Tag Archives: pipeline
Underground main oil pipelines are very extended objects which pass not only through stable areas with steady soil, but also areas with active manifestations of soil changes, including through bogs, the rivers, seismic breaks, is long-term – frozen soil, sites with karst manifestations, slopes and ravines. At long operation of pipelines on such sites it is necessary to watch the happening changes and to take anticipatory measures for safety of pipelines.
In article research of dependences of interaction of the pipeline with soil in a landslide zone from various factors is considered. The problem is solved by method of physical and mathematical modeling. The model of interaction of the pipeline with soil in a landslide zone represents a valuable contribution to the solution of the actual scientific and technical problem connected with safety of pipeline systems.
As a result of work the state equation in the form of the differential equation is received. Methods and features of the decision in some simple cases when reaction of soil is expressed by analytical expressions are investigated. At determination of tension from external forces difficult correctly and precisely to describe regularities of interaction of a pipe with soil which besides change at soil changes. Other complexity that in many cases boundary conditions for the considered pipeline site are in advance unknown; they are defined only during the solution of a task. Therefore in article decision methods in real cases when reaction of soil can’t be described by means of simple analytical expressions are considered. For these cases the algorithm based on numerical methods with consecutive approximations is made.
DETERMINATION OF PARAMETERS OF CHANGE OF PRODUCTIVITY OF TRANSFER TAKING INTO ACCOUNT SAFETY OF OPERATION OF THE PIPELINE
The article considers determination of parameters of change of productivity of transfer of a product through the pipeline taking into account safety of operation. Conditions of prevention of inadmissible deformations by restriction of the maximum equivalent tension with a limit of metal ductility and safety of the pipeline with achievement of the acceptable margin of safety on a ductility limit are formulated. Parameters of change of the mode of transfer are characterized by the length of the pipeline segment which is under the change of speed of the movement of the pumped-over product and the period of change of the specified speed. As a result of researches the analytical dependences of length of the pipeline segment which is under the change of speed of the movement of a product and the period of change of this speed from change of productivity of transfer, internal pressure inside the cavity of the pipeline, its geometrical characteristics and mechanical properties of metal of pipes taking into account conditions of ensuring durability of pipes and safe operation of the pipeline are received. Because the specified analytical dependences depend on geometrical characteristics of pipes and their connections, the connections of pipes with equal and different thickness of walls, and also connections of pipes with the element having very big rigidity on deformation, for example, with shutoff valves are considered. The quantitative and qualitative analysis of influence of geometrical characteristics of pipes and their connections, properties of metal, necessary margin of safety on values of parameters of the mode of transfer at which durability of pipes and safety of operation of the pipeline is provided were carried out. Increases in parameters of change of productivity of transfer of a product are necessary for all considered schemes of connection of pipes for the purpose of prevention of inadmissible deformations and achievement of the acceptable margin of safety on a limit of ductility. At the same time, on a site of connection of the pipeline with an element, rigid on deformation, higher values of parameters of change of the mode of transfer are necessary for prevention of inadmissible deformations and achievement of the acceptable margin of safety. The increase in value of change of productivity of transfer results in the need of increase of a period of change of speed of the movement of a product and extent of the site of the pipeline on which there is a change of this speed.
Foamed plastics are an effective material for pipe insulation. Among the advantages of this material include the ability to form heat-insulating coating with a given density distribution through the thickness, to obtain a so-called integral foams. This allows to increase the density and hence the strength of external insulation layers most exposed to external mechanical influences. This decreases the moisture permeability of the coating, which is important for underground laying underground pipeline. Insulation effect of the inner layers, and consequently the coating is enhanced through reduction of their density, since there is a direct correlation between the density of the insulation and its thermal conductivity. Achieved such a redistribution of density by influencing the technology of production of foam during the polymerization. In the presented work are given the solution of the heat conduction equation for a stationary case at the steady state temperatures at the inner and the outer surfaces of the insulation. The thermal conductivity of the insulation was considered as a variable depending on the density of the insulation, which is distributed in a certain way through the thickness of the coating. The formula allowing to calculate the equivalent thermal conductivity of the coating at any possible density distribution along its thickness. Taking into account the linear character of the dependence of the thermal conductivity of polyurethane foam is its density, obtained a modification of this formula for the case when the heat-insulating coating consists of two layers: the inner, fixed minimum allowable density, and external, where the density increases to the maximum value on the surface of the coating. A recommendation to determine the thickness of each layer at a known specific weight of foam per unit of pipe length. On the example of thermal insulation of polyurethane foam with an integral structure for medium diameter tubing shown the ability to reduce heat loss by nearly 14% compared with homogeneous insulation of the same specific gravity.
THE IMPROVEMENT OF THE METHOD OF ESTIMATION OF FIRE RISK PIPELINE ON THE EXAMPLE OF OJSC JSC “TRANSNEFT”
In the Russian Federation transition to the practice of flexible regulation occurs gradually in the field of fire safety. In connection with the adoption in 2008 of the Federal law № 123-FL «Technical regulations on fire safety requirements» of great importance for the development and implementation of the domestic practice of evidence-based methodologies of quantitative fire risk assessment that allows you to match the actually existing level of risk of legally established limit value.
The procedure of calculation of individual fire risk is determined by methods approved by orders of the Ministry of emergency situations of Russia No. 382 No. 404. However, in cases of risk assessment of linear facilities (pipelines, roads, and so on) it is rational to apply the above techniques in conjunction with specialized documents.
In this paper we propose an algorithm to estimate values of fire risk on pipelines using existing EMERCOM of Russia dated 10.07.2009 No. 404 in conjunction with a specialized methodology for risk assessment of oil pipelines adopted by the Order of OJSC JSC «TRANSNEFT» from 30.12.1999 No. 152. This approach to determining the values of fire risk will enable to estimate the mass of combustible material capable of spillages to participate in the settlement scenario, since the application of the Order of OJSC JSC «TRANSNEFT» from 30.12.1999 No. 152 allows us to calculate not only the volume of oil spilled before closing the valve (in pressure mode), but after its closure (by gravity).
Was carried out comparative calculations showed that the values of fire risk, obtained without taking into account the amount spilled by gravity oil (without application of the Order of OJSC JSC «TRANSNEFT» from 30.12.1999 No. 152) are low, which further led to underestimation of the scale of the accident, as well as the possible number of affected people.
INFLUENCE OF MODES OF WELDING ON THERMAL DIFFUSION PROCESSES IN MULTILAYERED WELDED CONNECTIONS OF PIPELINES
In article nature of change of nonmetallic inclusions in welded connections pipe staly welding from modes is considered. Ring welded seams of connections of pipelines according to the technological project generally are multilayered. Researches are conducted on welded seams staly pipe purpose of type 17G1S-U. The thermal diffusion processes proceeding at welding of multipass seams, depend on welding modes, and conduct to change of nonmetallic inclusions in separate layers of welded connection. The special attention is deserved by a seam root because is in more difficult conditions in use and is exposed to mnograktony thermal impact of welding. Nonmetallic inclusions have no kogeretny communication with metal and are concentrators of tension owing to what can lead in use to formation of more difficult defects like cracks that pipeline destruction is the reason of formation of the main crack and, as a result. Nature of formation of inclusions influences quality of welded seams and ensuring reliability of welded connection of the pipeline as a whole. During researches change of a volume fraction of inclusions and them layer-by-layer in welded seams of quantity is analysed at different modes of welding. It is established that the parameter of optimization of technologies of welding is the size of running energy defining both properties, and a version, size and distribution of nonmetallic inclusions in welded connections.