Modern valve engineering technology for oil and gas (interview with S.A. Istomin)

Sergey Istomin, CEO, Central Scientific Research Design Institute for Modern Technologies in the Valve Engineering Industry, on new designs and development prospects in valve engineering.

Corr.– What are the design solutions in the manufacture of control valves that you find the most up to date?

SI – There are several types of control valves: control gates (slide valves), control valves, control cocks, control butterfly valves.Each of these types has its own advantages and disadvantages.However, the advent of modern computer simulation methods to model flow in the working medium compensates for those shortcomings by more accurate profiling of flow parts of control valves to meet the needs of customers.

Let us consider several types of control valves most commonly used in modern pipeline systems – i.e. butterfly control valves, ball control valves and axial control valves.Advantages of control butterfly valves (butterfly dampers): high capacity; small size and light weight; very low hydraulic resistance; simple design and small number of parts; absence of deposition spots; no need for continuous maintenance; ease of use; easy and simple installation and repair.

Disadvantages: low coefficient of critical flow leads to low critical pressure drop (as a consequence – tendency to cavitation); in the open position the disk partially blocks the body clearance, as a result hydraulic properties deteriorate and mechanical cleaning of pipelines becomes very difficult; application has pressure and temperature limitations.

Advantages of control ball valves: high capacity; very low hydraulic resistance;
Disadvantages:low coefficient of critical flow leads to low critical pressure drop (as a consequence – tendency to cavitation); narrow control range.

Control ball valve designed by OOO TSNIPI STARK using modern computer design methods features cavitation-free operation, low noise, vibration, as well as shut-off function.

Advantages of axial control valves: critical flow rate is high enough, as a result high critical difference is maintained in the valve; can be designed with a tight seal and act as an isolating valve; less powerful drives can be used; high capacity, wide control range; low erosion and vibration.
Disadvantages: complicated design; high cost.In our opinion, the most promising design solutions in control valves are axial control valves and ball control valves.

Corr.– Adverse conditions in the extraction and processing of oil and gas often require the use of wear- and corrosion-resistant alloys.Could you tell more about the new alloys that are used in the manufacture of oil and gas valves.

SI – The application of new alloys, steels, materials in oil and gas production and processing equipment is a fairly lengthy and multifaceted subject.This is a serious topic for the analysis of trends, efficiency, reliability criteria, application of new materials, and practical implementation of equipment, feedback on operational performance, and so on.Nevertheless, major development trends can be highlighted in oil and gas production and processing technology that ultimately determine the requirements to materials, alloys and steels:

  • intensification of technological processes of production and transportation of oil and gas;
  • more difficult production conditions – increased depth of occurrence, more complex climatic conditions (Arctic, offshore fields, increased seismicity), fracturing, and so on;
  • higher reliability of pipeline systems in terms of service life;
  • introduction of new technologies of oil and gas processing with the use of more complex chemical compounds and thermal conditions.

These and other conditions determine current requirements to equipment and materials.

There are three main areas in the development of new materials.

  • The first one is improving the quality of traditional steels and alloys by producing cleaner steels with less harmful impurities (sulfur, phosphorus), special thermal and chemical-thermal treatments, protective coatings on steels and alloys.
  • The second one is using well-known steel grades with high strength, heat resistance, corrosion resistance, instead of traditional steels: using steel 35ХМЛ instead of 20ГМЛ increases service life of gate valve DN65 PN210 for wellhead equipment by 1.5 times and reduces its weight by 30%; using steel 12Х18Н9ТЛ in the petrochemical valves instead of steel 15Х5М improves corrosion resistance of the product by more than 1.5 times.
  • The third one is the use of new materials and steels: ceramics and metal ceramics, new surfacing materials such Stellit, Colmonoy, steel EP-987 (10Х18Н11С5М2ТЮ) that can without surfacing successfully replace traditional surfaced steels in valves (in wedge gate valves); thermally expanded graphite combined with metal in valve saddles, rings, gaskets.

Corr.– Maintenance of pipe valves is a major part of costs over the service life.What are, in your opinion, the most effective ways to reduce these costs?Are there valves with minimum maintenance costs?Is there research into new types of pipe valves with longer service life?

SI – One of the most effective ways to reduce the maintenance costs is to increase the time to first repair (maintenance) and subsequent turnaround intervals, or, in other words, to extend the service life of pipe valves.

Reducing valve maintenance costs by increasing the time to first repair can be achieved not only through designing valves with sufficient reliability margin, but also by selecting right valves for the given operating conditions, and subsequently following proper maintenance, repair and diagnostics strategy.

