dished heads

Dished Heads: An Overview of Their Uses and Manufacturing Process

Dished heads, also known as dish ends or tank heads, are important components used in various industries, including pressure vessels, storage tanks, and boilers. These curved structures serve as end closures, providing strength, structural integrity, and sealing properties to the vessels they are attached to. In this article, we will explore the uses, types, and manufacturing process of dished heads.

Uses of Dished Heads:

1. Pressure Vessels: Dished heads are commonly used in the construction of pressure vessels, which are containers designed to hold gases or liquids at high pressures. These vessels can be found in industries such as oil and gas, chemical processing, and pharmaceuticals. Dished heads help to maintain the structural integrity of the pressure vessel and ensure safe operation under high-pressure conditions.

2. Storage Tanks: Dished heads are also employed in storage tanks used for storing liquids, such as water, oil, and chemicals. The dished heads seal the ends of the tanks, preventing leaks and ensuring the contents remain securely contained. Storage tanks with dished heads can be found in industries such as food and beverage, wastewater treatment, and petrochemicals.

3. Boilers: In the field of power generation, dished heads are utilized in boilers, which are vessels used to generate steam for various applications. The dished heads in boilers help to contain the high-pressure steam while maintaining structural stability and ensuring efficient heat transfer.

Types of Dished Heads:

1. Torispherical Heads: Torispherical heads are the most common type of dished heads. They have a shallow toroidal shape with a knuckle radius, providing a smooth transition between the cylindrical shell and the dished portion. Torispherical heads offer good strength and are suitable for moderate-pressure applications.

2. Ellipsoidal Heads: Ellipsoidal heads have a more pronounced elliptical shape and a deeper dish compared to torispherical heads. They provide a greater volume for the same diameter, making them suitable for higher pressure applications. Ellipsoidal heads offer excellent resistance to internal pressure and are widely used in the construction of pressure vessels.

3. Hemispherical Heads: Hemispherical heads have a shape similar to half of a sphere. They offer the maximum internal volume for a given diameter, making them ideal for high-pressure applications. Hemispherical heads distribute pressure evenly across their surface, resulting in uniform stress distribution.

Manufacturing Process of Dished Heads:

The manufacturing process of dished heads involves several steps, including:

1. Material Selection: The choice of material depends on the application, pressure requirements, and compatibility with the stored substance. Common materials used for dished heads include carbon steel, stainless steel, and various alloys.

2. Cutting and Forming: The initial blank for the dished head is cut from a flat plate or obtained through specialized forming processes like hot or cold spinning. The blank is then pressed into a dished shape using hydraulic or mechanical presses.

3. Heat Treatment: Depending on the material and required mechanical properties, the dished heads may undergo heat treatment processes such as stress relieving, normalizing, or annealing to enhance their strength and durability.

4. Edge Preparation and Welding: The edges of the dished head are prepared by beveling or chamfering to ensure proper welding. The dished head is then welded to the cylindrical shell of the vessel using various welding techniques, such as submerged arc welding or gas tungsten arc welding.

5. Final Inspection and Testing: The completed dished head undergoes a thorough inspection to verify dimensional accuracy, weld quality, and integrity. Non-destructive testing methods like ultrasonic testing or radiographic examination may be performed to detect any defects or flaws.

In conclusion, dished heads are essential components in the construction of pressure vessels, storage tanks, and boilers. Their curved shape and structural integrity ensure the safe containment of high-pressure substances. With different types available, dished heads can be tailored to meet specific pressure requirements. The manufacturing process involves cutting, forming, heat treatment, welding, and rigorous inspection to ensure quality and reliability.