Tareq Awadallah

NATIONAL PRIORITY RESEARCH PROGRAM Development of large ball valves with PVD coated Metal to Metal sealing NPRP No.: 6 - 099 - 2 - 035 NPRP No. : 6 - 099 - 2 - 035 Table of Content-. Background / literature survey ................................................................................................... 1 Objectives / significance ............................................................................................................ 2 Preliminary data or studies .......................................................................................................... 3 Research design and methods .................................................................................................. 4 Anticipated results and evaluation criteria ............................................................................... 8 Strategy for project continuation ............................................................................................... 9 Plans for disseminating research results ................................................................................... 10 QNRF Form RP (Revised Sep. 2012) NPRP No. : 6 - 099 - 2 - 035 Research Plan 1. Background / literature survey Pipelines are traditionally employed for the transportation of crud gas and oil, as they sustain the safe transfer of these mediums in large quantities in a cost efficient and environmental friendly manner. Pipeline infrastructures have to maintain reliable operational characteristics over a long period of time or ease the replacement of degenerated network parts. Even though several proactive inspection procedures have been developed to detect pipeline defects, their restoration might prove problematic due to the restricted accessibility of the majority of installed pipelines, since a big portion of them are not conventionally piggable. The foregoing facts, underline the necessity of long term leak-free performance of network parts, especially those controlling the gas or oil flow, like cut-off valves. The term valve leakage refers to its sealing tightness eliminating internal leakage across the seat from upstream to downstream. Moreover, this term concerns external losses towards the environment. External losses can be avoided through proper valve design and material selection, whereas long term sealing tightness is a difficult to be attained target. Even though elastomeric sealing technologies can provide leakage free operation, the presence of abrasive media within the gas/oil flow rapidly deteriorates the contact geometry through repeated impacts of these particles thus impairing the valves' sealing tightness. This phenomenon often leads to the replacement of conventional elastomeric sealings by metal to metal ones. Conventional elastomeric ball valves are inclined to drastic debilitation of their sealing capacity due to the previously mentioned abrasive particles' impacts on the elastomeric sealing rings. Such particles are also jammed in the ball-ring seat interface piercing the elastomeric during opening and closing valve cycles, resulting in leakages after restricted valve operating cycles. In contrast metal to metal valves, based on high alloyed steels and PVD coatings, exhibit increased wear resistance and almost constant opening torque during their operational life. QNRF Form RP (Revised Sep. 2012) Page 1 NPRP No. : 6 - 099 - 2 - 035 2. Objectives / significance According to P&GJ's latest international survey, 39.042 km of pipelines were under construction in early 2010, increasing by more than 35% compared to 2009, while the planned projects at that point accounted for roughly 106.802 km, affirming the global importance of this rapidly growing sector. Pipeline infrastructures have to consider several international legislations, concerning hazards and pipeline integrity, not only arising from the life threatening nature of possible failure, but also in view of the enormous capital investments associated to these networks.In these terms, it is crucial to maintain reliable operational characteristics over a long period of time or ease the replacement of degenerated network parts. The estimated operational life spam of an elastomeric seated ball valve in deduced to less than 5 opening-close cycles which fails to account for the components development cost. Considering that elastomeric ball valves represent 50% of the installed pipeline shutoff valves introduces fluctuations in the function of the existing gas/oil infrastructure while adding a degree of uncertainty to the operation of high risk components. The objective of this project is the development of a cost efficient procedure to manufacture PVD coated metal-to-metal ball valves of large dimensions, capable of achieving Class VI shutoff up to 100bar. The selection of proper PVD technologies will facilitate the deposition of a low friction coating with improved wear resistance, providing superior operational characteristics when compared to other sealing technologies, thus resulting in a substantially increased life spam of the introduced valves. QNRF Form RP (Revised Sep. 2012) Page 2 NPRP No. : 6 - 099 - 2 - 035 3. Preliminary data or studies In the frame of the EUREKA-EUROSTARS Ʃ!4389 project, with