Consequences of accidents on pipelines. Types of accidents on the main gas pipeline
Accidents on the pipeline occur not only for technical reasons: there are a number of others, the main of which is the so-called human factor. A huge number of accidents occur as a result of negligence, both employees and superiors. This is precisely what is emphasized in a number of further examples.
On June 5, in the Vitebsk region, the repair of more than 40-kilometer section of the Russian main oil product pipeline "Unecha - Ventspils" was completed. At the same time, the culprit of the largest accident on this transport line was officially announced.
As the BelaPAN was told in the directorate of the Russian unitary enterprise "Zapad-Transnefteprodukt" (Mozyr), oil products have been pumped through the Unecha-Ventspils pipeline for forty years already. During the diagnostics of the pipeline in 2005, specialists found many defects. The owner of the oil pipeline considers the culprit to be the manufacturer - the Chelyabinsk Metallurgical Plant (Russia), on the basis of which four enterprises currently operate. After two accidents at the oil pipeline in the Beshenkovichi district of the Vitebsk region (in March and May 2007), specialists from Zapad-Transnefteprodukt conducted a re-examination of the pipeline and began to replace potentially dangerous sections on their own. Transportation of diesel fuel from Russia to Latvia through Belarus was suspended for 60 hours. During this time, five Belarusian repair teams of Zapad-Transnefteprodukt from Mozyr and Rechitsa (Gomel region), Senno and Disna (Vitebsk region), Krichev (Mogilev region) replaced 14 fragments of the oil pipeline.
The prosecutor's office identified the Chelyabinsk Metallurgical Plant as the culprit of its outbursts on the territory of the Beshenkovichi district, which manufactured defective pipes in 1963.
It should be reminded that on March 23, 2007 in the Beshenkovichi district of the Vitebsk region there was a rupture of the Unecha-Ventspils oil product pipeline. As a result of the accident, diesel fuel through the reclamation canal and the Ulla River got into the Western Dvina and reached Latvia. Zapad-Transnefteprodukt compensated the Ministry for emergencies Belarus losses to eliminate the consequences of the accident on March 23. Ministry natural resources and protection environment Belarus has calculated the damage caused to the environment from the first rupture of the oil pipeline. It is expected that by June 15 the amount of damage will be agreed with the owner of the pipeline and presented to the public.
The second pipe break at the Unecha-Ventspils oil product pipeline occurred on 5 May. "The breakthrough is local. A small amount of oil products leaked out of the pipeline," Minister for Emergency Situations of Belarus Enver Bariyev told the BelaPAN at the time.
He assured that the accident would not bring severe consequences for the environment. "Oil products will not get into the rivers," the minister said.
It is symptomatic that the second break occurred near the village of Baboyedovo, Beshenkovichi district, near the place where the first major pipe break occurred in March.
As they say, where it is thin, it breaks there.
On February 27, 2007, in the Orenburg region, 22 km from the city of Buguruslan, an oil leak occurred from the infield pipeline of the Buguruslanneft Oil and Gas Production Department (a subdivision of Orenburgneft, a part of TNK-BP).
Fortunately, or unfortunately, but the spill, the volume of which, according to the preliminary estimates of the Ministry of Emergency Situations, was about 5 tons, hit the ice of the Bolshaya Kinel River. Unfortunately, the pipe leaked right in the area of the river. Fortunately, it seems that the oil did not spill directly into the water, but onto ice 40 cm thick.
In Makhachkala, an oil leak occurred due to a gust on an oil pipeline. The leak occurred in the Leninsky district of the city on a section of an oil pipeline with a diameter of 120 millimeters.
As a result of an oil pipeline rupture, about 250-300 liters of oil spilled out, the slick is about ten square meters. To eliminate the accident, they blocked the flow of oil in this area.
"The slick is bunded (contamination is localized)," the Ministry of Emergency Situations said. According to him, there were no reports of casualties.
An operational group of the Ministry of Emergency Situations of the Republic of Dagestan worked on the spot. At the moment, specialists from OAO Dagneftegaz are dealing with the liquidation of the accident.
The oil pipeline Omsk - Angarsk - the largest (2 threads with a diameter of 700 and 1000 mm) stretches from the western border of the region and almost to the east. Crude oil is pumped. The oil pipeline is owned by OAO Transsibneft AK Transneft of the Ministry of Fuel and Energy of the Russian Federation. In the Irkutsk Region, the oil pipeline is operated by the Irkutsk Regional Oil Pipeline Administration (IRNPU). In 2001, IRNPU developed the “Plan for the Prevention and Response of Emergency Oil Spills of the Irkutsk Regional Oil Pipeline Department of OAO Transsibneft” - is being approved. The number of accidents on the oil pipeline for the period from 1993 to 2001:
- 1. March 1993. At 840 km of the main oil pipeline Krasnoyarsk - Irkutsk (the pipeline was damaged by a bulldozer), 8 thousand tons of oil spilled onto the relief. Timely measures taken to localize the place of the strait made it possible to minimize the consequences of this accident. The spilled oil was mostly pumped to storage facilities. The contaminated soil was collected and taken out for disposal.
