Vertical steel tank

RVS are intended for the following operating conditions ^{[1] [4]} :

• reception, storage, delivery and accounting (quantitative and qualitative) of oil-containing effluents, oil and oil products ;
• storage and sediment of produced water and solids;
• storage of fire or drinking water;
• storage of liquid food (subject to sanitary standards), aggressive chemical products, mineral fertilizers ;
• a mixture of oil and petroleum products;

and other technological processes of extraction, transport and storage.

Isothermal RVS are also used for storage of liquefied gases ; storage tanks for hot water.

RVS can be: cylindrical, isothermal and storage tanks; they differ: purpose, location, material of manufacture.

According to the methods of manufacturing and installation of sheet metal structures ^[5]

• in roll version - tanks of roll assembly, for which the sheet structures of the wall, bottom, pontoon and roofs (stationary, floating) are manufactured and mounted in the form of rolled panels;
• sheet design - tanks of sheet assembly, the manufacture and installation of all sheet structures of which is carried out from separate sheets;
• combined performance - tanks of combined assembly, the walls of which are made and mounted from separate sheets, and the sheet structures of the bottom, fixed roof, floating roof or pontoon (all or some of them) - in the form of rolled panels.

Tanks of the 1st and 2nd hazard classes are not allowed to be manufactured and mounted by the roll assembly method.

By appointment

• raw material tanks - for storage of crude oil;
• technological tanks - for discharge of produced water, sludge and oil cutting;
• Commodity RVS - for storage of salable oil (dehydrated and desalted).

By the method of manufacturing belts

• belts are welded in steps;
• butt welded;
• made telescopically.

Hazard Class ^[6]

• Class I - tanks with a volume of more than 50,000 m ³ ;
• Class II - reservoirs with a volume of 20,000 - 50,000 m ³ inclusive, also reservoirs with a volume of 10,000 - 50,000 m ³ inclusive, located directly on the banks of rivers , large reservoirs and within urban areas;
• Class III - tanks with a volume of 1,000 - less than 20,000 m ³ ;
• Class IV - tanks with a volume of less than 1,000 m ³ .

Hazard class (taken into account when assigned):

• special requirements for materials, manufacturing methods, quality control volumes;
• reliability factors for liability.

Technical Parameters ^[1]

• The level of responsibility of the structure ;
• Hazard class of the tank - the degree of danger that arises when the limit state of the tank is reached, for the health and life of citizens, property of individuals or legal entities, and environmental safety
• The total service life of the tank is the designated period of safe operation during which the tank does not reach the limit state with probability γ when the necessary maintenance and repair procedures are performed;
• Estimated reservoir service life - the period of safe operation until the next diagnosis or repair, during which the reservoir does not reach the limit state with probability γ.

According to GOST 27751, tanks for storing oil and oil products belong to the I (increased) level of responsibility.

Types of reservoirs by design features ^[6]

• fixed roof tank
  • with a pontoon;
  • without pontoon;
• tank with a floating roof.

A pontoon or a floating roof is a floating coating located inside the tank on the surface of the liquid, designed to reduce the loss of products from evaporation ^[7] , improve environmental and fire safety during storage.

The type of reservoir depends on the classification of oil and petroleum products (see GOST 1510) by flash point and saturated vapor pressure at storage temperature ^[6] :

• with a flash point of not more than 61 ° C with a saturated vapor pressure of 26.6 kPa (200 mmHg) - 93.3 kPa (700 mmHg) (oil, gasoline , jet fuel, jet fuel) are used:
  • tanks with a fixed roof and a pontoon or with a floating roof;
  • tanks with a fixed roof without a pontoon, equipped with GO and UVL;
• with a saturated vapor pressure of less than 26.6 kPa, as well as a flash point above 61 ° C ( fuel oil , diesel fuel , household kerosene , bitumen , tar , oil, produced water), tanks with a fixed roof without GO are used.

RVS are made of steel of different grades, vertical tanks are also made of reinforced concrete .

Basic tank designs:

• Bearing: wall, including insets of pipes and hatches , bottom edge, frameless roof, frame and support ring of the frame roof, wall anchoring , stiffening rings;
• enclosing: central part of the bottom, fixed roofing, floating roof, pontoon .

