Zebco Engineering LLP

Sg Highway, Ahmedabad, Gujarat

A ball valve is a valve that opens by turning a handle, gearbox or other actuation methods attached to a ball inside the valve. The ball has a hole, or port, through the middle so that when the port is in line with both ends of the valve, flow will occur. When the valve is closed, the hole is perpendicular to the ends of the valve, and flow is blocked. The handle or lever will be in line with the port position letting you "see" the valve's position, position indicators will be applied to gearbox or actuators when required. Ball valves are durable and usually work to achieve perfect shutoff even after years of disuse. They are therefore an excellent choice for shutoff applications. There are two type of ball valve based on the ball type, floating ball valve and trunnion mounted ball valve. Depends on the bore size, ball valve is separated into full port ball valve and reduced port ball valve. There are three types of body styles of ball valve: one-piece, two piece split, three piece split, top entry and welded, GVC ball valves are available in two piece split, three piece split and welded.

Advantages of using Ball Valves:

• Quick quarter turn on-off operation

• Tight sealing with low torque

• Smaller in size than most other Valves

Types of Ball Valves

Ball Valves are basically available in three versions: full port, venturi port and reduced port. The full-port Valve has an internal diameter equal to the inner diameter of the pipe. Venturi and reduced-port versions generally are one pipe size smaller than the line size.

Ball Valves are manufactured in different body configurations and the most common are:

• Top entry Ball Valves allow access to Valve internals for maintenance by removal of the Valve Bonnet-cover. It is not required to be removed Valve from the pipe system.

• Split body Ball Valves consists of a two parts, where one part is smaller as the other. The ball is inserted in the larger body part, and the smaller body part is assembled by a bolted connection.

The Valve ends are available as butt welding, socket welding, flanged, threaded and others.

Gate Valves are primarily designed to start or stop flow, and when a straight line flow of fluid and minimum flow restriction are needed. In service, these Valves generally are either fully open or fully closed.
The Gate (also called wedge) of a Gate Valve is completely removed when the Valve is fully open; the wedge is fully drawn up into the Valve Bonnet. This leaves an opening for flow through the Valve at the same inside diameter as the pipe system in which the Valve is installed.
A Gate Valve can be used for a wide range of liquids and provides a tight seal when closed.

Advantages of using Gate Valves:

• Good shutoff features

• Gate Valves are bidirectional and therefore they can be used in two directions

• Pressure loss through the Valve is minimal

A Globe Valves is a linear motion Valve and are primarily designed to stop, start and regulate flow. The disk of a Globe Valve can be totally removed from the flow path or it can completely close the flow path.

The fundamental principle of the Globe Valve operation is the perpendicular motion of the disk away from the seat. This ensures that the ring-shaped space between the disk and seat ring gradually close as the Valve is closed. This property gives a Globe Valve reasonably good throttling capability. Therefore, the Globe Valve can be used for starting and stopping flow and to regulate flow.

Advantages of using Globe Valves:

• Good shutoff capability

• Reasonably good throttling capability

Construction of a Globe Valve

Globe Valves consists of three main parts: body, Bonnet, and trim. The body is generally connected to other equipment by means of flanged, screwed or welded connections. The Bonnet, which containing the moving parts, is attached to the body, usually with bolts, to permit maintenance. The Valve trim consists of the stem, the disc and the seat rings.

All valves shall meet API-609 MSS-SP-67 ISO 5272 face-to-face dimensions. Valve sizes from 2" to 12" are rated at 200 psig WOG service and valve sizes from 14" to 30" are rated at 150 psig WOG service. All valves are full rated on dead-end service. All bodies shall be ductile iron 65-45-12 and bi-directional tested in both directions and be bubble tight with zero leakage. Lug bodies shall be full lug rated and all bodies shall be suitable for ANSI 125/150 lb, JIS, DIN or B.S. Flanges. Secondary seals shall be self-adjusting. All elastomers, all internal bearings shall be non-corrosive and non-metallic. All seats shall be suitable for 250F sustained high temperature and capable of 2000 PPM on chlorinated applications.

Advantages of Butterfly Valves:

• Open and close easily and quickly, effort, fluid resistance is small, can operate frequently.

• Simple structure, small size and light weight.

• It can carry mud, with the least accumulation of fluid in the pipeline opening.

• Low pressure, it can achieve a good sealing.

• Good regulating performance.

Many different types of valves are used in flow control. They are used for a variety of reasons, such as phase (liquid or gases), pressure, piping restrictions and solids content. Other valves are chosen for their capability to open and close in a quarter turn. Of all the valve types, the butterfly valve is used as a control device for many reasons including some or all of the above.

This article explains the workings of a butterfly valve and its operation. The butterfly valve offers many advantages that include quarter-turn, openness for less plugging and good control capabilities. Both manual and control versions are used.

Check valves, or non-return valves, are installed in pipeline systems to allow flow in one direction only. They are operated entirely by reaction to the line fluid and therefore do not require any external actuation. In this text, the expected, or desired direction of flow is termed 'forward flow', flow in the opposite direction is 'reverse flow'.

There are a number of reasons for using check valves, which include:

• Protection of any item of equipment that can be affected by reverse flow, such as flow meters, strainers and control valves.

• To check the pressure surges associated with hydraulic forces, for example, water hammer. These hydraulic forces can cause a wave of pressure to run up and down pipe work until the energy is dissipated.

• Prevention of flooding.

• Prevention of reverse flow on system shutdown.

• Prevention of flow under gravity.

• Relief of vacuum conditions.

Construction of a NRV Check Valve

The Swing Check Valve is a one-piece body, top entry design for reliable operation and extended seat seal life. Top entry construction allows field service and in-line maintenance if necessary.

All major components of the check valve are normally made from cast and wrought forms, allowing the use of a variety of widely accepted materials. The full bore to API-6D assures unrestricted flow and allows pigging and hot tapping.

Design

• Forged or casted body and cover
• Bolted cover
• Stainless Steel Screen with different meshes
• Threaded plug or valve fitted on cover for draining
  
  Advantages
• Possibility of installation in any position
• Long service life
• Easy handling and maintenance

The plugs in plug valves have one or more hollow passageways going sideways through the plug, so that fluid can flow through the plug when the valve is open. Plug valves are simple and often economical.

When the plug is conically-tapered, the stem/handle is typically attached to the larger diameter end of the plug. Plug valves usually do not have bonnets but often have the end of the plug with the handle exposed or mostly exposed to the outside. In cases like that, there is usually not much of a stem. The stem and handle often come in one piece, often a simple, approximately L-shaped handle attached to the end of the plug. The other end of the plug is often exposed to the outside of the valve too, but with a mechanism which retains the plug in the body.

The simplest and most common general type of plug valve is a 2-port valve, which has two positions, opento allow flow, andshut(closed) to stop flow. Ports are openings in the valve body through which fluid can enter or leave. The plug in this kind of valve has one passageway going through it. The ports are typically at opposite ends of the body; therefore, the plug is rotated a fourth of a full turn to change from open to shut positions. This makes this kind of plug valve aquarter-turn valve. There is often a mechanism limiting motion of the handle to a quarter turn, but not in glass stopcocks.