The person for transportation of firm and piece freights thought up other means of transport (automobile, railway, air, water). They at all on a look. Therefore many consider that the railway and motor transport the bulk of freights moves. But, such statement not absolutely objectively. Total length iron and highways in Russia a little more than 800 thousand km, and extent of only external pipelines of systems water - warm, gas supply, water disposal and technological communications exceeds 2500 thousand km. Land means of transport in 2010 transported 3,4 billion tons of freights. Pipelines moved only oil, oil products and gas of nearly 1000 million tons, and on water supply systems 214,5 billion tons of water are rolled. In other words, on pipelines annually moves freights 64 times bigger, than all other means of transport together taken. At such volumes loss even 1% of pumped-over water exceeds the weight of all firm freights transported in the country within a year. Pipelines belong to the life support systems, which criteria of quality - reliability and durability.
The most widespread way of protection of metal of pipes from aggressive influence of transported environments is drawing on internal and external surfaces of pipes of a layer of an insulating corrosion-resistant coating. However, at construction of extended trade and main pipelines where a main type of connection is welding, pipes with internal and external coverings are applied so far restrictedly. It is caused by that at installation of pipelines during welding the considerable cover zone around a welded seam burns out. Especially it concerns pipelines in which the person (diameter less than 600 mm) can't get. Naked metal of a welded seam at long contact with hostile environment is exposed to corrosion that can serve as a cause of accident.
There are sets of types of solutions of this problem.
The way of connection of pipes with the internal thermoplastic covering, including placement in the ends of pipes of the plug with the internal covering, having the ring flutes located at the edges of the plug, with sealing rings in them, and a ring pro-point in a middle part of the plug in which the thermoplastic material, installation over a thermoplastic material in an interval between the ends of a covering of a heat-insulating ring and connection of pipes by welding end-to-end is placed is known. When welding pipes, due to allocated heat, there is an oplavleniye and welding of the ends of a thermoplastic covering to a similar material in the central pro-point of the plug that has to provide additional sealing of a joint (No. 2157479, F 16 L 13/02 patent Russian Federation, опубл. 10.10.00).
Shortcomings of this way are:
1) change of cross section of the pipeline, bringing to:
- to the hydraulic losses reducing volume of transported liquid;
- to whirl emergence in the pipeline, creating additional load of pipeline walls;
- to restriction of introduction of a shell for pipeline monitoring;
2) formation of deposits on sites of installation of the plugs, over time bringing to a pipeline blockage;
3) the increased technological complexity and the labor input connected with process of connection of pipes and, in this regard, and cost;
4) the low reliability of connection connected by that tightness and adhesion between the plug and an internal surface of a pipe in a zone of a welded seam not sufficient for 100% of protection. It means that plugs can't resist against the internal pressure of transported aggressive liquid during a warranty period of service of the pipeline, i.e. plug service life is much less than pipe service life with a sheeting.
As a result of it there is a probability of penetration of hostile environment to joints of pipes and their corrosion destruction.
Today, the market of the pipe industry on welding installation works, more than for 65% is occupied with similar services (technologies, with use of the protective plug).
The carried-out analysis shows that intensive search of ways of protection of a zone of a welded seam at connection of pipes with a protective internal covering in which acceptable requirements to efficiency of protection would be combined with made expenses proceeds now.
The offered project is directed on elimination of the shortcomings inherent in analogs, and is a consequence of such search.
The main objective of the project is receiving the reliable and durable pipeline in operation having internal and external coverings. And also preservation of capacity of the pipeline and convenience of its installation.
The basis of an offered way represents the special device by means of which in a zone of a welded seam, from within, the sheeting is put.
The technology of drawing a covering consists of several stages:
Stage 1 – Welding.
At this stage the device for drawing a sheeting in inside pipeline is installed. Further pipes are aligned, and traditional manual arc welding is made.
Stage 2 – Cleaning of surfaces of the pipeline.
After welding internal, by means of the special device, and external surfaces of a zone of a welded seam subject to cleaning of various slags, inclusions, deposits, etc.
Stage 3 – Drawing covering.
Further on the cleared surfaces of a zone of a welded seam put a protective anticorrosive covering, with the subsequent its polymerization. On an internal surface by means of the special device.
Stage 4 – Quality control.
After polymerization, a covering subject to check on a dielectric sploshnost, thickness, etc.
Advantages of this way before existing analogs:
1 . Keeps uniformity of a design of the pipeline, i.e. excludes change of a form of cross section on length of the received connection of pipes that prevents:
a) emergence of hydraulic losses;
b) formation of a whirl of the transported environment;
c) formation of deposits in a zone of a welded seam;
d) restriction on introduction of a shell for pipeline monitoring;
2 . Excludes application of expensive, corrosion-proof materials (staly, alloys) and considerably reduces prime cost of expenses;
3 . Reduces labor input and requirements to technology of welding as welding of a uniform material is made and one seam cooks, i.e. traditional welding which is mastered in the organizations occupied with installation and laying of pipelines is made;
4 . Increases corrosion resistance of a zone of a welded joint on external and internal surfaces, due to technology of drawing and application of an anticorrosive covering of the class "premium", tightness and which adhesion will be sufficient for working capacity throughout a warranty period of service of the pipeline.