Improving Safety of Crude Oil and
Regional Water System Pipeline
Crossings
Pipeline Safety Conference
November 5, 2010
Delvin E. DeBoer, Ph.D., P.E.
South Dakota State University
Outline
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•
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•
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Who is the affected community?
What is their safety concern?
What is needed to address the concern?
What is the project approach?
What do we hope to accomplish?
South Dakota Regional Water Systems
Pipeline Crossings in SD
• Crossing characteristics
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PVC pipe through steel casing
PVC pipe through fusible PVC
PVC pipe through restrained joint PVC
Ductile Iron
Restrained joint PVC
PVC
• No Single Standard for design
• Desired elements of the crossing
– Protect oil pipeline from water pipe maintenance and repair
activities
– Protect the water pipeline in a spill event
• High cost of environmental liability insurance
AwwaRF (2008) study
• Focused on polyethylene and PVC pipes
• Exposed to pure gas and BTEX along with
water/solvent mixtures
• Studied gasket joints and ungasketed pipe
• Focused on permeation (exceeding drinking
water standards) under field conditions
(flowing water and stagnant water)
Conclusions - AwwaRF (2008)
• Permeation through Pipe Wall
– PE Pipe
• Rapid permeation (also documented in case studies)
– PVC pipe
• Depended on concentration of BTEX
• Pure solvents permeated in a matter of days (toluene
16 days, benzene 20 days) – pipes noticeably swollen
• Gasoline (BTEX) did not permeate in 2 years (due to
lower concentrations of BTEX than in pure solvent)
Conclusions - AwwaRF (2008)
• Hydrocarbon Permeation through gaskets in PVC
pipe
– IS a source of contamination
– NBR more resistant to permeation than SBR gaskets
– Under stagnant-flow conditions, can exceed MCL for
Benzene when submerged in free product gasoline
– Water flow through pipe dilutes benzene below MCL
(required flow depends on pipe size)
– Less potential for contamination if ground water
dilutes the gasoline
Unknowns
• What is the impact of crude oil products on
permeation through PVC pipe and gaskets?
• What are the permeation characteristics of
restrained joint pipe configurations (joints and
fittings)?
• What is the impact of crude oil on pipe
strength characteristics?
Scope of Project
• Assumption - restrained joint casing is likely the
low cost crossing option with good potential for
approval as a local design standard.
• Determine impacts of crude oil on small diameter
PVC pipe characteristics
– Permeability through PVC pipe wall and through joints
– Impacts on strength and physical characteristics
• Convene a committee to review results and
develop a local design standard
Rural Number Water
Water
of
Pipe
System crossings diameters
A
14
1.5" - 8"
B
4
2" - 12"
C
7
1.5" - 4"
D
11
2" - 6"
E
F
13
21
2" - 12"
Water Pipe
material
Yelomine PVC
Casing
material
Casing
Provider
Vertical
Distance
from
Total
water
Casing pipe to oil
length
pipe
Yelomine
PVC
Winwater
Works
Company
300 ft
7 ft
Yelomine
300-340
Yelomine PVC PVC, Steel
DSG
ft
6 ft
Yelomine
Yelomine PVC
PVC
DSG
100 ft
7 ft
C900 fused Underground
Yelomine PVC
PVC
Solution
200 ft 10 - 12 ft
Yelomine PVC
Bell/Spigot PVC,
Yelomine PVC,
1.5" - 18" ductile iron
Yelomine
PVC
none
DSG
100 ft 10 - 20 ft
1.5 ft or
more
Tensile Strength Tests
Tension Test Data
7000
Stress, psi
6000
5000
4000
3000
2000
1000
0
0
0.05
0.1
0.15
Strain, in/in
0.2
0.25
Parallel Plate Compression Test
Axial Load, lbf
Parallel Plate Compression Test
4000
3500
Slope = 5447 lbf/in
3000
2500
2000
Control 1B
Pipe stiffness, lbf/in
1500
Stiffness factor in^3 * lbf/in^2
1000
Slope = 427 lbf/in
500
Slope = 3068 lbf/in
0
0
0.5
1
Axial Displacement, in
1.5
2
O-Ring Tension Test
O-Ring Test
140
Force, lbf
120
100
80
60
40
20
0
0
5
10
15
Extension, in
1A (lbf)
2A (lbf)
3A (lbf)
4A (lbf)
5A (lbf)
20
Next Steps
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Obtain Crude Oil Sample
Conduct tests (6-10 months)
Interpret results
Convene Design Standard Committee
– Draft a local design standard
– Agency review