Library of Congress Cataloging-in-Publication Data Parisher, Roy A. Pipe drafting and design / Roy A. Parisher, Robert A. Rhea-2nd ed. p. cm. Includes index. pipe drafting and design third musicmarkup.info - Ebook download as PDF File .pdf), Text File .txt) or read book online. download Pipe Drafting and Design 3rd edition () by Roy A. Parisher for up to 90% off at musicmarkup.info
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Pipe Drafting and Design - 3rd Edition - ISBN: , . View on ScienceDirect eBook ISBN: Paperback ISBN. Pipe Drafting and Design, Third Edition provides step-by-step instructions to walk pipe designers, drafters, and students through the creation of piping. Editorial Reviews. Review. "Parisher (engineering design graphics, San Jacinto College Pipe Drafting and Design 3rd Edition, Kindle Edition. by.
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Your rating has been recorded. Write a review Rate this item: Preview this item Preview this item. Pipe drafting and design, third edition Author: Waltham, Mass. Gulf Professional Pub. Subjects Piping -- Drawing -- Handbooks, manuals, etc. Piping -- Design and construction -- Handbooks, manuals, etc. Piping -- Design and construction.
More like this Similar Items. Allow this favorite library to be seen by others Keep this favorite library private. Find a copy in the library Finding libraries that hold this item Electronic books Handbooks and manuals Handbooks, manuals, etc Material Type: Document, Internet resource Document Type: Reviews User-contributed reviews Add a review and share your thoughts with other readers.
Be the first. Add a review and share your thoughts with other readers. Similar Items Related Subjects: Linked Data More info about Linked Data. Primary Entity http: Book , schema: The lumber does not actually measure 2" x 4", nor does a 6" pipe actually measure 6" in diameter.
It's just an easy way to identify lumber and pipe. Outside diameter OD and inside diameter ID , as their names imply, refer to pipe by their actual outside and inside measurements. In process piping, the method of sizing pipe maintains a uniform outside diameter while varying the inside diameter. This method achieves the desired strength necessary for pipe to perform its intended function while operating under various temperatures and pressures.
Wall thickness is also commonly referred to as a pipe's weight. Originally manufactured in weights known as standard, extra strong, and double extra strong, pipe has since increased in complexity with the development of new chemical processes.
Commodities with ever-changing corrosive properties, high temperatures, and extreme pressures have necessitated the development of numerous additional selections of wall thicknesses for pipe. Now called schedules, these additional wall thicknesses allow a pipe to be selected to meet the exact requirements needed for safe operation. An example of this variance in wall thickness is shown in Figure As you can see in Table , nominal size is not equal to either the actual OD or the ID for pipe 12" and smaller.
It is simply a convenient method to use when referring to pipe. As a piping drafter, you should be aware however, pipe 14" and larger is identified by its actual outside measurement. The chart in Table shows typical pipe diameters and wall thicknesses. The following formula can be used to calculate a pipe's inside diameter ID: downloading and installing pipe that does not meet the minimum requirements can be dangerous and deadly.
Using pipe that far exceeds what is required to do the job can result in tremendous cost overruns. The three methods we will focus on are those most widely used in piping systems made of carbon steel, as shown in Figure Later in the chapter, cast iron and plastic pipe uses will be discussed.
Pipe thickness. MM IN. MM 2 Otherwise, the root gap would not be considered at all. Figure shows the Vie" root gap and the resulting butt-weld joint.
Pipe joints. Butt-Weld Connections A butt-weld joint is made by welding the beveled ends oi pipe together. Beveled ends BE indicate that the ends oi the pipe are not cut square, but rather are cut or ground tc have a tapered edge. In preparation for the welding process, a welder will separate two pieces of pipe by a Vie" space, known as a root gap.
If twc pieces of pipe 3'-0" long were welded together in this manner, the result would be a total length of 6'-0". However, sometimes a back-up ring is used in critical situations.
The back-up ring is used when there is a need to prevent the formation of weld icicles inside the pipe. The back-up ring creates a gap of Vs" between the two pieces of pipe. In this situation, the ring does not allow Figure Butt-weld joints. Screwed or Threaded Connections Another common means of joining pipe is the threaded end TE connection. Typically used on pipe 3" and smaller, threaded connections are generally referred to as screwed pipe.
With tapered grooves cut into the ends of a run of pipe, screwed pipe and screwed fittings can easily be assembled without welding or other permanent means of attachment. Male threads are cut into the outside of a pipe or fitting, while female threads are cut into the inside of the fitting.
