There are several ways to validate the performance of a cathodic protection (CP) system for buried pipelines. Over the years, pipeline networks and their corrosion challenges have become increasingly complicated, not least due to the many sources of both AC and DC interference that affects CP operation. Also, the various measurement techniques that can be applied to test CP effectiveness has increased over the years. Finally, the sheer number of buried pipeline miles has been constantly increasing.
Oil and gas buried pipelines are protected against corrosion by both organic coatings, a passive protection system, and cathodic protection, an active protection system. When coating defects occur, CP controls the corrosion of the exposed steel surface. From an operating point of view, cathodic protection interruptions can occur on the network during interventions, consignments, or technical problems. Literature indicates that during CP interruption the corrosion rate of the metal remains lower than its free corrosion rate. Application of CP confers a remanence of protection to the metal. The objective of this study is to determine the safe duration for cathodic protection interruptions depending on environmental and cathodic protection conditions.
Scale and corrosion inhibitors are commonly used in many oil and gas production systems to prevent inorganic deposition and to protect asset integrity. Scale inhibitor products are based on organic compounds with phosphate or carboxylic functional groups such as amino phosphonates, phosphate esters, phosphino polymers, polycarboxylate and polysulfonates,1 as shown in Figure 1. These anionic groups have strong affinity to alkaline earth cations and can adsorb on the active growth sites of scale crystal (Figure 2), resulting in stopping or delaying the scale formation process.