7. Rubber Gasket Joints
7.1 Before Assembly
Before joining the spigot into the bell of
the pipe previously laid. the spigot
groove, the rubber gasket and the bell
shall be thoroughly cleaned. Then the
spigot groove, the rubber gasket and the
first 2 inches of the bell shall be lubricated with a soft, vegetable soap
compound. Gasket shall be positioned
in spigot groove so that the rubber is
distributed uniformly around the
circumference.
Note: Uniform distribution of gasket may be
accomplished by passing a smooth, round steel
rod under gasket and up onto opposite edge of
gasket groove, then moving the rod in this
position around the entire circumference of
the spigot.
7.2 Assembly
Pipe shall be joined together to provide
the proper space between abutting ends
of pipe. To maintain the laying length
shown on the contract drawings, the
width of the space provided at the joint
may be varied to compensate for the
permissible manufacturing tolerance in
pipe lengths of plus or minus % inch.
In pipel ines 24 inches and larger, metal
or wooden spacers shall be placed against
the inside shoulder of the bells. Joints in
smaller pipelines shall be prepared in
accordance with Section 8.1.
For long radius curves and for slight
changesor correction in alignment and
grade, joints may be pulled on one side
of pipe and most joint designs may be
partially closed on opposite side. The
amount of deflection must not exceed
that recommended for the type of
joint being used.
7.3 After Assembly
After a joint is assembled, a thin metal
feeler gauge shall be inserted between bell
and spigot and the position of the rubber
gasket checked around the complete
circumference of the pipe. If gasket is
not in proper position, the pipe shall
be withdrawn, the gasket checked to see
that it is not cut or damaged,the pipe
relaid, and the gasket position again
checked.
encasethe outside joint except for an
opening near the top where mortar
grout is to be poured into the joint
recess.
8. Irlside Joint Recess
8.1 Pipe, 21-lnch Diameter and Smaller
Prior to assembling the joint, the inside
shoulder of the bell shall be "buttered"
with a stiff mortar consisting of 1 part
Portland cement to 1'12parts of sand.
An accessory such as a specially designed
rubber ball wrapped with burlap shall
be used (1) to provide back-up against
which the mortar is squeezed while the
centered spigot is pushed "home" and
(2) to hold mortar in place in the
assernbled joint while alignment and
grade are adjusted, the next bell is
"buttered" and the next spigot is
centered. The accessory shall screed off
excess mortar to leave a smooth and
continuous surface between pipe sections
as it is drawn through the pipe.
8.2 Pipe, 24-lnch Diameter and Larger
After the pipe zone bedding and backfill
have been densified, the inside joint
recessof pipe 24 inches in diameter and
larger shall first be moistened, then
filled and pointed with a stiff cement
mortar consisting of 1 part cement to
lY. parts of sand. The finished joint shall
be smooth and flush with the adjacent
pipe surfaces. Interior joint pointing
operations shall not be conducted within
two joints of pipe laying operations.
9. Exterior
Joint Recess
9.1 Mortar Coated Pipe
After joining mortar coated pipe, a cloth
or plastic* band at least 8 inches in
width shall be centered and secured over
the exterior joint recess. The band shall
be bound to the pipe by the use of
steel box strapping or by an equivalent
method and shall completely and snugly
After the band is properly secured, the
joint recessshall be moistened with water
and then filled with mortar consisting
of 1 part Portland cement to 2 parts
of sand mixed with water to the
consistency of thick cream. The mortar
grout shall completely fill the outside
annular space between the ends of the
pipe and around the complete
circumference. After the recesshas been
filled, the opening shall be clo~d and the
mortar allowed to ~t before bedding and
backfilling at the joint.
9.2 Asphalt or Coal-Tar Wrapped Pipe
After the joint has been properly
assembled,areasto be coated shall be
thoroughly cleaned. An asphalt or
coal-tar wrap shall then be applied in
accordance with the recommendations of
the pipe manufacturer. Coal-tar coated
field joints shall be inspected as required
by Section 2.14.3.5 of "Coal-Tar Enamel
Protective Coatings and Linings for
Steel Water Pipelines-Enamel and Tape-'Hot Applied" (ANSI/AWWA C203).
