Low resistance electrically bonded connections in seconds

Citation

(2000), "Low resistance electrically bonded connections in seconds", Anti-Corrosion Methods and Materials, Vol. 47 No. 5. https://doi.org/10.1108/acmm.2000.12847eab.004

Low resistance electrically bonded connections in seconds

Low resistance electrically bonded connections in seconds

Keywords BAC Corrosion Control, Brazing, Bonding

From its early days as a method of connecting signaling system cables to railway lines, pin brazing is now increasingly being specified as a safe, quick and cost effective alternative to exothermic welding attachment techniques, which – according to BAC Corrosion – although cheap, do have some distinct disadvantages.

BAC considers that mechanical clamp type devices are not easy to apply, particularly as a retrofit on an existing buried pipeline and conductive resin systems need sufficient cure time to ensure a positive connection, thermit welding requires skilled application whereas pin brazing is safe, quick and reliable and permits a large number of connections to be made in a relatively short time using unskilled labour – training takes about an hour. The process can reportedly be carried out in all weathers and damp pipes pose no problem.

Pin brazing dates back to the early 1950s but it was not until the 1980s that BAC Corrosion Control introduced its own fully portable equipment to produce electrical bonds for connections in pipeline cathodic protection systems. Each connection is said to take about a minute to complete. It is claimed to be the most common method used in the North Sea, is extensively used in the Middle East and is approved for use by Transco. For ductile or cast iron pipes, threaded pins to accept a crimped cable lug and a nut are used. For steel pipes, either threaded brazing pins with nuts or a special lug for direct cable brazing is the norm (Plate 3). In a cathodic protection system there are often a great number of connections for anode cables, test posts and measuring cables to be made.

Plate 3 Low resistance electically bonded connections with pin brazing from BAC Corrosion Control

It is also thought that the portable nature of the equipment means that connections can be made in almost any location above or below ground and, if necessary, overhead. In situations where a great many connections need to be made in one place such as pipecoating yards and pipelay barges, the BAC pin brazing system can use a welding generator as its power source.

As demand for pipelines as a cost-effective means of transporting fluids over vast distances continues to grow, so does pressure from the world's safety bodies to ensure that installations conform to accepted standards. Welding of steel pipelines on land and offshore is a critical element and operators need to ensure that undue stresses or damage to the internals of lined pipes are not being created when attaching components for protective systems. Extensive tests are reported to have confirmed that as pin brazing is a relatively low temperature process, the heat affected zone is only a small percentage of that produced by thermit welding techniques which, being exothermic, produce high temperatures. These can generate stresses in the pipe and possibly damage internal linings.

BAC Corrosion Control Ltd, Tel: +44 (0)1952 290321; Denmark: BAC Corrosion Control, Denmark, Tel: +45 70 26 89 00.