Ra is stated in micro inches pin or microme- ters pm and shown as an arithmetic average roughness height AARH or root mean square rms. AARH and rms are different methods of calculation giving essentially the same result and are used interchangeably for these products.
The micro profile on the flange face bites into the soft gasket that is trapped between the other mating flanges by the compressive forces applied during the bolt-up.
The industry standard Ra supplied by manufacturers is to pin or 3. The short form is AARH or 3. Other finishes are available at the customer's request.
The gasket contact surface for a ring-type joint flange is inside the groove cut into the face. The steel ring gasket fits into the grooves of the mating flanges and is sealed with pressure. The finish in the ring grooves and on the ring gasket is 63 pin AARH or 1. The pipe is inserted into the socket hub and fillet welded into place. Radiography is not practical on the fillet weld; therefore, correct fit- ting and welding is crucial. The fillet weld may be inspected by sur- face examination, magnetic particle, or liquid penetrant examination methods.
The fillet weld used to attach the pipe to the flange is not considered a high-integrity weld, and NDE is not so easy to perform. Hence, the use of socket weld flanges is restricted to low- and medium-pressure classes, up to ASME class. The flange facings also usually are restricted to raised-face and flat-faced flanges. Use of these flanges at elevated temperatures is not recommended, because the geometry of the thread may deform at elevated temperatures. Because it is a screwed connection, it lacks the integrity of either a butt-weld or a socket-weld joint.
A n advan- tage is that the threaded connection is not permanent and it can be disassembled. The integrity of this connection can be improved by seal welding using fillet weld; however, this makes it a permanent joint. Lap-JointFlanges with a Stub End A lap-joint flange is a two-component assembly, with a stub end that has a lap-joint ring flange placed over it. The stub end is then butt welded to the pipe, and the flange ring can be rotated to align with the mating flange. This type of flange connection is particularly useful for large or hard-to-adjust flanges.
The lap joint flange can be used in sizes and pressure classes similar to that of a weld-neck flange. The nature of this joint means that the stub end facing is also the flange facing, which makes it raised faced, and the gasket seating surface. Like the weld-neck fitting, the lap-joint flange butt-weld connection can be examined using magnetic particle inspection, dye penetrant inspection, radiography, or ultrasonic inspection.
Slip-on Flanges The slip-on flange has a very low-profile hub, through which the pipe is passed. Generally, two fillet welds are performed, one internal and one external. Although the initial cost of a slip-on flange is less than a weld neck, by the time the two fillet welds have been performed, there is very little difference in the cost.
Generally, the slip-on flange is available in similar sizes as a weld-neck flanges, but it is not commonly used above ASME class Blind Flange A blind flange is a closure plate flange that terminates the end of a piping system. It can be used in combination with all of the previous flanges at all sizes and all pressure classes. It comes in the following facings: raised faced low-, medium-, and high-pressure classes , flat faced low-pressure class , and ring-type joint low-, medium-, high-, and very high-pressure classes.
This standard is limited to flanges and flanged fittings made from cast or forged materials, blind flanges, and certain reducing flanges made from cast, forged, or plate materials. Also included in this standard are requirements and recommenda- tions regarding flange bolting, flange gaskets, and flange joints.
The subject matter is as follows: Committee Roster. Flanges may be cast, forged, or plate for blind flanges only materials, as listed in Table 1A. The subject matter is as follows: Standards Committee Roster.
Unlike pipe and piping fittings, valves are multicomponent items, with a variety of materials of construction and static statio- nery and dynamic moving parts. They are a vital part of a piping system and, depending on their design, are capable of transporting liquids, gases, vapors, and slurries.
Next Page 2. The origins of valves can be traced back to the Romans, who used what would be called a pZug-type vaZve to start, stop, and divert the flow of water in channels and pipes. Globe valves. Check valves. Ball valves. Plug valves. Butterfly valves. Pinch or diaphragm valves. Control valves. Each of these can be subdivided in other groupings based on their design and materials of construction.