As screwed pipe and fittings are assembled, a short length of pipe is drawn into the fitting. This connection length is called a thread engagement. When drawing and dimensioning screwed pipe, a piping drafter must be aware of this lost length of pipe. As the diameter of the pipe increases, so will the length of the thread engagement.
Table provides a chart indicating the thread engagements for small bore pipe. Considering the low cost of raw manufacturing materials and the relative ease of manufacture, cast iron is the least expensive of the engineering metals.
These benefits make cast iron the choice application in environments that demand good corrosion resistance. Water will not leak out and, when used underground, roots cannot grow through the joints. See Figure Joining Cast Iron Pipe Cast iron pipe is grouped into two basic categories: The hub, or bell, and spigot joint uses pipe with two different end types. The hub end of the pipe has an enlarged diameter, thus resembling a bell. The spigot end of the adjoining pipe has a flat or plain-end shape.
The spigot is inserted into the bell to establish a joint. Two methods of preventing leaks on bell and spigot joints are compression and lead and oakum.
The compression joint uses a one-piece rubber gasket to create a leak-proof seal. As shown in Figure , when the spigot end of the pipe is placed into the hub containing a gasket, the joint is sealed by displacing and compressing the rubber gasket. The lead and oakum joint is made with oakum fiber and molten lead to create a strong, yet flexible, leak-proof and root-proof joint.
When the molten lead is poured over the waterproof oakum fiber, which is a loose, oil laden, Hubless cast iron pipe uses pipe and fittings manufactured without a hub. The method of joining these pipe and fittings uses a hubless coupling that slips over the plain ends of the pipe and fittings and is tightened to seal the ends. Hubless cast iron pipe is made in only one wall thickness and ranges in diameter from IVi" to 10". Figure depicts the hubless cast iron pipe joint. Compression joint.
Hubless pipe coupling. Lead and oakum joint. Not originally thought of as a product capable of performing in the environs of a piping process facility, plastic has emerged as a reliable, safe, and costeffective alternative material. There is a broad range of plastic compounds being developed today. For piping systems, two categories are most effective: Thermoplastics are those that require melting during the manufacturing process. These plastics can be welded or injection molded into shapes for machining into piping system components.
For some piping systems, it is now inconceivable not to use plastics. Pipes made from plastic are replacing traditional, expensive materials like glass or ceramic-lined pipe. The Taber Abrasion Test cycles an abrasive wheel over the face of a plate made of the material being tested.
After 1, cycles of the wheel, the plate is measured to determine the amount of weight loss. Table lists the results. Table Taber Abrasion Tester wall thicknesses are required, and leaks from high pressures and expansion and contraction are difficult to control. Joints made with solvent cement have proven more reliable. Though, once hardened, cemented joints cannot be disassembled. They offer good resistance to abrasive chemical and high-pressure commodities and are available in a large selection of fittings without the need of threads.
Heat fusion must be performed on some plastic compounds that are resistant to chemical solvents. Pipe can either be buttjoined or socket-joined. Heat fusion can be used with thinner wall thicknesses and are pressure resistant beyond the burst pressure of the pipe. Socket fittings provide large surface contact between pipe and fittings and are resistant to separation. For this reason they cannot be disassembled. Though fabrication with plastic may sound simple, caution must be exercised when using plastic pipe.
The effectiveness of a particular grade of plastic must be tested before it is chosen for a particular service. Four important variables must be evaluated: The various molecular components of plastics make them susceptible to chemical reactions with certain compounds. Hazardous mixtures must be avoided. Pressure and temperature limitations must be established for obvious reasons.
Pipe that is overheated or pressurized beyond capacity can rupture, split, or burst. Stress, as applied to pipe, entails physical demands such as length of service, resistance to expansion and contraction, and fluctuations in pressure and temperature.
Excessive stresses in the form of restricted expansion and contraction, and frequent or sudden changes in internal pressure and temperature must be avoided. Threading plastic pipe is not a viable option because it is expensive. Pipe 12" and smaller is typically drawn single line and pipe 14" and larger is drawn double line. Single-line drawings are used to identify the centerline of the pipe. Double lines are used to represent the pipe's nominal size diameter. Typically hand drawn, single-line pipe is drawn with a.
Double-line pipe uses standard line widths to draw the pipe's nominal size diameter. A centerline is used on all double pipe to allow for the placement of dimensions. Steel Pipe Figure provides several representations of pipe as it may appear on a drawing.