The edges of the bottom of the tank are thickened, in comparison with the central part, sheets located along its perimeter in the zone of abutment of the wall.

The belt of the wall of the tank is a cylindrical section of the wall, consisting of sheets of the same thickness, while the height of the belt is equal to the width of one sheet.

Underbody construction

The thickness of the bottom of the tank is not calculated and is assigned constructive for welding the walls, since the hydrostatic pressure of the liquid is perceived by the foundation plate ^[8] .

Wall Design

The walls of the reservoir, consisting of steel sheets of the same thickness, are called belts, which are stepwise, telescopically and end-to-end ^[8] .

Roof Construction

In the practice of reservoir construction, roofs are manufactured according to various standards and norms. The roof can be: flat, conical, domed, self-supporting spherical, with or without a pontoon (RVSP), stationary or floating (RVSPK); a floating roof can be one-day (PC) and two-deck (MPC).

The constructions of stationary roofs are divided into the following main types ^[9] :

• self-supporting conical roof;
• self-supporting spherical roof;
• frame conical roof;
• domed roof.

Roofs are installed on rafter ceilings (trusses), which abut on a central pillar inside the tank or on the walls ^[8] , and the roof can only be held around the perimeter by resting on the tank wall or support ring. The minimum thickness of the flooring, as well as any component of the internal and external elements of the roof frame is 4 mm, excluding the allowance for corrosion.

In the 20th century, the tank roof was usually made of steel sheets up to 2.5 mm thick ^[8] .

The load on the roof of the tank ^[8] :

• from the snow
• from vacuum within 245 Pa (25 kg / m ² ),
• from excessive pressure of the steam space (200 kg / m ² ).

Stationary self-supporting conical roof

Self-supporting conical roof, the bearing capacity of which is provided by the conical sheathing of the flooring.

Stationary self-supporting spherical roof

Self-supporting spherical roof, the bearing capacity of which is provided by rolled flooring elements forming the surface of the spherical shell.

Fixed frame conical roof

Frame conical roof, close to the surface of a shallow cone, consisting of elements of the frame and flooring.

Stationary dome roof

A domed roof, the surface of which is close to spherical and is formed by frame elements curved along the radius of the spherical surface and radially or otherwise cut flooring sheets.

Floating roof

Floating roof structures are used if ^[10] :

• tank volume 5000 m ³ and above;
• allowable ratio of the diameter (D) and height (N) of the tank D / N ≥ 1.5;
• maximum normative snow load:
  • 1.0 kPa for tanks with a diameter of up to 30 m;
  • 1.5 kPa for tanks with a diameter over 30 m to 60 m;
  • over 1.5 kPa for tanks with a diameter over 60 m.

Floating roofs are designed so that when filling or emptying the tank, the roof does not sink or damage its structural components and devices, as well as structural elements located on the wall and bottom of the tank ^[10] .

In an empty tank, the roof is on racks supported on the bottom of the tank. In the working position, the floating roof is in full contact with the surface of the stored product. The use of floating roofs on floats, not a contact type, is not allowed.

Stiffening Rings

To ensure the strength and stability of the tanks during operation, as well as to obtain the desired geometric shape during installation, stiffening rings (QL) are installed on the walls of the tanks ^[11] . Types of QOL ^[11] :

• upper wind ring - for tanks with an open top (without a fixed roof) or for tanks with fixed roofs of special types having increased deformability in the plane of their base;
• upper support ring - for tanks with fixed roofs;
• intermediate wind and seismic rings - for reservoirs of all types;
• intermediate forming rings - for tanks constructed by the roll method.

Rigidity rings have a continuous section along the entire perimeter of the wall and are joined end-to-end with full penetration. The installation of ring elements in individual sections, including in the area of ​​mounting joints of the walls of the rolled tanks, is not allowed by the standards ^[11] .

The connection of the rings is allowed on the pads ^[11] . KZh mounting joints are performed from vertical wall joints by at least 150 mm ^[11] . QOL is placed at a distance of at least 150 mm from the horizontal joints of the wall ^[11] . QOL, whose width is 16 or more times the thickness of the horizontal element of the ring, have supports made in the form of edges or struts. The distance between the supports is set no more than 20 sizes of the height of the outer vertical shelf of the ring ^[11] .

