Allan Thaddeus Ltd communicates on a daily basis with valve manufacturers and distributors globally. Quoting manufactururs on a wide array of valves – safety relief and industrial from the best known brands such as Crosby, Cameron, Fisher, GE, Dresser, OMB, Parker, Swagelok, SRI, Neway, Stockham, Shipham, Oliver, Sabre, James, Bifold, Alfa, Flowserve, Emerson, Virgo, Thompson, Wandfluh, Duvalco, Groth, Guichon, Versa, Spirax Sarco, Norgren, Velan, Broady, PBV, Starline, Cla-Val and many more.

Globe Valves
A Globe Valve is a type of valve used for regulating flow in a pipeline, consisting of a movable disk-type element and a stationary ring seat in a generally spherical body. Globe valves are named for their spherical body shape with the two halves of the body being separate by an internal baffle. This has an opening that forms a seat onto which a movable plug can be screwed in to close (or shut) the valve. The plug is also called a disc or disk. In globe valves, the plug is connected to a stem which is operated by screw action using a handwheel in manual valves. Typically, automated globe valves use smooth stems rather than threaded and are opened and closed by an actuator assembly.

Check Valves
Check (non-return) valves are installed in pipelines to allow flow in one direction only; helping to protect equipment and processes. The operation, benefits, applications and selection of different designs, including lift, disc, swing and wafer check valves. There are various types of check valves used in a wide variety of applications. Check valves work automatically and most are not controlled by a person or any external control; accordingly, most do not have any valve handle or stem. The bodies (external shells) of most check valves are made of plastic or metal.

Lift Check Valves
Lift check valves are similar in configuration to globe valves, except that the disc or plug is automatically operated. The inlet and outlet ports are separated by a cone shaped plug that rests on a seat typically metal; in some valves, the plug may be held on its seat using a spring. When the flow into the valve is in the forward direction, the pressure of the fluid lifts the cone off its seat, opening the valve. With reverse flow, the cone returns to its seat and is held in place by the reverse flow pressure.

Swing Check Valve
A swing check valve consists of a flap or disc of the same diameter as the pipe bore, which hangs down in the flow path. With flow in the forwards direction, the pressure of the fluid forces the disc to hinge upwards, allowing flow through the valve. Reverse flow will cause the disc to shut against the seat and stop the fluid going back down the pipe. In the absence of flow, the weight of the flap is responsible for the closure of the valve; however, in some cases, closure may be assisted by the use of a weighted lever. As can be seen from the image to the right, the whole mechanism is enclosed within a body, which allows the flap to retract out of the flow path.

Swing check valves produce relatively high resistance to flow in the open position, due to the weight of the disc. In addition, they create turbulence, because the flap ‘floats’ on the fluid stream. This means that there is typically a larger pressure drop across a swing check valve than across other types. With abrupt changes in flow, the disc can slam against the valve seat, which can cause significant wear of the seat, and generate waterhammer along the pipe system. This can be overcome by fitting a damping mechanism to the disc and by using metal seats to limit the amount of seat wear.

Wafer Check Valves
Both lift and swing check valves tend to be bulky which limits their size and makes them costly. To overcome this, wafer check valves have been developed. By definition wafer check valves are those that are designed to fit between a set of flanges. This broad definition covers a variety of different designs, including disc check valves and wafer versions of swing or split.

Other Major Valves we procure include;
• Ball
• Butterfly
• Gate
• Plug