The manual valves are control component in the pipeline fluid delivery system. They are used to change the passage section and the flow direction of the medium and have the functions of diversion, cutoff, regulation, throttling, check, diversion, or overflow relief.   Manual valves are divided into four groups according to the way the closure member moves onto the seat. Each valve group consists of a number of distinct types of valves that, in turn, are made in numerous variations. • Stopper type closure—globe, needle • Vertical slide—gate • Rotary type—ball, plug, butterfly • Flexible body—diaphragm   The way the closure member moves onto the seat gives a particular group or type of valve a typical flow-control characteristic. This flow control characteristic has been used to establish a preliminary chart for the selection ...

Valve selection is based on function, material suitability, design pressure/temperature extremities, plant life, end connections, operation, weight, availability, maintenance, and cost. If the valve does not meet the design criteria, then even if it is free, it is still too expensive, because of the costs to replace it when it fails. Just like life, valve selection is a series of compromises.   Valves are the components in a fluid flow or pressure system that regulate either the flow or the pressure of the fluid. This duty may involve stopping and starting flow, controlling the flow rate, diverting flow, preventing backflow, controlling pressure, or relieving pressure.   These duties are performed by adjusting the position of the closure member in the valve. This may be done either manually or automatically. The manual operation also includes the operation of the valve ...

What is Type acceptance test (TAT)? It is not uncommon for certain applications that a new type of valve will have to be developed to meet the end user’s needs. Most end users have the highest technical demands on valves they are aiming to use in an assembly. Needless to say these ‘prototypes’ will undergo extensive testing to verify the reliability, safety, etc. TAT (Shell MESC SPE 77/300) is one of the internationally recognized certification to ensure the quality of the valves. TAT is done as per  ‘Shell’  specification 77-300 in which the valve is subjected to seat test, fugitive emission test, and torque test under pressure, during and after mechanical and thermal cycling. The qualification range is mentioned in spec 77/300B.It is testing that is done on a product to confirm the design is good. It is a prod...