CENTRAL DE GASIFICACIÓN 250 kWe ESCENARIO 2

Dead end or tree systems: In this system, one main pipe line runs through the centre of the populated area and sub mains taken off from this to both sides. There are no cross connections

SJB Institute of Technology, Department of Civil Engineering Page 137 between the branches and sub mines. Due to several dead ends there is accumulation of sediment there and stagnation of water. However the flow rate in each pipe is easily known due to which the pipe diameters can be found.

Grid iron or reticulation systems: If the dead ends of the previous systems are interconnected, water can be made to circulate continuously through the whole of the distribution systems. This systems is there also known as the interlaced systems. The branch lines interconnect all the submains. The systems is ideal for cities laid out on rectangular plan resembling a grid-iron.

Circular systems or ring system: In this systems, the supply main forms a ring around the distribution district. The branches are connected cross wise to the mains and also to each

other.The systems is most suitable for the town or area having well planned streets and roads.The systems possesses the same advantage and disadvantage as those of grid iron systems.

Radial system: This systems is just the reverse of the circular system. In this systems the whole area is divided in to a number of distribution districts, Each district has a centrally located distribution reservoir from where distribution pipes run radially towards the periphery of the distribution district. This system gives quick service without much loss of head.

Design of distribution system 1. Surveys and maps 2. Tentative layout 3. Discharge in pipe line 4. Calculation of pipe diameter 5. Computation of pressures

SJB Institute of Technology, Department of Civil Engineering Page 138 UNIT 8 - MISCELLANEOUS

Pipe appurtenances

Pipe is a circular closed conduit through which the water may flow either under gravity or under pressure. Pipes are made of

1. Cast iron 2. Wrought iron 3. Steel

4. Galvanized iron 5. Cement concrete 6. Asbestos cement 7. Plastic

8. Lead 9. Copper 10. Wood.

Cast iron pipes: they are used in great majority of water distribution mains. Cast iron pipes are manufactured by two methods (1) Ordinary sand moulding (2) Centrifugal process.

Wrought iron: they are manufactured by rolling flat plates of the wrought iron to the proper diameter and welding the edges.Such pipes are much lighter than the CI pipes& can be more easily cut, thread and worked.

Steel pipes: It can be made from solid but large sizes are made by riveting or welding together the edges suitably curved plates, sockets being formed later in pres. The joints may be either transverse and longitudinal or transverse and spiral.

Cement pipes: Cement concrete pipes may be either in plain or reinforced, and are best made by spinning process. They are either precast or may be prepared at the sites. Water tightness of high pressure concrete pipe may be obtained by insertion of a thin steel cylinder in the pipe walls either with or without prestressed reinforcement.

Asbestos cement pipes: They are manufactured fiber and Portland cement combined under pressure to form a dense homogeneous structure having strong bond between cement and the fibre. Such a pipe is considered to be impervious.

Copper and lead pipes: Copper pipes are very costly and their use is restricted for conveyance of hot water in the interior of buildings and for making gooseneck in the service connections.

Wood pipes: They are prepared of staves or planks of wood held together by steel bands. They have been used for many years for water supply pipes, though they were replaced due to lack of capacity.

SJB Institute of Technology, Department of Civil Engineering Page 139 Pipe appurtenances

1. Sluice valve 2. Air valve 3. Reflux valve 4. Altitude valves 5. Scour valve

Sluice valve: They are extensively used in the distribution systems to shut off the supplies whenever desired. They are helpful in dividing water mains into suitable sections. They are also placed at street corners or where two pipe lines meet or intersect. The possess the

advantage over most other types of valves of combing relatively low cost and offering almost no resist

Air relief : The water flowing through the pipe lines always contain some air. This air tries to accumulate at high points and may interfere with the flow. Air relief valves are therefore provided at the summits along the water pipe to provide an exit for such accumulated.

