PRCI PR-186-04304

L52265e

CC Technology

Need: There is no specific guidance available on the use of electrical isolation devices and how to protect against faults. Because of this, the practice of isolation is varied, which at times may lead to a possible loss of pipeline integrity or electrical safety hazards. Electrically isolating devices are common in cathodically protected piping systems. They can be used to electrically isolate the pipeline from terminal facilities and pumping systems, to divide the pipeline into sections for individual CP, or to manage stray current interference. NACE International defines these devices as an Electrical Isolating Joint.

Result: This document addresses the conditions when the use of isolating devices is indicated and outlines the conditions when installing an isolating device may either create an adverse condition or require additional measures (such as protective devices) to ensure the proper operation. Installation of electrical isolation (EI) devices may be a requirement for cathodically protected underground pipe. The primary purpose of the isolation is to open an electrical circuit formed by the protected structure and other metallic objects such as terminal facilities, pumping and compressor stations, metering stations, river crossings, etc.

Benefit: The information with regard to the use of isolating devices indicates that these are generally employed in line with the regulatory requirements and CP engineering principles. Thus, the electrical isolation devices are used primarily to separate the metering equipment from the mainline and to optimize the existing cathodic protection systems by installing the isolating flanges and the entry and exit points of compressor stations (fire gates), at the wells and gathering stations, etc. Other instances of the use of EI devices are at the change-of-ownership points.

Product Details

Published:

08/31/2004

Number of Pages:

44

File Size:

1 file , 1.1 MB