Dist_FriAM_Willson_Light Rail Transit.pdf

Stray current corrosion on pipelines due to DC metro in cities.

1. Light Rail Transit Systems
Stray Current:
A Pipeline Owner’s Guide
2009 Spring Conference
Pacific Northwest Section, AWWA
May 8, 2009

2. Light Rail System Operation

3. Why Care? ™
Historically (pre-1920s) stray current was
a problem
™
Without measures, can effect your pipe
™
Present current mitigation measures do
work

4. Why Care? ™
“Do no harm”
™
Light Rail system
owner is responsible
for mitigation

5. What the Utility Owner Should Know ™
Location of all light rail crossings
™
Type of trackworkat your crossing
™
Location of traction power substations

6. What the Utility Owner Should Know ™
Baseline pipe-to-soil
potential testing prior
to light rail system

7. Rail Designers ™
Locate all light rail
alignment utility crossings
™
Determine the depth of
crossings
™
Determine what utilities
need to be relocated
™
Set up maintenance
testing and inspection
program

8. Factors Affecting Vulnerability ™
Rail-to-earth resistance
™
Substation spacing & placement
™
Voltage/train load
(current)

9. Factors Affecting Vulnerability ™
Soil resistivity
™
Distance of piping
from track
™
Quality of piping
coating

10. Factors Affecting Vulnerability ™
Orientation and
geometry of piping to
the trackwork
™
Long electrically
continuous piping
™
Crossings

11. Means to Reduce Stray Current ™
High resistance
fasteners
™
“Rail Boot”
(embedded
trackwork)
™
High resistance tie
materials

12. Means to Reduce Stray Current ™
Computer simulations
CatPro Approximation

13. Recommendations for Utility Owners ™
Establish committee with owner/utility
companies/industry
™
Ensure Light Rail System Owner has stray
current testing program
™
Perform pipe-to-soil potential testing prior
to and after the Light Rail System
energization
♦
Use 24-hour recorders

14. Recommendations for Utility Owners ™
Crossings
♦
Install insulation joints on each side of crossing
♦
Install cathodic protection system
♦
Install neoprene mat
♦
Use plastic pipe

15. Recommendations for Utility Owners ™
Parallel
♦
Install test stations
♦
Install cathodic protection system

16. Q&A