Reflux valves: Reflux valves are also known as check valves or non return valves. It is an automatic device which allows water to flow in one direction only. They are placed in water pipes which obtain water directly from the pumps. When the pump is stopped the water in the pipe line does not rush back and damage the pump

Altitude valves: They are mainly used on those lines which supply water to elevated tanks or stand pipes. They are close automatically when the tank is full and open when the pressure in the pump side is less than that on the tank side of the valve.

Scour valve They are also called as blow of valve or washout valves are ordinary sluice valve hat are located either at the dead ends or at lowest points in the mains. They are provided to blow off or remove the sand and silt deposited in the pipe line, They are operated manually.

Fire Hydrants are an integral part of private fireline construction and public water pipeline main systems. Fire hydrants are basically outlets that release large quantities of pressurized water to extinguish fires. Public fire hydrants are typically supplied by municipal potable water pipeline mains; whereas private fire hydrants are typically located behind a detector check and

specifically only used for fire suppression and is not typically drinking water.

Public fire hydrants are usually designed and spaced to be installed in a new construction setting approximately every 500 ft. They are usually located along a street, in the sidewalk at a certain distance away from the curb. Each public fire hydrant typically includes a gate valve on the branch off the municipal water pipeline supply.

Fire hydrant outlet sizes and number of outlets are determined by local zoning requirements and local fire department codes. Fire hydrants are designed with an operating valve for each outlet.

SJB Institute of Technology, Department of Civil Engineering Page 140 Outlets can range in size from 2 ½ to 4 ½ inches in diameter. Outlets range from two to three outlets, in most cases.

As mentioned, private fire hydrants are located behind a check valve. These fire hydrants are used specifically for fire suppression and are typically connected to a system that feeds a building's fire sprinkler system. Their location and quantity vary depending on what type of structure or property they are servicing.

There are generally two types of fire hydrants used in most instances. Whether serving public or private systems, they are either wet barrel or dry barrel fire hydrants. Wet barrel fire hydrants are pressurized up to their outlets and each outlet can be operated individually. Dry barrel fire

hydrants are not pressurized up to their outlets. Instead, there is only one internal valve, generally located at the base of the fire hydrant bury, that when opened, will pressurize all outlets at the same time.

Another difference between the two fire hydrant types is that the dry barrel, if struck or hit and separated from the base, will allow the valve in most cases to close, thereby not allowing water to be discharged. In contrast, wet barrel fire hydrants, if struck, do not have this feature. To combat this, several municipalities have introduced the use of a break-off check valves located just below the head of wet barrel fire hydrants.

Pipe fitting is the occupation of installing or repairing piping or tubing systems that convey liquid, gas, and occasionally solid materials. This work involves selecting and preparing pipe or tubing, joining it together by various means, and the location and repair of leaks.

.Fitters work with a variety of pipe and tubing materials including several types of steel, copper, iron, aluminium, and plastic. Pipe fitting is not plumbing; the two are related but separate trades.

Pipe fitters who specialize in fire prevention are called Sprinklerfitters, another related, but separate trade.

Materials, techniques, and usages vary from country to country as different nations have different standards to install pipe.

Steel pipe

Steel pipe (or black iron pipe) was once the most popular choice for supply of water and flammable gases. Steel pipe is still used in many homes and businesses to convey naturalgas or propane fuel, and is a popular choice in fire sprinkler systems due to its high heat resistance. In commercial buildings, steel pipe is used to convey heating or cooling water to heatexchangers, air handlers, variableairvolume (VAV) devices, or other HVAC equipment.

Steel pipe is sometimes joined using threaded connections, where tapered threads (see

NationalPipeThread) are cut into the end of the tubing segment, sealant is applied in the form of thread sealing compound or thread seal tape (also known as PTFE or Teflon tape), and it is then threaded into a corresponding threaded fitting using a pipe wrench. Beyond domestic or light commercial settings, steel pipe is often joined by welding, or by use of mechanical couplings

SJB Institute of Technology, Department of Civil Engineering Page 141 made by companies such as Victaulic or Grinnell that hold the pipe joint together via a groove pressed or cut (a rarely used older practice), into the ends of the pipes.

Other variations of steel pipe include various stainless steel and chrome alloys. In high-pressure situations these are usually joined by TIG welding.

