SSGC INTERNSHIP REPORT

SUBMITTED

TO

“SIR AKBAR KHATRI”

NAME: - MUHAMMAD AHSAN KHANYEAR: - 3RD BATCH: - 2012DEPARTMENT: - CHEMICAL ENGINEERING

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DEDICATION

We dedicate our efforts to our loving parents, friends,

colleagues, all teachers who have not only been a source

of motivation to us but also extended their help whenever

needed. Without their help and motivation it would have

not possible for us to do all this.

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ACKNOWLEDGMENT

In the name of Allah, the Most Gracious, the Most Merciful

All praises be to Allah, Lord of the Worlds, The Beneficent and the Merciful. Owner of the

Day of Judgment, Thee (alone) we worship; Thee alone we ask for help. Show us the

straight path, the path of those whom Thou hast favored; Not (the path) of those who earn

Thin anger nor of those who astray.

(Al-Quran)

Thanks are due to ALLAH Almighty Whose kind grace enabled us to accomplish this

report. We also pay our gratitude to loving parents, kind teachers especially our Sir Akbar

Khathri and Sir Qadir Bux and others who have not only been a source of motivation to us

but also extended their help whenever needed. Without their help and motivation it would

have not possible for us to do all this.

May almighty bless all these patrons and put on the right path!

(Aameen)

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Content

Introduction…………………………………………….……………………………6 History…………………………………………………………….………………….6 Vision…………………………………………………………………………………7 Mission………………………………………………………………………………..7 SSGC Pipe line Network………………………………………………..………….8 Ranking of Gas Development Countries……………………………..………….9 Measurement department……………………………………………….………..10 Flow Computers……………………………………………………….…………..10 Electronic Volume Corrector…………………………………………………….11 Gas Chromatography…………………………………………………………......11 Orifice plate……………………………………………………………...…………12 Rotary Meter……………………………………………………………………….13 Diaphagram Meter…………………………………………………………….…..13 Turbine Meter……………………………………………………………..……….13 Calorific Value……………………………………………………………………..14 Corrosion and Preventation……………………………………………..……….15 Corrosion……………………………………………………………………….…..16 Erosion………………………………………………………………………………16 Cathodic Prevention………………………………………………………………17 Sources of Power……………………………………………………………….….18 Transformer Rectifier (TR)…………………………………………………..…..19 Thermo Electric Generator (TEG)…………………………………………..….19 Solar Panels……………………………………………………………………..…19 Flow Diagram of sms KT…………………………………………………..……20 MAIN PIPE LINE INTRSTUMENTATION………………………………….…21 Valve………………………………………………………………………….…..…21 Types of valve………………………………………………………………………21 Gate Valve………………………………………………………………………….22 Ball valve……………………………………………………………………………22 Globe Valves…………………………………………………………………….…23 Plug Valve……………………………………………………………………….….24 Safety Valve……………………………………………………………………...…25 Control valves……………………………………………………………………...25 Butterfly Valves…………………………………………………………………....26 Diaphragm Valves……………………………………………………………..….27 Bypass Valves………………………………………………………………………28 Check Valve……………………………………………………………………...…28

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Actuator……………………………………………………………………………..29 Flow control valve…………………………………………………………………29 SCRUBBERS…………………………………………………………………..…...30 Wet scrubbing………………………………………………………………….…..30 Dry scrubbing………………………………………………………………..….…31 Filtration……………………………………………………………………………31 Gas Filter…………………………………………………………………………...31 Pressure Gauge…………………………………………………………………….32 Pressure…………………………………………………………………………..…32 Boyles Law………………………………………………………………………….33 Charles Law…………………………………………………………………..……34 Bernoulli's Equation………………………………………………………………35 Pigging…………………………………………………………………………..….35 Purpose of pigging………………………………………………………………...36 Natural gas………………………………………………………………………....36 British thermal unit……………………………………………………………..…37 Properties of Natural Gas………………………………………………….…….37 Chemical Formula……………………………………………………………..….38 Chemical Bonding……………………………………………………………..…..38 Liquefied petroleum gas………………………………………………………..…38 Chemical Formula………………………………………………………………...39 Compressed natural gas………………………………………………………….40 Classification of Gas Pressures………………………………………………….40 Transmission Pipelines……………………………………………………………40 Distribution Pipelines…………………………………………………………..…41 Service Pipelines…………………………………………………………………..41 Why H2S, CO2 remove from the natural gas…………………………………..41 References…………………………………………………………………………..42

Introduction:-

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Sui Southern Gas Company (SSGC) is Pakistan’s leading integrated gas Company. The company is engaged in the business of transmission and distribution of natural gas besides construction of high pressure transmission and low pressure distribution systems.