When pipe is represented on a drawing, typically the pipe's nominal size dimension is used to identify pipe size.
There are certain applications, however, when the pipe's true outside diameter dimension is used to 11 represent the pipe on a drawing. Drawings created with most software packages are an example. Piping software programs draw with such accuracy that pipe is drawn using the actual outside diameter.
Pipe created by means other than a piping software program in this text will be drawn using nominal sizes. Be aware that drawings created with a piping software program use actual outside dimensions and will differ slightly from manual and AutoCAD generated drawings.
Name three methods of manufacturing carbon steel pipe. Name the three most commonly used end preparations for joining pipe.
What is meant by the term nominal size pipel 4. Which diameter of pipe varies as the wall thickness changes? What is the most common material used in the manufacture of pipe? When drawing pipe, which pipe sizes are drawn single line and which sizes are drawn double line?
How long is the gap between two lengths of pipe when a back-up ring separates them?
What is the name for the amount of pipe "lost" when screwed connections are used? What is the standard drawing scale used on piping drawings? Name three-methods for joining carbon steel and plastic pipe. Pipe Fittings Fittings are fabricated pieces of pipe that are used to make changes of direction elbow , branch from a main pipe tee , or make a reduction in line size reducer see Figure Because fittings are part of the piping system, they must match as closely as possible in specification and rating to the pipe to which they are being attached.
Fittings, like pipe, are manufactured and classified according to their wall thickness. There are many more wall thicknesses of pipe however than there are thicknesses of fittings. Fittings are commercially manufactured in standard weight, extra strong, Schedule , and double extra strong.
In the petrochemical industry, most companies have guidelines known as piping specifications that state pipe 3" and larger will be fabricated with butt-welded connections.
These specifications, or specs, as they are more commonly called, may also require pipe smaller than 3" to have screwed or socket-weld connections. For uniformity, the previously mentioned specifications will be used throughout this book as a basis for determining pipe connection requirements. However, this is not to say this is the only spec that can be written.
There may be cases where small bore pipe is butt-welded, while larger sizes may be screwed or socket-welded, oniuc tLBUWo Of all the fittings, the elbow is the one most often used. Simply put, the elbow, or ell, is used when a pipe changes direction. Elbows can turn up, turn down, turn Figure Ninety degree ells can be classified as one of the following: When determining the length of an elbow, one must establish the center-to-end dimension.
The center-to-end dimension is the measurement from the centerline of the fitting to the end of the fitting see Figure Notice the relationship between the nominal size and the length of the fitting. The fitting's length is equal to the nominal pipe size plus one-half of the nominal size. A simple formula in the next column makes calculating this dimension easy to remember. Long radius elbow. Use this formula for butt-weld fittings only.
Long-Radius Elbow Dimensional sizes of fittings are typically provided by the manufacturer of the fitting. Manufacturers issue dimensioning charts containing lengths for a particular fitting.
The dimensional charts used to establish sizes of fittings discussed in this text are listed on the Welded Fittings-Flanges Chart provided in Appendix A. As a reference, portions of that chart are used throughout this chapter when fitting measurements are needed. The measurement labeled A represents the center-to-end length of the fitting. To find the fitting's length in inches, locate the appropriate nominal pipe size Figure Center-to-end dimension of a long-radius elbow. Welded Fittings-Flanges Chart.
Pipe Fittings 15 in the row labeled Nominal Pipe Sizes. Follow across the chart to find the desired pipe size. The center-to-end dimension A will be used as the radius for the elbow's centerline. Remember, in the single-line symbol only the centerline of the elbow is drawn. The double-line symbol requires that one-half of the pipe OD should be added and subtracted respectively from the elbow's centerline. To better visualize the long-radius elbow, we have attached a piece of pipe to each end of the fitting.
Figure shows the steps using manual drafting techniques and Figure shows those steps using AutoCAD commands. Manual drafting solutions. Step 1. Mark off the distance from the center of the fitting to the end of the fitting.
Step 3. Extend the ends of the fitting down and across respectively until they intersect.
This will be the centerpoint for drawing the arcs that will form the ell. Use a circle tern- Step 2. Determine the nominal size of pipe and mark off one-half of its size on each side of the fitting's centerline. Remember, for fittings 12" and below, only the arc representing the elbow's centerline is drawn when creating single-line symbols.
