Ensuring reliability and safety pressure vessel flanges

Pressure vessel flanges are essential components widely used in various industries such as petrochemical, power generation, nuclear, and light industries. Serving as fundamental elements for connecting different parts of pressure vessels, these flanges play a critical role in ensuring seamless operations.

Components of Flange Assemblies: For a pressure vessel, a flange assembly includes the flange itself, gaskets, connecting bolts or studs, and nuts. The primary function of these assemblies is to join different pressure components while ensuring leak-proof connections.

SS316 RTJ Blind Flanges

Sealing Forms of Flanges:

Forced Sealing: Achieved by tightening the connecting bolts or studs to press the sealing surfaces together, examples include flat gasket seals and Kammprofile seals.

Self-sealing: Utilizes the pressure of the vessel’s internal medium to generate sealing forces on the sealing surfaces. Examples include combination seals, O-ring seals, and C-ring seals.

Semi-self-sealing: Combines the use of internal medium pressure and fasteners to achieve sealing. Examples include double-cone seals.

slip on flanges DN1000 RF-AWWA C207 Hub A105

Working Principle: When pre-tension force is applied to the flange bolts, they compress the gaskets, causing them to deform. As the bolt force reaches a certain value, the sealing surfaces and the non-flat surfaces on the gaskets fill up, creating initial sealing conditions. The compression force per unit effective sealing area of the gasket is called the initial sealing ratio pressure. When the equipment or pipeline is subjected to medium pressure, the bolt experiences tensile stress, causing the flange sealing surfaces to move apart, resulting in a decrease in compression force and gasket compression. If the gasket has sufficient rebound ability, it can compensate for the separation of the bolt and sealing surfaces, maintaining a good sealing state.

Classification of Pressure Vessel Flanges: Flat welding flanges used on pressure vessels are divided into Type A and Type B.

Type A flanges are directly welded to the vessel, with smaller weld seams or non-beveled welding. Their strength is calculated based on slip-on flanges.

Type B flanges generally have a thicker short cylinder attached, ensuring reliable welding with the vessel and simultaneous force distribution. They are widely used in medium and low-pressure vessels and pipelines.

Both types have their advantages: Type B flanges with short cylinder bodies offer better rigidity, suitable for high-pressure and large-diameter applications. Meanwhile, Type A flanges, with V-shaped bevels, are easier to weld through, providing higher strength and stiffness.

Haihao Group has been engaged in the field of forged flanges for more than 40 years. We are capable of producing flange products for various environments, including pressure vessel flanges. If your project requires these products, please feel free to contact us.