Küresel vananın sonlu elemanlar analiz yöntemi kullanılarak optimize tasarımı
Optimized design of a ball valve using finite element analysis method
Yazar: TEYMUR MAMMAD
Danışman: DOÇ. DR. TİJEN ÖVER ÖZÇELİK
Sakarya Üniversitesi / Fen Bilimleri Enstitüsü / İmalat Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: Makine Mühendisliği = Mechanical Engineering

Özet:
Vana teknolojisi, endüstriyel süreçlerin temelini oluşturan ve birçok sektörde hayatibir rol oynayan önemli bir unsurdur. 19. yüzyıldan bu yana gelişen ve çeşitlenen vana modelleri, endüstriyel tesislerde, enerji santrallerinde, su ve atık su tesislerinde, kimyasal tesislerde, petrol ve gaz endüstrisinde ve daha birçok alanda kullanılmaktadır. Bu çeşitlilik, farklı uygulamalara ve gereksinimlere uygun olarak tasarlanmış vanaların mevcut olduğunu göstermektedir. Günümüzde kelebek, iğneli, küresel, soketli, flanşlı, monoblok gibi çeşitli modellerdeki vanalar, üretimin olduğu birçok sektörde yaygın bir şekilde kullanılmaktadır. Özellikle küresel vanalar, boru hattı sistemlerinde akış hızını ve akış yönünü kontrol etmek veya akışı tamamen kesmek için sıklıkla tercih edilen akış kontrol bileşenleridir.
Küresel vana üreticileri, tasarımlarını Amerikan Petrol Enstitüsü'ne (API) bağlı olarak API 6D ve ASME 16.34 standartlarına uygun şekilde değiştirmekte ve aynı zamanda API Q1 kalite beklentilerine uyum sağlamaktadır. Bu standartlar, küresel vanaların performans, güvenlik ve dayanıklılık açısından en yüksek şartları karşılamasını garanti etmektedir.
Bu çalışmada, iç çapı 100 mm olan 600 sınıfı flanşlı trunnion küresel vana, belirlenen standartlar çerçevesinde sonlu elemanlar analizi yöntemiyle optimize edilerek tasarlanacak ve vananın performansı detaylı bir şekilde incelenecektir. Tasarım için SolidWorks, analiz için ANSYS yazılımı kullanılmıştır. Belirlenen koşullar ve optimizasyon kriterleri doğrultusunda, vananın yapısal bütünlüğü, dayanıklılığı özellikleri değerlendirilecektir. Bu analizler, işletmelerin doğru vana seçimi yaparak hem maliyetlerini düşürmelerine hem de operasyonel verimliliklerini artırmalarına katkı sağlayacaktır.
Tezin yapısı beş bölümden oluşmaktadır:
Birinci bölüm olan giriş kısmında, tezin yapısı, vanalarla ilgili tarihi, literatür taraması, problemin tanımı, gerekçe, konu, genel ve özel hedefler, tezin katkıları, kapsamı, sınırlamaları ve tezin gerçekleştirilmesi için benimsenen araştırma yöntemi ele alınmaktadır.
İkinci bölüm olan küresel vanalar kısmında, küresel tip endüstriyel vanalarla ilgili literatür taraması yapılmaktadır. Bu bölümde ilgili çalışmalar, küresel vana, küresel vana tipleri, tasarım ve standartlaşma konuları incelenmektedir.
Üçüncü bölüm olan materyel ve yöntemler kısmında, küresel vanalar için kullanılan standartları, tasarlanacak parçalardaki malzemelerin seçimleri ve bu malzemelerin karakteristik özellikleri detaylı incelenmektedir. 
Dördüncü bölüm olan yapısal analiz bölümünde 3 parçalı trunnion tipi küresel vananın parçaları tasarlanarak analizler yapılmış ve 2 parçalı küresel vana tasarımı elde edilmiştir. 
Beşinci bölüm olan sonuçlar kısmında, tezin sonuçları ve tezin araştırma projesine devam edecek gelecekteki çalışmalar için öneriler sunulmaktadır. 
Bu yapıyla, çalışmanın bütünlüğü ve amacı net bir şekilde ortaya konacak, araştırma süreci ve bulgular detaylandırılacaktır.

Abstract:
Valve technology is a crucial element forming the foundation of industrial processes and playing a vital role across many sectors. Since the 19th century, evolving and diversifying valve models have been utilized in industrial plants, power stations, water and wastewater facilities, chemical plants, the oil and gas industry, and many other fields. This diversity indicates that valves are designed to meet different applications and requirements. Today, various models of valves, such as butterfly, needle, ball, socket, flanged, and monoblock, are widely used in many sectors where production occurs. Particularly, ball valves are frequently chosen as flow control components to control flow rate and direction or to completely shut off the flow in pipeline systems.
Ball valve manufacturers modify their designs in accordance with API 6D and ASME 16.34 standards related to the American Petroleum Institute (API) and adhere to API Q1 quality expectations. These standards ensure that ball valves meet the highest requirements for performance, safety, and durability.
