Pipelines protective coatings

The Institute has many-year experience of investigations and developments in the field of NDT. These are, mainly, developments which allowed creation of a series of eddy current flaw detectors for various applications. The Institute has traditionally studied the physico-mechanical properties of materials, their stressed-strained state, fracture mechanics and developed on this basis the procedures and instruments which measure the properties and predict the behaviour of materials. Quite important are also developments of technologies and equipment for control of thickness and adhesion of thin protective coatings on various bases, corrosion control of underground pipelines by indirect method, acoustic emission control of hydrogen and corrosion cracking in structural materials, etc. 

Filtration and water-knockout systems are used to clean up the gas before it enters a compressor. Cooling systems are sometimes required to maintain compressor discharge temperatures below 54°C to avoid damage to the pipeline s protective coatings. Automated compressor stations are typically staffed by maintenance and repair personnel eight hours per day, five days per week. Other stations are staffed on a 24-hour basis because personnel must start, stop, and regulate compressors in response to orders from the dispatch office. 

Normally a specialist works application these materials are useful protective coatings for such items as cable trays and switch boxes. They are also used for the externals of pipelines. 

As the general standard of protective coatings has improved (materials, application and construction standards) the use of sacrificial anodes has extended to soil of ca. 10 000 ohm cm or more for buried pipelines. By using anodes in extruded ribbon form and placing them as close as possible to the structure to be protected they can be used in soils of high resistivity. 

Recent trends in protective coatings used on buried pipelines have been away from reinforced hot applied coal tar and asphalt enamels and butyl rubber laminate tapes, particularly where applied over-the-ditch . The more recently developed coatings based on fusion bonded epoxies, extruded poly-ethylenes, liquid-applied epoxies and polyurethanes, require factory application where superior levels of pipe preparation and quality control of the application process can be achieved. 

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 insulation is formed with the help of special equipment that wraps the pipeline in the tapes without folds with about 15-25 mm overlap. A scheme for formation of the protecting coating is illustrated in Fig. 3.44. Application... 

High-alloy steels (> 5% alloy components) [Henker 1999] are stainless and acid-resistant and are therefore the most important materials in chemical plant construction. Pipelines and apparatus made of these materials are resistant to all types of weather and thus do not require protective coatings.Two widely used steel types, developed by Krupp in 1914, are V2A and V4A ... 

External corrosion problems in oil and gas production are similar to those in pipelines, but the economic impact on the total cost of production is limited as the lines are shorter and smaller in diameter. Atmospheric corrosion of structures and vessels is a problem for offshore fields and those operating in marine environments. The improved quality of the protective coatings for offshore environments resulted in reduced frequency of repainting platforms and tanks. 

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. 

M. E. Orazem, J.M. Esteban, K.J. Kennelley, R.M. Degerstedt, Mathematical models for cathodic protection of an underground pipeline with coating holidays Part 2—case studies of parallel anode cathodic protection systems. Corrosion 53 (1997) 427-436. 

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. 

General corrosion control, prevention, and monitoring should be planned for from the onset. To detect and monitor corrosion, various methods must be used, while corrosion protection would be done by the addition of inhibition and use of protection coatings [5]. Visual examination, laser methods, the replication microscopy liquid penetration testing method, magnetic particles testing, the eddy current inspection method, acoustic emission technique, thermal methods of inspection, and nondestructive methods are the various methods to be adopted when monitoring pipeline corrosion [5]. 

Inspection and testing of relief valves, regulators, and control valves Pipeline crossings Protective coatings... 

Chem. Descrip. Phenolic resin (68%) in butanol Uses Phenolic for phenolic/polyvinyl butyral combinations for internal/ external coating of pkg. containers binder for high-adhesion chemically resist, protective coatings for apparatus, vessels, pipelines binder for clear/pigmented oil/fuel/oil-resist. coatings on rigid substrates Properties Dilutable with MEK, MIBK, ethyl acetate, butyl acetate, methoxypropyl acetate, methoxypropanol, ethanol, butanol dens. = 1.16 g/cm (20 C) dynamic vise. 2300-3700 mPa s flash pt. = 48 C 66-70% NV... 

Chem. Descrip. Phenolic resin (55%) in isobutanol/butanol Uses Phenolic for internal/external coating of pkg. containers, can coatings, high-adhesion chemically resist, protective coatings for apparatus, vessels, pipelines, and for heat-curing phenolic/epoxide combinations Features Unplasticized... 

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