- 2. March 1993. At 643 km of the main oil pipeline Krasnoyarsk - Irkutsk (rupture of the oil pipeline due to a defect in the weld, the moment of the accident was not recorded in time) more than 32.4 thousand tons of oil poured onto the surface. The urgent measures taken to eliminate the consequences of this accident made it possible to quickly neutralize negative phenomena. However, about 1 thousand tons of oil penetrated into the bowels and was localized 150-300 m from the existing Tyret economic water intake groundwater. About 40% of the 2nd and 3rd belts of the sanitary protection zone of the water intake turned out to be contaminated with oil. About 1,000 more tons of oil penetrated into the soil in the area of the swampy floodplain of the river. Ungi and gradually migrated downstream to the economically valuable aquifer. In order to protect the Tyretsky utility groundwater intake from oil pollution, a special protective water intake was built and put into operation, which has been “cutting off” oil-contaminated water from the utility water intake for 9 years. The ecological and hydrogeological situation remains difficult in terms of oil pollution of the extracted water by economic water intake. Throughout the years, after the accident, state environmental control was carried out over the conduct of environmental and hydrogeological work in the area of the accident. Every year, joint meetings of persons and services interested in cleaning up oil-contaminated lands and underground horizons (land users, environmental authorities, sanitary and epidemiological supervision, hydrometeorological services, hydrogeologists, oil pipeline management) are held - the monitoring results for the past year are summed up and a further program of work is determined. Until 1999, maintenance of monitoring and control systems for the geological environment in the area of the Tyretsky water intake was carried out under the contract of the State Federal State Unitary Enterprise “Irkutskgeologia”. Since 1999 - IRNPU
- 3. March 1995. At 464 km of the main oil pipeline Krasnoyarsk - Irkutsk (crescent-shaped crack on the pipeline DN 1000 mm, length 0.565 m, width 0.006 m) 1683 m3 of oil poured onto the surface. The oil along the stream bed (300 m) reached the Kurzanka River and spread over the ice of the river to a distance of 1150 m. During the liquidation work, 1424 m3 of oil was collected and pumped into the reserve pipeline DN 700 mm. The Kurzanka River was completely cleared of pollution before the onset of the spring flood. Irretrievable oil losses amounted to 259 m3, of which 218.3 m3 was burned. Oil-contaminated soil from the stream bed was removed and stored in a quarry, where it was treated with bioprin.
- 4. January 1998. At 373 km of the main oil pipeline Krasnoyarsk - Irkutsk (a crack 380 mm long on the pipeline DN 1000 mm) oil outflow to the surface is about 25 m3, about 20 m3 is collected. Contaminated snow was removed to the oil traps of the Nizhneudinskaya PS.
- 5. November 1999. At 565 km of the main oil pipeline Krasnoyarsk - Irkutsk (depressurization of the Du 700 pipeline, as a result of damage to the valve during repair work, followed by ignition of spilled oil). The pollution area is 120 m2, 48 tons of oil burned.
- 6. December 2001 at 393.4 km of the main oil pipeline Krasnoyarsk - Irkutsk (during the emptying of the reserve line DN 700 mm, with the pumping of oil from the FPU into the pipeline DN 1000 mm), the suction line of the pump was depressurized. About 134 m3 of oil spilled onto the surface. Oil was localized in a lower part of the relief - a natural ravine located at a distance of 80 m from the accident site. After the damage was repaired, oil from the ravine - 115 m3 - was pumped into the operating oil pipeline. The rest of the oil was collected by a special vehicle. The volume of irretrievable oil losses amounted to 4 m3. The oil-contaminated soil surface was treated with the Econaft sorbent, followed by the removal of contaminated soil to the Nizhneudinskaya PS. According to the Order of the CRC, monitoring of lands and surface waters of the river is organized in the Irkutsk region. Oody
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Pipeline accidents under operating conditions occur mainly due to metal corrosion (33 - 50%), defects of construction origin (mechanical damage, defects in the annular seam), defects in the factory seam, violation of operating rules, equipment malfunctions and others. Statistical data on the destruction of gas pipelines and oil pipelines, presented in Table. 3.2 over a ten-year period (1967 - 1977) indicate a fairly large number of failures. More than 220 pipeline failures occurred annually.
An analysis of accidents in pipelines that have operated for more than 20 years shows that their aging affects the increase in the number of failures. This is primarily due to a decrease in the protective properties insulating coatings, with the accumulation and development of defects in pipes and welded joints, metal fatigue processes. Reduced plastic and viscous properties of the metal and welded joints.
The main causes of pipeline accidents are defects in their manufacture and installation, hydraulic shocks.
In case of pipeline failures due to defects in tees (bends), the entire tee assembly should be cut out and replaced with a new one.
Most often, pipeline accidents occur due to a malfunction at the junction of pipes.
To prevent accidents in pipelines laid in difficult engineering and geological conditions, it is necessary to establish the impact of changes in operating conditions and parameters on the strength and stability of the pipeline, as well as to find potentially hazardous areas. Failures and accidents of pipelines laid in these conditions, along with other factors, are facilitated by their excessive bending, which is accompanied by uneven settlement and unstable position of the soil-pipe-liquid or gas system.
The main causes of pipeline failures are defects in their manufacture and installation, hydraulic shocks.
When a pipeline accident is eliminated by underwater welding in a caisson, and in order to obtain a high-quality seam, the pipe is preheated to high temperatures, the diver-welder is subjected to a double effect: on the one hand - high temperature gases of the welding arc, on the other hand, the high radiation temperature emitted by the pipe. Working in a hot, humid environment of the caisson, sweating profusely, bending over the body can cause fainting. To prevent this from happening, it is necessary to provide active cooling of the worker, a supply of water for drinking.
When liquidating an accident in pipelines for liquefied gases, some additional measures are required, precautions related to the specific properties of the products.
There have been cases of pipeline accidents caused by errors in the selection of pipes and fittings according to normals, defects made during manufacture. During installation and repair work, it is necessary to strictly control the compliance of materials specified in the projects, GOSTs, standards and technical conditions. The placement and methods of laying gas pipelines should provide the possibility of monitoring their technical condition. On pipelines transporting liquefied gases, it is necessary to install safety valves for gas discharge. On gas pipelines supplying liquefied gases to tanks, check valves between the pressure source and the shut-off valve. On all gas pipelines liquefied gases before their entrance to the tank farm, it is necessary to install valves that disconnect the tanks from the internal network in case of an accident or any malfunctions. Shut-off valves with remote control outside the building.