In this study, a 600-class flanged trunnion ball valve with an internal diameter of 100 mm will be designed and optimized using finite element analysis within the framework of the specified standards, and the valve's performance will be thoroughly examined. SolidWorks was used for the design and ANSYS software for the analysis. The structural integrity and durability of the valve will be evaluated according to the specified conditions and optimization criteria. These analyses will help businesses make the right valve selection, reducing costs and increasing operational efficiency.
The thesis is structured into five chapters:
In the first chapter, the introduction, the structure of the thesis, the history of valves, literature review, problem definition, rationale, subject, general and specific objectives, contributions, scope, limitations, and the research method adopted for the thesis are discussed. This section lays the groundwork for understanding the significance of the study, outlining the key issues addressed and the expected contributions to the field of valve design and optimization.
The second chapter, ball valves, presents a literature review related to industrial ball valves. This section examines relevant studies, ball valve types, design, and standardization topics. It provides a comprehensive overview of the current state of ball valve technology, highlighting advances and identifying gaps in the existing body of knowledge. This chapter aims to set the stage for the subsequent research by contextualizing the problem within the broader scope of industrial applications and technological developments.
In the third chapter, materials and methods, the standards used for ball valves, the selection of materials for the designed parts, and the characteristic properties of these materials are examined in detail. This chapter delves into the technical aspects of ball valve construction, providing a thorough analysis of the materials chosen for different components. It discusses the criteria for material selection, such as mechanical strength, corrosion resistance, and suitability for specific operating conditions. Additionally, the methods used for the structural analysis and optimization of the ball valve design are explained, including the computational tools and techniques employed.
In manual ball valves, when the ball's opening aligns with the inlet and outlet ports, flow continues uninterrupted, and if a full port ball is used, there is minimal pressure drop. However, if a reduced port ball is used, the pressure drop increases. When the manual operator is positioned parallel to the pipeline, the flow paths of the ball align with the flow paths of the body, providing full flow. When the manual operator is turned to the closed position, the ball's opening becomes perpendicular to the flow stream, blocking the flow.
In throttling applications, when the ball is in the middle-turn position, the flow experiences a double pressure drop as it passes through the valve. When a customizable ball is used, a specific opening in the ball is exposed to the flow at a certain position as the ball rotates from closed to open, providing 100% flow in the fully open position.
WCB cast steel valves can be divided into three categories: cast carbon steel, cast low alloy steel, and cast special steel. These categories are generally preferred for manufacturing parts with complex shapes that are difficult to forge or machine. The selection of this material offers significant advantages in design and optimization processes, particularly because it meets high strength and plasticity requirements, making it ideal for parts with intricate geometries. These reasons are among the important factors influencing the decision to choose WCB material in valve design.
In the ball valve material selection table, the valve body and cover are made from ASTM A216 Gr. WCB material. The ball holder is made from PTFE, while the body shaft is constructed from ASTM A182 Gr. F6a material. The bolts are ASTM A193 Gr. B7, and the bolt nuts are ASTM A194 Gr. 2H. The packing is composed of Teflon material with graphite braided end rings. The ball and lower bearing are manufactured from SS304 material, and the lower bearing flange is also made from ASTM A216 Gr. WCB material. The eye bolt nuts are made from ASTM A194 Gr. 2H material.
In the fourth chapter, structural analysis, the parts of the 3-piece trunnion ball valve were designed and analyzed, ultimately leading to a 2-piece ball valve design. Optimization studies were conducted to enhance valve performance and reduce costs. Pre-optimization analyses identified weaknesses in the existing design, evaluating parameters such as stress and deformation. Post-optimization analyses then evaluated the effectiveness of the design changes. In this process, optimizing the ball valve cover played a critical role in ensuring system safety and efficiency. Changes in the cover design post-optimization were assessed through stress and deformation analyses, resulting in a reduced weight and an optimized design for the valve.
The analysis concluded that transitioning from a 3-piece flanged ball valve to a 2-piece valve offers many opportunities for valve optimization. This transition can result in savings on components such as the lower bearing shaft and sealing elements. While the additional components and connections in 3-piece valves provide ease in maintenance and repair processes, they also pose a cost disadvantage. On the other hand, the fewer components in 2-piece valves reduce production costs and shorten assembly time due to fewer connecting elements.
In the fifth chapter, conclusions, the results of the thesis and recommendations for future studies in the research project are presented. These results show that the optimized design achieves weight reduction while maintaining safe operating conditions. In the numerical model, it is assumed that the material is homogeneous, free from pores and foreign matter, and does not contain residual stresses produced by the manufacturing process. However, the presence of foreign matter, pores, and residual stresses in the actual components of the valve can lead to differences between numerical and experimental analysis results. The placement of strain gauges can also cause significant differences between experimental and numerical results because the locations of these elements may not exactly match the points determined in the finite element software.
In this context, it has been proven that applying CAE (Computer-Aided Engineering) technology using the finite element method is suitable for the analysis of trunnion ball valves. This technology allows for the determination of deformations and stresses that occur due to various loads the valve will be exposed to throughout its service life. These analyses encompass assembly stages, approval tests, factory acceptance tests, and operational processes. Applying CAE technology through the finite element method emerges as an alternative tool for analyzing different shapes and applications of a specific valve, enabling optimization by focusing on value addition and eliminating waste.
With this structure, the integrity and purpose of the study will be clearly presented, and the research process and findings will be detailed.