AutoCAD commands. Drawing set-up. The 21" radius should be measured above PT. Step 2. The offset distance will be equal to one-half of the. Step 4. Use the LINE command to draw the ends of elbow. The step-by-step instructional procedures presented using computer-aided drafting techniques presume each student has a comprehensive knowledge of basic AutoCAD commands. These self-instructional steps provide a simple method to create each fitting.
They are not intended to restrict the student to any particular commands. Each student is encouraged to experiment with new commands that may achieve the same result.
Conversely, the short-radius ell also creates a rather large pressure drop inside the line and does not have the smooth flow characteristics the longradius ell has. For these reasons the short-radius ell is seldom used. Center-to-end dimension of the shortradius elbow. Whenever a short-radius ell is used, the abbreviated note S. The mitered elbow is not an actual fitting, but instead is a manufactured turn in the piping system. This elbow is made by making angular cuts in a straight run of pipe and then welding the cuts together after they have been rolled to a different angle see Figure The mitered ell may be classified as one, two, three, or four weld miters.
The number of welds used depends on the smoothness of flow required through the turn. A twoweld miter will create more turbulence within the pipe than will a four-weld miter. Long-radius and short radius elbows. Drafting Symbols for Mitered Elbows Figure shows the double-line drafting symbols for two-weld and three-weld mitered elbows.
Unlike the previous ells, the weld lines in the adjacent views of the mitered elbow are represented by ellipses. Ellipses are used because the welds are not perpendicular to your line of sight. Therefore, when projecting from the front view to any of the four adjoining views, the welds must be drawn elliptical in shape. Short-radius elbow symbols Figure Mitered elbows. Pipe Fittings 19 Figure Miter elbows drafting symbols.
This elbow is also used to make changes in direction within the piping system. Figures and describe two manual methods for constructing the elbow. Figure defines steps using AutoCAD commands to draw the elbow. Pipe Fittings 21 Figure Alternative manual solution. Determine one-half of the pipe's diameter and mark Step 2.
This will P'P Step 4. Use a circle template to draw the inside and outside arcs representing the elbow. Draw an arc to represent the elbow's centerline. ERASE the two construction lines. Use LINE to draw the two ends of the elbow.
In some orthographic views, these elbows will appear at an angle to our line of sight. In those views where the open end of the elbow appears at an angle to our line of sight, ellipses must be used to represent the end of the fittings. It is a three-way fitting used to make perpendicular connections to a pipe see Figure Lines that connect to the main run of pipe are known as branches.
The main run of pipe is often called the header. Figure shows a pipe header with two branch connections. Drafting Symbols for the Weld Tee Notice that the weld tee requires three welds be made to install the fitting. Two types of tees are used in the piping industry: Figure shows the drawing symbols for straight and reducing tees.
A callout is required on the reducing tee to identify the header and branch sizes. The header size is shown first. Pipe Fittings Figure Weld tee. Header and branch connections. Weld tee symbols. Pipe Fittings 25 Figure From the center of the tee, draw a perpendicular line, either up or down, depending on the direction of the branch, Step 2. Measure 7" one-half the header pipe size on either side of the centerline to draw the sides of the tee.
Measure 7" one-half the branch pipe size on either side of the perpendicular line to draw the branch of the tee. Draw and darken the sides and weld lines of the tee. Add break symbols. ZOOM, Extents. These dimensions are required to determine the center-to-end length of the header and the length of the branch end.
If a straight tee is being used, the C dimension found on the Welded Fittings-Flanges Chart in Figure must be added twice to find the total length of the fitting. On a straight tee, the C dimension is also used as the length of the branch end. If a reducing tee is being drawn, the M dimension must be substituted as the length of the branch end. Figures and provide the manual and AutoCAD steps for drawing the tee. Another method of making a branch connection is called a stub-in.
The stub-in is most commonly used as an alternative to the reducing tee. The stub-in is not an actual fitting but rather a description of how the branch connection is created. A hole is bored into the header pipe, either the size of the OD or ID of the branch, and the branch is then stubbed into it.
The two pipes are fitted together and then welded. Although the branch connection can be the same pipe size or smaller as the header, it cannot be larger.
Figure depicts the attachment of a stub-in. Figure provides the single-line and double-line drawing symbols for a stub-in. Stub-in connections. Stub-in symbols. Pipe Fittings How close stub-ins are made is an important consideration. A general rule is to allow a minimum of 3" between welds. This means a minimum of 3" should be allowed between the outsides of branches made from a common header, and a header should be attached no closer than 3" to a fitting.
