Trunk pipelines

The main pipelines include:

1. a pipeline with branches and loopings , shutoff valves , natural and artificial obstacles, connection points for oil pumping stations, compressor stations, gas metering units, gas reduction points , start-up and receiving units for purification devices, condensate collectors, and methanol injection devices;
2. installation of anticorrosive electrochemical protection of pipelines;
3. lines and facilities for technological communications;
4. telemechanics of pipelines;
5. power lines , including those designed to control installations for electrochemical protection of pipelines and valves;
6. fire fighting equipment;
7. tanks for storage and degassing of condensate;
8. barns for emergency release of oil, oil products, liquefied hydrocarbons and condensate;
9. buildings and structures of the pipeline operation service;
10. roads and helipads, identification marks for the location of pipelines;
11. head and intermediate pumping and liquid pumping stations, compressor stations, gas distribution stations, tank farms;
12. underground gas storage stations;
13. points for heating oil and oil products;
14. warning signs and pointers.

The main gas pipelines are divided into two classes depending on the working pressure:

• I - at a working pressure of 2.5 - 10.0 MPa (from 25 to 100 kgf / cm2);
• II - at a working pressure of 1.2 - 2.5 MPa (from 12 to 25 kgf / cm2).

Main pipelines are divided into four classes depending on the diameter :

• I - with a diameter of 1000-1200 mm;
• II - 500-1000 mm;
• III - 300-500 mm;
• IV - less than 300 mm.

According to SNiP, trunk pipelines should be laid underground. As an exception, if necessary (crossing over natural and artificial obstacles), it is allowed to lay pipelines on the earth's surface in an embankment or on supports . Joint laying of oil pipelines (oil pipelines) and gas pipelines in one technical corridor is allowed.

The selection of the pipeline route should be made according to the optimality criteria , while the criteria for the construction, maintenance and repair of the pipeline during operation are taken as such criteria, taking into account the costs of ensuring environmental protection . In addition, metal consumption, safety, the specified construction time and the availability of roads are taken into account.

The laying of trunk pipelines is not allowed in settlements, agricultural and industrial enterprises, at airfields and railway stations, as well as within sea and river ports and marinas. It is also not permitted to lay trunk pipelines in tunnels of railways and roads, in tunnels together with electric cables and communication cables and other pipelines. It is also prohibited to lay pipelines on bridges of railways and roads. In addition, it is not allowed to lay pipelines in the same trench with electric cables, communication cables and other pipelines - the exception is the technological communication cables of this pipeline at underwater crossings and at crossings through railways and highways. Another exception is the laying of gas pipelines with a diameter of up to 1000 mm and oil pipelines (oil product pipelines) with a diameter of up to 500 mm along fireproof bridges of highways of certain categories. When laying pipelines on such bridges, where communication cables are also laid, coordination with the Ministry of Communications of Russia is required.

The minimum distance from the axis of the underground (or land in the embankment) pipeline to settlements, individual agricultural and industrial enterprises, buildings and structures, as well as other infrastructure facilities, is calculated depending on the class and diameter of the pipeline and is from 10 m (long-distance communication cables and power electric cables) up to 3000 m (from oil pipelines to water intakes ). Allowed distances are indicated in part 3 of SNiP 2.05.06-85 (SP. 36. 13330. 2012 - updated version)

The deepening of pipelines to the top of the pipe should be taken at least 0.8 meters with a pipe diameter of less than 1000 mm, and 1 meter with a diameter of 1000-1400 mm (also when laying pipes in sand dunes, on arable and irrigated lands). At the same time, on swamps or peat soils to be drained , the depth of penetration should be at least 1.1 meters (the same when crossing irrigation and drainage channels). In rocky soils and marshy areas in the absence of vehicles, the depth of penetration should be at least 0.6 m.

The material for the pipes of the main pipelines is steel . According to the method of manufacturing pipes for main pipelines are divided into seamless, electric-welded straight-seam and welded with a spiral seam. Pipes with a diameter of up to 500 mm inclusive are made of calm and semi-quiet carbon and low alloy steels . Pipes with a diameter of up to 1020 mm are made of calm and semi-quiet low alloy steels. And in the manufacture of pipes with a diameter of up to 1420 mm, low alloy steels are used in a thermally or thermomechanically hardened state.

The welded joint of the pipes should be equal to the strength of the base metal. Moreover, the curvature of the pipes should not be more than 1.5 mm per 1 m of length, and the total curvature should not be more than 0.2% of the length of the pipe. The length of the pipes supplied by the plant should be in the range of 10.5-11.6 m. As a material for pipes with a diameter of 1020 mm and more, sheet and coiled steel, which has passed 100% control by physical non-destructive methods ( ultrasound followed by decoding of the defective places by X-ray transmission ).

Corrosion-resistant coatings on underground pipelines must have dielectric properties, be continuous, waterproof, mechanically strong, heat-resistant and elastic.

The types of protective coating are divided into 1) insulating polyethylene coatings of factory application (powder polyethylene for spraying or granular polyethylene for extrusion); 2) insulating coatings of route deposition based on polyethylene (polyethylene tape, duplicated), polyvinyl chloride (adhesive PVC tape), organosilicon (heat-resistant silicone tape) or bitumen (bitumen-rubber mastic). Paints and varnishes ( epoxy paint) are also used.

The most common are coatings based on bituminous mastics. Electrochemical protection is performed using cathodic polarization by connecting an external DC source .

