Pipeline protection

In the case of older pipelines and offshore pipelines, protection current densities can amount to several mA m" For older onshore pipelines, the protection current densities are determined by a drainage test according to Section 3.4.3. 

R. G. Buchheit, T. E. Hinkebein, R F. Hlava, and D. G. Melton. The effects of latex additions on centrifugally cast concrete for internal pipeline protection. In Proceedings Volume, volume 4, pages 2854-2864.12th SPE/NACE Int Corrosion Congr (Houston, TX, 9/19-9/24), 1993. 

Figure 4-4 Expansion chambers for liquid chlorine pipeline protection. Courtesy of...

Galvanic anode systems are generally used in well-coated electrically isolated structures, offshore structures, ship hulls, hot-spot pipeline protection, heat exchanger water boxes and other environments of resistivity below 10000 Q cm. 

The United States removed Thailand from the priority foreign country list and threatened trade sanctions. Thailand remained on the priority watch list. Currently, there is pipeline protection for five years for pharmaceuticals. 

As shown in Fig. 15.6, external DC current is supplied from a power source such as a rectifier. The external DC current is used to cathodicaUy polarize the pipeHne. Impressed Current System (ICS) can be used to protect bare and poorly coated pipeHnes because of high current capacity. The anodes are made of durable materials that resist wear or dissolution. Iron with 14% silicon, carbon, and graphite are some commonly used anodes for pipeline protection [17,18]. All impressed current CPs require routine maintenance because they involve a power supply and more electrical connections than sacrificial systems. 

Underground pipelines are essential requirement of any developed country. Transportation of crude oil, gas, and many hydrocarbons are carried out through underground CCPs, as they are one of the safest modes of transportation, causing minimum disturbance to mankind. Since the material of construction of pipelines is steel, which is prone to severe corrosion, both from inside and outside, safety of pipelines depends upon a foolproof system of corrosion protection. All three major techniques of corrosion protection, namely, coatings, inhibitors, and cathodic protection, are used to protect pipelines. Protection of pipelines alone is not enough it is also important to monitor... 

J. J. W.B. Cox. Three layer HDPE exterior pipelines coatings job reference and case histories. Proceedings of the 14th International Conference on Pipeline Protection, OcL 29-31, 2001, Barcelona, Spain. 

Sauvant-Moynot, V, Duval, S, Kittel, J, Lefebvre, X. 2005. Contribution to a better FBE selection for 3 layer polyalefin coatings, in Proceedings of the 16th Pipeline Protection Conference, Phapos, Cyprus, November 2-4, p. 173. 

Cathodic protection is optimum within a specific potential range (see Section 13.7), so that the length of pipeline protected by one anode increases as the metallic pipe resistance, Rl, decreases, and coating resistance, z, increases. 

Figure 12.54 shows an underground pipeline, protected by two anodes, buried deeply in the ground, separated by the distance 2b. The ohmic resistance of the electrolyte (soil) is concentrated near the anode as described in the previous section. As a consequence, the potential in the soil is uniform over the length of the pipe. Indeed, because of the very large electrol3de volume, the ionic current density far from the anode is quite small. The cathode potential, is given by the relation E =... 

Rigosi, G.L., Marzola, R. and Guidetti, G.P. (1995) Polypropylene thermal insulated coating for pipelines, in Pipeline Protection, (ed. A. VWlson), Mechanical Engineering Publications, London, pp 297-310. 

E-6 Standard for Hydraulic Type Pipeline Protective Devices. Provides information on hydraulic type (NFPA designated Pf) pipeline protective devices, including materials and construction, design requirements, marking, and maintenance (4 pages). 

Coetzee (1990) determined that one-third of the loss of pipeline wall thickness associ ated with pumping mine water is due to corrosion because mine water is often acidic. Since corrosion is an important contributor to wear of backfilled pipes, it became evident that lining the pipes was necessary. To compare piping materials, tests were conducted by Steward (1996) and indicated that a polyurethane rubber at a Shore hardness 55 Shore A provided the best pipeline protection in a test with slurry pumped at a speed of 3 m/s. By comparison, ASTM steel 106 grade B wore seven times faster than polyurethane 82 Shore A, or high-density polyethylene. 

Figure 8-28. Elimination of the harmful interaction of cathodic protection using a sacrificial anode, where 1 is the pipeline protected cathodically and 2 is the endangered pipeline.

In addition to corrosion protection, many pipelines require thermal insulation to prevent hydrocarbons to produce waxes or hydrates. These heavier components can clog lines and require immediate attention. There is thus a continuous need of improvements in coating as oil and gas operations extend to unprecedented depths and temperatures [7]. As indicated in Fig. 10.4, pipelines have been coated with a variety of protective coatings with a wide performance range over the past 50 years. The advantages and disadvantages of the main coatings used for pipeline protection are summarized in Table 10.8. 

Close ground-bed In this arrangement series of anodes are used. The length of the pipeline protected by a single closed anode depends on changing the potential of earth around the pipeline with respect to earth. The earth is made more positive in areas where protection is needed. 

Touloupis, E., Flint, J.A., ChouUaras, V.A., Ward, D.D. Study of the Effects of SEU-Induced Faults on a Pipeline Protected Microprocessor. IEEE Transactions on Computers 56(12), 1585-1596 (2007)... 

R. Johnsen 1988. A review of materials for pipelines transporting unprocessed well fluid. International Conference on Pipeline Protection and Maintenance, Stavanger, Norway, 20-21 Sept., 1. 

R.K. Vagapov 2008. Increasing the corrosion resistance of oil production equipment and pipelines. Protection of Metals 44 (7), 667-672. 

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