Tinker and Rasor PD/S - Pearson Method Short Locator

The Tinker & Rasor PD is effective in locating shorts or undesirable electrical contacts to buried coated pipe. Such electrical contacts should be removed prior to placing a pipeline under cathodic protection, as these contacts would drain a large amount of protective potential from the coated pipe.

The method of locating shorts or contacts on a coated pipe is that of applying a relatively large amount (5 to 15 watts) of audio frequency AC between the pipe and a remote ground connection. A traverse is made along the pipeline with a Receiver equipped with a search coil. A short or contact is observed along the traverse where the average AC signal picked up over the line suddenly drops to a very low level. This is assumed to be a point directly above the contact.

Pipe location

The PD can be used very effectively as a pipe locator on coated pipelines that are electrically connected by a screw or welded joints. This application is particularly effective where it is desired to locate and follow one pipeline along a right-of-way where there are a number of buried lines.

To locate pipe, an audio frequency AC signal is placed between the coated pipe and a good ground connection. The Receiver, containing a search coil, is passed over the area where the pipe is assumed to be located. As the Receiver is moved back and forth in a horizontal plane over the pipe, a sharp null will occur in the received signal. The pipe to be located is assumed to be directly under this null. A well-coated pipeline can be followed for a very great distance by this method when audio power of from five to fifteen watts is applied to the coated pipe.