SSGCL transmission system extends from Sui in Balochistan to Karachi in Sindh comprising over 3,220 KM of high pressure pipeline ranging from 12 – 24″ in diameter. The distribution activities covering over 1200 towns in the Sindh and Balochistan are organized through its regional offices. An average of about 388,828 million cubic feet (MMCFD) gas was sold in 2009-2010 to over 2.5 million industrial, commercial and domestic consumers in these regions through a distribution network of over 37,000 Km. The company also owns and operates the only

gas meter manufacturing plant in the country, having an annual production capacity of over 750,000 meters.

The Company has an authorized capital of Rs. 10 billion of which Rs 6.7 billion is issued and fully paid up. The Government owns the majority of the shares which is presently over 70%.

The Company is managed by an autonomous Board of Directors for policy guidelines and overall control. Presently, SSGC’s Board comprises of 14 members. The Managing Director/Chief Executive is nominee of GOP and has been delegated with such powers by the Board of Directors as are necessary to effective conduct the business of the company.

History:-

The Sui Southern Gas Company (SSGC) (Formerly Sui Gas Transmission Company Limited) was formed in 1954. The Company in its present shape was formed on March 30, 1989, following a series of mergers of three pioneering companies, namely Sui Gas Transmission Company Limited, Karachi Gas Company Limited and Indus Gas Company Limited.

Sui Southern Gas Company is Pakistan's leading integrated gas company. The company is engaged in the business of transmission and distribution of natural gas in southern part of Pakistan. Sui Southern Gas Company transmission system extends from Sui, Balochistan to Karachi, Sindh.

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Vision:-

“To be a model utility providing quality service by maintaining a high level of ethical and professional standards and through optimum use of resources.”

Mission:-

“To meet the energy requirements of customers through reliable, environment-friendly and sustainable supply of natural gas, while conducting business

professionally, efficiently, ethically and with responsibility to all our stakeholders, community and the nation.”

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RANKING OF GAS DEVELOPMENT COUNTRIESRank Country Continent Annual natural gas production (m³) Date of

information— World — 3,359,000,000,000 2010 est.1  Russia Eurasia 669,600,000,000[5] 2011 est.2  United States North America 651,300,000,000[5] 2011 est.—  European Union — 167,600,000,000 2011 est.3  Canada North America 160,100,000,000 2011 est.4  Iran Asia 146,100,000,000 2010 est.5  Qatar Asia 116,700,000,000 2010 est.6  Norway Europe 103,100,000,000 2011 est.7  China Asia 102,700,000,000 2011 est.8  Saudi Arabia Asia 99,230,000,000 2011 est.9  Nigeria Africa 92,000,000,000 2010 est.10  Algeria Africa 84,610,000,000 2010 est.10  Indonesia Asia 82,800,000,000 2010 est.11  Netherlands Europe 81,090,000,000 2011 est.12  Malaysia Asia 66,500,000,000 2010 est.13  Egypt Africa 61,330,000,000 2010 est.14  Uzbekistan Asia 60,110,000,000 2010 est.15  Turkmenistan Asia 59,500,000,000 2011 est.16  Mexico North America 55,100,000,000 2011 est.17  United Arab Emirates Asia 51,280,000,000 2010 est.18  United Kingdom Europe 47,430,000,000 2011 est.19  India Asia 46,100,000,000 2011 est.20  Australia Oceania 44,990,000,000 2011 est.21  Pakistan Asia 42,900,000,000 2011 est.

Measurement department :-

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Measurement department is responsible for the monthly check of the meters installed on the point of delivery. There are two meters installed on Point of Delivery one is of seller, to cross check their meter SSGC have installed its own meter.

Measurement Department is also responsible for the monthly check of meters installed on the SMS’s.

They are responsible to measure the gas quality. They make sure that the gas coming from the gas field should be greater than 900 B.T.U.

Flow Computers:-

Flow computer is a device which receives differential pressure, static pressure and temperature information about the flowing gas and gas quality information from a gas chromatograph and stores the record for a period of time.

It is a Micro Processor- Based Flow Computer that provides functions required for gas flow measurement and custody transfer in accordance with the standards such as AGA-3, Orifice Metering.

The interface electronics controls Communication with the sensor modules, does scaling of process variables i.e.: Differential Pressure, Static Pressure & Temperature, aids calibration, provides storage of operating parameters, performs protocol conversion and responds to the requests from the flow Computer.

Electronic Volume Corrector:-10

The electronic volume corrector takes incoming pulses from a meter and records the pressure and temperature to calculate the standard cubic feet of gas that has passed through the meter.

