Why oil and gas transportation companies of Ukraine have been forced to make do with falsification since 2015? What equipment is needed to produce LDP, according to GOST 20295-85 and international standards? What is the difference between expansion and calibration and who benefits from the substitution of concepts? In the article you will find answers to these questions and learn how to protect yourself from counterfeiting even at the stage of publishing a tender for the state procurement of LDP.

NPP UKRTRUBIZOL revives the production of LDP that meet the best international standards. The principal difference of the new line is the modern equipment for the full technological cycle of LDP production for main gas and oil pipelines. The key advantage of the unique equipment is the pipe expanding mechanism.

What is LDP expansion?

Expansion is performed by cold extension of the pipe diameter along its entire length. In the process of expansion, the metal goes into the plastic deforming region. Plastic deformation increases the strength of the pipes, resulting in the longer lifetime of the pipe, while the likelihood and extent of destruction is reduced. 

Pipes that have not passed the expansion stage tend to take the expanded shape. This is due to a hidden fault - harmful residual stresses. Residual stresses reduce pipeline reliability.

Expansion stabilizes the mechanical properties of the material and helps to reduce residual stresses, so expanded pipes do not tend to unfold.

Expansion is a unique technological solution to produce high-quality large-diameter pipes.

Pipe expansion functions:

Material hardening:
increase in tensile strength in the direction perpendicular to the pipe axis
Preliminary metal testing
at stresses above the yield point
Removal of residual stresses and deformations,
arising in the process of forming a pipe billet and welding
Additional quality control
of base metal and welded pipe joint
Calibration:
giving the pipe a round shape, reducing curvature, providing a set of required geometric parameters
Enforcement of requirements
of up-to-date modern regulatory documentation
According to GOST 20295-85, international standards and world practice, expansion is an integral stage in the production of large diameter longitudinal welded steel pipes for the construction of trunk pipelines to transport oil and gas.

To provide a set of technical requirements for gas and oil pipeline LDP, the production cycle must include specialized equipment, including an expander.

Causes and consequences of the shortage of high-quality LDP in the Ukrainian market

Previously, the pipe for trunk pipelines that meets the technical requirements for the Ukrainian market was supplied by the Khartsyzsk Pipe Plant PJSC located in a temporarily uncontrolled territory. The shutdown of the plant in 2015 led to a total shortage of high-quality pipes in Ukraine.

The vacant niche was occupied by enterprises that do not have equipment for a full technological cycle of production and testing. Lack of equipment for expansion in Ukraine and inability to produce quality pipe gave rise to the myth that the advantage of expansion lies only in calibration. This misconception turned out to be convenient for everyone. The domestic market was captured with a pipe for gas and oil produced without performing the necessary technological and control operations. 

With no alternative, certification and legal requirements conformity assessment bodies were forced to issue permits for such a pipe without actual confirmation of the producers' compliance with the requirements of regulatory documents and technical regulations for pressure equipment. 

Danger of using LDP produced without expansion

Neglecting expansion due to the lack of the necessary working technological and testing equipment by the producer is:

Violation of technical requirements for trunk gas and oil pipelines due to inconsistency of pipes with regulatory documents
Threat to the safety, reliability and durability of the trunk pipelines of Ukraine made of such a pipe
The risk of using counterfeit products in the construction and reconstruction of gas and oil pipelines
The quality of LDP, and, consequently, of the life-supporting pipelines of Ukraine depends on the awareness of personal responsibility on the part of all participants of the process: 

Consumers
Producers
State bodies
Bodies for assessing compliance with legal requirements
Scientific organizations providing technological support of production.

Expanded pipe is a guarantee of the quality of the trunk pipeline

To obtain a large diameter pipe that fully meets your requirements, it is essential to prescribe in the tender the need for the mandatory use of an expander in the production process. It is required to request documents proving the availability of the necessary processing and test equipment. This will provide your facility:

·        Safety:
reducing the likelihood and scale of an accident

·        Durability:
increase in the period of trouble-free operation 

·       Quality:
compliance with the strict requirements of ISO 3183: 2019, API Specification 5L and national GOST 20295-85, DSTU ISO 3183: 2017

The experience of LDP production and research shows that a complex of strength and toughness properties of the base metal and welded joints of pipes, their geometric parameters, which determine the durability and reliability of the oil and gas transportation system, play an important role in the structural strength of welded pipes. Ensuring a set of technical requirements for LDP requires the organization of the technology for their production using specialized industrial equipment, including the expansion operation in the technological process.

Ukraine’s only line for the production of expanded pipes for oil and gas pipelines 

Considering the compliance with quarantine measures, it took a year and a half for the installation, debugging, obtaining permits and launching the line for the production of expanded large-diameter pipe. Now work is underway to install a hydromechanical expander for through expansion of pipes with a diameter of 406.4 mm to 1422 mm with a wall thickness of up to 24 mm. This equipment provides high strength and precise geometry of pipes along the entire length. There are no analogues of such equipment in Ukraine.

The new line is additionally equipped with a hydraulic press for internal pressure testing. Hydraulic test is performed to check the strength and continuity of the base metal and pipe welds. This guarantees the reliability and durability of pipelines operating under pressure.

The principle of operation of NPP Ukrtruboizol’s hydromechanical expander 

A cone-shaped expansion head located at the end of the rod of a pipe hydromechanical expander is inserted into the pipe at a certain distance - a step. Expansion head segments extent and exert pressure on the inner surface of the pipe along the entire perimeter. Stresses appear in the pipe walls equal to the metal's yield point. An increase in diameter - plastic deformation - occurs. After the segments of the expansion head take the initial position, the pipe slightly decreases in diameter due to the spring return of the metal and takes the given form. The cycle circulates with each step of the expander movement along the pipe axis. As a result, the pipe gets the specified geometric parameters (perimeter, curvature, ellipticity) and stabilization of mechanical properties.

NPP UKRTRUBOIZOL is a reliable producer and supplier

With the commissioning of a new line for the production of steel pipes, UKRTRUBOIZOL is:

The only pipe plant in Ukraine with a complex of equipment for a full technological cycle of LDP production for trunk pipelines.
Ukraine's largest producer of large diameter steel longitudinally welded pipes with external and internal anticorrosive or smooth coatings for gas and oil trunk pipelines. 
 

Save as installing a new line for the production of steel pipes, the plant is involved in modernizing its existing production lines for coating. In 2020, the enterprise mastered the production of pipes with an outer polypropylene coating and carried out a global reconstruction.

 The company installed a modern set of equipment to coat powder primer. Due to its flexibility, elasticity, resistance to cracking and mechanical damage, the coating has higher adhesion, impact strength and relative fracture elongation.

A new line with a capacity of up to 25,000 tons of pipes per year was installed and put into operation. The line provides the production of longitudinal electric-welded steel pipes with a diameter of 406.4 to 1422 mm, a wall thickness of 6 to 24 mm and a length of up to 12 meters from steel of up to K60 strength class.

The plant's products are certified for compliance with the requirements of the Technical Regulations for Pressure Equipment (Resolution of the CMU No. 27 dated 01.16.2019) and standards:

GOST 20295-85
GOST 10706-76
GOST 10705-80
GOST 10704-91 
 

The company operates an integrated management system that meets the requirements of international standards, which is confirmed by the Bureau Veritas certification body:

ISO 9001:2015
ISO 14001:2015
ISO 45001:2018
NPP UKRTRUBOIZOL has been producing and supplying high-quality products to the market of anti-corrosion insulation for more than twenty years to create reliable pipelines with a service life of up to 50 years. Due to the quality of the products, the company won authority in the markets of Ukraine and the world.