Underground Flashcards
Standard for the installation of private fire service mains
NFPA 24
What determines minimum earth cover on water mains
Frost line and surface load conditions
Excavation must conform with
Federal, Provincial, and municipal regulations
Once the frost line has been determined, the top of pipe shall be
1’ below the frost line
In areas where frost is not a factor, where shall the top of pipe be
Top of pipe 2’-6” below grade
Piping underneath driveways shall be buried a minimum of
3’ to the top of the pipe
Any pipe crossing underneath railroad tracks shall be a minimum of
4’ to top of pipe
Depth cover map is read from the
Top down
Why do fire mains require a deeper depth then city water mains
Because they are mostly static for there daily service
Trench bottom must be
True and even to fully support pipe
Trench bottom can be improved by adding crushed stone how big
3” in diameter (should be compacted)
Where rock sub grade or stones larger then 1 1/2 are encountered, how much bedding shall be used on top
4”
Flat bottom is defined as
Un-disturbed earth
Loose soil or select material is defined as
Native soil excavated
Type 1 laying condition is
Flat bottom
Type 2 laying condition is
Flat bottom, backfill lightly to centreline of pipe
Type 3 laying condition
Pipe bedded in 4” minimum loose soil, backfill to top of pipe
Type 4 laying condition
Pipe in sand, gravel, or crushed stone to depth of 1/8” of pipe diameter. 4” minimum
Type 5 Laying condition
Pipe bedded to its centreline in compacted granulated material, 4” min under pipe
Ductile iron pipe can be cut using
- abrasive cut off saw
- rotary wheel cutter
- guillotine saw
- milling saw
What saw is used for out of trench cuts/quick cuts
Abrasive cut off saw
Rotary wheel cutter can cut pipe up too what size
30”
Guillotine saw can cut pipe up to what size
16”
Miling wheel saw can cut pipe up too
6” or larger
Cast iron cut ends should be
Beveled to 30 degrees and 1/8” back from the edge
Time required for mechanical cutting of ductile iron is
1 minute per 1” of diameter
Gauge lines on PVC pipe indicate
If the pipe is in the bell socket
4 parts of mechanical joint for ductile are
Flange with bell, rubber gasket, a gland, and tee head bolts
Ductile iron pipe lengths are
18 feet
18 foot lengths of ductile iron (3-12” pipe) can be deflected how much
12-19” per joint
18 foot lengths of ductile iron (14-42” pipe) can be deflected how much
11” per joint
PVC max deflection is
1 degree
Thrust forces are created when pipeline
Changes direction
Soil under streets must be compacted
To the street sub grade
Soil under streets are generally compacted in
6-12” lifts
When can frozen backfill be used
Never
Underground acceptance test consists of
200 psi for 2 hours or 50 psi above system pressure, whichever is greater. Allowed up to 5 psi loss
Tested for underground must occur where
-At the lowest elevation point of the system (no hydrants)
-hydrant outlet
Flushing must produce a flow of at least
10ft/Sec (3m/sec)
Incoming spigot can be no higher then
24”
What is used to anchor fittings
Pipe clamps
Tie rods
Thrust blocks
Concrete mixture for thrust blocks is
1 part cement
2 1/2 parts sand
5 parts stone
Cast iron pipe first made in
1600’s western Germany
Asbestos cement pipe is commonly used in areas with
Corrosive soil conditions
Rubber gaskets in mechanical joints should be
Dipped in water or dipped in glycerine if in sub freezing weather
Steel pipe that is externally wrapped and internally Galv can be used
Between FDC and check valve
All pipe in underground shall be rated for a max system working pressure of not less then
150psi
Underground pipe shall be permitted to extend into a building (wall or slab) no more then
24”
Fittings shall be rated too no less then
150 psi
All connections of copper tube shall be
Brazed or joined using pressure fittings
2 dissimilar pipe types are joined, what is required
Insulated against the passage of electric current
The depth of pipe shall be measured from the
Top of the piping to final grade
Mains under large piles of heavy commodities or subject to heavy vibrations shall be buried at a minimum depth of
4 feet
Mains above ground shall be protected with
Bollards or other means approved by AHJ
Fire mains to extend no further than ____ under the building
10 feet/3 metres (measured from outside wall to centre of pipe going vertical)
Piping shall be a minimum of ___ from foundation or footings
12 inches
All joints shall be
Mechanically restrained
A valve shall be installed before the piping enters the building within ____ from the building
24”
Fire mains shall be restrained against movement at
Changes in direction
Thrust blocks shall be placed so that
Joints are accessible for repair
Clamps for pipe 4-6”
1/2 x 2”
Clamps for pipe 8-10”
5/8 x 2 1/2”
Clamps for 12” pipe
5/8 x 3”
Diameter of a bolt hole in clamps shall be
1/8” bigger then the bolt
Bracing Rods shall not be less then
5/8”
Rods must be
Symmetrically spaced
Clamp bolts 4-8”
5/8
Clamp bolts for 10”
3/4”
Clamp bolts 12”
7/8”
Washers shall be
Cast iron or steel, round or square
When using bolting rods, the diameter of the mechanical joint bolts cannot be bigger then
3/4”
Bell ends shall be installed facing
Uphill
Type 1&2 sloping
1:1 with max of 4’ from ground
Type 3 sloping
1:1 starting from the bottom
Type 4 sloping
1:3 starting from bottom
Angle for sloping
45 degrees
Type 1 soil
Hard ground, difficult to drive pick axe into
Type 2 soil
Soft ground, easy to drive pick axe into
Type 3 soil
Previously excavated
Type 4 soil
Material containing high moisture
Ladders to be no more then ___ apart in trenches
25 feet
Cathodic protection is
Anode welded to pipe, will corrode instead of pipe
Copper underground can only be what type
type k
PVC comes in lengths of
20 feet
HDPE stands for
High density polyethylene
Bend radius for high density polyethylene pipe
25x the pipe diameter
What pipe uses a form of fusion
HDPE (high density polyethylene)
What size pipe is minimum for supplying hydrants
6”
Non-Metallic pipe requires trace wire ___ above it for trace purposes
1 foot
Caution tape is out how far below finish grade
2 feet
Incoming main for pipe scheduled system shall be no smaller then
The riser feeding the system
Ductile iron has what kind of joint
Tyton
Cast iron has what kind of joint
Poured led
PVC has what kind of joint
Push on
4-24” pipe has what size bolts and what is the Torque
3/4 bolts, 75-90ft/lbs
Joints that do not require restraint are
-threaded
-grooved
-welded
-heat fused
-chemical or solvent
Asbestos cement joining method
AC couplings
HDPE joining method
Fusion or victualic
Concrete pressure pipe is for sizes ____ and up
16”
Formula for hydrostatic allowance loss is
L=SD✔️P divided by 148000
S=length of pipe
D=Diameter of pipe
P=pressure test of system
Washers to be used on pipe that are which size
3-12”
Most common thrust block
Bearing
Bearing thrust block is used where on fitting
On outside of fitting
Gravity thrust block is used when
There is a change in elevation in the trench
Thrust blocks shall be installed in
Stable soil
Minimum size pipe for underground
6 inch
6” GPM to achieve 10ft/sec
880Gpm
8” GPM to achieve 10ft/sec
1560gpm
10” GPM to achieve 10ft/sec
2440gpm
12” GPM to achieve 10ft/sec
3520gpm
Peto tube measures
Velocity
Gauge of wire for tracer wire is
10-14 gauge
AWWA means
American water works association
Hydrants to be installed how far from building
40 feet
Hydrants outlets are how far above the ground and how far above the floor in hose houses
18” and 12”