Gas Chromatography :-

Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture (the relative amounts of such components can also be determined). In some situations, GC may help in identifying a compound. In preparative chromatography, GC can be used to prepare pure compounds from a mixture.

In gas chromatography, the mobile phase is a carrier gas, usually an inert gas such as helium or unreactive gas such as nitrogen.

The stationary phase is a microscopic layer of liquid or polymer on an inert solid support, inside a piece of glass or metal tubing called a column.

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Orifice plate:-

An orifice plate is a device used for measuring flow rate, for reducing pressure or for restricting flow. Either a volumetric or mass flow rate may be determined, depending on the calculation associated with the orifice plate. It uses the same principle as a Venturi nozzle, namely Bernoulli's principle which states that there is a relationship between the pressure of the fluid and the velocity of the fluid. When the velocity increases, the pressure decreases and vice versa.

Description:-

An orifice plate is a thin plate with a hole in the middle. It is usually placed in a pipe in which fluid flows. When the fluid reaches the orifice plate, the fluid is forced to converge to go through the small hole; the point of maximum convergence actually occurs shortly downstream of the physical orifice, at the so-called vena contracta point. As it does so, the velocity and the pressure changes. Beyond the vena contracta, the fluid expands and the velocity and pressure change once again. By measuring the difference in fluid pressure between the normal pipe section and at the vena contracta, the volumetric and mass flow rates can be obtained from Bernoulli's equation.    

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Rotary Meter:-

Rotary meters are highly machined precision instruments capable of handling higher volumes and pressures than diaphragm meters. The rotors spin in precise alignment. With each turn, they move a specific quantity of gas through the meter. The rotational movement of the crank shaft serves as a primary flow element and may produce electrical pulses for a flow computer or may drive an odometer-like counter.

Diaphagram Meter:-

Within the meter there are two or more chambers formed by movable diaphragms. With the gas flow directed by internal valves, the chambers alternately fill and expel gas, producing a near continuous flow through the meter. As the diaphragms expand and contract, levers connected to cranks convert the linear motion of the diaphragms into rotary motion of a crank shaft which serves as the primary flow element. This shaft can drive an odometer-like counter mechanism or it can produce electrical pulses for a flow computer.

Turbine Meter:-

Turbine flowmeters use the mechanical energy of the fluid to rotate a “pinwheel” (rotor) in the flow stream. Blades on the rotor are angled to transform energy from the flow stream into rotational energy. The rotor shaft spins on bearings. When the fluid moves faster, the rotor spins proportionally faster.

Shaft rotation can be sensed mechanically or by detecting the movement of the blades. Blade movement is often detected magnetically, with each blade or embedded piece of metal generating a pulse. Turbine flowmeter sensors are typically located external to the flowing stream to avoid material of construction constraints that would result if wetted sensors were used. When the fluid moves faster, more pulses are generated. The transmitter processes the pulse signal to determine the flow of the fluid. Transmitters and sensing systems are available to sense flow in both the forward and reverse flow directions.

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What is Calorific Value?

Calorific value (CV) is a measure of heating power and is dependent upon the composition of the gas. The CV refers to the amount of energy released when a known volume of gas is completely combusted under specified conditions.

The CV of gas, which is dry, gross and measured at standard conditions of temperature and pressure, is usually quoted in megajoules per cubic metre (MJ/m3).

Why is Calorific Value Important?Knowledge of the CV of natural gas is an essential part of the day to day activities of National Grid as this information is used to determine the amount of energy transported by National Grid. CV information is provided daily to gas shippers and suppliers, which is then used to bill gas consumers. This data is also used by National Grid to determine transportation charges for gas shippers and suppliers.

How is Calorific Value Measured?

The CV of natural gas is measured continually using process gas chromatographs.

Process gas chromatographs separate natural gas into its constituent compounds (i.e. methane, ethane, carbon dioxide, etc.) and measure the amount of each in the gas. The physical characteristics of each component, are programmed into the chromatograph and an overall CV is derived from the measured composition.

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CORROSION AND

PREVENTATION:-

Corrosion and Prevention department is responsible for the maintenance of the pipeline using following steps.

Cathodic Test Post (CTP) maintenance

Pipe to Soil Potential (PSP)monitoring

Coating Integrity Surveys;

Power Source performance evaluation

Ground Bed performance evaluation

Stray current (Interference) survey with parallel pipelines evaluation & necessary mitigation

After every 3 months the team of CP department checks the PSP. They held surveys to see whether the PSP is according to their standard. The PSP is checked every 30km. The standard value of PSP is between 0.85-1.5. If the value is found to be above 1.5 then the current is regulated to the standard value. If the PSP is found to be below 0.85 then they check Cathodic Test Post connection, Terrain (Soil Resistivity), CP Power Source Status and current interference of parallel pipeline.

