HomeMy WebLinkAbout15_CorrosionAvgCalcs&Table5
< 500 ohm-cm 30
500 - 1000 ohm-cm 25
> 1000 - 1500 ohm-cm 22
> 1500 - 2000 ohm-cm 19
> 2000 - 3000 ohm-cm 10
> 3000 - 5000 ohm-cm 5
> 5000 ohm-cm 0
> 100 ppm = positive 8
50 - 100 ppm = trace 3
< 50 ppm = negative 0
> 15% = Wet 5
5 - 15% = Moist 2.5
< 5% = Dry 0
Pipe below the water 5
table at any time
pH 0 - 4 4
pH > 4 - 6 1
pH 6 - 8, with sulfides
and low or negative redox 4
pH > 6 0
positive ( 1 ppm)4
trace ( > 0 and < 1 ppm) 1.5
negative ( 0 ppm) 0
= negative 2
= positive 0 - 100 mv 1
= positive > 100 mv 0
Connected to noble metals 2
(e.g. copper) - yes
Connected to noble metals 0
(e.g. copper) - no
TOTAL POSSIBLE POINTS
Cinders, Mine Waste, Peat Bog,
Landfill, Fly Ash, Coal
RESISTIVITY
CHLORIDES
MOISTURE
CONTENT
GROUND WATER
INFLUENCE
pH
SULFIDE
IONS
REDOX
POTENTIAL
BI-METALLIC
CONSIDERATIONS
Known Corrosive
Environments
POINTS
30
8
5
5
4
4
2
2
60
21
* Soils with Known Corrosive Environments shall be assigned 21 points
or the total of points for Likelihood Factors, whichever is greater.
Likelihood Score Sheet
TABLE 2
– >
– >
MAXIMUM
POSSIBLE
POINTS
LIKELIHOOD FACTOR AVG. CALCS
19 (1740 OHM)
3 (50 PPM)
5 (19.4%)
5 (YES)
0 (7.58)
1.5 (ASSUMED)
0 (287.75 mV)
2 (YES)
35.5/60
6
DIPRA and Corrpro again listened to the needs of utility
operators and recognized the differences between long,
large diameter, straight-run transmission mains and the
more complicated networks of distribution pipelines that
bring water to our neighborhoods and businesses. The result
provides a more practical solution for pipeline networks that
comprise the distribution systems within a utility’s service
area. The use of V-Bio® enhanced polyethylene encasement
in conjunction with metallized zinc provides water operators
with an effective alternative to controlling corrosion in
distribution systems.
3” to 24” 0
30” to 36” 8
42” to 48” 12
54” to 64” 22
Routine (Fair to good access,
minimal traffic/other utility 0
consideration, etc.)
Moderate (Typical business/
residential areas, some right 8
of way limitations, etc.)
Difficult (Subaqueous
crossings, downtown
metropolitan business areas, 20 multiple utilities congestion,
swamps, etc.)
0 to 10 feet depth 0
> 10 to 20 feet depth 3
> 20 feet depth 5
Alternate supply available - no 3
Alternate supply available - yes 0
TOTAL POSSIBLE POINTS
PIPE SERVICE
LOCATION:
Construction-Repair
Considerations
DEPTH OF COVER
CONSIDERATIONS
ALTERNATE WATER SUPPLY
POINTS
22
20
5
3
50
Consequence Score Sheet
TABLE 3
The revised
DDM® recognizes
the practical
differences in
corrosion control
needs between
transmission mains
and distribution
systems.
MAXIMUM
POSSIBLE
POINTS
CONSEQUENCE FACTOR AVG. CALCS
0 (8")
8
0 (6.5')
0 (YES)
8/50