10. Anchorage for Bends and Fittings
Where indicated on the contract
drawings, suitable meansof anchoring the
pipeline against movement shall be
provided. Details of anchoragesshall be
as specified by the engineer or as
submitted by the contractor and
approved by the engineer. Anchorage
of the pipeline may be provided by
casting concrete thrust blocks or by
field-welding joints.
10.1 Concrete Thrust Blocks
Concrete blocking shall be cast-in-place
between undisturbed earth-bearing
surfaces and the fitting or bend to be
anchored. Should any sloughing of the
*Plastic bands are closed-cell polyethylene foam excavation sides OCCUr,additional
.
t
. d ft
strips with cloth backing and are recommended
f
ed -' ...
I I .concre
e require a er removi ng the
or ,mprov Joint protection, partlcu ar y In
aggresivesoils. Additional information will
loose earth shall be placed at the
be supplied on request.
contractor's expense. Blocking shall,
3
unless otherwise shown or directed, be
so placro that joints of pipe and fittings
will beoccessible for repair.
"Standard Test Method for Relative
Density of Cohesionless Soils" (ANSI/
ASTM C'2049).
10.2 Field-Welded Joints
Where specifically permitted on the
drawings, or approved by the engineer.
the contractor may substitute fieldwelded joints capable of withstanding
axial tension in place of. or in conjunction
with. the regular rubber gasket joints.
Note: In this specification, a "cohesion less
free-draining soil" is defined as a soil whose
dry density in pounds per cubic foot at 70
percent relative density is greater than its dry
density at 90 percent of laboratory standard
maximum dry density.
12. Soil Cement Grout
12.1 Materials
Soil cement grout shall consist of a
mixture of properly selected soil.
11. Pipe Zone Bedding and Backfill
Portland cement and water. Portland
Pipe installation shall be classified as
cement shall conform to the "Standard
E'=400. E'=700, E'=1000, or Soil Cement Specification for Portland Cement"
Bedding along the entire reach of the
(ANSI/ASTM C 150), Type lor II.
pipeline as shown on the plans and
unlessotherwise specified. The minimum
drawings. Bedding and backfill shall
cement content shall be two sacks (94
be densified around the pipe to the height pounds per sack) per cubic yard.
over top of pipe as shown in Figure 1.
Soil may be any combination of gravel,
Soils shall be blended sufficiently to
sand, silt and clay, native or imported,
secure t~ best practicable degree of
which meets the following requirements:
density,.)d stability.
12.1.1 Not more than 10 percent of the
The dry oonsity of compacted soil for
material by weight shall be larger than
each bedding and backfill shall be not
314
inch, and none of the material shall
less than shown in Figure 1.
be larger than one inch.
Bedding and Backfill
Soil densities are expressedas a percent
of the Icjx)ratory standard maximum dry
soil density as determined in accordance
with "Sta'ldard Test Methods for
Moisture-Density Relations of Soils
Using 5.5-lb Rammer and 12-in. Drop"
iASTM Designation: D 698 or AASHTO
Designation: T 99).
tn-place tests of soil density shall be made
wnaccordance with "Standard Test
Method for Density of Soil in Place by
Sand-C~ Method" (ASTM Designation:
U 1556) or "Standard Test Method for
Density of Soil in Place by the RubberBalloon Method" (ANSI/ASTM D 2167).
Cohesionk!ssfree-draining soils shall be
classified ~ E'=700 and shall be
consolidated to 70 percent relative
density when tested in accordance with
4
12.1.2 The soil fraction passingthe
No. 200 sieve shall, in combination with
the cement, be sufficient to insure that
the soil remains in suspensionwhile the
mixture is being placed.
12.1.3 Materials which contain
considerable amounts of organic matter
shall not t>eused.
Soil cement and water shall be so
proportioned that the minimum
compressive strength will be at least 50
psi at sevendays as determined on two
companion cylinders taken twice during
each working shift. Material poured into
cylinder molds shall not be vibc.atedor
tamped.