In the presence of fire irrigation systems (cooling devices) on the reservoir, QOLs installed on the outer surface of the wall are carried out with a structure that does not impede the irrigation of the wall below the level of the ring ^[11] . Rings of a structure capable of collecting water are provided with sewage holes ^[11] .

The customer as part of the design assignment provides initial data for the design of metal structures and the foundation of the tank, the Customer also participates in the control of their manufacture, installation and during testing and acceptance of the tank through authorized representatives.

The initial data for the design provided by the Customer to the designer ^[6] :

• area (site) of construction;
• tank service life;
• annual number of filling / emptying cycles of the tank;
• geometric parameters or tank volume;
• type of tank;
• name of the stored product indicating the presence of corrosive impurities in the product;
• product density;
• maximum and minimum product temperatures;
• overpressure and relative pressure;
• load from thermal insulation ;
• average annual tank turnover ratio;
• corrosion allowance for tank elements;
• data of engineering and geological surveys of the construction site.

If the complete assignment from the Customer is not provided, the operating conditions are accepted by the Designer taking into account the provisions and requirements of standards, building codes and are agreed with the Customer in the design specification ^[6] .

With design loads exceeding the values ​​given in the current regulatory documents, as well as with a nominal tank volume of more than 120,000 m ^3, calculation and design are performed according to special technical conditions (STU) ^[6] .

The terms of reference for the development of the tank determines the necessary requirements at all stages of the creation of the tank (design, manufacture, transportation, installation, control, testing and acceptance). The composition of the design specification should be taken in the form of an “Order Form” in accordance with the standards ^[12] .

Reliability

Reliability of the tank - the property of its design to fulfill the purpose of receiving, storing and selecting products from it at the parameters specified by the technical documentation on the tank; reliability criteria: operability, failure-free operation, durability of reservoirs and its elements, maintainability of reservoir elements ^[7] .

The main parameters ensuring the reliability of the RVS ^[6] :

• cross-sectional characteristics of the main supporting and enclosing structures, steel properties;
• quality of welded joints;
• tolerances in the manufacture and installation of structural elements.

The operability of the tank is the state in which the tank is able to fulfill its purposes according to the technological mode specified (set) by the project without deviations from the parameters established by the technical documentation made in accordance with the standards.

The reliability of the reservoir - the property of the reservoir and its elements to maintain operability without forced interruptions in operation.

The durability of the tank and its elements is the property of the structure to remain operational to the limit state with the necessary interruptions for maintenance and repairs.

Maintainability of the tank elements - the adaptability of the elements to the prevention and detection of malfunctions, as well as their repair during the service period before failure.

Life

The service life of the tanks is assigned by the Customer or determined during design according to technical and economic indicators agreed with the Customer ^[13] . The service life of the tank includes routine maintenance and repair of tanks. At the end of the service life of the tank, its repair is impossible or impractical for economic reasons.

The total service life of the tanks is ensured by the choice of material, taking into account temperature, power and corrosion effects, rationing of defects in welded joints , optimal structural solutions of metal structures, foundations and foundations, tolerances for the manufacture and installation of structures, methods of anticorrosion protection and the appointment of service regulations ^[13] .

The estimated service life of statically loaded tanks is governed by the corrosion of structures.

In the presence of anticorrosive protection of load-bearing and enclosing structures, the service life of the tank is ensured by the adopted corrosion protection system, which has a guaranteed service life of at least 10 years, which coincides with the term for a full technical diagnosis.

When using an anti-corrosion protection system with a guaranteed service life of less than 10 years, corrosion protection and unprotected elements of the tank elements are assigned an increase in their thickness due to corrosion allowance.

The estimated service life of cyclically loaded reservoirs, along with corrosion wear, is regulated by the generation of low-cycle fatigue cracks.

In the absence of crack-like operational defects, the design life of the tanks is determined by the angularity f _i (clause 5 of table 12 of GOST 31385-2008) of the vertical welds of the wall.

For reservoirs of hazard classes II and III (with a volume of 5,000 m3 - 50,000 m3) with an accepted service life of 40 years and an average annual number of filling-emptying cycles of the tank of not more than 100 (over a 10-year period of operation), the fatigue life of the tank wall will be ensured by the total service life with the following angular values:

• f _i / t _i ≤ 0.33 - for 1-4 belts;
• f _i / t _i ≤ 0.4 - for other belts.