partners from Greece (Aristotle University/Fraunhofer PCCM and ENIMEX S.A.) and Germany (Fraunhofer IPT Aachen and CemeCon A.G.) the design and production of 2' metal to metal ball valves with PVD coated sealing mechanisms was conducted. This concept, protected by corresponding IPR, leads to improved functional and operational ball valve properties compared to existing ones. The finishing of the developed valve’s ball was conducted by form grinding using a corundum (Al2O3) grinding wheel within a tolerance field of ± 1μm. The wheel was shaped to the desired geometry by a developed tool with diamond grains on a ball body which was employed also for resharpening the grinding wheel. This technological approach is however feasible only up to components of restricted dimensions and thus, a new concept has to be developed to overcome these dimensional restrictions. The new concept will be based on hard turning of the components counter-faces, although this approach requires machine tools of high rigidity, complex tool kinematics and highly specific tools (both in geometry and material-coating) it compares favorably to grinding in several aspects i.e. shorter setup and production times, environmental friendly process (dry cutting) simple clamping of the work-piece etc. The RTD performer of the consortium has a wide range of experience in tool-coating development as well as process layout and optimization of cutting kinematics which is based on tenths of international research projects and has been repeatedly published in peer reviewed scientific journals (more than 100 times). The demonstrators have proven expertise on customized valve and pipeline manufacturing thus possessing the knowhow to develop state of the art components and integrate corresponding testing protocols to ensure their flawless operation. QNRF Form RP (Revised Sep. 2012) Page 3 NPRP No. : 6 - 099 - 2 - 035 4. Research design and methods The envisioned project aims at the development of large ball valves with physical vapor deposition (PVD) coated surfaces of their metal to metal sealing mechanisms. The contact interface of the ball valves, subject of the present proposal, will be designed based on good practice obtained within the aforementioned EUROSTARS Ʃ!4389 project. 4.1 Ball Valve main characteristics The new valve parts will be designed based on computational fluid dynamics (CFD) calculations (Bouzakis et al., 2012, J Balk. Tribol. Assoc. 18(3), 390-404). The high manufacturing accuracy of the contact surfaces will be obtained by high accuracy turning of the hardened steel ball body and ring seat. Ball and ring seats will be subsequently coated with a Physical Vapor Deposition (PVD) nanostructured coating, tailored to the applications requirements. The applied film will provided superior surface mechanical properties and a low friction coefficient, thus ensuring long term leakage free operation (Class VI shutoff up to 100 bar and at elevated temperatures) at low opening-closing torque. 4.2 Ball valve manufacturing The technological challenge of manufacturing large metal to metal ball valves is threefold: • Determining a suitable substrate material and geometry for the coated valve components. The selection of appropriate materials will allow the deposition of a PVD at high temperatures while maintaining the material’s structural integrity. For these purposes high alloyed steel with elevated hardness and annealing stability will be selected. The chemical composition of the applied steel will ensure through hardening, high thermal stability and the obtaining of narrow tolerances of these components after the pre-machining. In order to reduce valve weight and cost, the hollow valve balls will be examined through advanced Finite Element simulations concerning the occurring stress and deformation during the valve operation. QNRF Form RP (Revised Sep. 2012) Page 4 NPRP No. : 6 - 099 - 2 - 035 • Selecting a proper high accuracy manufacturing process. The sealing of ball valves is attained by utilizing the network pressure to press the floating ball onto the ring seats. The optimum gap width, contact length and inlet pressure, referring to the contact between ball and ring seat, as a function of the functional characteristics of the valve (i.e. operating torque) can be calculated based on procedures available from previous project. In order however to ensure proper contact between ball and ring seat, both high form and surface accuracy at convenient low roughness levels are required. This will be achieved through a hybrid hard turning process, by a special CNC machine tool technique of high rigidity. As a process, hard turning is based on a single point cutting of the hardened pieces (between 58 and 62 HRC) within a 2 micron range. Hard turning has established itself as worthy alternative to more expensive and time consuming grinding procedures. The advantages of the hard turning over the grinding are among others: ➢ Accuracy: Finishing through hard turning produces machine parts in one set up, thus reflecting high accuracies especially on features such as concentricity, squareness and roundness. ➢ Flexibility: With a single standard tool and clamping set-up hard turning can be employed to manufacture