Forty-eight hours before testing,
cylinders shall be totally immersed in
water. Twenty-four hours before capping
and testing, cylinder shall be removed
from water and allowed to drain and air
dry. The averagediameter of the
cylinders used for calculating the crosssectional area shall be determined before
the cylinders are immersed in water.
Cylinders shall otherwise be tested in
accordance with "Standard Test Method
for Compressive Strength of Cylindrical
Concrete Specimens" (ANSI/ASTM
C39).
12.2 Mixing and Placing
Soil cement grout shall be thoroughly
mixed and the presenceof lumps, clods
or foreign matter shall be minimized.
Water added in the mixer shall not exceed
that required to insure a fluid, readily
pumpable mixture. Grout shall be placed
in lifts on both sides of pipe in a manner
that will prevent floating or shifting of
pipe. Light poling or vibration will be
permitted. Soil cement grout may not
be placed if the ground is frozen or the
ambient temperature is below 40 degrees
Fahrenheit.
Within 1 hour after placement, soil
cement grout shall be covered with a
maximum of 6 inches of damp earth.
Pipe zone backfill may not be completed
until 24 hours after placement of grout.
Fill material shall not be dropped directly
on the pipe.
13. Densification
Regardlessof the method of densification
used, materials shall be brought up at
substantially the same rate on both sides
of the pipe and care shall be taken so that
the pipe is not floated or displaced.
Fill material shall not be dropped directly
on the pipe.
Pipe Zone Bedding and Backfill Classifications
Notes:
1. Soil densities are expressed asa percent of maximum
dry soil density as determined by ASTM Designation:
D 698 or AASHTO Designation T 99.
2. Backfills require that the contractor prepare a firm but
yielding subgrade.
3. Pipe zone backfill height over top of pipe (HT) shall
be at least % pipe inside diameter for pipe larger than
24 inches, and 6 inches for pipe 24 inches or smaller.
4. E' values shown are Spangler's Modulus of Soil
Reaction.
5. Trench sides may remain vertical or may be sloped as
required. See Section 1.
5
13.1 Mechanical Col11>action
Soils identified as cohesive shall be
densified by compaction using
mechanical or hand tamping. Equipment
with suitably shaped tCMnpingfeet shall
be used to compact the material and
insure that the ~ecified soil density is
obtained beneath the haunches of the
pipe. All material shall pass a .1Y2-inch
screen and not more than 50 percent
shall pass a No. 200 sieve. At the time of
placement, the materials shall have the
optimum moisture content requ ired for
compaction, and the moisture content
shall be uniform throughout each layer.
Materials shall be placed in layers not
more than 6 ind1es thick after
compaction.
13.2 Hydraulic Consolidation
Soils identified as free-draining may be
densified by tamping or by consolidation
with water using any or all of the
following devices or rTW!thods:water jets,
immersion type vibrators, bulkheading
and flooding, or sluicing. Consolidation
of earth materials by hydraulic methods
shall be used only if both the materials
to be densified and the native soil in
which the trend1 is excavated are free
draining. Materials shall passa 1 Y2-inch
screen and not more than 15 percent shall
pass a No. 200 sieve. The thickness of
layers shall not be more than the
penetrating depth of the vibrators jf
consolidation is performed by jetting and
internal vibration.
14. Backfill Above PipeZone
Trench backfill above the pipe zone
bedding and b;K;kfill to the surface of the
native ground shall be placed so that the
resulting density will be approximately
equivalent to the density of the original
material in which the trench was
excavated. Trench backfill shall not be
placed until conform~ce of pipe zone
bedding and backfill with specified
compaction test requirements has been
confirmed. Free-draining materials may
be densified by hydraulic methods if
the native soil in whim the trench was
excavated is also free-draining but such
6
methods shall not distrub pipe zone
bedding and backfill. Cohesive materials
shall be compacted with tamping or
rolling equipment. To prevent excessive
live loads on the pipe, sufficient densified
backfill but not less than 3 feet over the
pipe shall be in place before poweroperated hauling or rolling equipment
travels over the pipe.
