06 Dec

What Is A Plug Valve And When Is It Used?

what-is-a-plug-valve-and-when-is-it-used

We’ve previously discussed how to select specific valves for improving production time and MTBF and thought it would be a good time to review one of the most simple and economical valves available: the plug valve.

Plug Valve Basics

 A plug valve is shaped like a cylinder or cone and can be rotated inside the valve body to control flow of fluids. Plug valves have one or more hollow passageways often placed horizontally to allow ease of flow through the valve when open. The most common type of plug valve is the 2 port model with an open and closed position. The two ports are usually located on opposite sides of the valve with one passageway leading from inbound to outbound and the stem and handle located on the top. A plug valve also uses a quarter turn valve, which is useful where quick and frequent operation is essential. The valve ends can be flanged, hub type, or butt weld.

Plug Valve Types and Their Uses

 Although there are many types of plug valves, there are four general categories, each with their own benefits.

1. Lubricated Plug Valve

 As the name suggests, a lubricated valve uses a lubricant usually made up of a base oil and viscosity improver (like amorphous or fumed silica) that is injected under pressure between the plug face and body seat to reduce friction and seal ports. Valve manufacturers generally recommend lubricant suitable for the process fluid, and the valves often must be resealed after only a few cycles, and in some cases, after every cycle. Considered a high maintenance plug valve, they are often used in applications that have infrequent operations. Lubricated plug valves perform well in processes that utilize fluids which carry mildly abrasive particles such as dirty upstream applications, gas pipeline systems that need bypass valves, and as blow-down valves on valve stations and kicker valves.

2. Non-Lubricated Plug Valve

This plug valve utilizes a tapered or cone-shape that acts as a wedge and presses a polymeric sleeve against the body cavity. The use of the sleeve reduces friction between the plug mechanism and body.  Non-lubricated plug valves are often used instead of lubricated ones in applications where maintenance needs to be kept to a minimum, such special services in sulphur, hydrogen fluoride, or where liquids could be trapped or solidify and potentially jam the valve. However, non-lubricated plug valves are limited by temperature and chemical compatibility of the non-metallic materials they are made of.

The three main types of non-lubricated plug valves are:

Lift-type plug valve

Elastomer sleeved plug valve

Fully lined plug valve

3. Eccentric Plug Valve

The design of this plug valve uses a half plug that is advantageous for applications needing a higher seating force with minimal friction from open to closed position. The torque seated valves also feature improved shut off capabilities. Eccentric plug valves are used for a wide range of flow control and isolation applications including clean and dirty water, sewage, sludge and slurries, air, and other services.

4. Expanding Plug Valve

 This complex plug valve uses multiple components that allow the valve to mechanically expand and give it a true double block and bleed function in one valve. The plug valve uses a mechanism that rotates between the open and closed position and protects both seals from the flow path. During rotation there is no contact between body and seals, and slips expand onto the body seat when the valve is closed to avoid causing any wear or abrasion to the seals. They are often used to prevent product contamination in applications that do not require a double isolation.

In conclusion, plug valves have a number of useful applications, and new technology and designs are sure to give them an even wider variety of applications within many processes. And if you need more information on different types of valves, check out this piece on check valves or the rest of the site.

 

Sourced by ekomeri.com

02 Dec

DIFFERENT TYPES OF PIPE FITTINGS IN PLUMBING SYSTEM

Various types of pipe fittings are available in plumbing systems for different purposes and functions. A pipe fitting is used in plumbing system to join multiple pipes of same size or different sizes, to regulate the flow or to measure the flow. They are made up of different materials like copper, iron, brass, PVC etc.

 

Types of Pipe Fittings in Plumbing System

Different pipe fittings and their functions are explained below.