In order to avoid an accident of pipelines, they are laid in such a way that self-compensation of thermal elongations of pipelines occurs. However, it is not always possible to achieve self-compensation. In most cases, special devices called compensators are used.
Data on the most significant pipeline accidents with complete rupture of joints show that such joints also had significant lack of penetration along the entire length of the seam, reaching 40% and even 60% of the wall thickness, and other defects.
The severity of the consequences of a pipeline accident is determined by the ratio of the size of the reservoir and the amount of oil that got into it. However, whatever these ratios may be, impacts of this kind can be considered very dangerous for wildlife.
The gas transportation system of Russia is characterized by an unprecedented concentration of energy pipeline capacities in the world practice. Multi-line gas pipelines are combined into technical corridors. From the gas fields of the northern regions Tyumen region a unique gas transmission system of 20 pipelines 1220-1420 mm in diameter is in operation, which will soon be joined by two more pipelines with a diameter of 1420 mm SRTO-Torzhok and SRTO-Chernozemye, and then the Yamal-Europe gas pipelines. Up to 250 billion m 3 per year are transported along the technical corridors, and in some areas the total capacity reaches 340 billion m 3 per year.
Naturally, this concentration creates a zone of high risk. But perhaps the greatest risk is the intersection of technical gas corridors with other corridors or pipelines for other purposes. Special requirements are imposed on the reliability and safety of such nodes. The risk assessment model at intersections should take into account the possibility of a “domino effect” in case of accidents, which disables crossing lines.
The most sensitive environmental damage is caused by pipeline accidents. With the destruction of the gas pipeline and the instantaneous release of gas energy, mechanical damage to the natural landscape and relief occurs, as well as a violation of the integrity of the soil and vegetation cover. Approximately half of the accidents are accompanied by a gas fire. Therefore, mechanical and blasting effects are exacerbated by thermal radiation. The radius of thermal influence determines the zone of complete destruction of the surrounding vegetation in the focus of failure, there is a zone of landscape transformation, a buffer zone in case of mechanical damage.
In case of accidents on gas pipelines with a diameter of 1420 mm, the maximum spread of individual pieces of metal reached 480 m, the heat affected zone - 540 m. Gas losses during the destruction of a gas pipeline average about 5 million m 3.
On gas pipelines in 1985-1986. accidents were 0.41-0.44% per 1000 km per year, in last years 0.18-0.22. Most accidents are related to stress corrosion. Thus, in 2009, accidents due to this cause accounted for 27% of all accidents at gas pipelines.
As practice shows, more than 51% of the total length of the route of main pipelines is laid through forest areas. This causes a significant likelihood of forest fires as a result of accidents on gas pipelines. For 25% of the total length, the main gas pipelines cross arable land and other agricultural land. Due to accidents under the thermal impact of burning gas, crops burn out on areas of hundreds of hectares and soil sintering to a depth of several centimeters.
When the product pipeline of a wide fraction of light hydrocarbons (NGL) in Bashkiria was destroyed, the affected area was 2 km 2 .
There were accidents of pipelines with cascade development of destruction. In this case, element by element, construction by pipeline construction fail sequentially. Such a series of very rare accidents cause the greatest economic and environmental damage. A prime example The accident at the Yuzhno-Solenenskoye gas condensate field in November 1989 can serve as a cascade destruction of the pipeline.
Compressor stations are the main source of chemical pollution of the atmosphere in pipeline transport. When used to drive turbines natural gas, as a result of its combustion, harmful substances are emitted into the atmosphere, including nitrogen oxides, carbon monoxide, sulfur oxides (if the gas contains sulfur compounds). The amount of emissions depends on the type of gas turbine units. Their number is about 0.5 million tons per 1 billion m 3 of commercial gas production. In 1996, they amounted to 2.5 million tons. The task is to reduce the content of oxides to 50 mg/nm 3 by modernizing combustion chambers and replacing obsolete gas pumping units.
VNIIpriroda, studying the transboundary transport of pollutants, found that oxides in the products of gas combustion, dispersed by wind with excess air moisture, can form acids, which, falling to the ground, inhibit vegetation, and affect some species of valuable fish. As a result of such processes, for example, a "lunar landscape" appeared around Norilsk.
The greatest noise pollution of the atmosphere occurs due to the operation of the GPU and construction mechanisms. Noise levels at the CS significantly exceed the operating sanitary norms, which creates unfavorable conditions for service personnel and the habitat of local wild animals and birds.
Due to the impact of noise, animals and birds are forced to leave their usual habitats. There are examples when even such adapted to life in extreme conditions species, such as, for example, wolves, are forced to migrate to breed at 100-300 km from the CS or the facility under construction.
Methane is a greenhouse gas and can contribute to global warming when leaked from gas transmission systems. One kilogram of methane over a time horizon of 20 years is equivalent to the global warming potential of 21 kilograms of carbon dioxide.
There is a common opinion that one should not focus on the loss of methane in the systems of the gas industry, since an infinite amount of it is released into the atmosphere by swamps and coal mines. Of the latter, more than 12 billion m 3 of methane per year enters the atmosphere in Russia. Probably much more from swamps. And yet, it is necessary to assess the impact on the climate of methane leaks, including from gas transmission systems in case of accidents, through holes and cracks, leaky fittings, discharges during repairs and retests.
On average, calculated for one year, the accounted gas losses from leaks through fistulas and other damage to gas pipelines are at least 1.5 times higher than in case of emergency pipe rupture.
RAO Gazprom data confirm gas losses at an average transportation distance of 2,500 km at 1.0% of the total volume of pumping.