Valves can be operated either manually, by operating personnel, or using an independent power source, either electric, pneumatic, or hydraulic, depending on the power requirement and availability. A valve is a multicomponent item that has both dynamic moving and static nonmoving parts. Regulate flow butterfly valve -throttle or globe valve.
Prevent backflow-nonreturn or check valve. Control flow-control valve. Valves selected for ASME B31 code projects are governed by numerous international standards and specifications, which have been created to ensure that the valve selected will function predictably and the possibility of in service malfunction is avoided. These standards cover the type of valve, design, construction, compo- nents, dimensions, testing, and marking. These codes and standards contain the rules and requirements for design, pressure-temperature ratings, dimensions, tolerances, materials, nondestructive examinations, testing, and inspection and quality assurance.
Compliance to these and other standards is invoked by reference to codes of construction, specifica- tions, contracts, or regulations. C, Cast-Iron Sluice Gates. A valve whose closure member moves in a straight line to the open or closed position is linear.
This includes gate, globe, and diaphragm valves. A valve whose closure member travels rotation- ally from the fully open to the fully closed position, usually in go", is rotary; it is also known as a quarter-turn valve. A valve whose clo- sure member moves without manual or motorized assistance is automatic. This includes check valves, such as piston lift, swing, dual plate, and relief valves.
Table summarizes the types of valves. Printed with the kind permission of Valvosider,srl, Italy. In the metric system, valve size is designated by the diarn2tre nominal DN in millimeters. Many valves have a reduced internal port size; however, the valve size referenced is still based on the end connections. Printed with the kind permission of Goodwin International, Ltd. Printed with the permission of Resistoflex. The temperature shown for a corresponding pressure rating is the temperature of the pressure-containing shell or body of the compo- nent.
It defines three types of classes: standard, special, and limited. Pressure Containing Parts Valve body, bonnet or cover, disc, and body-bonnet bolting are classified as pressure-retainingparts of a valve and form the pressure envelope or boundaries of the valve. Printed with the permission of Curtiss Wright Controls. Printed with the permission of Durco.
The following list provides a brief description of pressure retaining parts see Appendix B, Figure B-9 : Body. The valve body or shell forms part of the pressure containing envelope and is the essential framework that houses the internal valve parts. The body is in contact with the process media and should be compatible with the fluid that is transported. It has an inlet and an outlet, which can be threaded, flanged, or weld end. The body can either be of a cast or a forged construction.
Bonnet or Cover. The bonnet or cover is connected to the valve body by flanges, threaded or welded to complete the pressure- retaining shell. This part is in contact with the process fluid. The body can be of either cast or a forged construction.
Bonnet or Cover Bolting. This fastening assembly includes bolts, nuts, and occasionally washers. The bolting used must be made from materials acceptable for the application in accordance with the applicable code, standard, specification, or the governing regulation.
Printed with the permission of Saunders. Body Bonnet Gasket. This component is trapped between the body and the bonnet. The gasket is a sealing element held in place by the compressive forces applied by the set of bolts. Disc, Wedge, Ball, Plug, or Plate. A n intermediate position, between fully opened and fully closed, means that the part is in the throttling mode.
The part is not permanently a pressure-retaining part. Non-Pressure-ContainingParts These parts are not part of the pressure containing envelope, but they may be housed inside it. Non-pressure-retaining parts are the valve seat s , stem, yoke, packing, gland bolting, bushings, hand wheel, and valve actuators: Valve Seat s. A valve may have one or more sealing seats, and this surface isolates the fluid.
Globe, butterfly, and swing- check valves usually are referred to as single-seat valves. Gate and ball valves could be either single- or double-seat valves. A gate valve has two seating surfaces, one on the upstream side and the other on the downstream side. The gate-valve disc or wedge has two seating surfaces, one on either side of the gate that comes in contact with the valve seats to form a seal for stopping the flow. The flow direction dictates that the downstream seat is more effective because of the force applied by the fluid.
