Pipes & Tubes Prepared by : Sojitra Jalpa B. ( )

Pipe, Tubes & Valves  Pipe and tubing:  Importance of Pipes & Tubing In chemical industry, the fluid is usually transferred from one point of the process to the another through pipe or tubing. Pipe or tubing is circular in cross-section and available in widely varying sizes, wall thicknesses and material of construction. The material of construction includes metals and alloys, wood, ceramic, glass, plastics, etc. PVC pipes are widely used for water lines.

Difference between pipe & tubing:  The pipe is heavy walled while tubing is thin walled.  The pipe is available in standard lengths of 20 to 40 feet while tubing is available in coils several hundred feet long.  The pipe diameter is relatively larger than tubing.  The pipe surface is rough while surface of tubing is smooth.  Pipe sections may be joined by threaded, welded or flanged fittings while tube pieces are joined by compression, flare or soldered fittings.  Tubing is usually extruded or cold drawn while metallic pipe is made by welding, casting etc.

Difference between pipe & tubing:  The wall thickness of pipe is indicated by a schedule number. The approximately relationship is schedule number approximately equal to 1000 P/S Where P = internal working pressure S = allowable stress.  Ten schedule numbers 10, 20, 30, 40, 60, 80, 100, 120, 140 and 160 are in use. The wall thickness increases with schedule number.  The wall thickness of tubing may be expressed as BWG (Burmingham Wire Gauge) number, which ranges from 24 (very light) to 7 (heavy).

Sizes for pipe and tubing:  Pipe and tubing are specified in terms of their diameter and wall thickness.  For steel pipes, the nominal diameter is neither an inside nor an outside diameter.  For pipe size 2 inches to 3 inches, the nominal diameter is close to actual inside diameter but for small pipes, this is not true.  The wall thickness of pipe is indicated by a schedule number. The approximately relationship is schedule number approximately equal to 1000 P/S Where P = internal working pressure S = allowable stress.  Ten schedule numbers 10, 20, 30, 40, 60, 80, 100, 120, 140 and 160 are in use. The wall thickness increases with schedule number.

Sizes for pipe and tubing:  The size of tubing is indicated by outside diameter. It may range from 6 to 50 mm in diameter.  The wall thickness of tubing may be expressed as BWG (Burmingham Wire Gauge) number, which ranges from 24 (very light) to 7 (heavy).  Purpose of fittings: To join two pieces of pipe (eg: couplings, union) To change diameter of a pipeline (eg: reducer) To change direction of a pipeline (eg: tee, elbow, bend) Branching of pipeline (eg: tee) Termination of pipeline (eg: cap, plug) Controlling the flow through the pipeline (eg: valves)

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A ball valve is a valve with a spherical disc, the part of the valve which controls the flow through it.valvespherical The sphere has a hole, or port, through the middle so that when the port is in line with both ends of the valve, flow will occur. When the valve is closed, the hole is perpendicular to the ends of the valve, and flow is blocked. The handle or lever will be inline with the port position letting you "see" the valve's position. Different Types of Valves Ball Valves

 Ball valves are durable and usually work to achieve perfect shutoff even after years of disuse.  They are therefore an excellent choice for shutoff applications (and are often preferred to globe valves and gate valves for this purpose).globe valvesgate valves  They do not offer the fine control that may be necessary in throttling applications but are sometimes used for this purpose.  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).pressuresbartemperatures Ball Valves

 Sizes typically range from 0.2 to 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.metalplasticceramic  The ball is often chrome plated to make it more durable.chrome plated Ball Valves

 The Globe valves as name suggests is having a globe type spherical body which is divided in two parts by a baffle.  A type of valve used for regulating flow in a pipeline.  Flow direction is steeply changed in this type of valve so the controlling of flow is better by the movement of restriction element.  It consists of a movable disk-type element and a stationary ring seat in a generally spherical body. Globe Valves

 Like Gate valve which is the most common for isolation type service,  Globe valves are most common for flow regulation service.  Globe Valves are used when a valve must be opened and closed frequently under high water pressure.  Volumetric flow is usually controlled by a globe valve. Globe Valves

 These valves have two chambers with a partition between them for passage of water that must change course several times from port to port. Globe Valves SR NOITEMQTY 1BODY1 2SEAT1 3VALVE1 4BACK SEAT1 5GLAND PACKINGREQ 6SPINDLE1 7GLAND1 8BONNET1 9YOKE BUSH1 10HAND WHEEL1 11STUD/NUTREQ

Gate Valves  Gate valves are by far the most widely used in industrial piping.  That's because most valves are needed as stop valves - to fully shut off or fully turn on flow - the only job for which gate valves are recommended.  Gate valves are used when a straight-line flow of fluid and minimum restric­tion is desired. The gate is usually wedge shaped.