Thus, the gas tightness of pipeline systems both during the commissioning of facilities, and even more so during the operation period, is the most important factor in environmental discipline.
The most severe environmental impact cause emergency situations on oil pipelines, although the destructive effect on them is much less than on gas pipelines. In this case, the release of a large amount of oil during an emergency spill plays a dominant role. The physical and chemical impact of the product on soil and water often leads to a difficult-to-recover or practically unrecoverable regime of natural self-purification.
The destruction of pipelines by its nature causes a man-made impact affecting the biochemical processes occurring in the atmosphere, soil and water bodies. During emergencies, the concentration of oil and oil products in water reaches 200-300 mg/l. Pollution of rivers and reservoirs adversely affects the fish stocks of the regions.
On the oil pipeline Kharyaga-Usinsk to Komineft, or, more precisely, on the field collector 148 km long, since 1994 there have been destructions with large losses of oil, mainly due to internal corrosion. Losses in these accidents are still being debated. The true size of the oil spill turned out to be in a "fork" between the overestimated estimates of Western experts and the opinion of Russian experts. But the latter also different results estimates: from 14 to 103 thousand tons. In a word, politics, business, technology and ecology are mixed here.
One way or another, it was a big environmental disaster with the pollution of a large area, the ingress of oil into the Usa and Kolva rivers.
Let me remind you that such accidents are expensive. Komineft received a loan of $124 million to eliminate the consequences of the oil spill. The Exxon Volders oil spill cost Exxon over a billion dollars.
The scale of oil loss from the Vazoi-Usa reservoir can be judged from Komi-neft data on the extraction of 49 thousand tons of oil from the sludge formed as a result of leaks. It is expected to produce another 40 thousand tons. Oil leaks from pipelines at industrial sites in some cases have become catastrophic. Thus, on the territory of Permnefteorgsintez, Novokuibyshevsk and Angarsk oil refineries, as a result of oil and oil products losses from pipelines and spills in emergency situations, technogenic deposits were formed, the volume of which reaches 900 thousand tons of oil products. One of them produces 40-60 tons of grade 50 gasoline per day.
Carrying out selective repairs on oil pipelines based on the results of in-line diagnostics has allowed for the period since 1993 . by 1998 to reduce the number of accidents from 0.25 to 0.06 per 1000 km. Of course, this is a very encouraging result. Back in 1977, Transneft had to cut out 47,000 defects on main oil pipelines, including those of construction origin.
Many repairs are related to the discharge of oil into barns, i.e. associated with environmental degradation. However, significantly greater oil losses through fistulas, cracks, reinforcement leaks, and discharges during repairs. According to the European Organization of Oil Companies "Konkau" from 1971 to 1995, the number of oil spills (leaks) per 1000 km decreased from 1.4 to 0.4. As can be seen, the rate of failures (leaks) for well-maintained European oil pipelines is much higher than the accident rate for Russian oil pipelines, but it should be compared with recorded leaks, and not with accidents. According to ecologists, in the conditions of an acute fuel and energy crisis, it is annually lost, taking into account oil gases in terms of oil equivalent, approximately 16 million tons of oil.
Unfortunately, until now, the design of pipeline systems is carried out without a preliminary assessment and analysis of the risk of their operation, i.e. the level of potential danger to the environment. The task of risk theory is not only to identify the “weak” links of the technological chain, but also to predict the development of events in the event of accidents. In other words, we are talking about the construction of reliable "scenarios" (i.e. logical schemes) for the development of accidents, as well as a mathematical description and software accompanying physical processes. All this methodology was developed by the Highly Reliable Pipeline Transport Association, VNIIGaz, Russian state university oil and gas them. I. M. Gubkin.
A serious danger for pipelines is landslide processes, which are especially often observed on the coastal sections of underwater crossings. Soil movement, especially if it is at an angle to the axis of the pipeline, causes landslide pressure - passive pressure within the height of the pipe. The consequence of this is the bending of the pipeline in the plan, damage to the insulation and, when the limiting deformations are reached, destruction. So at the 9-thread crossing of gas pipelines across the river. Kamu, despite the fact that the steep landslide right bank was significantly laid down in the 600 m corridor (the steepness of the slope was 9-10°), in 1990 the pipeline ruptured. As a result of the explosion, a funnel with a diameter of 40 m was formed. The additional anti-landslide measures carried out turned out to be insufficient, and in 1995, as a result of landslide deformation, another line of the gas pipeline broke.
On this transition, Giprorechtrans made control calculations according to the P izt program and confirmed its trouble. This program has proved to be a reliable means of assessing landslide hazard. It should be used in design and monitoring when it is required to assess the stability of the slope, the location, depth and length of the soil mass involved in the landslide process, the effectiveness of engineering slope protection measures, and identify the most unfavorable sections of the pipeline in terms of possible deformations.
Landslides are a frequent occurrence along pipeline routes. Thus, the Blue Stream gas pipeline will cross the landslide area in a long section. To reduce the risk of emergencies associated with landslide processes, it is necessary to speed up the release of updated regulatory and technical documentation governing modern rules design and calculation of structures on landslide slopes.
For pipelines the world- this is a soil massif, this is the earth that lives according to its own laws, including the laws of geodynamics. But if it is proved that “tectonic stresses” originating in the depths of the interior are reflected even in the atmosphere, tracing “weather spots”, then the possibility of the influence of these phenomena on pipelines, as if grown into the earth's surface, cannot be neglected.
The Research Institute of Mining Geomechanics and Mine Surveying tried to link emergency situations on pipelines with seismic phenomena. Having studied the nature of 1021 failures, the Institute came to the conclusion that almost all the destruction of long pipelines occurred in zones of possible influence of tectonic faults. Thus, the time intervals between accidents were subject to a certain periodicity, coinciding with the periods of seismic activity, established on the basis of the materials of the Tashtagol seismic station.