With a loading mode of more than 100 full cycles per year, to ensure fatigue life during the total tank service life, the permissible values ​​of f _i / t _{i are} determined by calculation for all zones of the tank wall.

For reservoirs of hazard classes I and IV, the wall fatigue life is determined by calculation taking into account specific (specified) loading conditions and actual wall shape deviations along the belts.

Based on the test results, the operational loading mode (maximum and minimum product loading levels, loading frequency) and the tank service life are specified.

The service life of the tank is justified by the fulfillment of the requirements of regulatory documents on the maintenance and repair regulations, including the diagnosis of metal structures, foundations, foundations and all types of equipment ensuring its safe operation.

Operation

The category of operating conditions depends on temperature, air humidity, air or gas pressure, taking into account altitude, solar radiation, rain, wind, temperature changes, etc. ^[14]

The operation of tanks is carried out in accordance with the instructions for supervision and maintenance, approved by the head of the operating enterprise ^[13] .

Diagnostics

The total service life of the tank should be ensured by regular two-level diagnostics with an assessment of the technical condition and repair (if necessary) ^[13] . The frequency of partial or complete diagnosis depends on the design features and the specific operating conditions of the tank ^[13] . Full technical diagnosis of tanks is carried out with an interval of not more than 10 years; specific dates are assigned by an expert organization ^[13] .

Two-level diagnosis of reservoirs includes ^[13] :

• partial diagnosis (without decommissioning);
• full diagnosis (with decommissioning, cleaning and degassing).

The first partial diagnosis is carried out ^[13] :

• three years after commissioning - for tanks of hazard classes I and II;
• after four years - for tanks of hazard class III;
• in five years - for tanks of hazard class IV.

1 - combined respiratory valve KDS,
2 - mechanical breathing valve KDM,
3 - emergency valve AK,
4 - combined mechanical breathing valve SMDK,
5 - mechanical breathing valve KDM-50,
6 - pipe ventilation PV,
7 - metering hatch LZ,
8 - hatch mounting LM,
9 - sunroof light LS,
10 - generator foam medium multiplicity GPSS,
11 - sampler floating reservoir PP,
12 - sampler stationary reservoir organ type PSR OT,
13 - sampler stationary sectional reservoir PSR,
14 - side clapperboard control mechanism MU-1,
15 - control mechanism clapper upper MUV,
16 - HP clapperboard,
17 - receiving device PRU,
18 - siphon valve KS,
19 - manhole LL
20 - receiving pipe PRP.

The brand, type of equipment and apparatus, dimensions, completeness must comply with the requirements and directions of the project, depending on the stored product and the speed of filling and emptying of the tank. The project “Tank Equipment” is carried out by a specialized design organization (General Designer) ^[15] . The equipment should ensure reliable operation of the reservoir and reduce losses of oil and oil products.

Tanks, depending on the purpose and degree of automation , taking into account the grade of stored oil and oil products or other liquid media are equipped ^{[15] [3]} :

• receiving and distributing devices with local or remote control;
• respiratory equipment ;
• control devices and automatic alarms
  • devices for local or remote measurement of the level and temperature of stored liquids ( level gauges , pressure gauges for monitoring pressure in a gaseous medium);
  • automatic signaling of upper and lower limit levels (level signaling devices);
• sampling devices or medium samples (reduced RPS samplers);
• devices for removing commercial water;
• devices for heating highly viscous and hardening oils and petroleum products;
• devices to prevent accumulation of deposits in the tank;
• stripping devices;
• light and mounting hatches, manholes and nozzles for equipment installation;
• devices and means of detection ( fire detectors ) and fire extinguishing;
• devices of lightning protection , grounding and protection against static electricity ;
• safety valves.

Typically, local level and temperature measurement is not provided for facilities that perform complex dispatching of technological processes in the tank farm with the organization of centralized control from a control point ^[15] .

In the absence of top-level remote signaling devices , overflow devices are connected connected to the reserve tank or drain pipe , which exclude the excess of the product's gulf level above the design level ^[15] .

The issues of releasing reservoirs from stored liquids in emergency situations are solved by the technological piping scheme in accordance with the requirements and standards of technological design of the respective enterprises ^[15] .