Pipeline design - the process of creating a comprehensive technical documentation containing a feasibility study ( feasibility study ), calculations, estimates, layouts, drawings, explanatory notes and other materials necessary for the construction of pipeline transport facilities. The methodology of the integrated design of pipelines involves strict regulation of the sequence and content of the design stages in accordance with the rules of the Unified system of design documentation .

Pipeline design includes a range of geological , geodetic , hydrological and environmental studies, the collection of geographical and economic information necessary for the formation of the pipeline project. The feasibility study for the construction of the main pipeline identifies the needs of customers at the current moment and in the future, determines the supply zone, justifies the volume of pumping, provides information on the location of the head and end points of the pipeline, as well as information on the points of route selection of the product.

When compiling a feasibility study, the main characteristics of the pipeline are determined: its diameter, operating pressure, and the number of pumping stations. Also, according to aggregated indicators, the construction cost is calculated, and the economic parameters of the pipeline are compared with other modes of transport.

After the feasibility study is completed, a design assignment is created, which indicates the purpose of the pipeline, its annual throughput, breakdown of the construction phases of the facility, the properties of all products to be transported, the initial, final and intermediate points of the pipeline, a list of route points for pumping or pumping products, start dates and the end of construction in turn, the deadline for submitting technical documentation for the design stages, as well as the names of the designer and general contractor.

The task for the design of the pipeline is the main source document, all the provisions contained in it are required to be reflected in the project. At the stage of technical design, all the necessary studies are carried out, the basic engineering solutions for the designed pipeline facilities and environmental protection are developed, and the organization of construction is also determined. In addition, the design assignment determines the total cost of construction and the main technical and economic parameters of the project. In English practice, design stages include the preparation of a Feasibility Study, Design Basis Scoping Paper, and Project Specifications.

Studies to prepare the pipeline project include a comprehensive study of the natural conditions of the construction area. After reviewing the technical project and cost estimates by the expert commission and approving them, the design organization proceeds to draw up working drawings. Orders for equipment and materials are also placed, a contract is concluded with the general contractor (one or more). Working drawings are made in accordance with the approved technical design.

Offshore pipelines and design issues

Offshore pipelines are pipelines that are located in offshore areas. Their design issues, in particular, are covered in the American national standard ASME B31.8-1995 "Gas transmission and distribution piping systems", as well as in addition to this standard API 1111 "Design, construction, operation and maintenance of offshore pipelines for hydrocarbons." In addition, the rules for designing offshore pipelines are described in British Standard BS 8010, Part 3: 1993, Norms and Practices for Pipelines. Submarine pipelines: design, construction, installation. " The Norwegian standard Det Norske Veritas (DNV) OS-F101 Submarine Pipeline Systems is also applied. In Russia, the main document regulating the design and construction of pipelines, including submarines, is SNiP 2.05.06-85 “Main pipelines”.

Electronic as-built documentation is a database that reflects the actual implementation of design decisions and the actual position of the main pipeline facilities and their elements after construction, reconstruction, and overhaul.

The database structure used to describe the design, technical and environmental conditions of the main pipeline is developed on the basis of the PODS (Pipeline Open Data Standard) data model for piping systems.

The structure of electronic as-built documentation includes passport data of mounted parts and structures, data on the actual geometry of the pipeline, information about the work performed, characteristics of the route and intersected objects.

The accuracy of the data should provide the ability to verify the compliance of the constructed, reconstructed, repaired trunk pipeline with the requirements of technical regulations (norms and rules), other regulatory legal acts and design documentation.

The electronic as-built documentation for the main pipelines is prepared by the contractor. Data on the actual execution of design decisions and the actual position of the structural elements of the main pipeline are collected before they are backfilled.

The data of electronic as-built executive documentation can be used to generate executive documentation in paper form for final inspection by the state construction supervision body.

After-commissioning of the main pipeline, the electronic as-built documentation is transferred by the customer in the established order to the operating organization for use as input data (“zero point”) in information systems for managing production assets: inventory, maintenance and repair, integrity management, emergency risk analysis, environmental monitoring, etc.

STO Gazprom 2-2.2-382-2009 “Main gas pipelines. The rules for the production and acceptance of work during the construction of onshore sections of gas pipelines, including in the conditions of the Far North, ”instructs the contractor to draw up electronic executive documentation reflecting the planned and high position of the pipeline and its parts;

Gazprom R 2-2.1-161-2007 "Methodological guidelines for the preparation of electronic as-built documentation for gas pipelines" defines the procedure for the development of electronic as-built documentation;

Gazprom R 2-2.1-160-2007 “Open Standard Data Model for Pipeline Systems” (OSMD TS) defines the list, content, formats and relationships of data included in the electronic as-built documentation;

ASME B31.8S - 2010 “The Managing System Integrity of Gas Pipelines” contains recommendations for the creation of gas pipeline integrity management information systems. In such systems, electronic as-built documentation is one of the main sources of source data.

• SP 36.13330.2012 Main pipelines. Updated edition of SNiP 2.05.06-85 *
• SP 86.13330.2012 "SNiP III-42-80 * Trunk pipelines"
• Offshore pipelines / Yu. A. Goryainov, A. S. Fedorov, G. G. Vasiliev et al., M .: Nedra-Business Center LLC, 2001
• STO Gazprom 2-3.5-051-2006 Norms of technological design of gas pipelines
• RD 153-39.4-113-01. Norms of technological design of oil trunk pipelines