For a deeper study and prevention of accidents, the Institute proposes to carry out geodynamic zoning of the earth's crust along the routes of existing, under construction and prospective pipelines.
Separate areas Eastern Siberia, Baikal and Far East, where a large pipeline construction program is planned, are seismically dangerous. Earthquakes of 6-10 points on the MZK-64 scale are possible here. The appearance of damage on pipelines is usually observed at an intensity of about 7 points on the MZK-64 scale. Destruction in old pipelines damaged by corrosion can also be expected at lower intensity seismic impacts.
A serious source of environmental pollution are cavity cleaning procedures and testing of pipelines before commissioning.
Depending on the area of construction, seasonality of work, features of technological operations of the construction of the gas pipeline, its internal cavity can be contaminated with soil, corrosion products, welding beads and cinders, water, snow, ice and, finally, objects that have accidentally fallen.
As practice has shown, the mass of contaminants per meter of the length of the cleaned gas pipeline with a diameter of 1420 mm is up to 0.6 kg, and in some cases this amount increases by 2-3 times. Only corrosion products make up 20 g/m 3 of the cavity volume. When blowing a section of 30 km, up to 50 tons of pollution is removed from such a pipeline, including up to half a ton of corrosion products. The release of such a quantity of pollution through the open end of the gas pipeline leads to pollution of an area up to 1000 m long and up to 300 m wide.
When flushing gas pipelines with a diameter of 1420 mm in a section 30 km long, the volume of polluted water is 55 thousand m 3 . The discharge of such a quantity of water onto the relief is fraught with contamination and salinization of the soil, erosion of the surface and thawing of permafrost soils.
Such unorganized dumping is prohibited. After washing, water is sent to settling tanks and, after clarification, is lowered into reservoirs. However, in the event of a pipeline failure during testing, the release of a large volume of water in an unprogrammed place with the development of erosion processes is inevitable.
The construction and operation of river crossings cause great damage to the environment. During the construction of underwater trenches, water is polluted, the hydrological conditions of the territory are violated when digging trenches of pipelines at water crossings, fish spawning grounds are disturbed during dredging, underwater storage of soil for backfilling the trench after laying the siphon, harvesting sand and gravel mixtures in river beds. Dissolved cellulose from the “wood residues” buried on the route gets into the watercourses, the river beds are littered with wood waste.
Drilling and blasting work is still being carried out in rocky soils. All this has a sharp negative effect on the ichthyofauna. When designing, technogenic deformations of channels, especially tundra rivers, are often not predicted. Many negative consequences caused by channel processes are associated with this.
The risk zone should include the state of individual river crossings, mainly due to exposure in the channel part, unreliable fixing of the banks in the crossing site, and the impossibility of passing in-line diagnostic projectiles along individual lines. In addition, it should be noted that out of a total length of 3,500 km of river crossings, 40% were laid more than 20 years ago. During the years of the pipeline “boom”, 30 km of siphons were laid annually in the channel part of the rivers alone with the processing of up to 15 million m 3 of bottom soil per year. Hydrodynamic forces act on eroded (open) sections of underwater pipelines. The accumulation of fatigue damage can lead to the release of maximum dynamic stresses beyond the permissible level, crack growth to critical sizes is possible and, as a result, the destruction of the underwater pipeline.
In the very technology of laying siphons in a trench at the bottom of reservoirs, there are many unforeseen and complicating circumstances. Much greater reliability and safety of transitions can be achieved using the directional drilling method. In this case, the pipeline is laid in a well drilled in an array of undisturbed soil at a great depth. Obviously, in this case, subsidence, washouts, and rise of the underwater pipeline, i.e. changes in its design position are excluded, the natural landscape is not disturbed, flora and fauna are not oppressed.
The main task of designers, builders and operators is to build and operate environmentally friendly pipelines, compressor stations, pump stations, tank farms and underground storage facilities, and man-made impacts would practically not affect the environment, would be compensated to the normal background state of nature. So far this has not been achieved.
Control questions:
1. Accidents on main gas pipelines.
2. The main source of air pollution during the transport of oil and gas.
3. Methane losses in gas industry systems.
4. Accidents on the main oil pipelines.
5. Landslide processes on pipeline routes.
The dominant causes of accidents on main gas pipelines are the following:
Corrosive destruction of gas pipelines, 48%;
Marriage of construction and installation works (SMR), 21%;
generalized group mechanical damage, 20%;
Factory pipe damage 11%.
Where, the generalized group of mechanical damage is as follows:
Accidental damage during operation, 9%;
Terrorist acts, 8%;
Natural impacts, 3%.
Most accidents in main pipelines limited to gas leakage equal to the volume of the pipe up to the shut-off valve. Or burning a torch. But big catastrophes are also possible, such as Railway accident near Ufa- the largest railway accident in the history of Russia and the USSR, which occurred on June 4 (June 3 Moscow time), 1989 in the Iglinsky district of the Bashkir Autonomous Soviet Socialist Republic, 11 km from the city of Asha (Chelyabinsk region) on the Asha - Ulu-Telyak stretch. At the time of the passage of two passenger trains No. 211 "Novosibirsk-Adler" and No. 212 "Adler-Novosibirsk", a powerful explosion of a cloud of light hydrocarbons occurred, formed as a result of an accident on the Siberia-Ural-Volga region pipeline passing nearby. 575 people died (according to other sources 645), 181 of them were children, more than 600 were injured.
