking
installation must ensure proper drainage in the low portions of
6.1 When installing piping systems that include joints that
the line.
are not self restraining (for example, elastomeric seal type)
thrust blocking may be necessary at certain points in the
5. Pipe Assembly and Installation
system, such as changes in direction, in order to prevent
5.1 Preparation of Joints—Joint assembly shall be done in possible disengagement of the fitting from the pipe.
accordance with specifications listed under 2.1.3. 6.2 Thrust blocking is required where line shift or joint
5.2 If the pipe is to be assembled above ground, it should be separation at system operating pressure can be anticipated, that
lowered into the trench, taking care not to drop it or damage it is, pump discharge, directional changes, reducers, and dead
against the trench walls, nor to subject it or its joints to ends. Thrust blocking is essential to the proper performance of
treatment, such as, dragging or excessive bending which could high pressure irrigation piping when the system includes
be injurious to the piping. With elastomeric seal joints, take non-self-restraining joints. (See Fig. 1.)
care to avoid joint displacement and pull out. Allow heat-fused 6.3 Thrust Block Construction:
NOTICE:¬This¬standard¬has¬either¬been¬superceded¬and¬replaced¬by¬a¬new¬version¬or¬discontinued.¬
Contact¬ASTM¬International¬(www.astm.org)¬for¬the¬latest¬information.¬
F 690
FIG. 1 Types of Thrust Blocking
6.3.1 The thrust block should be constructed of concrete 7.2.3 Ensure that all entrapped air is released from the line
having a compression strength of 2000 psi (14 MPa) or more. while filling. The system should include appropriate air and
Wood blocking, or stone blocking with wood wedges, are not vacuum relief valves for proper function during operation after
acceptable. installation.
6.3.2 The thrust block acts as an anchor between pipe or 7.2.4 The pipeline should be filled but not pressurized until
fitting and the solid trench wall. The size of the thrust block the engineer is ready to witness or conduct the pressure test.
should be adequate to prevent pipe movement at the point of 7.3 Inspection and Repairs—The line should be pressurized
thrust. Consult the system designer. to 125 % of the system’s design operating pressure, for the
6.3.3 The thrust block cavity should be hand dug into time necessary to check all joints but not to exceed 1 h. While
undisturbed soil and framed, with soil or wood to hold freshly under pressure, inspect all joints for leaks. Any leaks found
poured concrete. The earth-bearing surfaces should be undis- should be repaired, and the line recharged and retested.
turbed.
8. Backfilling Procedures
6.3.4 Before pressurizing the line, ensure that adequate time
is allowed for the concrete thrust blocks to set.
8.1 Haunching and Initial Backfill—This practice covers
those thermoplastic piping products which may be deflected
7. Line Charging and Testing
considerably, without structural damage. The flexibility of the
7.1 If possible, the pipeline should be thoroughly inspected pipe enables it to utilize the passive resistance of the soil to
and tested for leaks before backfilling. When so testing, it is support loads externally applied to the pipe. The resistance of
advisable to anchor the pipe by placing haunching and initial the soil is affected by the type of soil, its density and moisture
backfill up to about 6 in. (150 mm) over the pipe, taking care content. Therefore, the higher the soil resistance, the less the
to leave all joints and fittings exposed for inspection. pipe will deflect. Proper techniques for pipe embedment are
7.2 Line Charging: necessary to ensure that the passive soil resistance required to
7.2.1 Before filling and proceeding to test, sufficient time prevent excessive pipe deflection will be developed and
should be allowed for solvent-cemented joints to cure or maintained. The designer will determine the minimum material
heat-fused joints to cool. requirements and extent of compaction depending on pipe
7.2.2 With valves at ends and high points open, the pipelines selected and the end-use conditions. The following embedment
should be slowly filled with water, limiting the flow velocity to materials are recommended (see Classification D 2487 and
1 ft/s (0.3 m/s) to prevent surge, or water hammer
...
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