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Corrosion:-

General definition of corrosion is the degradation of a material through environmentalinteraction. In other words, most metals are thermodynamically unstable and will tend to seek a lower energy state, which is an oxide or some other compound. The process by which metals convert to the lower-energy oxides is called corrosion.

corrosion process:

The corrosion process involves the removal of electrons (oxidation) of the metal [Equation (1)] and the consumption of those electrons by some other reduction reaction, such as oxygen or water reduction [Equations (2) and (3), respectively]:

The oxidation reaction is commonly called the anodic reaction and the reduction reaction is called the cathodic reaction. Both electrochemical reactions are necessary for corrosion to occur. The oxidation reaction causes the actual metal loss but the reduction reaction must be present to consume the electrons liberated by the oxidation reaction, maintaining charge neutrality.

Erosion:-

Erosion is a physical process that refers to the gradual wearing away of a solid through abrasion. This article will focus on erosion in steam and condensate piping, a common problem in steam plants wherein sections of piping are eroded away causing significant steam leakage.

Cathodic Prevention:-

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Catodic Prevention Or CP is a technique to reduce the corrosion rate of a metal surface by making it the cathode of an electrochemical cell. This is accomplished by shifting the potential of the metal in the negative direction by the use of an external power source (referred to as impressed current CP) or by utilizing a sacrificial anode. In the case of an impressed current system, a current is impressed on the structure by means of a power supply, referred to as a rectifier, and an anode buried in the ground. In the case of a sacrificial anode system, the galvanic relationship between a sacrificial anode material, such as zinc or magnesium, and the pipe steel is used to supply the required CP current.

In each case, anodic areas and cathodic areas are present on the pipe surface. At the anodic areas, current flows from the pipeline steel into the surrounding electrolyte (soil or water) and the pipeline corrodes. At the cathodic areas, current flows from the electrolyte onto the pipe surface and the rate of corrosion is reduced. In light of the above, it becomes obvious that the rate of corrosion could be reduced if every bit of exposed metal on the surface of a pipeline could be made to collect current. This is exactly what CP does. Direct current is forced onto all surfaces of the pipeline. This direct current shifts the potential of the pipeline in the active (negative) direction, resulting in a reduction in the corrosion rate of the metal. When the amount of current flowing is adjusted properly, it will overpower the corrosion current discharging from the anodic areas on the pipeline, and there will be a net current flow onto the pipe surface eat these points. The entire surface then will be a cathode and the corrosion rate will be reduced.

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Sources of Power:-

The power sources used in cathodic protection are: Transformer Rectifier (TR) Thermo Electric Generator (TEG) Solar Panels

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Transformer Rectifier (TR):-

Transformer Rectifier is the combination of transformer and rectifier in which input AC current may be varied and then rectified into required DC current.

Thermo Electric Generator (TEG):-

Thermoelectric generators are devices that convert heat (temperature differences) directly into electrical energy, using a phenomenon called the thermoelectric effect. Standard thermoelectric generator units are available at power outputs up to 600 W and voltages up to 48 V. Higher power outputs can be achieved by adding parallel units. If higher voltages are required for a CP installation, it is also possible to convert the low DC voltage from the generator to a higher DC voltage. The converters, although of high efficiency, do cause some power loss. For this reason, maximum efficiency will result if ground beds can be built to directly use the output of the thermoelectric generator.

Solar Panels:-

Solar panels are devices that convert light into electricity. They are called "solar" panels because most of the time, the most powerful source of light available is the Sun, called Sol by astronomers. Some scientists call them photovoltaics which means, basically, "light-electricity." A solar panel is a collection of solar cells. Lots of small solar cells spread over a large area can work together to provide enough power to be useful. The more light that hits a cell, the more electricity it produces. It works on the principle of photoelectric effect.

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FLOW DIAGRAM OF SMS KT :-

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MAIN PIPE LINE INTRSTUMENTATION :-

Valve:-

A valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing. Valves are technically valves fittings, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure. Valves have many uses, including industrial uses for controlling processes, residential uses such as on / off & pressure control to dish and clothes washers in the home etc. Valves may be operated manually, either by a handle, lever, pedal or wheel. Valves may also be automatic, driven by changes in pressure, temperature, or flow.

Types of valve:-

Valves can be categorized into the following basic:

Ball valve. Butterfly valve Check valve. Diaphragm valve Gate valve Globe valve Plug valve Safety valve Control valve Bypass valve

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Gate Valve:-

Gate valves are often used when a straight-line flow of fluid and minimum restriction is desired. Gate valves are primarily used to permit or prevent the flow of liquids, but typical gate valves shouldn't be used for regulating flow, unless they are specifically designed for that purpose. Gate valves are typically constructed from cast iron, ductile iron, cast carbon steel, gun metal, stainless steel, alloy steels, and forged steels.