A narrow gap 1.7 m long was formed on the pipe of the Western Siberia-Ural-Volga region product pipeline, through which a wide fraction of light hydrocarbons (liquefied gas-gasoline mixture) was transported. Due to pipeline leakage and special weather conditions gas accumulated in a lowland along which the Trans-Siberian Railway ran 900 meters from the pipeline, the stretch Ulu-Telyak - Asha Kuibyshevskoy railway, 1710th kilometer of the highway, 11 kilometers from the Asha station, on the territory of the Iglinsky district of the Bashkir ASSR.
Approximately three hours before the disaster, the instruments showed a pressure drop in the pipeline. However, instead of looking for a leak, the personnel on duty only increased the gas supply to restore pressure. As a result of these actions, a significant amount of propane, butane and other flammable hydrocarbons flowed through a nearly two-meter crack in the pipe under pressure, which accumulated in the lowland in the form of a "gas lake". The ignition of the gas mixture could have occurred from an accidental spark or cigarette thrown out of the window of a passing train.
The drivers of passing trains warned the train dispatcher of the section that there was a strong gas contamination on the stretch, but they did not attach any importance to this.
On June 4, 1989 at 01:15 local time (June 3 at 23:15 Moscow time), at the moment of the meeting of two passenger trains, a powerful volumetric gas explosion thundered and a giant fire broke out.
There were 1,284 passengers (including 383 children) and 86 members of the train and locomotive crews. 11 wagons were thrown off the tracks by the shock wave, 7 of them were completely burned out. The remaining 27 cars were burned on the outside and burned out on the inside. According to official data, 575 people died (according to other sources 645), 623 became disabled, having received severe burns and bodily injuries. There were 181 children among the dead.
The official version claims that a gas leak from the product pipeline became possible due to damage caused to it by an excavator bucket during its construction in October 1985, four years before the disaster. The leak started 40 minutes before the explosion.
According to another version, the cause of the accident was the corrosive effect on the outer part of the pipe of electric leakage currents, the so-called "stray currents" of the railway. A microfistula formed 2-3 weeks before the explosion, then, as a result of the cooling of the pipe, a crack growing in length appeared at the place of gas expansion. Liquid condensate soaked the soil at the depth of the trench, without going outside, and gradually descended down the slope to the railway.
When two trains met, probably as a result of braking, a spark arose, which caused the gas to detonate. But most likely the cause of the gas detonation was an accidental spark from under the pantograph of one of the locomotives.
Figure 2.1 - disaster near Ufa
One of the key problems of providing industrial and fire safety- establishment of minimum safe distances between sources of accidents and neighboring structures and objects. The requirements for the justification of the minimum safe distances, including those based on modeling and calculation of the consequences of accidents, are contained in a number of regulatory legal documents.
The task of determining the minimum safe distances in connection with the development of the system of main pipelines (MT) is especially relevant. Analysis of the accident rate shows that accidents with the death of people on Russian MTs are quite rare, however, in the conditions of their laying near settlements, production facilities and transport infrastructure the possibility of injury to people in an accident is not ruled out. Major industrial accidents with mass deaths of people cause a special resonance. Below are the scales and features of some major accidents at MT:
The minimum safety distance is the minimum allowable distance from the axis of the linear part of the main pipeline to neighboring buildings, structures, structures, settlements, transport routes, installed in order to ensure the safety of people.
- July 1, 1959 Mexico, state of Veracruz, Coatzacoalcos. Explosion and fire on the oil pipeline. 12 people were killed, more than 100 were injured.
- July 19, 1960 USA, Wisconsin, Merrill. When conducting earthworks there was a pipeline failure. A gas leak followed by an explosion killed 10 people.
- March 4, 1965 USA, Louisiana, Natchitoches. An explosion on a 32-inch Tennessee gas pipeline. 17 people died, 9 were injured. The reason is depressurization of the gas pipeline due to stress corrosion cracking.
- May 29, 1968 USA, Georgia, Hepville. The bulldozer touched an inch gas pipeline at kindergarten resulting in an explosion and fire. Seven children and two adults were killed, and three children were seriously injured.
- June 4, 1989 USSR, Ufa. Accident on the main product pipeline (VY 700, Ppa6 = 3.5 - 3.8 MPa) near Ufa on the stretch between the stations Kazayak and Ulu-Telyak on the 1710th km of the Kuibyshev railway with the release and ignition of vapors of a wide fraction of light hydrocarbons (NGL ). The cloud drift distance is 900-1350 m. Two passenger trains were in the explosion zone. 573 people died, more than 600 received injuries of varying severity. In the area of the explosion, a zone of continuous forest blockage with an area of 2.5 km2 was formed. Within a radius of up to 15 km from the site of the explosion, glass was broken in the houses of settlements, frames and slate pediments were partially destroyed.
- October 17, 1998 Nigeria, Delta State, Jesse. There was an explosion on the pipeline of the Nigerian National Petroleum Corporation, pumping gasoline. The cause of the accident is deliberate damage to the pipeline. Residents of nearby villages came to the destroyed pipeline to collect spilled fuel. There was an explosion and a fire, which killed about 1,200 people. The fire was extinguished only on 23 October.
- July 10, 2000 Nigeria, Delta State, Jesse. Depressurization of the pipeline with subsequent explosion. About 250 people died.
- July 16, 2000 Nigeria, Delta State, Warri. The destruction of the pipeline and the subsequent explosion killed 100 villagers.
- August 19, 2000 USA, New Mexico, Carlsbad. A gas fire from a rupture of a 30-inch gas pipeline led to the death of 12 people who were in a campsite 180 m from the accident site. A pit 16 m wide and 24 m long was formed at the site of the gas pipeline rupture. A 15-meter section of the pipe was torn out and thrown out of the pit in the form of three fragments (the largest - at a distance of 87m). The cause of the accident is internal corrosion.