a wide variety of products with different forms and sizes. This provides more flexibility in industrial environments and reduces changeovers. ➢ Productivity: Finishing through hard turning removes more material per machining operation than grinding. This translates in up to 3 to 4 times faster production cycles compared to cylindrical grinding. ➢ Cost efficiency: Multiple operations can be conducted in one set-up, thus eliminating multi-step procedures encountered in grinding. The hard turning process will be optimized along with the corresponding tools for the specific manufacturing procedure, to attain the desired high surface form accuracy at low roughness values, while facilitating sustainable productivity. QNRF Form RP (Revised Sep. 2012) Page 5 NPRP No. : 6 - 099 - 2 - 035 • Development of an application based nano-structured PVD coating The developed coating will combine high elasticity and elevated hardness to improve wear resistance in terms of impact abrasion. This coating will provide among others, a low coefficient of friction with improved wear resistance, providing superior operational characteristics, when compared to other sealing technologies. The surfaces of the valve balls and ring seat will be coated via a PVD process. The coating’s properties will be tailored to the applications requirements (abrasive and/or chemical resistance, operational temperature, transport medium etc.) while significantly contributing to the smooth valve operation at low opening-closing torques. Following the fabrication of the new ball valve, a series of test protocols will be established to quantify its functional characteristics. 4.3 Ball valve testing in a laboratory environment The mechanical properties of the substrate materials and applied coatings will be determined by nanoindentations at ambient and elevated temperatures. The maximum employed penetration load in the conducted nanoindentations by a Berkovich indenter will be limited to 15mN, for avoiding substrate effects. For investigating impact abrasive resistance induced by micro particles impacts, under test conditions close to the real valve operation, a nano impact test will be employed. This test imitates operational conditions, as the valves' ball wear is pivotal for the contact accuracy between ball and ring seat during the valve operation. In conventional elastomeric valves, the ball wear increases and form deviations develop due to high velocity impacts of small hard particles. Since balls and their ring seat are mainly exposed to network micro-sized impurities impacts, the impact abrasion significantly affects the wear development on these part surfaces' during the valve operation. Nano-impact tests will be carried out by a sharp cube corner diamond indenter. During the nano-impact test, a solenoid is used to pull the indenter off the surface and to re-accelerate it from a small distance against the film. An appropriate automation enables repetitive impacts at the same position on the sample surface at a set frequency. The evolution of the indentation depth, due to the progressing film damage during QNRF Form RP (Revised Sep. 2012) Page 6 NPRP No. : 6 - 099 - 2 - 035 the repetitive impacts, will be continuously monitored. The performance of the coated valve components will be assessed by this test and compared to existing sealing concepts. Although it is intended to employ materials for the ball and ring seat that will practically diminish annealing effects on the material hardness up to extremely high temperatures and thus allow these components to maintain their contact geometry (due to the same thermal expansion coefficient), extensive leakage testing will ensure the desired Class VI sealing tightness up to high temperatures. Corresponding tests will be conducted using air, water and nitrogen up to 100 bars. Upon the application of the low friction coating, the operating torque of the valve will be compared to conventional ball valves, employing a fully automated experimental set up allowing the assessment of the operating torque increase versus the open-close cycles. 4.4 Ball valve testing in an industrial and field environment The laboratory tests will be followed by field ones of the developed ball valves through the integration of corresponding prototypes in fully functioning pipeline networks. These valves will be closely monitored to determine their sealing capacity over a long period of time. QNRF Form RP (Revised Sep. 2012) Page 7 NPRP No. : 6 - 099 - 2 - 035 5. Anticipated results and evaluation criteria The project envisions the development of a new generation of metal to metal ball valves that will provide competitive mechanical properties at sustainable production costs. The criteria against which the developed product will be evaluated will be twofold: ➢ Lab-scale experimentation concerning mechanical strength, abrasive resistance and environment dependent sealing tightness. ➢ Field tests verification of life spam, sealing capacity, wear propagation and operational characteristics (i.e. opening-closing torque) It is anticipated that both, state of the art production methodologies will be developed/optimized while pioneering aspects will be investigated in the coating composition and