Figure provides the minimum measurements allowed between branches and fittings on an 18" header. Stub-in Reinforcements Even though the use of the stub-in is limited by the pressure, temperature, and commodity within a pipe, its use is becoming increasingly more popular. Its chief advantage over the tee is cost.
Not only can the cost of downloading a fitting be avoided, but the stub-in requires only one weld; whereas, the tee requires three.
Three remforcmg alternat. Resembling a metal washer that , 0 ,been. Qr, K f f ,, has bent. T plate ,. It is slipped onto the branch pipe then welded to both branch and header. A downloadd reinforcing pad, the welding saddle has a short neck designed to give additional support to the branch. Figure shows 27 drawing representations of reinforcing pads and saddles. downloadd fittings, o-lets have one end shaped to the contour of the header and the other end manufactured to accept the type of end connections being used on the branch.
Weldolets are manufactured for butt-weld fittings. Sockolets are made for socket-weld fittings. And threadolets are available for screwed fittings. Figure shows a typical threadolet. Figure gives drawing symbols for weldolets, sockolets, and threadolets.
Figure shows a latrolet and the elbolet. There are two common methods M used to make branch connections with couplings: The coupling rests on the external surface of the pipe header and is welded from the outside.
A hole is bored into the pipe header large enough to accept the OD of the coupling. The coupling is inserted into the hole and is then welded. Figure shows the coupling in use. Welding minimums for stub-ins. Reinforcing pads and saddles. Latrolet and elbolet. Appropriately named, the reducer is available in two styles as shown in Figure Concentric—having a common centerline.
Eccentric—having offset centerlines. The concentric reducer maintains the same centerline at both the large and small ends of the fitting. The eccentric reducer has offset centerlines that will maintain a flat side on the top or the bottom of the fitting, depending on how the fitting is rolled prior to welding. The eccentric reducer is used in piperacks to maintain a constant bottom of pipe BOP.
Because pipe supports within a piperack are of the same elevation, a pipe must have a consistent bottom of pipe elevation so it can rest on each support throughout its entire length. Using a concentric reducer in a piperack would not permit the small diameter end of the pipe run to rest on a pipe support. Eccentric reducers are also used on pump suction nozzles to keep entrained air from entering the pump.
By keeping a flat on top FOT surface, vapor pockets can be eliminated. It is important that a designer not forget to include the dimensional difference between the two centerlines of an Pipe Fittings 29 Figure Couplings as branches. Eccentric and concentric reducer. A quicker, though less accurate method, is to take onehalf the difference between the two outside diameters. Drawing the Reducers Drafting Symbols for the Concentric and Eccentric Reducer The orthographic views for the concentric and eccentric reducers are shown in Figure No matter the size of the reducer, it is always drawn as a double-line symbol.
Notice the callouts that must be included with the eccentric reducer. The large end is always listed first, no matter the direction of flow, and the flat side must be indicated. Prior to drawing the reducer, the length of the fitting must be found on the Welded Fittings-Flanges Chart see Figure The H dimension will provide the end-toend length for either the concentric or eccentric reducer. Always use the H dimension of the large end to determine the fitting length.
Figures and provide the manual and AutoCAD steps for drawing the reducer. Eccentric reducers. Concentric and eccentric drawing symbols. Using the H dimension found on the chart, draw a centerline 14" long. Connect the opposite ends of the fitting by drawing lines from endpoint to endpoint.
Measure 8" one-half the large end size on either side of the centerline on one end and 7" on either side of the centerline on the opposite end. Darken the sides and weld lines of the reducer, Pipe Fittings 31 Figure ZOOM, All. Place note as required.
The last weld fitting we will discuss is the weld cap. It Welding one fitting directly to another is called fittingis used to seal an open end of pipe. When dimensioning make-up see the examples in Figure The cap will be system require the designer to use pipe of various lengths welded to the end and need not be included in the length between the fittings.
In these cases, pipe is cut to the dimension of the run of pipe. When fittings are not assemble-line symbol for all sizes of pipe. By maintaining this to construct the round end of the fitting. Notice the weld dot on the single line see Rgure 3. We will now look at how each fitting relates to other fittings when used in the design of various piping systems. Welds may seem insignificant to the designer, but, it goes without saying, a piping facility could not be built without them.
Remember, all welds must be shown on drawings. Use weld dots on single-line pipe symbols and weld lines on double-line pipe symbols. At the present time, we are only concerned with butt-weld fittings.