Gate Valves  When the valve is wide open, the gate is fully drawn up into the valve, leaving an opening for flow through the valve the same size as the pipe in which the valve is installed.  Gate valves are not suitable for throttling purposes since the control of flow would be difficult due to valve design.  Since the flow of fluid slapping against a partially open gate can cause extensive damage to the valve.

Gate Valves  Except as specifically authorized, gate valves should not be used for throttling.  Gate valves provide optimum performance in conditions where high flow efficiency, tight shut off and long service is required.  Gate Valves are designed to operate fully open or fully closed.  Because they operate slowly they prevent fluid hammer, which is detrimental to piping systems. There is very little pressure loss through a gate valve.

Gate Valves  A gate valve usually requires more turns - more work - to open it fully. Also, unlike many globe valves, the volume of flow through the valve is not in direct relation to number of turns of hand wheel.

Butterfly Valves  A Butterfly Valve is a valve which can be used for isolating or regulating flow.  The closing mechanism takes the form of a disk. Operation is similar to that of a ball valve, which allows for quick shut off.  Butterfly valves are generally favored because they are lower in cost to other valve designs as well as being lighter in weight, meaning less support is required.

Butterfly Valves  The disc is positioned in the center of the pipe, passing through the disc is a rod connected to an actuator on the outside of the valve.  Rotating the actuator turns the disc either parallel or perpendicular to the flow.  Unlike a ball valve, the disc is always present within the flow, therefore a pressure drop is always induced in the flow, regardless of valve position.

Butterfly Valves  A Butterfly Valve is from a family of valves called quarter- turn valves.  The "butterfly" is a metal disc mounted on a rod.  When the valve is closed, the disc is turned so that it completely blocks off the passageway.  When the valve is fully open, the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the fluid.  The valve may also be opened incrementally to throttle flow.

Butterfly Valves  There are different kinds of butterfly valves, each adapted for different pressures and different usage.  The resilient butterfly valve, which uses the flexibility of rubber, has the lowest pressure rating.  The high performance butterfly valve, used in slightly higher- pressure systems, features a slight offset in the way the disc is positioned, which increases the valve's sealing ability and decreases its tendency to wear.

Butterfly Valves  The valve best suited for high- pressure systems is the triple offset butterfly valve, which makes use of a metal seat,and is therefore able to withstand a greater amount of pressure.

Diaphragm Valves  Diaphragm valves (or membrane valves) consists of a valve body with two or more ports, a diaphragm, and a "saddle" or seat upon which the diaphragm closes the valve.valve  The valve is constructed from either plastic or steel.plasticsteel  Originally, the diaphragm valve was developed for use in non- hygienic applications. hygienic  Later on the design was adapted for use in the bio-pharmaceutical industry by using compliantmaterials that can withstand sanitizing and sterilizing methods.materials

Diaphragm Valves There are two main categories of diaphragm valves: one type seals over a "weir" (saddle) and the other (sometimes called a "straight-way" valve) seals over a seat.weir

Diaphragm Valves  The saddle type is the most common in process applications and the seat- type is more commonly used as a tank bottom valve but exists also as a process valve.  While diaphragm valves usually come in two-port forms (2/2-way diaphragm valve), they can also come with three ports (3/2-way diaphragm valves also called t-valves) and more  (so called block-valves).

Diaphragm Valves  When more than three ports are included, they generally require more than one diaphragm seat; however, special dual actuators can handle more ports with one membrane.membrane  Diaphragm valves can be manual or automated.  Their application is generally as shut-off valves in process systems within the food and beverage, pharmaceutical and biotechindustries.pharmaceutical biotech