Like ball valves, gate valves are not usually used to regulate flow. One of the reasons for this is because the valving element can be damaged when in the partially open position. Similarly, they also limit the pressure drop across the valve when fully open. However, setting the valve to the fully open or closed position requires the handle to be turned many times, which generally makes these valves have the longest operating times among those valve types mentioned here.

Ball valve:-

Ball valves offer very good shut-off capabilities. A simple quarter-turn (90°) completely opens or closes the valve. This characteristic minimizes valve operation time and decreases the likelihood of leakage due to wear from the gland seal.

Ball valves can be divided into two categories: reduced bore and full bore. In reduced bore valves, the valve opening is smaller than the diameter of the piping; in full bore valves, the valve opening is the same size as the diameter of the piping. Full bore ball valves are often valued because they minimize the pressure drop across the valve.

A ball valve is a valve with a spherical disc, the part of the valve which controls the flow through it. Ball valves are durable and usually work to achieve perfect shutoff even after years of disuse.

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Ball valves are used extensively in industrial applications because they are very versatile, supporting pressures up to 1000 bar and temperatures up to 482°F (250°C). Sizes typically range from 0.2 to 11.81 inches (0.5 cm to 30 cm). They are easy to repair and operate. The body of ball valves may be made of metal, plastic or metal with a ceramic center. The ball is often chrome plated to make it more durable.

Balls valves are usually only recommended for use in the fully open or fully closed position. They are not suited to regulate flow by being kept partially open because ball valves make use of a ring-shaped soft valve seat.When used in the partially open position, pressure is applied to only a portion of the valve seat, which can cause it to deform. If the valve seat deforms, its sealing properties are impaired and it will leak as a result.

Globe Valves:-

The globe valve is suitable for use on a wide variety of applications, from flow rate control to open/close operation.

In this type of valve, flow rate control is determined not by the size of the opening in the valve seat, but rather by the lift of the valve plug (the distance the valve plug is from the valve seat). One feature of globe valves is that even if used in the partially open position, there is less risk of damage to the valve seat or valve plug by the fluid than with other types of manual valves. Among the various configurations available, needle type globe valves are particularly well suited for flow rate control.

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Other points to consider about globe valves is that the pressure drop accross the valve is greater than that of many other types of valves because the passageway is S-shaped. Valve operation time is also longer because the valve stem must be turned several times in order to open and close the valve, and this may eventually cause leakage of the gland seal (packing). Furthermore, care must be taken not to turn the valve shaft too far because there is a possibility it could damage the seating surface.

Plug Valve:-

Plug valves are valves with cylindrical or conically tapered "plugs" which can be rotated inside the valve body to control flow through the valve. 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.

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Safety Valve:-

Safety Valve is a one type of valve that automatically actuates when the pressure of inlet side of the valve increases to a predetermined pressure, to open the valve disc and discharge the fluid ( steam or gas ) ; and when the pressure decreases to the prescribed value, to close the valve disc again. Safety valve is so-called a final safety device which controls the pressure and discharges certain amount of fluid by itself without any electric power support.Safety Valve is mainly installed in a chemical plant, electric power boiler, gas storage tank, preventing the pressure vessels from exploding or damaging.

Control valves:-

Control valves are valves used to control conditions such as flow, pressure, temperature, and liquid level by fully or partially opening or closing in response to signals received from controllers that compare a "set point" to a "process variable" whose value is provided by sensors that monitor changes in such conditions.

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Butterfly Valves:-

In butterfly valves, the flow is regulated through a disc-type element held in place in the center of the valve by a rod. Similar to ball valves, valve operation time is short because the valving element is simply rotated a quarter turn (90°) to open or close the passageway.

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Butterfly valves are characterized by their simple construction, lightness in weight, and compact design. Their face-to-face dimension is often extremely small, making the pressure drop across a butterfly valve much smaller than globe valves (see below). Materials used for the valving element and sealing can limit their applications at higher temperatures or with certain types of fluids. Butterfly valves are often used on applications for water and air, and in applications with large pipe diameters.

Diaphragm Valves:-

Diaphragm valves use a 'pinching' method to stop the valve flow using a flexible diaphragm. They are available in two types: weir and straight-way. The most commonly seen of the two is the weir-type. This is because the straight-way type requires additional stretching of the diaphragm, which can shorten the diaphragm's life-span.