In Canada, with respect to natural gas (NG) and propane (LP gas), black iron pipe (BIP) is commonly used to connect an appliance to the supply. It must however be marked (either painted yellow or yellow banding attached at certain intervals) and certain restrictions apply to which nominal pipe size (NPS) can be put through walls and buildings. With propane in particular, BIP can be run from an exterior tank (or cylinder) provided it is well protected from the weather, and an anode-type of protection from corrosion is in place when the pipe is to be installed

underground.

Copper pipe

Copper tubing is most often used for supply of hot and cold water, and as refrigerant line in HVAC systems. There are two basic types of copper tubing, soft copper and rigid copper.

Copper tubing is joined using flare connection, compression connection, or solder. Copper offers a high level of resistance to corrosion, but is becoming very costly.

Soft copper

Soft (or ductile) copper tubing can be bent easily to travel around obstacles in the path of the tubing. While the work hardening of the drawing process used to size the tubing makes the copper hard/rigid, it is carefully annealed to make it soft again; it is therefore more expensive to produce than non-annealed, rigid copper tubing. It can be joined by any of the three methods used for rigid copper, and it is the only type of copper tubing suitable for flare connections. Soft copper is the most popular choice for refrigerant lines in split-system air conditioners and heat pumps.

Flare connections

Flare connections require that the end of a tubing section be spread outward in a bell shape using a flare tool. A flare nut then compresses this bell-shaped end onto a male fitting. Flare

connections are a labor intensive method of making connections, but are quite reliable over the course of many years.

Rigid copper

Rigid copper is a popular choice for water lines. It is joined using a sweat, compression or crimped/pressed connection. Rigid copper, rigid due to the work hardening of the drawing process, cannot be bent and must use elbow fittings to go around corners or around obstacles. If heated and allowed to slowly cool, called annealing, then rigid copper will become soft and can be bent/formed without cracking.

SJB Institute of Technology, Department of Civil Engineering Page 142 Soldered connections

Solder fittings are smooth, and easily slip onto the end of a tubing section. The joint is then heated using a torch, and solder is melted into the connection. When the solder cools, it forms a very strong bond which can last for decades. Solder-connected rigid copper is the most popular choice for water supply lines in modern buildings. In situations where many connections must be made at once (such as plumbing of a new building), solder offers much quicker and much less expensive joinery than compression or flare fittings. The term sweating is sometimes used to describe the process of soldering pipes.

Compression connections

Compression fittings use a soft metal or thermoplastic ring (the compression ring or "olive") which is squeezed onto the pipe and into the fitting by a compression nut. The soft metal

conforms to the surface of the tubing and the fitting, and creates a seal. Compression connections do not typically have the long life that sweat connections offer, but are advantageous in many cases because they are easy to make using basic tools. A disadvantage in compression

connections is that they take longer to make than sweat, and sometimes require retightening over time to stop leaks.

Crimped or pressed connections

Crimped or pressed connections use special copper fittings which are permanently attached to rigid copper tubing with a powered crimper. The special fittings, manufactured with sealant already inside, slide over the tubing to be connected. Thousands of pounds-force per square inch of pressure are used to deform the fitting and compress the sealant against the inner copper tubing, creating a water tight seal. The advantages of this method are that it should last as long as the tubing, it takes less time to complete than other methods, it is cleaner in both appearance and the materials used to make the connection, and no open flame is used during the connection process. The disadvantages are that the fittings used are harder to find and cost significantly more than sweat type fittings.

Aluminium pipe

Aluminium is sometimes used due to its low cost, resistance to corrosion and solvents, and its ductility. Aluminium tube is more desirable than steel for the conveyance of flammable solvents, since it cannot create sparks when manipulated. Aluminium tubing can be connected by flare or compression fittings, or it can be welded by the TIG or heliarc processes.

Glass pipe

Tempered glass pipes are used for specialized applications, such as corrosive liquids, medical or laboratory wastes, or pharmaceutical manufacturing. Connections are generally made using specialized gasket or O-ring fittings.