Thursday, October 13, 2016

The Commonly Used Type Steam Jacketed Valves

By Lisa Green

Valves are devices that regulate, direct, or control the of fluids either by opening or closing fully or partially the obstructing passageways. Examples of fluids are liquids, slurries, gases, and fluidized solids. These are often considered as fittings technically, but is being discussed and categorized separately. Fittings are being used for pipe systems in connecting sections of pipe or tubing and for measuring the running of fluids.

For open valve types, the fluid will flow into a direction coming from a high pressure down to a low pressure. The most simple and ancient valves are just hinged flaps that will drop in order to obstruct flow of the fluid, either gas or liquid, in only one direction and it is propelled open by the flow in its opposite direction. Steam jacketed valves are the most commonly used types in Houston, TX.

The main purpose for the production of steam jackets are to maintain the temperature. A steam is consists of hot fluids circulated for keeping the fluids warm and for maintaining its liquid state. The location of circulation is between the vessel walls and jackets. It will also allow the heat to be transferred through a vessel wall.

Before jacketing and after jacketing, the valves must be leak tested and pressure tested. There many considerations in order to perform jacketing. This includes the materials, location and type of heated medium connection, full or partial coverage, flange size, and the bonnet jacket or additional heat coverage to specific areas.

There 11 components that consist the valve and the two common components are bonnet and body. The outer part which contains the trim or internal parts is a body. Bodies are often made plastic or sometimes metallic. Brass, bronze, gunmetal, cast iron, steel, alloy steels, and also stainless steels are other common materials.

The bonnet serves as the cover to its body. Usually, it is screwed or bolted into its body semi permanently. During the manufacturing, all the internal parts will be placed inside the body and a bonnet will then be attached to the whole part in order to hold every piece inside. The bonnet can be taken out for the maintenance of the parts inside.

The ports are the passages from which the fluid flow will occur. Typically, valves have two ports. The handle controls the valve manually from outside the body and an actuator is the mechanism that automatically controls it. The disc is an obstruction which is movable and would restrict the flow.

The seat is a part that will contact the disc in forming the leak tight seal. This is classified into hard seats or soft seats. The stem will transmit the motion coming from the handle or will control the device into a disc. Gaskets are used to prevent any leakages of fluids.

Valve balls are applied into processes that have high tolerance, high pressure, or severe duty. Stellite, nickel, titanium, brass, stainless steel, and hastelloy are the common materials. Springs will shift discs to default positions and will also allow to reposition the discs. Internal parts of valve are called trims.

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