Mobile pavement breakers or pile-driving
equipment shall not be used for
compacting backfill at any stage of the
operations.
performed until a satisfactory test has
been completed. Regardlessof the test
results, all detectable leaks shall be
repai red by the contractor.
References
1. ..A Method of Determining Permissible
Earth Cover Loads on Concrete Cylinder
Pipe." Ameron Engineering Library
No. 1-1.
Testing
2. "Guide Specifications for Installation
of Concrete Pressure Pipe, Rigid
Designs," Ameron.
15. Hydrostatic Field Tests
Test sections and test pressuresshall be
planned so that during the field test no
pipe section will be subjected to a
pressure lessthan 100 percent or more
than 120 percent of the actual operating
pipeline pressure.
3. Lowitz, C. A. and DeGroot, G., "SoilCement Pipe Bedding: Canadian River
Aqueduct,"
Proceedings, American
Society of Civil Engineers, Journal,
Construction Division, 94, C01, January,
Prior to testing, the section of the
pipeline to be tested shall be filled with
water and placed under a slight pressure
for at least 48 hours. The pipeline shall
then be brought up to the test pressure
determined by the engineer and that
pressure shall be maintained on the
section under test for a period of not
less than 4 hours. Accurate means shall
be provided for measuring the quantity
of water required to maintain full
pressure on the line for the test period.
The volume of water required to maintain
the test pressureshall not exceed. ..*
gallons per inch of diameter per mile of
pipe per 24 hours.
In the event that the rate of loss of water
during the test is greater than that stated
above, the contractor shall locate the
leaks and perform the required repairs.
If necessary,additional tests shall be
.Since pipeline leakage is dependent on many
factors. allowable values vary. Recommended
requirements for specific designs may be
obtained on request. A value of 50 gallons is
commonly used for pressure pipe with steel
cylinder and rubber gasket joint.
1968.
4. Chappelear, D. L. and Gloyna, E. L.,
"Innovations in the Laying and Bedding
of Pipe," Civil Engineering-ASCE,
December, 1967, pp. 57-60
To insure long life and trouble-free
service from a successfulpipeline
installation, proper application by the
contracting agencyof the essential
principles of excavation, laying and
jointing, bedding, backfilling and field
testing is required. It is equally essential
that these principles be reflected in the
phrasing of contract documents and that
the agencyenfor~ them through its
inspection.
specification should be properly
administered and enforced by the
contracting agency, there is no
assurance-specific or implied-that
inclusion of theseparagraphs in a
specification will insure a successfuljob,
however, they should assist materially
in accomplishing this objective.
The recommended practices presented
in this guide specification for the
installation of rubber gasketed,cementmortar lined pressure pipe, ranging from
semi-rigid to flexible, are developed from
the two basic concepts outlined below.
80th should be rigorously maintained
to obtain best results.
First, each section of pipe should be
kept substantially round during
unloading, storage and throughout
backfilling operations. Properly
embedded pipe will remain essentially
round becauseof the passiveresistance
of the soil on its sides and the uniform
support of the bedding. As the degree
of pipe flexibility increases,structural
behavior becomes more dependent on
the supporting value of the pipe zone
material.
Second, the manufacturer's recommendations for assemblingpipe sections
and completing joint protection should
be enforced. Rubber gasketsshould be
stretched uniformly when in position
on spigots; joint surfacesand gasket
should be clean and well lubricated;
entry of spigot end into bell of adjacent
pipe section should be performed with
reasonablecare; position of the gasket
should be checked after joint closure;
and inside and outside annual joint
recessesshould be correctly filled with
cement mortar.
Thesespecifications are intended to be
used as a guide and should be amended
and expanded to meet the requirements
of a specific job. Becauseany
7
5.
Scope
This specification covers the usual
procedures involved in the installation of
mortar-lined pressure pipe, including
excavation, laying, jointing, bedding,
backfilling and testing. Th is specification
does not cover sheeting or bracing of
trenches, restorations required, special
obstructions or conditions, or general
con tractu raI obligations.