One of the major advantages of using diaphragm valves is that the valve components can be isolated from the process fluid. Similarly, this construction helps prevent leakage of the fluid without the use of a gland seal (packing) as seen in other types of valves. One the other hand, the diaphragm becomes worn more easily and regular maintenance is necessary if the valve is used on a regular basis. These types of valves are generally not suited for very high temperature fluids and are mainly used on liquid systems.

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Bypass Valves:-

Valves such as pressure reducing valves, control valves and steam traps often have bypass piping installed. The valve in such bypass piping is called a bypass valve.

Check Valve:-

A check valve is a type of valve that allows fluids to flow in one direction but closes automatically to prevent flow in the opposite direction (backflow).

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Actuator:-

An actuator is a type of motor for moving or controlling a mechanism or system. It is operated by a source of energy, typically electric current, hydraulic fluid pressure, or pneumatic pressure, and converts that energy into motion. An actuator is the mechanism by which a control system acts upon an environment. The control system can be simple (a fixed mechanical or electronic system), software-based (e.g. a printer driver, robot control system), a human, or other agent.

Flow control valve:-

A flow control valve regulates the flow or pressure of a fluid. Control valves normally respond to signals generated by independent devices such as flow meters or temperature gauges. The control valve manipulates a flowing fluid, such as gas, steam, water, or chemical compounds, to compensate for the load disturbance and keep the regulated process variable as close as possible to the desired set point.

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SCRUBBERS:-

Scrubber systems are a diverse group of air pollution control devices that can be used to remove some particulates and/or gases from industrial exhaust streams. Traditionally, the term "scrubber" has referred to pollution control devices that use liquid to wash unwanted pollutants from a gas stream. Recently, the term is also used to describe systems that inject a dry reagent or slurry into a dirty exhaust stream to "wash out" acid gases. Scrubbers are one of the primary devices that control gaseous emissions, especially acid gases. Scrubbers can also be used for heat recovery from hot gases by flue-gas condensation.

Wet scrubbing:-

A wet scrubber is used to clean air, flue gas or other gases of various pollutants and dust particles. Wet scrubbing works via the contact of target compounds or particulate matter with the scrubbing solution. Solutions may simply be water (for dust) or solutions of reagents that specifically target certain compounds.

Process exhaust gas can also contain water soluble toxic and/or corrosive gases like hydrochloric acid (HCl) or ammonia (NH3). These can be removed very well by a wet scrubber.

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Dry scrubbing:-

Dry scrubbing systems are used to remove acid gases (such as SO2 and HCl) primarily from combustion sources. Dry scrubbing systems are often used for the removal of odorous and corrosive gases from wastewater treatment plant operations.  Dry scrubbers have an efficiency of over 90 percent for removing sulfur dioxide under the right conditions.

Filtration:-

Filtration is commonly the mechanical or physical operation which is used for the separation of solids from fluids (liquids or gases) by interposing a medium through which only the fluid can pass. The fluid that pass through is called a filtrate. Oversize solids in the fluid are retained, but the separation is not complete; solids will be contaminated with some fluid and filtrate will contain fine particles (depending on the pore size and filter thickness).

Gas Filter:-

A device that is used to remove something unwanted from a gas that passes through it.

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Pressure Gauge:-

Instrument for measuring the condition of a fluid (liquid or gas) that is specified by the force the fluid would apply, when at rest, to a unit area, such as pounds per square inch (psi) or pascals (Pa). The reading on the gauge, called the gauge pressure, is always the difference between two pressures. When the lower of the pressures is that of the atmosphere, the total (or absolute) pressure is the sum of the gauge and atmospheric pressures.

P ressure :-

There are many physical situations where pressure is the most important variable. If you are peeling an apple, then pressure is the key variable: if the knife is sharp, then the area of contact is small and you can peel with less force exerted on the blade. If you must get an injection, then pressure is the most important variable in getting the needle through your skin: it is better to have a sharp needle than a dull one since the smaller area of contact implies that less force is required to push the needle through the skin.

When you deal with the pressure of a liquid at rest, the medium is treated as a continuous distribution of matter. But when you deal with a gas pressure, it must be approached as an average pressure from molecular collisions with the walls.

Pressure in a fluid can be seen to be a measure of energy per unit volume by means of the definition of work. This energy is related to other forms of fluid energy by the Bernoulli equation.

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Boyles L aw :-

Boyle's law (sometimes referred to as the Boyle–Mariotte law) is an experimental gas law which describes how the pressure of a gas tends to decrease as the volume of a gas increases. A modern statement of Boyle's law is:

The absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies if the temperature and amount of gas remain unchanged within a closed system.[1][2]

which can be written as:

or

where:

P is the pressure of the gasV is the volume of the gask is a constant.