- November 30, 2000 Nigeria, Lagos State. Leakage of oil product from the pipeline with subsequent ignition. About 60 inhabitants of the fishing village were killed.
- June 19, 2003 Nigeria, state of Abia. An explosion occurred while trying to steal oil from the pipeline. 125 inhabitants of a nearby village were killed.
- July 30, 2004 Belgium, Brussels. Leakage and explosion of gas on the main gas pipeline (MG) (OY 900) of the Bilagag gas processing plant, 40 km from Brussels. A chain of explosions destroyed two factories, leaving a large crater between the factories. The bodies of the dead and pieces of equipment were scattered within a radius of 500 m from the crash site. At a distance of up to 150 m, all parked cars burned out, the vegetation burned out at a distance of up to 250 m. The effect of the blast wave was felt at a distance of up to 10 km from the accident site. 24 people were killed (at a distance of up to 200 m), more than 120 were seriously burned and injured. Most of the dead are police and firefighters who arrived at the scene of the leak on alarm.
- September 17, 2004 Nigeria, Lagos State. An explosion occurred while trying to steal oil from the pipeline. Dozens of people died.
- May 12, 2006 Nigeria, Lagos State. There was an explosion on the oil pipeline while trying to steal oil. About 150 people died.
- December 26, 2006 Nigeria, state "Lagos. Vandalism led to the explosion of an oil pipeline. More than 500 people died.
- May 16, 2008 Nigeria, Lagos State. A bulldozer damaged an underground oil pipeline. The explosion and subsequent fire killed about 100 people.
- December 19, 2010 Mexico, San Martin Texmelucan de Labastida. Bang on pumping station Re1goek Mekh1kano8 led to the depressurization of the oil pipeline, followed by the outflow of burning oil. 27 people died, 52 were
- injured. The explosion was caused by an unsuccessful attempt to tie into an oil pipeline in order to steal oil.
- September 12, 2011 Kenya, Nairobi. In the industrial area of Lunga Lunga, a pipeline of the Kenya Pipeline Company pumping gasoline, diesel and jet fuel was depressurized. Some of the fuel ended up in the river. People in the nearby densely populated slums of Sinai began to collect the leaking fuel, which exploded, creating a giant fireball. The fire spread to nearby slums. The source of ignition is sparks from a burning landfill. About 100 people died, 116 were hospitalized with varying degrees of burns. The bodies of the dead and fragments of buildings were found 300 meters from the explosion site.
Among these accidents, attention is drawn to numerous cases of explosions during emergency depressurization at main oil and product pipelines (MN) in Mexico, Nigeria and Kenya, which is obviously associated with a warm climate that contributes to the formation of fuel-air mixtures (FA) in case of leaks. ) due to elevated ambient temperature. A large number of victims is due to the tense social conditions of the nearby population.
Methodological approaches to establishing minimum safe distances can be conditionally divided into three areas based on the use of: actual data on the affected areas recorded during accidents (“a posteriori” approach); calculations of the maximum size of affected areas; quantitative risk assessment (QRA) of accidents.
The reliability of the data in the first case is based on the representativeness of statistical data on known major accidents at the MT, in the second - on the calculation and modeling of the consequences of accidents with the most extended damage zones, in the third - on the account of the probability of an accident with certain consequences and the use of acceptable (permissible) criteria risk. In any of these approaches, "margin factors" can be used to compensate for the incompleteness of existing knowledge and understanding.
Let us consider for which types of MT (gas and oil pipelines, LPG pipelines) and in what cases the above approaches to establishing minimum safe distances are mainly used.
The most common and well-established method is to determine safe distances based on the experience of accidents at similar facilities. This approach is partially (together with the modeling of consequences) implemented in Secs. 3.16, 12.3 SNiP 2.05.06-85* "Main pipelines". An analysis of the quite numerous accidents that have occurred at main pipelines shows that the dimensions of the zones of human injury (fragmentation, thermal radiation from burning jets) lie in the range from 100 to 350 m from the pipe axis and are determined in the first approximation by the diameter and pressure in the pipeline. IN this case Sufficiently representative accident statistics do not, as a rule, require the application of additional "margin factors" for safety, and the minimum safe distances are taken to be equivalent to the maximum observed affected areas
The experience of the accident near Ufa in 1989 indicated an increased danger of liquefied hydrocarbon gases (LPG) emissions associated with the instantaneous boiling of superheated liquids and the formation of extended clouds of heavy gases that can spread near the earth's surface while maintaining the ability to ignite at a distance of several kilometers. The consequence of this catastrophe is a tenfold increase in the standard values of safe distances1 from LPG MT to objects with the presence of people.
The second way to establish minimum safe distances for MT is to calculate the affected areas in case of a maximum hypothetical accident (MHA) with consideration of a specific section of the pipeline (route profile, valves, etc.), properties of transported hydrocarbons, technological parameters of pumping, environmental conditions and actions to localization and liquidation of the accident. The "margin factor" for safety in this case is implicitly embedded in the assumptions and assumptions about the occurrence and development of the accident and is determined by the degree of pessimism when choosing the calculated MGA scenario.
This deterministic approach is based on the calculation of the scenario with the complete destruction of the MT and the maximum range of propagation of damaging factors during accidental releases of hazardous substances. In table. 1 shows examples of areas of lethal human injury calculated using the TOXI+ software package in case of accidents at certain sections of the MT according to the data of industrial safety declarations and reports on CDF.
Among the main damaging factors typical for accidents at main gas pipelines, the most significant in terms of the size of the affected zones is thermal radiation from burning gas jets (see Table 1).
When calculating the maximum affected area on MN and MT, the LPG is taken maximum size leaks for the section of the route under consideration, the area of the oil (oil product) spill is conservatively estimated and the distance over which the cloud of their vapors can drift, while maintaining the ability to ignite, is calculated.