The downstream force makes the stem flex slightly and forces the gate against the downstream seat. Generally, a gate valve has a metal-to-metal sealing surface, which makes a leaktight joint more difficult; therefore, a certain degree of leakage is acceptable, and this is defined in a valve standard, such as ASME B Valve Stem. The valve stem is the part that applies the necessary torque to raise, lower, or rotate the closure element; it opens, closes, or positions the closure element.
In the globe valve, this is a linear motion. For ball, plug, and butterfly valves, this is a rotary motion. The stem must be of sufficient mechanical strength not to shear during operation, and it is partially in contact with the process fluid, so the two must be compatible. The part of the stem exposed to the outside environment is threaded, while the section of stem inside the valve is smooth. There are two styles of stems, one with the handwheel fixed to the top of the stem, so that they rise and fall together, and the other with a threaded sleeve that causes the stem to rise through the center of handwheel.
In the latter, a rising stem with outside screw and yoke O. Rising Stern with Inside Screw. The threaded part of the stem is inside the valve body, and the stem packing is along the smooth section exposed to the outside atmosphere. In this case, the stem threads are in contact with the flow medium.
When rotated, the stem and the handwheel rise together to open the valve. This design is commonly used in the smaller-sized low- to moderate-pressure gate, globe, and angle valves. Nonrising Stem with Inside Screw. The threaded section of the stem is inside the valve and does not rise.
The valve disc travels along the stem like a nut when the stem is rotated. Stem threads are exposed to the flow medium and, as such, are subjected to its impact.
Therefore, this design is used where space is limited to allow linear stem movement, and the flow medium does not cause erosion, corrosion, or wear and tear of stem material. Sliding Stem. The stem does not rotate, and it is without a thread.
It slides in and out of the valve packing to close, open, or position the valve closure member. This design is used in hand-lever-operated, quick-opening valves. It is also used in control valves operated by hydraulic or pneumatic cylinders. Rotary Stem. This is the most commonly used stem design in ball, plug, and butterfly valves. A quarter-turn motion, 90" rotation of the stem opens, closes, or positions the valve closure member, Stem Packing.
The stem packing of a valve performs one or both of the following functions, depending on the application: prevents leakage of flow medium to the environment most common or prevents outside air from entering the valve in vacuum applications less common. The stem packing must have the mechanical characteristic to be compressed and create a sealing contact against the walls of the chamber of the stuffing box. The packing also is partially in contact with the process fluid, so the two must be compatible.
Stern Protector. A stem protector is used when the gate or globe valve is of an outside-screw-and-yoke,rising-stem design. The backseat is the part with a shoulder on the stem and a mating surface on the underside of the bonnet.
This combination forms a seal when the stem is in the fully open position. It prevents leakage of flow medium from the valve shell into the packing chamber and, consequently, to the environment.
In some cases, it provides support for the gland pull-down bolts. The yoke must be mechanically robust enough to withstand forces, moments, and torque developed by an actuator. Yoke Bushings. The yoke bushings are internally threaded nuts held in the top of a yoke through which the valve stem passes.
As long as the correct materials are selected, the bolting method and procedures necessary to create a leak-free joint are in place, and suitably qualified personnel are avail- able, then a leak-free joint can be achieved.
This section deals with mechanical bolted flanged joints. It covers the necessary jointing components, gaskets and bolts, the various mate- rials of construction, and the procedures necessary to complete a leak- free seal between the two compatible flange faces. A flanged connection can be assembled and disassembled more easily than a welded joint, which should be considered an advantage if the mechanical joint is leak free.
A number of international standards cover the individual compo- nents required for a bolted jointing: flanges, gaskets, and bolts that must be used to achieve a satisfactory joint. Several standards have been written to enable designers to design bolted joints that ensure mechanical integrity, and they must be followed to obtain the best results. External environmental conditions. Flange face design. Flange material. Gasket type and materials of construction. Fastener bolt and nut material.
