№ 12 (December 2006)
Integrated Systems for Pipeline Security: Does Anybody Object?
Tougher sanctions for the environmental pollution, oil market situation, as well as the growing number of unauthorized tie-ins designed to steal oil and oil products call for improvement of efficiency, reliability, and security of the pipeline management.
By Sergei Kutukov
Since the disintegration of the Soviet Union, the Russian industry inherited a vast network of worn oil- and oil product pipelines. Some of them are under-loaded and in periodic operation, others have been closed down temporarily. From the macroeconomic viewpoint, this state of affairs benefits Russia greatly, enabling the country to held the leading positions in the European energy market under the current political situation. Yet, from the ecological point of view, it is a national disaster. According to ecologists\' estimates, between 8 to 10 percent of oil produced in Russia is lost «in transit» between the well and the fuel tank, and considerable part of this oil falls on the pipelines. These dozens of millions of tons cause pollution of soil and water, destroy flora and fauna, population habitat and health.
The official statistics of the reasons for oil and product pipeline accidents admits fault of operators only in 10-15 percent of the total amount of cases, the same percentage falls on pipe and fitting damage occurring during construction and assembly operations, as well as on workmanship defects which could be revealed immediately, rather then after dozens of years since the commencement of operation. It is difficult to determine the fraction of accidents which happened through the third party\'s fault, both unintentional and criminal. News summaries abound with reports on detected criminal pipeline tie-ins (Stavropol Territory, Rostov Region, Chechen Republic, Kazakhstan, etc.), but facts of impleading of guilty parties are not numerous, which certainly distorts the official statistics. After the long-term pipeline operation, its corrosion (both internal and external) is considered to be the reason of leakage in the majority of cases (50-70 percent). But is corrosion a spontaneous and absolutely unpredictable phenomenon? And, certainly, it is not the corrosion itself which becomes the reason of ecocatastrophes, but oil spills, the size of which depends on the production standards and personnel qualification, pipe quality and maintenance promptness, on efficiency of the pipeline management on the whole and sensitivity, operating speed and reliability of the leakage detection systems in particular.
The range of the proposed means for pipeline leakage detection is rather wide: from primitive leakage detectors utilized in the communal services to aerospace monitoring based on GIS-technologies. However, there is no universal tool available. Pipeline diagnostics by internal devices is characterized by high sensitivity, selectivity and accuracy, but apart from its very high cost, periodicity of this diagnostics should be stressed. Operators can afford performing inner pipeline inspection only every five years, which excludes these methods from the group of on-line control means. Static methods imply oil pumping shutdown for rather long period of time and are used either prior to start-up of new (repaired) sections of pipelines, or could be recommended as additional proving methods when leakage is suspected. The radioactive method is not ecological, the visual or acoustic ones are very labor-consuming, they require permanent presence of the personnel equipped with special devices at the pipeline, therefore their application is limited to verification of the location of identified leakages.
Parametric methods of leakage detection are in the highest demand and are widely utilized in the pipeline management systems. At present, over 50 companies offer their developments in the area of the leakage detection systems for the main pipelines, different in their physical bases and peculiarities of realization. The main part of the monitoring systems market, which exceeded $200 mln long ago and continues to develop by 15-20 percent a year on average, belongs to the foreign companies which offer leakage detection systems based on various algorithms.
Basic capabilities for extension of the leakage detection system parametric base within the framework of the conventional telecontrol system hardware and pipeline instrumentation are virtually exhausted; but none of the conventional methods can satisfy increasing requirements of the ecological and industrial safety of the major pipeline facilities. Modern tendency for development of the leakage detection system analytic tool implies application of combination methods which utilize information coming from independent sources (mass balance and pressure monitors). Their top achievement is the methodology for building of an open analytic system capable to combine numerous competing on-line estimates of leakages obtained by different diagnostic algorithms.
In conclusion, it should be stressed that only an integrated system for pipeline security including aerospace and parametric monitoring, visual control over the pipeline route, and legal backup may resolve the problems of accidental oil spills and theft from oil- and oil product pipelines.
Composite Materials to Improve Pipelines\' Operating Characteristics
Vladimir Pepelyaev, Director, «Technologiya Kompositov», Perm
Operating companies have permanent concerns and troubles with their steel gas and oil pipelines in cities and villages of Russia. Corrosion damage caused by roaming currents and aggressive soil is the main reason for the pipeline failures.
In Russia, this problem is solved by transfer of the facilities for gasification, oil production, transportation and gathering systems to utilization of polyethylene pipes, as they have a number of advantages:
- low gas permeability;
- resistance to gas components, corrosion and cracking;
- high plasticity, frost resistance.