  • Elbow
  • Reducer
  • Tee type
  • Cross type
  • Coupling
  • Unions
  • Adaptors
  • Olet
  • Plug
  • Cap
  • Valve

 

Elbow Pipe Fittings

Elbows are used to change the direction of flow between two pipes. Elbows are generally available with an angle of 22.5o, 45o and 90o. If pipes are of same diameter then normal elbows are used otherwise Reducer elbows are used. Elbows are made of different materials. These are generally coming with female threads and we can fix them by butt or socket welding also.

elbow-pipe-fittings

 

Reducer Pipe Fittings

Reducer is a pipe fitting component which reduces the flow size from larger to smaller by reducing size of pipe. Usually there are two types of reducers are available. One is concentric reducer which is like cone shaped with gradual decreasing around the pipe but in this case accumulation of air may possible and it results in cavitation. Other one is eccentric reducer which is having one edge parallel to connecting pipe due to which air accumulation is not possible.

reducer-pipe-fittings

 

Tee type Pipe Fitting

Tee type fitting is a component of plumbing system which is in T-shape. It is having one inlet and two outlets, outlets are arranged at 90o to the main line connection (inlet). It can also be used to combine the flow from two inlets to one outlet. They are also available in different materials and different sizes. If the 3 sides of T-fitting are similar in size then it is called as Equal tee otherwise it is called as Unequal tee.

tee-type-pipe-fitting

 

Cross type

Cross type fittings contains 4 opening in 4 directions. These are connected when there are 4 pipes are meeting at a point. These fittings generate more amount of stress on pipe as the temperature changes, because they are located at the center of four connection points. Cross fittings are generally used for fire sprinkler systems.

cross-type

Coupling

A coupling is used to connect the pipes of same diameter. Coupling are also useful if the pipe is broken or leakage occurs. Generally there are two types of couplings are available. Compression coupling and slip coupling. Compression coupling is regular coupling which is connected between two pipes and it prevents leakage by the arrangement of gaskets or rubber seals on both sides, otherwise glue is provided. Slip coupling is easier to install and it contains two pipes which are arranged as one into other, inner pipe can slide up to some length. So, we can fix long length damaged pipe by slip coupling.

coupling-pipe-fitting

 

Unions

Union is a type of fitting, which functions as similar to coupling. But coupling cannot be removed after fixing but in this case we can remove the union whenever we needed. Unions consists nut, male and female ended threads. So, this is also useful for maintaining purpose of pipe.

unions

 

Adaptors

If the pipes are not having special ends or plain ends then adaptors make them threaded either male or female whichever is needed. Adopters are generally used for copper and PVC pipes. Male adapters contain male threads and female adapters contains female threads. One end of adapter is plain which is glued or welded or soldered to the plain pipe end.

adaptors-pipe-fittings

 

Olet

Olets are used when there is standard sizes of fittings are not suitable for our requirement. Sometimes the inlet pipe size is larger compared to outlet pipes in t-sections then also Olets are used. There are many types of olets are available. Some important types of olets are:

  • Butt-Weld Olet
  • Socket weld Olet
  • Threaded olet
  • Elbow olet
  • Nipple olet
  • Lateral olet
  • Sweep olet
  • Flanged olet

Olet Pipe Fittings

 

Plug

Plug is a component of plumbing component which is generally used to close pipe opening during inspections and repairs. Plug are generally contains male threads.

Plug for Pipes

 

Cap

Cap is a type of pipe fitting which function is same as plug but the only difference is plug contain male threads and cap contain female threads which is screws on the male thread of pipe. These are available in different materials like rubber, copper, steel, plastic etc.

Pipe Cap

 

Valves in Pipe Fittings

Valves are components of plumbing system which are used to stop or regulate flow of fluid in its path. Different types of valves are available depending up on their applications.

Valves in Pipe Fittings

Some important types of valves and its applications are listed below.

  • Gate valve, plug valve and Ball valve – used for isolation only
  • Globe valve – used for throttling
  • Check valve – used for preventing reverse flow (non-return)
  • Butterfly valve – used for isolation as well as throttling
  • Diaphragm valve – used for isolation as well as throttling

 

Sourced by ekomeri.com