Bolting lubricant. Bolting procedure-torque tensioning and bolt-up sequence. Skilled workforce. Failure to address all of these will likely lead to a leak path that may result in a costly plant shutdown. For standardization and interchangeability, these var- ious options are covered in numerous international standards. ASME has its own group of standards that cover the relevant components used in a mechanical bolt-up.
Flange Standards A variety of standards are used in the design and selection of flanges. The following codes and standards relate to pipe flanges, and these are the ones most commonly used for process piping systems: ASME Codes and Standards B End Connection of flange The end connection of the flange specifies how the flange is attached to a neighboring pipe. There are several alternatives, each with its own technical and commercial merits. This is a list of commonly available flange end types that have been discussed earlier: weld neck, slip on, lap joint, threaded, and socket weld.
The surface finish of the faces is specified in the flange standards quoted previously: Raised Face. The raised face is the most commonly used facing employed for steel flanges. The facing on the RF flange has a concentric or a spiral phonographic groove with a controlled surface finish. Sealing is achieved by compressing a flat, soft, or semi-metallic gasket between mating flanges in contact with the raised face portion of the flange. Ring-Type Joint. This type is typically used for more severe duties than the RF surface, usually ASME classes above ; however, it is valuable in the lower-pressure classes.
The seal is made by plastic deformation of the metallic RTJ gasket into the groove on the flange face, resulting in intimate metal-to-metal contact between the gasket and the flange groove. The faces of the two opposing flange faces do not come into direct contact with each other, because a gap is maintained by the presence of the gasket. Such RTJ flanges normally have raised faces, but flat faces may also be used or specified. These flanges incorporate special metallic ring joint gaskets.
The pitch diameter of the ring is slightly greater than the pitch diameter of the flange groove. A Type 6BX flange joint that does not achieve face-to-face contact will not seal and, therefore, must not be put into service. Flat Face. Flat-face flanges are a variant of raised-face flanges. Sealing is achieved by compression of a flat nonmetallic gasket between the two serrated surfaces of the mating FF flanges.
The gasket covers the entire face of the flange sealing surface. FF flanges are normally used for the least arduous duties, such as low-pressure water piping having class and class flanges and flanged valves and fittings. Less Commonly Used Flange Faces.
Other alternative types of flanges are available; however, due to international standardization in the energy industry, they are very rarely used on projects designed to one of the ASME B31 codes. Maze-and-Female Facings. The outer diameter of the female face acts to locate and retain the gasket.
Custom male- and-female facings are commonly found on the heat exchanger shell to channel and cover flanges. Tongue-and-groovefacings are standardized in both large and small types. They differ from male-and-female facings in that the inside diameters of the tongue-and-groove do not extend into the flange base, thus retaining the gasket on its inner and outer diameter.
These are commonly found on pump covers and valve bonnets. This is a very short identifier that describes the design of the flange and the type of flange facing. Nominal Pipe Size. NPS is a dimensionless designation to define the nominal pipe size of the connecting pipe, fitting, or nozzle. Flange Pressure Class. A material specification for flanges must be specified and be compatible to the piping material specifications.
Pipe Schedule. This is only for WN, composite lap-joint, and swivel-ring flanges, where the flange bore must match that of the pipe, such as schedule 40, 80, , or Gaskets A gasket is a sealing element placed between the two flange faces and held in position by the compressive forces of the set of bolts located around the circumference of flange blades.
Gaskets are constructed from a variety of materials and, in some cases, a combination of mate- rials. The gasket must be capable of maintaining a leak-free seal during the lifetime of the joint at the design pressures and tempera- tures of the fluid being transported.
Casket Standards The following are three of the most commonly used international standards for gaskets specified in process plants designed to ASME B3 1 codes. Types of Caskets Gaskets can be divided into three categories based on their materials of construction: nonmetallic, semi-metallic, and metallic.
Prior to withdrawal from the industry because of health and safety issues, asbestos was commonly used and termed compressed asbestos fiber CAF gaskets. The term has been changed and now is referred to as compressed nonasbestos fiber CNAF gaskets. Nonmetallic gaskets are made from materials such as elastomers nat- ural and synthetic rubbers , Teflon PTFE , and flexible graphite.