2.2 Subgrade for Soil Cement Bedding
Trenches for pipe which is to be bedded
with a soil cement grout shall be
excavated to the depth and shape
indicated on the contract drawings. All
loose material shall be removed from the
trench.
the pipe be installed permanently on
timbers, earth mounds, pile bents or
other similar supports unlessspecific pipe
designs which are adequate for these
abnormal conditions are provided by
the engineer.
Note: The radius of the cradle excavation
should be sufficient to provide at least a 2-inch
space between pipe and subgrade for adequate
placement of the soil cement grout.
Laying and Jointing
Excavation and Subgrade
3. Special Subgrade Densification
1. Trench Width
The narrowest practicable trench width
at top of pipe which will allow proper
densification of pipe zone bedding and
backfill materials shall be maintained
regardlessof the type of soil in which
the pipeline is to be laid, the depth of
the excavation or the method of
densification. If sides of the trench
remain vertical after excavation, and
bedding and backfill are to be consolidated by hydraulic method, the minimum
width of trench at top of pipe shall be 00
plus 16 inches. If the pipe zone bedding
and backfill require densification by
compaction, the width of trench at
bottom of pipe shall be determined by
the space required for proper and
effective use of tamping equipment,
but not less than pipe 00 plus 16 inches.
3.1 Unyielding Material
Where excavation is in rock, hardpan,
shale or other similar hard and unyielding
materials, the trench shall be excavated
to a depth at least 4 inches below the
established grade line and filled with welldensified material* to a depth 1 inch
below the grade line. The subgrade shall
then be completed with 1 inch of loose
selected materials as described in
Section 2.1.
2. Normal Subgrade
The contractor shall prepare a subgrade
which will provide continuous, uniform
support under the haunches of the pipe
after bedding and backfilling.
2.1 Flat Bottom Trenches
Flat bottom trenches shall be excavated
to a depth not lessthan 1 ind1 below the
established grade line of the outside
bottom of the pipe. The exress
excavation shall then be filled with loose
bank run material from whiffi all stones
larger than 1 ind1 in diameter have been
removed. This loose subgradematerial
shall be graded uniformly to the
established grade line for the full length
of the pipe.
2
3.2 Unstable Material
When excavation is in soft, unstable
material which is unsuitable as a
foundation for pipe. such material shall
be removed asdirected by the engineer
and replaced with well-densified material
to a depth 1 inch below the established
grade line. The subgradeshall then be
completed with 1 inch of loose selected
material as described in Section 2.1.
3.3 Non-Uniform Material
Voids formed by removal of boulders or
other interfering objects extending below
ilormal excavation limits shall be filled
with suitable, well-densified material.
4. Special Support
Special means of support may be
provided but under no conditions shall
*In this specification, "well-densified material"
is defined as that which is densified to at least
85 percent of the laboratory standard
maximum dry soil density as determined by
ASTM Designation: 0698, or at least 70
percent relative density in free-draining soils
as determined by ANSI/ASTM 02049 (see
Section 11).
Laying
The pipe shall be laid to the lines and
grades shown on the contract drawings
except as amended and supplemented
by the manufacturer's tabulated layout
schedule and approved by the engineer.
The work shall be scheduled so that the
bell end of the pipe faces in the direction
of laying wherever practicable. When
laying pipe, the pipe trench shall be
kept free from water which might impair
the integrity of bedding and joining
operations. Pipe sections to be bedded
with soil cement grout may be laid to
grade using mounds of a free-draining
soil near each end for temporary support.
5.1 Handling and Storage
Handling and storage of pipe shall be in
accordance with the recommendations
of the manufacturer. All necessary
precautions shall be taken to maintain
the protection afforded by the lining and
coating. The pipe shall at all times be
handled using proper equipment and
must never be pushed or draggedalong
the ground. Pipe shall further be handled
and stored so that the dimensional
integrity of joint configuration and
roundness of pipe are assured. The
dielectric resistance of asphalt or coal-tar
coatings shall be preserved by careful
storage and handling, including slings and
supports padded as necessary.
6. Interior Bracing of Pipe
Design, installation and performance of
pipe bracing used during installation
shall be the responsibility of the
contractor. Use of bracing placed wholly
or in part by the manufacturer shall not
relieve the contractor of this
responsibility.