Table 1
Consequences of the accident | The damaging factor | Area of effect of the damaging factor, m |
MGOY600, P=5.7MPa |
||
gas expansion | Baric (Exposure^ | |
Mechanical impact | ||
jet burning | thermal effect | |
Fire in the pit | ||
MNOY1000, P=6,ZMPa |
||
Strait fire | thermal effect | |
Ignition of a cloud of fuel assemblies | ||
MT NGL OM 700, P = 5.5 MPa |
||
Strait fire | thermal effect | |
Ignition of a cloud of fuel assemblies | ||
jet burning | ||
Dispersion of hazardous substances in the atmosphere is calculated according to the Methodological Guidelines for Assessing the Consequences of Accidental Releases of Hazardous Substances (RD-03-26-2007) at worst conditions scattering in the surface layer of the atmosphere. As a conservative estimate of the minimum safe distance when calculating the drift of a fire and explosion cloud, the distance at which the cloud dissipates to a concentration equal to half the lower flammable limit (LEL) is taken, which takes into account the inhomogeneity of the distribution of concentration in the cloud. If necessary, the possibility of combustion (explosion) of a drifting cloud, and the corresponding this process affected area subject to assumptions.
The approach based on the analysis of the consequences of the accident is also applicable for determining the safe distances for the "typical" section of the gas pipeline, since the distances established by the calculations of thermal damage from burning gas jets differ slightly from the distances recorded during accidents, and the results of the calculation using the model have a smaller set initial data and accepted assumptions in comparison with the models for calculating the consequences of accidents at MN and MT LPG.
The third way to justify the minimum safe distances is based on the use of QRA, which makes it possible to assess the possibility of an accident, including MHA.
On the considered section of the MT route, release options are calculated for the entire range of sizes of defective holes (from a hole to a guillotine rupture of the pipeline) and all possible outcomes of accidents based on the event tree.
When modeling the distribution in space of zones of action of damaging factors, the probability of an accident and the conditional probability of an accident developing according to one or another scenario are taken into account. Criteria for human injury are determined by the probit function.
The distance at which the calculated value of the potential risk of human death does not exceed the level specified as acceptable is taken as a safe distance.
According to clause 4.2.6 of the Guidelines for the risk analysis of hazardous production facilities (RD 03-418-01), the criteria for accepting the risk of an accident are determined on the basis of regulatory legal documents (for example, it is advisable to take into account the criteria for MT of combustible substances) or justified in project documentation based on operating experience of similar facilities.
The practice of using KOR according to the model based on, when declaring and developing special technical conditions, has shown that the size of the affected areas and the severity of the consequences in case of accidents at the MT, which determine the minimum safe distances, are associated with the technological parameters of the pipeline (diameter, pressure), characteristics of the pumped product, including fire, explosive or toxic properties, state of aggregation in the pipeline (gas, liquid, including liquefied gas); features of the surrounding area (relief); weather conditions (air temperature, wind speed and direction, stratification (stability) of the atmosphere); vulnerability of objects of influence (presence of residential areas, production facilities, transport infrastructure); effectiveness of the leak detection and liquidation system, personnel actions.
Note that the significance of these factors depends on the type of MT (MG, MT or MT SUG).
For example, the main factors that determine the scenarios for the development of accidents at main pipelines and the area of human impact are: the bearing capacity of the soil, the pressure at the rupture site, the location of the rupture site relative to compressor stations and line shut-off valves, and meteorological factors (wind speed and direction, atmospheric stability class, humidity) have little effect.
On the contrary, for MT LPG, the greatest emergency hazard of which is determined by the possibility of drift and ignition of clouds of TV C, the size of the affected zones significantly depend on meteorological factors at the time of the accident.
We also note the weak influence of distances between nodes stop valves for the calculated maximum damage zones in case of accidents
Calculations of minimum safe distances using the methodology of quantitative accident risk analysis show that for modern LPG product pipelines, the size of emergency zones for people to stay does not exceed 1.4 km, while deterministic calculations give an estimate of the size of lethal damage zones up to 2.4 km. The ratios of the sizes of the zones calculated by different approaches depend on the probability of an accident, considered as an MHA.
Thus, from the analysis of the regulatory framework, accidents and the results of calculating the consequences of accidental releases of hazardous substances and assessing the risk of accidents at MPs, the following conclusions can be drawn:
1. The impact on the size of the affected areas and safe distances of the technological parameters of the pipeline, the characteristics of the pumped product, the characteristics of the surrounding area, weather conditions and other factors has been established. The significance of these factors depends on the type of MT (MG, MT or MT LPG), therefore, to solve practical problems, it is necessary to analyze the hazard of specific MT sections and a reasonable choice of safety criteria.
2. The application of the quantitative risk assessment methodology makes it possible to justify the minimum safe distances, the size of which may be significantly less than the normative or certain zones of damage in MHA.
3. The presented results are proposed to be used in the development normative documents on the safety of pipeline transport facilities, including the draft law - the Technical Regulations on the Safety of Main Pipelines for the Transportation of Liquid and Gaseous Hydrocarbons and the Safety Rules for Main Pipelines
Table 3
Pipeline parameters | Pipeline area | Distance according to SNiP 2.05.06-85* (to settlements), m | Area of effect of damaging factors during MHA, m | Distance, m, at which the potential risk of human death is reached, year - 1 |
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OM 250, R a6 = 1.8 MPa | Samara region | |||||
OM 500, /> pa6 = 3.3 MPa | Yamalo-Nenets Autonomous Okrug | Not defined (for product pipelines OY 400 - 3000-5000 m) | ||||
OM 700, R slave = 5.5 MPa | Khanty-Mansi Autonomous Okrug | |||||