Full- face gasket types are held between flat-face flanges. Flat-ring gasket types, which do not cover the full face and are located within the bolt circle of the flange, can be used with raised-faced flanges. Flat metallic gaskets are available in a variety of steels, copper, and other materials; however, they are very rarely used on oil and gas projects.
Semi-Metallic Gaskets Semi-metallic gaskets are a combination of two or more metallic and nonmetallic materials. The metal gives strength and robustness to the gasket, and the nonmetallic portion of a gasket provides sealability to the integrated component.
Spiral wound gaskets are the most com- monly used gaskets for raised-face flanges. They are used in all pres- sure classes from ASME class to class The section of the gasket that creates the seal between the flange faces is the spiral wound section, which houses the soft sealing element.
It is manufac- tured by winding a preformed metal strip and a soft filler material around a metal mandrel. The spiral wound gasket has an outer or cen- tering ring that holds the windings in place and locates the gasket within the bolt circle.
The term cumprofiZe or KummprofiZe gaskets comes from the Dutch word for comb, Kam, which describes the design of the gasket. The gaskets are made from a solid serrated metal core faced on each side with a soft nonmetallic material. Kammprofile gaskets are used on all pres- sure classes from class to class in a wide variety of service fluids and operating temperatures.
Jacketed gaskets are made from a nonmetallic gasket material housed within a metallic jacket. This inexpensive gasket arrangement is used occasionally on standard flange assemblies, valves, and pumps. Jack- eted gaskets are easily fabricated in a variety of sizes and shapes and provide an inexpensive gasket for heat exchangers, shell, channel, and cover flange joints.
Their metal seal makes them unforgiving to irregular flange finishes and cyclic operating conditions. Metallic gaskets are usually constructed from one grade of metal to a predetermined size and shape. The most widely used type of metallic gasket in the process industry is the ring-type joint, which can be used at elevated pressures and temperatures. The API 6A standard covers both flanges and matching gaskets, which can be divided into three distinct groups: Style R, either ring or octagonal.
Style RX, a pressure-energized adaptation of the standard style R ring-joint gasket. Style BX, pressure-energized ring joints designed for use on pressurized systems up to 20, psi MPa. Flange faces using BX-style gaskets come in contact with each other when the gasket is correctly fitted and bolted up.
The BX gasket incor- porates a pressure-balance hole to ensure equalization of pressure, which may be trapped in the grooves. The gasket is the sealing element in the assembly, and its purpose is to deform into the spirally grooved surface of the two flange faces to create a leak-free seal that prevents the fluid from leaking out and the ingress of the outside environment.
The leak performance of the gasket depends on the loads applied on the gasket during the bolt-up procedure. The higher the gasket stress, the higher the leaktightness capability.
This is why it is essential that the correct bolting procedure is followed. Correct flange and gasket selection are meaningless if the bolting procedure is ignored. There have been cases where, in error, a gasket has not been installed between two flanges, but because the bolting procedure was correct, the flanged assembly passed a low-pressure test with no leakage.
Gasket Selection The type of gasket and its materials of construction depend on the flange facing, service, design pressure and temperature, and external environment. Bolts and Nuts To complete any flanged assembly, two additional components are essential: bolts stud or machine and nuts. Bolts and nuts are the fas- teners that provide compressive clamping forces to trap the gasket between the two sealing surfaces on the flange faces.
The term bolting applies to the bolt, nuts, and if required, the washer. The ASME pressure class and the NPS size of flange determine the number of bolts, the outside diameter and length of the bolt, and the geometrical positioning of the bolt circle on the flange.
The number of bolt holes increases by four: 4, 8, 12, 16, 20, 24, and so forth. This bolting pattern has been carefully calculated to create a leak-free joint plus an acceptable safety factor. Bolts A bolt is a steel fastener made from a bar, with an integral head at one end and a shank length that is threaded.
