Pressure vessel heads and dished ends are essentially the same – the end caps of a pressure vessel tank or an industrial boiler. They are supplied with a flanged edge to make it easier for the fabricator to weld the head to the main body of the tank.

The Flanging Process. The operation that follows dishing is the forming of the edge, which will allow the dished end to be welded to the tank body to support the pressure inside. During the flanging operation, the plate edge is formed with a flanging roll moving against and with the radius of the shaping roll.

Flanged and Dished (F&D) Here a 48” inside radius (equal to the outside diameter of the cylinder) used for the crown of the head, along with a tight 2.973” knuckle results in a head that is lower than the semi-elliptical. The flanged and dished head requires more thickness than the matching cylinder, here 0.8901”.

The closing end (either one side or both side) of the pressure vessel is termed as Head or End closure or Dished Head. Somewhere it also works/considered as manhole of the vessel. Different Types of End closure are as below: Flat Heads.

Ellipsoidal heads are deeper than comparable torispherical heads. The shape of the ellipsoidal head is defined by the ratio of the major and minor axis. A standard arrangement on vessels is the 2:1 elliptical head. Due to shallow dished shape the forming cost is reduced.

Tank heads are the end caps on cylindrically-shaped pressure vessels. They generally comply with ASME standards or similar codes because of the high pressures they must withstand for use with gas storage tanks, driving cylinders, distillation towers, and reactors.

Korbbogen head This is a torispherical head also named Semi ellipsoidal head (According to DIN 28013). The radius of the dish is 80% of the diameter of the cylinder ( ). The radius of the knuckle is ( ). Also other sizes are , rest of height ( ) .

The Math / Science

1. V is the volume of the Torispherical Head.
2. R is the crown radius.
3. h is the head height.
4. a is the knuckle radius.

Conical Head (also called the tapered tank head) is widely used for vessel bottom or cover plates. With the shape of concentric cone, the conical head consists of a large end cone and a small end.

A sphere is the ideal shape for a head, because the pressure in the vessel is divided equally across the surface of the head. The radius (R) of the head equals the radius of the cylindrical part of the vessel. These heads have a dish with a fixed radius (CR), the size of which depends on the type of torispherical head.

The reason why LPG is stored in spherical tank is liquid form gas is to be highly pressurized in order to keep it in liquid form. As spherical shape is uniform pressure gets equally distributed. Also being no edges there are no chances of any uneven pressure area.

Interview Answer. Gas bottles are cylindrical or spherical because circular hoops can withstand internal pressure by pure tension in the tank material instead of bending. Materials can take more force in tension than in bending. But cylinders are easier to pack together.

Types of Pressure Vessel Heads Cylindrical, horizontal, and vertical pressure vessels are the most common kinds of vessels and they all require specialized ASME caps on each end. These caps are called “heads” and there are three primary kinds.

A) Categories of Failures in Pressure Vessels Design-Incorrect design data; inaccurate or incorrect design methods; inadequate shop testing. Fabrication-Poor quality control; improper or insufficient fabrication procedures including welding; heat treatment or forming methods.

Shape. Pressure vessels can theoretically be almost any shape, but shapes made of sections of spheres, cylinders, and cones are usually employed. A common design is a cylinder with end caps called heads. Head shapes are frequently either hemispherical or dished (torispherical).

The first actual inspection work on the pressure vessel is the raw materials inspection. Based on the ASME Code, providing material test reports for pressure vessel plate is mandatory….Third Party Inspection for Pressure Vessel / Procedure

1. Design code.
2. Purchase order specification.
3. Purchaser’s standards.
4. Approved drawings.

It’s almost inevitable that a pressure vessel that’s been in service for a long time will develop defects and need repairs. Pressure vessel fabricators wishing to repair pressure vessels must obtain a certificate of authorization as an approved repairer from the National Board of Boiler and Pressure Vessel Inspectors.

Hydrostatic Tests: This is one of the important ways following which the pressure vessels such as boilers, fuel tanks, and pipelines are tested for their leaks as well as strengths. Pneumatic Tests: These tests demand a high level of potential energy, which is why they are only performed whenever required.

High pressure cylinders and gun barrels are known to fail by fatigue when subjected to pulsating internal pressures. Prior autofrettage and compounding with interference improves the fatigue life for a given pressure range.

Pressure Vessels are containers which are designed to hold liquids, vapors, or gases at high pressures, usually above 15 psig.

Pressure Vessels calculates the wall thickness of plain cylinders of same material and equal wall thickness throughout. If you wish to evaluate cylindrical pressure vessels of different diameter and material the wall thickness of each section should be calculated separately.