Detecting Causes of Electrolysis in Pipelines – An Early Harbour Survey in Vancouver BC

Corrosion of pipelines and submerged metal caused by stray currents has been a problem since DC powered electric transit systems were introduced. Corrosion affects the infrastructure of the transit system but also underground telephone and electrical cables and pipelines carrying water and gas.

The construction of electric powered street cars in Vancouver triggered a study to determine if electric fields set up by the power system was causing electrolysis in the harbour. This could have easily caused damage to propellers and propeller shafts – and even to steel hulls of ships.

Engineers shown in the image undertaking a survey (that probably took several weeks) constructed a makeshift raft to carry their measurement devices as they surveyed the harbour to map the electrical field (on the 6th of May 1914 they undertook their study).

Retired civil engineer George Duddy surmises "One of the instruments on top of the stand on the raft appears to be a theodolite (probably used for triangulating the position of the float and streamed objects from the raft/ the boat shown in the other photo). It is also evident that streaming from the raft is a line of small floats perhaps supporting an unseen electrical cable."

A contemporary newspaper report stated that the electrolytic impact of an electric tram line on a proposed pipeline could be significant. Perhaps this work was part of the calculation of the impact of construction of underground infrastructure through electrolysis on existing systems.

Duddy further comments "I think what the photos probably show is probably a couple of electrodes (one appears to be lying on the deck of the raft) connected by cable of measured separation through some form of electrical measuring device (such as a galvanometer, voltmeter or some other similar instrument). Perhaps by doing measurements of stray currents throughout the waterway they hoped to determine changed patterns of voltage potential near electrical cables and perhaps the metal pipeline mentioned in the newspaper article."

All buried or immersed metallic structures are susceptible to stray current corrosion. Direct current powered tramways, underground pipelines, and storage tanks without corrosion protection systems are particularly susceptible to stray current corrosion. Modern technology now substantially reduces stray currents, and this is now less of a problem than when this study was undertaken.

References

Barlo, Thomas J. and Alan D. Zdunek (1995) Stray Current Corrosion in Electrified Rail Systems – Final Report

Email Communication (George Duddy – John MacFarlane 06/07/2019)

Vancouver Daily World (Vancouver BC) Friday, 08/08/1913 Page 17