Stud bolts usually are used for flanges in a process plant. These are bars that are partially or totally threaded along the length. Coupled with the stud bolt are two hexagonal nuts, which are tightened to compress the gasket and create a leak-free seal. Bolts can be tightened either manually, using a torque wrench, or, if a more accurate method is required, using a hydraulic stud tension meter that delivers a preselected load.
Nuts Heavy-series hexagonal nuts generally are used with studs on pressure piping. The nonbearing face of a nut has a 30" chamfer, while its bearing face is finished with a washer face. Bolt and Nut Selection Bolts and nuts should be selected to conform to the design specifica- tions set out with the flange design. Care is taken to ensure that the correct grade of material is selected to suit the recommended bolting temperature and stress ranges.
Grade of material, identifying symbol of bolt or nut. Form-bolts or stud bolts; nuts, in regular or heavy series. Dimensions-nominal diameter and length; diameter of plain and reduced portion, length of thread if applicable. Identification of tests in addition to those stated in the standard.
Fully threaded stud bolts and heavy series nuts are most common in industrial applications. Function of Bolts The function of a bolt is to provide a clamp load that compresses the gasket between the two flange faces and creates a leak-free seal. As the load is applied to the bolt, the nut travels down the shank and a com- pressive stop on the back of the flange face stretches the bolt and compresses the gasket to create a seal.
Flange Condition The condition of flange surfaces and selection of the proper flange material play very important parts in achieving a leak-free joint assembly. It is essential that the following flange conditions are within acceptable limits: surface finish, waviness or roughness, flat- ness, surface imperfections, and parallelism.
Gasket Condition The gasket must be new: It should never be reused. It must be clean and clear of all visible surface defects. Imperfections and foreign material may create a radial leak path that will affect the sealing capa- bilities of the gasket.
Bolt Condition Bolts and nuts may be reused: however, it is always best to use new components. Ensure bolts and nuts are clean, free of rust, and the nut runs freely on the bolt threads. Install bolts and nuts well lubricated by using a high-quality antiseize lubricant to the stud threads and the nut face. Methods of Bolt Tightening Once the total bolt loads W are calculated for the flanges, specifica- tions and procedures should be adopted outlining how to achieve the design bolt load.
The total bolt load W for the flange is divided by the number of bolts to determine the individual bolt preload Fp. To achieve improved leak tightness, sufficient and uniform gasket stress must be realized in the field. This obviously requires uniform and cor- rectly applied bolt load. The higher the requirement to reduce leakage, the more controlled must be the method bolt tightening. The common methods of bolt tightening use hammer or impact wrenches, torque wrenches, and hydraulic tensioning systems.
Each method has its merits. Hammer or Impact Wrenches Method This method remains the most common form of bolt tightening. The advantages are speed and ease of use. Disadvantages include a lack of preload control and the inability to generate sufficient preload on large bolts. Torque Method Torque wrenches are often regarded as a means to improve control over boltpreload in comparison with hammer-tightening methods. In most cases, leakage is not due to gasket failure but is more likely to result from poor installation, assembly, or bolting practices; damaged flanges; incorrect or no bolt lubricant; or a combination of variables associ- ated with a bolted gasketed flanged joint.
The following must be considered when installing a gasket: Fasteners nuts and bolts. The correct material for the nut and bolt must be selected-type, proper material, grade, appropriate coating or plating, class, correct stud and bolt length.
A bolt-up procedure must be very carefully followed to achieve a leak-free seal. Install a new gasket on the gasket seating surface and bring the mating flange in contact with the gasket. Do not apply any compounds on the gasket or gasket seating surfaces. Install all bolts, making sure that they are free of any foreign matter and well lubricated.
Lubricate nut bearing surfaces as well lubrication is not required for PTFE coated fasteners. Run-up all nuts finger tight. Develop the required bolt stress or torque incrementally in a minimum of four steps in a crisscross pattern. After following this sequence, a final tightening should be performed bolt to bolt to ensure that all bolts have been evenly stressed. Note: The use of hardened washers enhances the joint assembly by reducing the friction due to possible galling of the nut bearing surfaces.
