Scientists of Empress Catherine II Saint Petersburg Mining University have received a patent for a fundamentally new device to reduce residual stresses. This projectile will reduce the number of pipeline defects and, as a consequence, increase the inter-repair period of their operation.
As it is known, one of the most vulnerable places of any pipe is the welded seam. And it is not only that the worker can perform it unprofessionally, i.e. fuse the edges of two products unevenly or allow some foreign micro-particles to get on the deformed area, which will lead to cracks. Even when all quality standards are met, the probability that sooner or later a leak will occur here is very high.
This is because when the metal is exposed to high temperatures, tensile residual stresses arise in its crystalline structure, which negatively affect the strength and durability of the structure. In other words, no matter what efforts the owner of an oil or gas pipeline makes, welded joints will still remain weak links in the chain of fossil fuel transport.
In order to minimise the number of defects, the welds, after they have cooled down, are subjected to special treatment in order to restore the properties of the material and return it to its former resistance to the aggressive effects of the environment. For this purpose, you can use devices of various modifications, depending on the preferences of each next engineer or welder. But all of them have one big disadvantage - they cannot be used after insulation and laying works on the pipeline, as they are designed only for works on its external side.
"We conducted a lot of laboratory experiments, which made it clear that ultrasonic treatment of the periweld zone gives much better results and reduces tensile stresses more effectively if it is carried out from the inside. The next stage of our research was to design and create a product that could move inside the pipe together with the transported medium, i.e. hydrocarbons, and affect the welded joints with the required intensity," said Alexander Palaev, Associate Professor of the Department of Oil and Gas Storage at St. Petersburg Mining University.
The second member of the scientific team, postgraduate student Anton Krasnikov, specified that all trunk oil and gas pipelines are equipped with special chambers for launching and receiving cleaning and diagnostic devices located at compressor stations. They make it possible to fight clogs that periodically occur in the pipe due to the deposition of solid particles carried out of the well, precipitation of paraffin crystals or some other reasons, and can be used, among other things, to operate the projectile created by scientists of the first technical university of Russia.
"Our device is equipped with a removable battery and a control unit, where certain commands are remotely given, including the start and end of work, switching on the ultrasonic generator and treatment of the peri seam zone of the welded joint using oscillating systems. It is produced by powerful indenters, i.e. converters of ultrasonic frequencies into mechanical vibrations, due to which the process of metal processing to reduce residual stresses takes place," explained Anton Krasnikov.
The technology created at Mining University has already attracted the interest of companies involved in the transportation of fossil fuels. After all, the demand for it all over the world is getting higher and higher. Thus, according to the latest forecasts of the IEA, oil consumption on our planet at the end of this year will average a record 102 million barrels per day, and next year will increase even more - up to 103 million barrels. In other words, the relevance of such innovations will only grow in the future.
By the way, we can say that the scientists of the Department of Oil and Gas Transport and Storage of St. Petersburg University have already put such developments "on the stream". After all, just recently they presented another product designed for operation inside a pipe. It is a miniature device, the size of a tennis ball, whose task is to monitor oil and gas pipelines. Its capacitive and acoustic sensors are capable of transmitting information to the operator about a variety of problems that threaten the safety and productivity of hydrocarbon transport. For example, water accumulations, leaks or illegal taps.