Control Valve CONTROLVALVE Application

CONTROL VALVES AND ACCESSORIES – SIZING & SELECTION

 

This discussion will focus on proper sizing and selection of Control Valves with accessories for incompressible and compressible fluids. Today there is little excuse for poor specification and selection of Control Valve as most valves manufacturers provide computer programmers for selection and sizing.
The days of selecting Control Valves based on pipe line sizes are gone

CONTROL VALVE FLOW CHARACTERISTICS

 

LIQUID LEVEL SYSTEM CONTROL VALVE PRESSURE DROP BEST INHERENT CHARACTERISTIC

CONTROL VALVE Maintenance INTRODUCTION

 

In order to perform even routine maintenance procedures on a control valve, it is important that the maintenance man have a thorough understanding of the fundamental construction and operation of the valve. Without this knowledge, the equipment could be damaged inadvertently, or could cause injury to the maintenance man and others in the area. Most

Replacing Stem Packing CONTROL VALVE

 

Bonnet packing, which provides the pressure seal around the steam of a globe-style valve body, may need to be replaced if leakage develops around the stem, or inspection. Before starting to remove packing nuts, make sure there is no pressure in the valve body. If the packing is of the split ring variety, it can be

Replacing Threaded Seat Rings CONTROL VALVE

 

Many conventional sliding-stem control valves use threaded-in seat rings. Severe service conditions can cause damage to the seating surface of the seat ring(s) so that the valve does not shut off satisfactorily. In that event, replacement of the seat ring(s) will be necessary. Before trying to remove the seat ring(s), check to see if the ring

Grinding Metal Seats CONTROL VALVE

 

A certain amount of leakage should be expected with metal-to-metal seating in any globe-style valve body. If the leakage becomes excessive, however, the condition of the seating surfaces of the valve plug and seat ring can be improved by grinding. Large nicks should be machined out rather than ground out. Many grinding compounds are available

Lubricating Control Valve Packing

 

A lubricator or lubricator/isolating valve is required for semi-metallic packing and is recommended for graphite asbestos and TFE-impregnated asbestos packing. The lubricator or lubricator/isolating valve combination should be installed on the side of the valve bonnet, replacing the pipe plug used with packing types not requiring lubrication. Use Dow Corning X-2 lubricant or equivalent for

Trim TYPES VALVE

 

High Flow Plug and Cage Trim
The Plug and Cage trim design gives the maximum flow capacity for a cage trim choke valve. This trim type is proven for effectiveness in high flow liquid and dual phase flow.
In the closed position, the plug makes contact with a prepared shoulder in the cage to facilitate positive shut

The Ever-Popular Gate Valve

 

This low-tech valve may not have changed much in the last 100 years, but the gate valve plays a major role in virtually every refinery, chemical plant and industrial facility in the world.
The most popular style of valve in the world of flow control is the gate valve. They are the on/off switches of the

VALVE Body-Bonnet Design TRIM

 

The word “trim” is often overheard when valve professionals are talking about industrial gate valves. Trim has nothing to do with how slim and fit a valve is, rather it refers to the internal components of a valve that are exposed to great stress or subject to a harsh combination of erosion and corrosion. In

Disc Design VALVE disc or gate

 

Gate valves can have one of two different disc designs: parallel or tapered type. Both operate on the principle of a closure element (disc or gate) sliding into a slot in the pipeline and closing off the fluid path. The tapered disc of the “wedge gate” valve is machined to match a pair of body

VALVE Body-Bonnet Design

 

Gate valves are normally available in five different body/bonnet joint designs. They are: screwed, union, bolted-bonnet, welded-bonnet & pressure-seal.
* The screwed joint is the simplest design. However it is only used for inexpensive bronze valves that rarely if ever require disassembled.
* The union joint is also primarily used on bronze valves, but the union design

Stem Design inside screw rising stem non-rising stem outside screw yoke

 

Three different bonnet/stem designs are predominant in gate valve construction. They are: inside screw, rising stem (ISRS), non-rising stem (NRS), and outside screw and yoke (OS&Y).
* The ISRS bonnet/stem design is the most popular design in use today on bronze valves. Due to the fact that it exposes the stem threads to the process fluid

Materials of Construction Aluminum to Zirconium

 

Gate valves are manufactured in virtually every metal from Aluminum to Zirconium. They are also manufactured in a variety of engineering plastics. The most common materials however, are steel, iron and bronze. Bronze offers the greatest machinability and the lowest manufacturing cost. The features that make bronze easy to machine, its lower strength and softness, also

Gate Valve Actuation

 

The most common method of opening and closing (actuating) a valve is through a handwheel attached to the yoke or bonnet. This works fine on moderate size valves operating at reasonable pressures, but some severe operating situations call for more muscle. For example, an 18”, class 1500, main steam isolating valve in a power plant

Repair of Gate Valves

 

Industrial gate valves are often used in harsh environments and sometimes these valves need to be repaired. The decision to repair or replace a valve usually is a result of comparing the replacement cost to the repair cost. When the repair cost exceeds 50-65% of the cost of a new valve, the decision is usually

VALVE TRIM KINETIC ENERGY CRITERIA

 

The piping industry has long recognized the need to control the kinetic energy levels in the transport of fluids through a pipe. The industry has created design criteria that limits the fluid velocity in the pipe to acceptable limits. For example, a normal criteria for liquids in pipes is to limit the fluid velocity to

Heating Systems Gas Boiler Hot plus Wood Stoves

 

All Forced Air Systems: Conventional filters on forced-air systems should be checked monthly and cleaned or replaced as needed. Electronic filters should be checked monthly and cleaned as needed. Care should be taken to ensure the interior components are installed in the correct orientation after cleaning. Noisy blower sections should be brought to the attention

Control Valves and Flow Characteristics

 

Surfacing for Wear Resistance. For the successful hard surfacing or overlaying operation a welding procedure should be established. The procedure should be related to the particular part being surfaced and the composition or analysis of the part. It should specify the welding process to be used, the method of application, the prewelding operations such as cleaning,

Control Valves: Choke Valve Trim

 

Valve Bonnet The cover for the opening in the valve body is the bonnet. In some designs, the body itself is split into two sections that bolt together. Like valve bodies, bonnets vary in design. Some bonnets function simply as valve covers, while others support valve internals and accessories such as the stem, disk, and

TROUBLESHOOTING – THEORY AND PRACTICE

 

Questions to ask before proceeding
• Has the system ever worked before? If yes, has anything happened to it since then that could cause the problem?
• Has this system proven itself to be prone to certain types of failure?
• How urgent is the need for repair?
• What are the safety concerns, before I start troubleshooting?
• What

Control Valve direct acting spring-to-retract reverse acting spring-to-extend

 

Pneumatic actuators are commonly used to actuate control valves and are available in two main forms; piston actuators and diaphragm actuators. Piston actuators are generally used where the stroke of a diaphragm actuator would be too short or the thrust is too small. The compressed air is