The equation states that product of pressure and volume is a constant for a given mass of confined gas as long as the temperature is constant. For comparing the same substance under two different sets of conditions, the law can be usefully expressed as follows:

The equation shows that, as volume increases, the pressure of the gas decreases in proportion. Similarly, as volume decreases, the pressure of the gas increases. The law was named after chemist and physicist Robert Boyle, who published the original law in 1662

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Charles L aw :-

Charles's law (also known as the law of volumes) is an experimental gas law which describes how gases tend to expand when heated. A modern statement of Charles's law is:

The volume of a given mass of an ideal gas is directly proportional to its temperature on the absolute temperature scale (in Kelvin) if pressure and the amount of gas remain constant; that is, the volume of the gas increases or decreases by the same factor as its temperature.[1]

thisdirectly proportional relationship can be written as:

or

where:

V is the volume of the gasT is the temperature of the gas (measured in Kelvin).k is a constant.

This law explains how a gas expands as the temperature increases; conversely, a decrease in temperature will lead to a decrease in volume. For comparing the same substance under two different sets of conditions, the law can be written as:

The equation shows that, as absolute temperature increases, the volume of the gas also increases in proportion. The law was named after scientist Jacques Charles, who formulated the original law in his unpublished work from the 1780s.

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Bernoulli's Equation:-The Bernoulli equation states that,

where

points 1 and 2 lie on a streamline, the fluid has constant density, the flow is steady, and there is no friction.

Although these restrictions sound severe, the Bernoulli equation is very useful, partly because it is very simple to use and partly because it can give great insight into the balance between pressure, velocity and elevation.

Pigging:-

Pigging in the context of pipelines refers to the practice of using devices known as "pigs" to perform various maintenance operations on a pipeline. This is done without stopping the flow of the product in the pipeline.

These operations include but are not limited to cleaning and inspecting the pipeline. This is accomplished by inserting the pig into a 'pig launcher'- An oversized section in the pipeline, reducing to the normal diameter. The launcher / launching station is then closed and the pressure-driven flow of the product in the pipeline is used to push it along down the pipe until it reaches the receiving trap – the 'pig catcher' (or 'receiving station').

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Purpose of pigging :

Pipelines represent a considerable investment on behalf of the operators and can often prove strategic to countries and governments. They are generally accepted as being the most efficient method of transporting fluids across distances. In order to protect these valuable investments, maintenance must be done and pigging is one such maintenance tool.

During the construction of the line, pigs can be used to remove debris that accumulates. Testing the pipeline involves hydro-testing and pigs are used to fill the line with water and subsequently to dewater the line after the successful test. During operation, pigs can be used to remove liquid hold-up in the line, clean wax off the pipe wall or apply corrosion inhibitors for example. They can work in conjunction with chemicals to clean pipeline from various build-ups.

Natural gas:-

Natural gas is a fossil fuel formed when layers of buried plants and animals are exposed to intense heat and pressure over thousands of years. The energy that the plants originally obtained from the sun is stored in the form of chemical bonds in natural gas. Natural gas is a nonrenewable resource because it cannot be replenished on a human time frame. Natural gas is a hydrocarbon gas mixture consisting primarily of methane, but commonly includes varying amounts of other higher alkanes and even a lesser percentage of carbon dioxide, nitrogen, and hydrogen sulfide. Natural gas is an energy source often used for heating, cooking, and electricity generation. It is also used as fuel for vehicles and as a chemical feedstock in the manufacture of plastics and other commercially important organic chemicals.

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Dry natural gas refers to a purified product that is almost entirely methane. Wet natural gas contains compounds other than methane and ethane. Sour natural gas contains larger amounts of hydrogen sulphide, which is highly

undesirable due to corrosion, and results in SO2 formation upon combustion.

BTU:-

The British thermal unit (BTU or Btu) is a traditional unit of energy equal to about 1055 joules. It is the amount of energy needed to cool or heat one pound of water by one degree Fahrenheit. In scientific contexts the BTU has largely been replaced by the SI unit of energy, the joule.

Properties of Natural Gas:-

Natural gas is:

Lighter than air Highly combustible Clean burning Efficient Abundant Odourless and invisible (An odourant, called mercaptan, is added to natural gas to make

even the smallest leak easy to smell) Non-absorbing Non-corrosive Explosive under pressure

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Chemical Formula:-

CH4

Chemical Bonding:-

Methane is a tetrahedral molecule with four equivalent C-H bonds. Its structure is described by four bonding molecular orbitals (MOs) resulting from the overlap of the valence orbitals on C and H. The lowest energy MO is the result of the overlap of the 2s orbital on carbon with the in-phase combination of the 1s orbitals on the four hydrogen atoms. Above this level in energy is a triply degenerate set of MOs that involve overlap of the 2p orbitals on carbon with various linear combinations of the 1s orbitals on hydrogen.