The general rules-of-thumb for placing dimensions on a drawing are as follows: Pipe should be dimensioned from center of fitting to the end of pipe Figure provides some examples for placing dimensions on drawings. Weld cap drawing symbols. Fitting make-up. Minimum pipe lengths. There are, however, a few differences that must be examined. Screwed and socket-weld fittings are normally reserved for installations using fittings 3" and smaller. Screwed and socketweld fittings are also available in cast iron, malleable iron, or forged steel.
Cast iron and malleable iron fittings are typically used on low pressure and temperature lines such as air, water, or condensate. Lines containing high pressure and temperature commodities, which are subject to movement and vibration, require fittings made of forged steel. Forged steel screwed and socket-weld fittings are manufactured in two pressure classes— and Dimensional charts for screwed and socket-weld fittings are provided in Appendix A.
These dimensioning charts supply measurements for and fittings. Figures and provide a sample of the dimension charts for screwed and socket-weld fittings found in Appendix A.
Most screwed fittings are manufactured with internal, female threads per American Standard and API thread guidelines see Figure Some fittings, such as plugs and swages, however, are manufactured with external threads. The socket-weld fitting is replacing the screwed fitting as the choice of many fabricators because it offers greater strength. Even though screwed fittings can be seal welded if necessary, strength of the fitting is decreased when the threads are cut during the manufacturing process.
Socket-weld fittings can be easily fitted and welded without the need of special clamps or tackwelds, which are often required to hold a butt-weld fitting in place before the final weld is made see Figure Like butt-weld fittings, screwed and socket-weld fittings are used to make similar configurations in a piping system.
Screwed and socket-weld fittings differ in size and shape, but they achieve the same purpose as the buttweld fittings. Figure provides examples of some screwed and socket-weld fittings.
Screwed and socket-weld fittings are drawn with square corners using short hash marks to represent the ends of the fitting see Figure Manufactured for screwed and socket-weld applications, the union is represented on drawings as shown in Figure Unions should be positioned in locations that will facilitate the easy removal of critical pieces of equipment.
Figure shows how unions are placed in a configuration to allow easy removal of the valves. Plug The plug, like a cap, is designed to close off the end of a run of pipe. Plugs are manufactured for screwed fittings with male threads and are screwed into the end of a pipe to create a seal. Figure shows the drawing symbols for the plug. Coupling Although this fitting is used in butt-welding applications as a branch connection, its primary use is to connect lengths of screwed and socket-weld pipe together.
Some clients may stipulate, however, that all socket-weld pipe must be connected with a butt weld, rather than a coupling. Screwed fittings are manufactured with threads on the inside of the fitting, and socket-weld fittings have an internal socket that prevents fitting makeup assembly.
To facilitate the assembly of screwed and socket-weld fittings, small lengths of pipe called pipe nipples are used between fittings. Pipe nipples can vary in length depending upon the distance required to fabricate the pipe configuration. A close nipple is one that provides the minimum length of pipe between fittings. Remember, screwed and socket-weld fittings have a certain amount of lost pipe due to thread engagement and socket depth.
Therefore, each size pipe has a different minimum length for the dimension of a close nipple. Many companies will use 3" as the standard minimum for pipe nipples. This length will accommodate the amount of pipe lost inside the fitting on each end as well as provide sufficient wrench clearance during assembly for the larger screwed and socket-weld pipe sizes. Placement of dimensions.
Screwed fittings dimensioning chart. Socket-weld fittings dimensioning chart. Internal and external threads. Socket-weld fittings. Screwed and socket-weld fittings. Swage One exception to the standard 3" minimum rule is the swage nipple. Swages are functionally similar to reducers, but are specifically designed for screwed and socketweld pipe. Screwed swages have male external threads and can be connected to other screwed fittings without the use of a pipe nipple.
They are used to make reductions in the line size on a straight run of pipe. Swages, like reducers, are available in either a concentric or eccentric shape. Figure shows varying lengths and sizes of screwed pipe and swage nipples.
Screwed and socket-weld drawing symbols. Pipe Fittings 37 Figure Union Figure Positioning of unions. Union drawing symbols. Swages are unique in that they can be used in screwed, socket-weld, or butt-weld configurations. When used in these configurations, swages will have different end preparations. Screwed swages will have thread ends TE , socket-weld swages plain ends PE , and butt-weld swages have beveled ends BE.
