REMOTE MONITORING SYSTEMS FOR DETECTION OF CONTACT BY UNAUTHORIZED CONSTRUCTION EQUIPMENT AND THE CATHODIC PROTECTION CONDITION ON BURIED PIPELINES

摘要

It is necessary to avoid spreading damage to the pipe when it is struck by construction equipment It is difficult to install indirect methods (e.g. fiber optic sensors) for detection of construction equipment in heavy traffic areas. Therefore, remote monitoring systems, which can detect contact between such equipment and the steel of polyethylene-lined pipe, were developed and installed on a gas transmission pipeline ( φ 600 mm, Length 9.4 km). Detection uses the change in pipe-to-earth resistance which is derived from inner pipe current and pipe to soil potential when contact occurs. Old and new data of pipe-to-earth resistance are continuously compared. If equipment contacts the steel pipe, pipe-to-earth resistance will drop below 100 Ω. The detection systems include maximal length sequence signal (pseudo-random signal) processing. This signal processing is superior for noise reduction. These systems also have remote monitoring of the cathodic protection condition (pipe to soil potential, current of coupons (probes), and transformer rectifier output voltage and current). From the office, pipeline lining and cathodic protection conditions are monitored at all times.