Improving Safety of Crude Oil and Regional Water System Pipeline

CrossingsPipeline Safety Conference

November 5, 2010Delvin E. DeBoer, Ph.D., P.E.

South Dakota State University

Outline

• 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

– 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 Water System

Number of

crossings

Water Pipe

diametersWater Pipe

materialCasing

materialCasing

Provider

Total Casing length

Vertical Distance

from water

pipe to oil pipe

A 14 1.5" - 8" Yelomine PVCYelomine

PVC

Winwater Works

Company 300 ft 7 ft

B 4 2" - 12" Yelomine PVCYelomine PVC, Steel DSG

300-340 ft 6 ft

C 7 1.5" - 4" Yelomine PVCYelomine

PVC DSG 100 ft 7 ft

D 11 2" - 6" Yelomine PVCC900 fused

PVCUnderground

Solution 200 ft 10 - 12 ft

E 13 2" - 12" Yelomine PVCYelomine

PVC DSG 100 ft 10 - 20 ft

F 21 1.5" - 18"

Bell/Spigot PVC, Yelomine PVC,

ductile iron none 1.5 ft or

more

Tensile Strength Tests

Tension Test Data

Parallel Plate Compression Test

0

500

1000

1500

2000

2500

3000

3500

4000

0 0.5 1 1.5 2

Axi

al L

oad,

lbf

Axial Displacement, in

Parallel Plate Compression Test

Control 1B

Pipe stiffness, lbf/in

Stiffness factor in^3 * lbf/in^2

Slope = 5447 lbf/in

Slope = 3068 lbf/in

Slope = 427 lbf/in

O-Ring Tension Test

O-Ring Test

Next Steps

• Obtain Crude Oil Sample• Conduct tests (6-10 months)• Interpret results• Convene Design Standard Committee– Draft a local design standard– Agency review