Because socket-weld swages are inserted into mating fittings, many companies allow the substitution of beveled-end swages. Dual purpose fittings like these will make the job of the downloading group much easier. Swages are also manufactured with different preparations on the two ends. When specifying a swage, use the following abbreviations: Plug drawing symbols. Notice the end preparation combinations on the examples. Figure shows the drawing symbols for swages. The major difference is their method of connection.
The connection joint for flanged fittings is made by bolting two specially designed metal surfaces together. A gasket to prevent leaks is sandwiched between the two surfaces.
Flange types will be discussed at great length in the following chapter. Pipe and swage nipples. Swage drawing symbols. Concentric swages.
Because molten cast iron can be easily manufactured into many unique shapes that cannot be attained with steel, manufacturers use it to produce fittings with many varying turns, bends, and branches. The physical appearance of pipe routing configurations made of cast iron fittings is quite different from pipe routed with forged steel fittings because of the large assortment of fittings available and the method in which these configurations are assembled.
Above-ground Plastic fittings can also be manufactured in many diverse and unique shapes. All the standard fitting shapes are available: Plastic fittings are manufactured for either screwed, socket, or butted assembly.
Plastic screwed and socket fittings are available in sizes through 4" in diameter. Butt fittings are manufactured for sizes 6"". Typically, pipe smaller than 3" in diameter is manufactured as having end connections. What is the most common fitting used? What are the four classifications of elbows? What is the formula for calculating the center-to-end dimension for LR and SR elbows?
Describe a mitered elbow. When configuring tee connections, what is the main run of pipe called? Name the two types of tees. What are some alternate methods to a tee fitting when fabricating branch connections? Which fitting is used to make a reduction in the line size of a run of pipe? Name the two types of reducers. Define fitting make-up. What are the two pressure classifications for screwed and socket-weld fittings? What type of fittings must be bolted together?
What is the typical installation service for cast iron pipe? Name the three types of plastic fitting end types manufactured. To complete the exercises, draw the symbols below using the following guidelines. DO NOT include text with the blocked symbol.
Insert the required symbols into the appropriate locations. The pipe break symbol is created with ellipses. The ma or axis of each J ellipse is equal to one-half of the P1? AutoCAD drawing symbols and File names. They are , , , , , , and Cast iron flanges have pound ratings of 25 , , , and Pound ratings, when combined with the temperature of the commodity within the pipe, are used to select the appropriate size, rating, and type of flange. When temperature decreases the allowable pressure increases, and vice versa.
Pound ratings are also used to establish the outside diameter and thickness of a flange. Typically as pound ratings increase, so will the flange's diameter and thickness. The flange is a ring-shaped device designed to be used as an alternative to welding or threading various piping system components used throughout the piping system.
Flanged connections are used as an alternative to welding because they can be easily disassembled for shipping, routine inspection, maintenance, or replacement. Flanged connections are preferred over threaded connections because threading large bore pipe is not an economical or reliable operation.
The flange is an important component of any piping system. Flanges are primarily used where a connecting or dismantling joint is needed. These joints may include joining pipe to fittings, valves, equipment, or any other integral component within the piping system.
To erect the piping system, every piece of mechanical equipment is manufactured with at least one outlet called a nozzle. The nozzle is the point where, via the flange, the piping system is connected to the equipment. From this flange, the piping system is begun. Figure shows how a nozzle and flange are used to connect the piping system to a piece of equipment.
The face is usually machined to create a smooth surface. This smooth surface will help assure a leak-proof seal when two flanges are bolted together with a gasket sandwiched between. Although numerous types of flange faces are produced, we will focus only on the following three: Nozzle and flange. These pressure ratings, Flat face As the name implies, flanges with flat faces are those that have a flat, level connecting surface see Figure Forged steel flanges with a flat face flange are commonly 48 Flange Basics Figure Flat face.
Welding neck flange with flat face. Their principal use is to make connections with and cast iron flanges, respectively. Attaching steel pipe to the cast iron flanges found on some valves and mechanical equipment always presents a problem because of the brittle nature of cast iron. Using a flat face flange will assure full surface contact, thereby reducing the possibility of cracking the softer cast iron.
Figure shows a sectional view of a flange with a flat face. Raised Face The most common face type in use, the raised face is available in all seven of the aforementioned pound ratings. Appropriately named, this flange face has a prominent raised surface.
