Long-Distance Pipelines Crossing Rivers or Highways

Long-Distance Pipelines Crossing Rivers or Highways

How Deep Well Anodes Are Used:
A crude oil pipeline must cross underneath a highway or drill beneath a riverbed. The coating on the crossing section is easily scratched by rocks. After the crossing is completed, it is impossible to dig up the road or river to add more anodes. Before construction, the crew drills two deep wells at both ends of the crossing, lowers the tubular anodes into stable soil below the riverbed or highway subgrade, and welds the cables to the crossing pipe.

Primary Purpose:
To provide long-term, impressed current protection for crossing sections that cannot be accessed later.

Problems It Solves for Customers:

Difficult maintenance: Once the crossing is backfilled, any attempt to inspect or replace anodes would require closing the highway or stopping navigation, costing hundreds of thousands of dollars. A deep well anode is designed for a service life of over 20 years - one unit outlasts a dozen ordinary anodes.

High soil resistivity: Sandy gravel below a river or compacted subgrade below a highway has high resistivity. Ordinary anodes cannot deliver enough current. Tubular anodes have a large surface area and are surrounded by dedicated coke backfill, which lowers the ground resistance and pushes the current farther.

Avoiding pipe damage: Some have tried to install sacrificial anodes directly on crossing pipes, but the welding heat can damage the coating and create hidden corrosion pits. Deep well anodes are welded far away from the main pipe body and do not affect the crossing installation quality.