They are characterized by simplicity of welding, possibility to get reliable joints, high manufacturability and easiness of assembly. Durability and strength of polyethylene gas and oil pipelines are proved by the research studies and operating experience.
Due to the geographic position of the Russian Federation (territory extent, severe climatic conditions), it is necessary to transport oil and gas for large distances.
Economically sound conditions for gas transportation require increasing of pressure (over 1.2 MPa) provided the industrial safety requirements are fulfilled.
Such conditions, obviously, require pipes having advantages of polyethylene pipes in combination with high load-carrying capacity.
Pipes having the specified performance characteristics are designed based on two basic conditions. The basic principle is combination of the pipe material components, which ensures new properties of the material not present in each of the components separately. Another basic principle is development of the composition and structure of pipe material depending on the functionality. For example: A sample made of polyethylene collapses at tension stress 20-25 MPa (as polyethylene breaking load is 20-25 MPa, elongation is 250-350 percent). If a high-tensile reinforcing filament is introduced in the polyethylene sample (breaking load is 3,000-3,500 MPa, and elongation is 4-15 percent), and the sample is loaded in the direction of the filament, then polyethylene will not react to the load, as all the load will be taken by the filament. It is obvious that the character of destruction and strength of the reinforced polyethylene are significantly different compared to the common polyethylene. Thus, we obtain a new material with new technical characteristics; this material belongs to the class of composite materials.
Reinforcement of thermoplastic materials, different from common loading, implies basically different character of modification of their mechanical, thermophysical and other properties. Controlled reinforcement during winding ensures the predetermined anisotropy of the material physical and chemical properties both in direction and in value (corresponding to anisotropic axes). When polymers are reinforced by fiberfill having length exceeding critical values for the given composition of the material, the character of deformation and destruction changes, and increment of resistance of composite thermoplastic materials to external load can reach hundreds percent.
In the result, common thermoplastic materials become competitive to the widely applied expensive thermosetting composite materials (fiberglass plastic, organo-plastic, coal-basalt-fiber plastic). Taking into account that thermoplastic materials are characterized by low gas permeability, high chemical inertness, insignificant production costs, utilization of these materials will expand every year. The Technologiya Kompositov company designed the technology and equipment for production of high-pressure reinforced polyethylene pipes, which are protected by the appropriate RF patents.
Technical specifications TU 2248-001-55038886-01 have been prepared and approved by the RF Gosgortechnadzor (the State Mining Inspectorate)
The following permits are issued:
Permit No RRS 00-19707 for application (for subsurface gas pipelines, P oper. up to 1.2 MPa),
Permit No RRS 00-20719 for application (for oil and gas industry, P oper. up to 4.0 MPa).
Pipes are fabricated of polyethylene PE-80 by the method of extrusion and winding of load-carrying frames made of high-strength synthetic filaments in the direction of maximum stress axes. Structurally, pipes consist of three layers:
- internal layer of thermoplastic material resistant to the effect of the transported fluid;
- load-carrying layer of high-tensile reinforcing filaments winded according to the definite reinforcement pattern;
- external layer of thermoplastic material resistant to the effect of external factors.
The layers are formed sequentially in one process cycle, in the result of which solid pipe construction is produced with molded-in load-carrying frame of high-tensile synthetic filaments, which takes the whole load in the course of operation.
This technology enables fabrication of pipes not only of polyethylene, but of other thermoplastic materials depending on the operational requirements to the pipeline, for example, polypropylene-polyethylene.
At present, full-scale production of high-pressure reinforced polyethylene pipes is started by the Technologiya Kompositov company in Perm.
Pipes can be manufactured in diameter range from 63 to 160 mm.
Pipes with diameter up to 110 mm can be supplied in coils, which ensures the following:
- improved processibility during pipeline assembly;
- reduction of costs;
- improved labor productivity;
- improved reliability due to reduced number of connecting elements.
During pipeline construction, pipes are assembled by butt welding of the heating elements; then, after the external mold flash is removed, the joint is reinforced by electric sleeve. Both butt and electric sleeve welding are performed automatically, with obligatory recording of welding parameters. Fittings are also made of composite material and have the same strength characteristics, as pipes.
Damaged pipelines are repaired similar to standard polyethylene pipelines.
In conclusion, it may be said that reinforced polyethylene pipes have a great future in high-pressure pipelines construction due to their high strength characteristics, chemical stability, and also such features as easy assembly and maitenance.