deposition process respectively. The innovative aspects of the conducted research will be subject to Intellectual Property Rights (IPR) and patented accordingly by the partners considering possible rights fortified prior to project initiation, under the premises of full disclosure on behalf of all implicated parties. The IPR of the project will be defined in the Consortium Agreement (CA), signed by all project partners, in order to assure that all participants not mentioned in any IPR, are remunerated accordingly. In any case the industrial project partners will be provided with all the rights that are required for their intended use and dissemination of the project results. QNRF Form RP (Revised Sep. 2012) Page 8 NPRP No. : 6 - 099 - 2 - 035 6. Strategy for project continuation The project initiation is based on the premises that the successful production of all project deliverables will be followed by a self-funded/sustained project continuation until all developed technologies have been commercialized in their full extent. The demonstrators of the project, which are also the end-users of the developed products, commit their selves to integrate the project results in either their production environment (ENIMEX) or their infrastructure set-up, thus ensuring the unhindered transition from R&D to commercialization. This reflects the bottom up approach of the project, which tangles with an applicable technological challenge. QNRF Form RP (Revised Sep. 2012) Page 9 NPRP No. : 6 - 099 - 2 - 035 7. Plans for disseminating research results The R&D performing demonstrators of the project (RasGas and Enimex) will be of vital importance for the dissemination and exploitation of the results obtained in this project. Both companies have an extensive network in thematic area of the conducted research and strong links to international agencies and actions that are promoting pipeline infrastructures. The consortium will define a realistic, coherent and consistent Project Communication Action Plan to be implemented by the consortium during the project. The main issues to be considered by the consortium in defining of the Project Communication Action Plan are the following: • Production and dissemination of effective media information: e.g. printed brochures, flyers. • Participation at trade fairs or suitable conferences. • Strategic cooperation with European and International Networks on mechanical engineering, materials/ nanomaterials and coatings that share mutual benefits from the project results. • Participation at international conferences, fairs and technical and non-technical magazines • Publication in the daily/weekly press, specialized technical magazines. • Issuing of press releases to local, national or international press at suitable occasions. • Organization of media events such as press conferences, exhibitions or information days, for example on the occasion of a project meeting. A project related web-page will be launched with an area open to public to supply relevant information for potential endusers of technologies developed by the project. The web-page will be interactive in order to allow the consortium to constantly monitor external requirements. Meetings and conferences will be directed especially towards the commercial sector. The RTD performer involved in the project will offer his capacity and regional industrial relationships to support the dissemination and exploitation strategy. QNRF Form RP (Revised Sep. 2012) Page 10 NPRP No. : 6 - 099 - 2 - 035 The implementation of the projects outcome is the main objective of the proposed workplan. In these terms the exploitation of the results, as well as the dissemination of the obtained know-how, is of high priority to all participants. Since the involved market is a profound one, the furthering of the sector will have a direct impact on the demonstrators’ market share. The foreseen technique to achieve the assimilation and exploitation of the results by the demonstrators is based on the direct involvement of managing and engineering personnel of the participating companies to the progress meetings and the direct incorporation of the provided feedback into the projects deliverables. This will allow the direct implementation of the technological knowhow into the production line. Furthermore, all technological achievements will be available and demonstrated to the partners on a real time basis allowing them not only to evaluate the projects progress, but also start the training and education of their staff during the early stages of the project. Even though, the main objective of the project will be the commercial exploitation of the results by the industrial partners, non-confidential project results achieved during the project may be published in well established scientific journals allowing a wider distribution of the potentially achieved technological breakthrough. A steering committee established during the project, will be responsible for a “first- step-examination” of the sensitivity of the published work. Nevertheless any information will be examined carefully by the Managing Board prior to publication so that future development or IPR protection won’t be compromised. QNRF Form RP (Revised Sep. 2012) Page 11