With shallow grooves etched into the raised surface, this flange face assures a positive grip with the gasket. Flanges rated and have a Me" raised face, while flanges and above have a 1A" raised face see Figure It is important to note most dimensioning charts, including the ones provided in this text, include the Yi6r raised face thickness in the length dimensions for and flanges. However, the 1A" raised face thickness is not always included in the length dimensions for and higher pound ratings.
To assure accurate dimensioning, always determine if the dimensioning chart being used includes the 1A" raised face thickness for the larger pound rating flanges.
The 1A" raised face thickness must be added to the dimensioning chart measurement to obtain the overall flange length if the dimensioning chart indicates it has not been added. Figure includes a sectional view of a weld neck flange having a raised face. Raised face. Ring-Type Joint Also known simply as ring joint, the ring-type joint does not use a gasket to form a seal between connecting flanges.
Instead a round metallic ring is used that rests in a deep groove cut into the flange face see Figure The donut-shaped ring can be oval or octagonal in design. As the bolts are tightened, the metal ring is compressed, creating a tight seal.
Although it is the most expensive, the ring-type joint is considered to be the most efficient flange used in process piping systems. The ring and groove design actually uses internal pressures to enhance the sealing capacity of the connecting flanges. The superiority of this seal can have its disadvantages, however. When dismantling ring joint connections, the flanges must be forcibly separated to release the ring from the groove. In crowded installations, this could cause major problems.
Because of this, the ring 50 Pipe Drafting and Design Figure Each one has its own special characteristics, and should be carefully selected to meet specific function requirements. The following flanges will be discussed in this chapter: Ring-type joint. Although available for all pound ratings, flanges with ring-type joint faces are normally used in piping systems rated and higher.
See Figure for the sectional view of a flange with a ring-type joint face. A photograph and short description accompanies each flange as well as symbols to depict the flange as it would appear on a drawing. The manual and AutoCAD techniques for creating the drawing symbols are shown for the weld neck flange only. The drawing symbols for the remaining flanges can be created in a similar fashion with only a few minor alterations.
Flange Basics Weld Neck Flange The weld neck flange shown in Figure is occasionally referred to as the "high-hub" flange. It is designed to reduce high-stress concentrations at the base of the flange by transferring stress to the adjoining pipe. Although expensive, the weld neck flange is the best-designed butt weld flange available because of its inherent structural value and ease of assembly.
Known for its strength and resistance to dishing, the weld neck flange is manufactured with a long tapered hub. The tapered hub is created by the gradual increase in metal thickness from the weld joint to the flange facing. The symmetrical taper transition is extremely beneficial under conditions of repeated bending caused by line expansion, contraction, or other external forces. See Figure , for weld neck flange drawing symbols. Weld neck flanges are normally used in severe service applications involving high pressures, high temperatures, or sub-zero conditions.
Weld neck flanges are bored to match the ID of the adjoining pipe. In other words, the thinner the wall of the pipe, the larger the bore hole through the flange. The thicker the wall of the pipe, the smaller the bore. Because of these matching IDs, there is no restriction to the flow. Turbulence and erosion are therefore eliminated.
The figure in this chart represents the raised face weld neck flange. Notice the three dimensions: O, T, and L. The O dimension represents the flange's OD. The T defines the flange's face thickness and the L provides the flange's length or length-thru-hub dimension.
These three dimensions are required to construct the drawing symbols of each flange. To find the numerical values for these dimensions, locate the appropriate pound rating section, that is, , , etc.
Find the proper size pipe in the Nominal Pipe Size column. Follow across the chart to determine the O, T, and L dimensions. For our demonstration, we will be using a 14" raised face weld neck RFWN flange. These dimensions can be found on the welded 51 Figure Weld neck flange. Weld neck flange drawing symbols. Figure demonstrates steps using manual drafting techniques.
Figure presents the steps using AutoCAD commands. Slip-On Flange The slip-on flange shown in Figure has a low hub that allows the pipe to be inserted into the flange prior to welding. Shorter in length than a weld neck flange, the slip-on flange is used in areas where short tie-ins are necessary or space limitations necessitate its use.
Two significant disadvantages, however, are the requirements of two fillet welds, one internal and one external, to provide sufficient strength and prevent leakage, as well as a life span about one-third that of the weld neck flange. They are preferred over welding neck flanges by many users because of their lower initial cost.
However, the total cost after installation is not much less than the welding neck because of the additional welding involved, See the Taylor Forge Seamless Fittings Dimensioning Chart in Appendix A for dimensions of the slip-on flange, The drawing symbols for the slip-on flange are shown in Figure Welded fittings-flanges dimensioning chart.