To control the pressure in the tank, a fitting with a shut-off device is installed on the cover of the metering hatch for connecting a manovacuum meter, an automatic signaling device for limit values ​​of pressure and vacuum, or other devices ^[14] .

Tanks filled with oil and oil products in winter with temperatures above 0 ° C are equipped with breathing valves ^[14] . The installation of breathing valves for horizontal tanks on vertical tanks is prohibited ^[14] .

Normative literature

• "Rules for the technical operation of tanks and instructions for their repair." Approved by Goskomnefteproduct of the USSR on December 26, 1986.
• RD 39-015-02 "Rules for the technical operation of reservoirs of oil trunk pipelines."
• RD 16.01-60.30.00-KTN-026-1-04 “Design Standards for Steel Vertical Tanks for Oil Storage with a Volume of 1000-50000 m3”. M., 2004.
• GOST 31385-2016 "Vertical cylindrical steel tanks for oil and oil products. General specifications. "
• SN RK 3.05-24-2004 “Instructions for the design, manufacture and installation of vertical cylindrical steel tanks for oil and oil products”.
• Typical project 704-1-242.88 "Vertical tank without pontoon for oil and oil products with a capacity of 5000 m3 from bulky rolled sheets."
• STO-SA 03-002-2009 “Rules for the design, manufacture and installation of vertical cylindrical steel tanks for oil and oil products”. M., 2009.
• MI 3171-2008 "Steel vertical cylindrical tanks. Geometric calibration technique using laser scanning coordinate measuring systems. ” M., 2008.

Technical Literature

• “Collection and preparation of oil and gas. Technology and Equipment ”/ Ed. Khafizov A.R., Pestretsov N.V. - 2002. - 475 p.
• Lutoshkin G. S. “Oilfield tanks” // “Collection and preparation of oil, gas and water”. - 2nd, rev. and additional .. - M .: " Nedra ", 1979. - S. 250-264. - 319 p.
• "Handbook of equipment for integrated oil treatment." - “Premium Engineering”, 2011. - S. 776.
• Training course "Oil Production". - YUKOS instruction.
• Shukhov V. G. “Mechanical constructions of the oil industry”, “Engineer”, vol. 3, vol. 13, No. 1. Page 500-507, Prince 14, No. 1, pp. 525-533, M., 1883.
• Shukhov V.G. Selected Works. " Building mechanics ." Ed. A. Yu. Ishlinsky , USSR Academy of Sciences , M., 1977, p. 193.
• Shukhov V.G. Selected Works. T. 3. "Oil refining. Heat engineering ", 102 pages, under the editorship of A. E. Sheindlin , USSR Academy of Sciences , M., 1982.
• V. G. Shukhov, Oil storage projects (technical documentation): Moscow Central Historical Archive, fund No. 1209, inventory 1, file No. 64; Archive of the Russian Academy of Sciences, fund No. 1508, inventory 1, files No. 1, 31; Russian State Archive of Scientific and Technical Documentation (RGANTD). фонд № 166, опись 1, дела № 13, 14, 16, 17, 18, 53.
• Шаммазов А. М. и др.: «История нефтегазового дела России», М., «Химия», 2001, 316 стр., УДК 622.276, ББК 65.304.13, ISBN 5-7245-1176-2 .
• «В. Г. Шухов (1853—1939). Искусство конструкции». Райнер Грефе , Оттмар Перчи , Ф. В. Шухов , М. М. Гаппоев и др., 192 стр., « Мир », М., 1994, ISBN 5-03-002917-6 .
• «Владимир Григорьевич Шухов. Первый инженер России.», Е. М. Шухова, 368 стр., Изд. МГТУ, М., 2003, ISBN 5-7038-2295-5 .
• «В. Г. Шухов — выдающийся инженер и учёный: Труды Объединённой научной сессии Академии наук СССР, посвящённой научному и инженерному творчеству почётного академика В. Г. Шухова». М.: « Наука », 1984, 96 с.
• Rainer Graefe und andere, «Vladimir G. Suchov 1853—1939. Die Kunst der sparsamen Konstruktion.», 192 S., Deutsche Verlags-Anstalt, Stuttgart, 1990, ISBN 3-421-02984-9 .