Correct valve choice is based on a comprehensive assessment of the valve’s ability to comply with the operational requirements at the highest possible level of performance.An interesting operating experience in the nuclear power industry is to repair valves based on their actual technical condition, assessed by diagnostic tools.Valve condition indicators, as measured by appropriate diagnostic programs (torque, smoothness of operation, opening and closing time, etc.), allow to determine whether repair work is needed in the maintenance interval prescribed by the maintenance regulations.In our view, this experience can be used in critical valves, but this requires coordinated systemic efforts from the customer, designer of piping systems and installations, valve manufacturer and service departments.

As towhether there are valves with minimum maintenance costs, I would say say following: yes, there are such valves in the nuclear power industry – control supply valve, main steam valve.

Design and implementation efforts in pipe valves with extended service life and increased maintenance interval cycle have been led by OOO TSNIPI STARK together with Research Institute for Oil and Oil Products Transport, National Research University Moscow Power Engineering Institute, Research and Development Association Central Research Institute for Mechanical Engineering Technology, Polzunov Research and Development Association for Research and Design of Power Engineering Equipment.

Corr.– How do you assess the prospects of nanotechnology in valve engineering?

SI – Valve engineering is one of the branches of engineering.It is characterized by common trends in the introduction of nanotechnology that involve improving operating properties: weight reduction; increased service life through better erosion and corrosion resistance of the valve flow channel; reduction of the drag coefficient; reducing power rating of the drive unit, etc.

To achieve these goals we need to reduce friction in moving joints and improve their wear resistance, improve erosion resistance of the flow channel and valve components.Here we come to nanotechnology, namely application of nanotech coatings (one of the most promising areas) that make it possible with a varying degree of success to achieve the desired result.

Modifying only product surface layers and applying ion-plasma coatings with nanocomposite structure (PVD-coatings) is more cost-effective than modifying the entire component in bulk.Today, it’s not a secret that the decrease in the average grain size approximately to 10 nm or less results in a significant change in a number of physical properties of materials: thermal (melting point becomes lower), kinetic (diffusion coefficient increases sharply, thermal conductivity falls), mechanical (yield limit and durability increase, there appears a superplasticity effect at high temperatures), etc.This is due to the fact that the grain size in nanocomposites becomes smaller than the respective characteristic length (thickness of domain wall, critical radius of dislocation loop, etc.).
Certain limitations (that must be overcome) in the application of nanocoatings, along with the cost of implementation, are insufficient development level of the application technology used on complex surfaces, such as internal power screw thread, as well as coating quality control methods ensuring proper quality of the product.A major obstacle is the lack of comparative experimentally obtained properties of valve parts without and with coating.For this very purpose OOO TSNIPI STARK is working on the task set by AO Ust-Kamenogorsk Valve Plant to research and analyze coatings, conduct comparative tests in different operating environments, and implement respective technologies in slide gate valves and ball valves with extended service life.

Corr.– What, in your opinion, should be changed in valve engineering to bring this branch of Russian industry to a leading position in the international market?

SI – I would like to split up my answer to this question in two parts:

1) What do we need to do to get rid of the import dependence in valve engineering?

2) What should be done to increase the export potential of Russian valve engineering in the international market?

To answer the first part of the question, we need the following:

  • Develop detailed import substitution programs in the valve industry for following main application:Gazprom, Transneft, Rosneft, Surgutneftegaz, Novatek, Lukoil, based on actual technical needs of customers;
  • Provide opportunities for the trial operation of import substituting products;
  • Build at Research and Industry Association of Valve Manufacturers, together with relevant organizations (OOO TSNIPI STARK, OAO MosCKBA), a database of materials and blanks used in the manufacture of valves for challenging environments;
  • Carry out a series of comparative tests of Russian and imported valves.

To answer the second part of the question, the following is needed:

  • Valve manufacturers have to realize that the export potential of the company determines its position both on the global market and on the domestic market.Based on this, it is necessary and appropriate to design programs supporting development and improvement of the export potential of valve manufacturers.This is a complex and multicomponent task;
  • Build at Research and Industry Association of Valve Manufacturers, together relevant organizations, a database of European and American standards;
  • Develop a methodological program for implementation of the world’s main standards in oil and gas production and processing;
  • Interested valve manufacturers should develop cooperation programs with major foreign customers and designers in oil and gas production and processing on the basis of obtaining appropriate certificates and being approved as potential suppliers of equipment to other countries;
  • Specialized valve manufacturers should create conditions conductive to compliance with European (PED) and American (ASME Boiler and Pressure Vessel Code) safety standards.

Interview prepared by E.G. Ostroumova (OOO Gazoil press)
Journal Gazovaya Promyshlennost (September/711/2014)