Liquefied petroleum gas:-

Liquefied petroleum gas, also called LPG, LP Gas, liquid petroleum gas or simply propane or butane, is a flammable mixture of hydrocarbon gases used as a fuel in heating appliances and vehicles. LPG is prepared by refining petroleum or "wet" natural gas, and is almost entirely derived from fossil fuel sources, being manufactured during the refining of petroleum (crude oil), or extracted from petroleum or natural gas streams as they emerge from the ground. An odorant is mixed with LPG used for fuel purposes so that leaks can be detected more easily.

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LPG is heavier than air, unlike natural gas, and thus will flow along floors and tend to settle in low spots, such as basements. When specifically used as a vehicle fuel it is often referred to as auto gas.

Chemical Formula:-

LPG is Liquefied Petroleum Gas. It is a combination of Propane (chemical formula C3H8) and Butane (chemical formula C4H10).

Chemical Bonding:-

Propane :-

Butane :-

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Compressed natural gas:-

CNG is made by compressing natural gas (which is mainly composed of methane, CH4). It is stored and distributed in hard containers at a pressure of 200–248 bar (2,900–3,600 psi), usually in cylindrical or spherical shapes.

Classification of Gas Pressures:-

Low Pressure: A gas pressure equal or less than 7 kPa. This pressure is used to supply gas to low pressure appliances, both domestic and commercial; the most common pressure system used.

Medium Pressure: A gas pressure exceeding 7 kPa, but not exceeding 200 kPa. This pressure is used to supply gas over long distances to medium pressure commercial and industrial appliances in two stage regulation installations.

High Pressure: A gas pressure exceeding 200 kPa, but not exceeding 1050 kPa.This pressure is used to supply gas to specific high pressure commercial or industrial appliances. This pressure is present in LPG storage tanks as well as natural gas reticulated mains.

Transmission Pipelines:-

Purpose: Transmission pipelines carry natural gas across long distances and occasionally across interstate boundaries, usually to and from compressors or to a distribution center or storage facility.

Description: Transmission lines are large steel pipes (usually 2" to 42" in diameter; most often more than 10" diameter) that are federally regulated. They carry gas at a pressure of approximately 200 to 1,200 psi.

Special considerations: Transmission pipelines can fail due to: corrosion, materials failure, or defective welding.

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Distribution Pipelines:-

Purpose: Distribution pipelines, also known as "mains," are the middle step between high pressure transmission lines and low pressure service lines. Distribution pipelines operate at an intermediate pressure.

Description: Distribution pipelines are small to medium sized pipes (2" to 24" in diameter) that are federally regulated and varying pressure levels, from as little as 0.3 up to 200 psi. Distribution pipelines typically operate below their carrying capacity. Distribution pipelines are made from a variety of materials, including steel, cast iron, plastic, and occasionally copper.

Service Pipelines:-

Purpose: Service pipelines connect to a meter that delivers natural gas to individual customers.

Description: Service pipelines are narrow pipes (usually less than 2" diameter) that carry odorized gas at low pressures, such as 6 psi. Service pipelines are typically made from plastic, steel, or copper.

Why H2S, CO2 remove from the natural gas?

H2S gas very poisonous, corrosive, flammable and explosive. Dissolved in water, hydrogen sulfide is known as hydrosulfuric acid. Hydrogen sulfide is considered a broad-spectrum poison, meaning that it can poison several different systems in the body, although the nervous system is most affected.

Nitrogen is a common contaminant in natural gas and is quite difficult to remove. Nitrogen lowers the BTU value of the gas. Natural gas will be accepted for transport by pipeline only if it contains less than a specified amount of nitrogen, typically somewhere between 4% and 6%.

Carbon dioxide is an important greenhouse gas; burning of carbon-based fuels since the industrial revolution has rapidly increased the concentration, leading to global warming. It is also a major source of ocean acidification since it dissolves in water to form carbonic acid.Co2 gas is use as a Fire extinguisher. It reduces the heating value of natural gas.

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References:-

wikipedia.org/wiki/Valve http://en.wikipedia.org/wiki/List_of_valves http://en.wikipedia.org/wiki/Corrosion http://www.tlv.com/global/TI/steam-theory/types-of-valves.html http://en.wikipedia.org/wiki/Flow_measurement http://en.wikipedia.org/wiki/Natural_gas http://en.wikipedia.org/wiki/Pipeline_transport

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