Abstract
The internal cathodic protection of large steel pipe carrying sea water is discussed both from the practical and the theoretical viewpoint. Systems considered involved use of such devices as concentric cylindrical anodes, off-center cylindrical anodes, wall mounted anodes, and central point lead alloy anodes fed with impressed current from a dc source. The cathodic protection was applied to both bare and coated pipe. Testing was done both in the laboratory and on a full scale level.
The designing of a potential measuring device and the determination of protection criteria are considered briefly. Other topics discussed include coating the pipe interior, computing the costs of cathodic protection, and determining the relationship between anode separation and anode diameter in pipes with the same coating and electrolyte.
It was found that coatings will effect the largest economies on the smaller diameter pipe where the cost of the cable is lowest and where smaller anode supports can be used with small anodes. At the moment the most economical method of protection seems to involve the use of a cheap readily applied coating of reasonable resistance and cathodic protection from point anodes mounted at or close to the center line of the pipe. 5.2.3
