Lap Joint Flange

All the necessary information for the specifications of pipes, valves, fittings and accessories.

In the past 10 -15 years, flange joints designed for metalto-metal face contact with self seating and pressure activated seal rings have been used extensively in high-pressure applications in industrial piping, pressure vessels, pipelines, risers and associated equipment. These flange joints are generally much smaller and lighter, with smaller bolts, than equally rated standard gasketed flange joints, and are often called compact flange joints. This paper provides all necessary information to design compact flange joints for pressure and external loads and made from any suitable material. The paper includes design methods for design of the seal ring, flange and bolts in addition to assembly guidelines. Weld neck flanges, where the hub is of uniform thickness are discussed in detail. Similar method as presented has been applied to design compact flange joints with great success for many years.

Pipelines 2014, 2014

In the design of water pipe systems, bolted flange joints are usually given minor consideration in the overall scheme of things. Flanges have been successfully used in various types of pipe materials for over 100 years and their forms have been standardized for over 50 years. Most flange joint installations are completed without problem or concern, but when a complication arises, it can rapidly become a major issue for everyone involved. Most anomalies that arise during the service life of a flange joint are rarely due to erroneous design; they are almost always related to poor installation practices. This paper discusses installation issues that may occur with steel water pipe flanges, manufactured to AWWA C207 standards. Topics such as proper bolt and gasket selection, flange face arrangements, alignment during installation, bolt-up patterns and the relationship between applied bolt torque and achieved gasket stress are discussed, and practical recommendations are provided to avoid some of the common installation pitfalls. A comprehensive list of resources for the Practitioner is provided, along with a discussion of recent updates in various flange standards and guides. Water system owners, design engineers and installation contractors alike will benefit from the contents of this paper as a resource to achieve leak-free bolted connections on future projects.

Materiali in Tehnologije, 2018

Flange joints and their sealing play an important role in many industries. The gasket performance and its behaviour are influenced by a number of factors, such as non-linear material properties with permanent deformations, assembly procedures and the preparation of sealing surfaces. Additionally, a proper seal function is also affected by the design and strength design of the flanges. Determination of the respective tightening torque needed to achieve a suitable contact pressure between the seal and the flange face is equally important. This paper deals with finite element method (FEM) analyses of a flange joint designed in accordance with the modern standard EN 13445-3 Annex G and examines the influence of operating conditions on the gasket contact pressure. The article also discusses the effects of assembly on the tightness of the joint and the reason for the leakage of the operating medium that took place. The analyses show the effects of operating states on the contact pressures of gaskets and the pre-stressing of bolts. They demonstrate the contact pressure after the application of the pre-stressing of the bolts and its reduction after the temperature-field stabilization due to the start-up of the device. The results of the analyses show that only a relatively small surface of the seal achieves the compression required by the manufacturer to maintain the seal integrity during the application of the tightening forces determined in accordance with EN 13445-3 Annex G. The force of the pre-stressing of the bolts is reduced by approximately 6 % when the normal operation condition is reached. The analyses were performed due to a suspicion of a significant influence of the temperature distribution on flange joints. The main cause of the flange leakage was subsequently revealed by a physical inspection that demonstrated assembly failures when installing gasket 2. The description of these deficiencies is not a subject of this article.

Volume 5: High-Pressure Technology; ASME Nondestructive Evaluation, Diagnosis and Prognosis Division (NDPD); Rudy Scavuzzo Student Paper Symposium and 26th Annual Student Paper Competition, 2018

Flanged joints are used in high pressure applications such as process piping, pressure vessels, risers, pipelines and subsea production systems. These flanges are subjected to external loads in addition to pressure. A brief description of high pressure flanges standards is given. Design of high pressure flanged joints are covered in many design codes. A review of allowable stresses, load factors for bolting, flanges and bolt preload requirements has been made for the following codes: ASME VIII-2, ASME VIII-3, ASME B31.3 Chapter IX, API 6A, API 6X, API 17D, API 17TR7, API 17TR8, API 17G, EN 1591-1 and NORSOK U-001. This paper also presents analytically based structural load-capacity (ultimate strength) design equations for flanged joints. The design equations are used to calculate rated working pressure and flange-face separation load-capacity of API 6A type 6BX flanges. Future code recommendations for flange design are provided.

International Journal of Engineering Research and, 2016

Structures in aerospace are often connected by different types of bolted flange joints. A basic function of bolted joint is to provide adequate joint strength, stiffness and sealing to minimize leakages. The capability of the joints is determined by analysis, augmented by testing. Therefore accurate evaluation of bolt force in a bolted joint under external loads is a fundamental requirement in bolted joint design. Different types of bolted joints such as conventional back to back flange, stepped flange (Dogleg flange), triple stack flange are generally used to connect casings, bearing housings, rotors of gas turbine aero engine. Bolted joints are complex to design and difference in behavior is expected for different design configuration of bolted joints. While hand calculations are used for simple bolted joint design, finite element analysis found to be effective for complex geometry and loading conditions. The objective of present study is to assess the flange separation, contact pressure distribution between flanges, flange stress and load sharing of bolt for back-to-back and stepped flange bolted joints. The nonlinear contact analyses have been carried out for these two bolted joints using FEA software ANSYSver14.0. Analyses were performed for external axial load with assembly preloading. Finite element analysis results indicate different flange separation, contact and load sharing behavior between back-to-back and stepped flange bolted joint. The flange separation starts at the inner radius of flange and grows towards outer diameter of flange, as the axial load is increased in the back-to-back flange joint. The bolt hole zone is critical compare to between bolts for leakage point of view. In the case of stepped flange, no significant flange separation is observed at the interface of flanges as the entire stack pivots about bolt axis with flange corners taking the bending load. The contact pressure between the two flanges is much higher at the bolt position than between bolts. The flange stress induced in the stepped flange is higher compare to convention flange joint. The major portion of the external load is shared by the flanges in case of stepped flange joint, while the bolt shares major portion of the load in back-to-back flange joint. These critical observations provide insight for selecting appropriate joint to ensure structural integrity or to design bolts for failure for worst load case like fan blade off in case of aero engine to reduce load transfer to Airframe.