CHAPTER 3 Metallic Materials for Piping Components Technological advances and the use of computer aided design has had no direct effect on the materials of construction of piping compo- nents for process systems. Carbon steel is the workhorse of industry, and coupled with an adequate corrosion allowance, this material can cover most eventualities.
Low-temperature carbon steel is used for subzero temperatures and low-alloy carbon steel is used at elevated temperatures. After carbon steel, stainless steel is the next most used metal, followed by the duplexes and more exotic metals. Very little has changed over the last 30 years. The purpose of this chapter is not to go into metallurgy in depth but to cover the most relevant points that apply to the base materials of construction of piping components.
The construction material for process piping still is dominated by the use of carbon steel, low-alloy carbon steel, low-temperature carbon steel, and supported by the numerous stainless steels grades.
Used to a lesser degree are the exotic materials, such as alloy and alloy , and nonmetallic materials, like GRP and PVC.
This MSR forms the basis from which the piping material classes are created to cover the numerous fluids at various pressures and temperatures within the process plant.
Piping engineers do not necessarily have to know the fine details of this specialist field; however, they should be aware why the metallurgist came to his or her conclusion.
The material selected must be suitable for the following conditions: Media corrosion, erosion. Design life usually 20 to 25 years. Design temperature range. Design pressure range. External environment aboveground, buried, subsea, etc. Mechanical cycling. Thermal cycling. Mechanical impact. Method of jointing. Availability of material.
Labor available. All materials have different chemical compo- sitions, which have an effect on the mechanical and physical characteristics and their resistance to corrosion at differing tempera- tures and pressures. These factors determine how a particular metal behaves under certain conditions, and they enable the engineer responsible for material selection to specify material with confidence. This knowledge must go right down to the atomic construction of a material.
Metals are rarely, if ever, used in their purest form, but have numerous elements, metallic and nonmetallic, added to create the desired mechanical characteristics and resistance to corrosion see Appendix B, Figure B Some of these are intentional additions and some are unavoidable and have to be controlled.
This action, called alloying, improves and modifies the behavior of the metal. The most commonly used additional element to iron is carbon, which increases ultimate strength and hardness and lowers the ductility. Some alloying elements are listed later in this chapter, indicating what improvements they bring to steel. Carbon steel is the most commonly used of all the construction mate- rials for piping components; and it always contains the elements carbon, manganese, phosphorous, sulfur, and silicon in varying per- centages, depending on the grade.
Small amounts of other elements may be found either entering as gases during the steelmaking process hydrogen, oxygen, nitrogen or introduced intentionally through the ores or metal scrap used to make the steel nickel, copper, molyb- denum, chromium, tin, antimony, etc. The addition of each ele- ment has a specific effect on the properties of the steel. The chemical composition, various grades, and the subsequent dif- fering mechanical and physical properties of a metal are documented in various specifications, such as those from the ASME, APT, and ASTM.
The test methods necessary to record and document these properties are defined in ASTM specification E series.
This information is essential when selecting a material for process piping. The test methods for measuring these properties are covered in ASTM specification E and fall into two categories, strength and ductility. Yield, ksi or MPa. Hardness, Brine11 or Rockwell number. Ultimate Tensile Strength When a load is applied to a test piece, it will stretch as the loss of load-carrying cross section causes a reduction in the cross section until eventually it fractures and fails.
The ultirnute tensile strength UTS is defined as the maximum applied load divided by the original specimen cross-sectional area. In most cases, materials do not suddenly trans- form from an elastic to a plastic state. A gradual transition phase occurs, and this can be represented by a curve, or knee, in the stress- strain curve. There is no accurately defined transition between the elastic and plastic phases: however, a number of ASTM testing methods determine the yield strength of metals.
This yield test is performed at a constant rate of strain and is mea- sured in newtons per square meter in the metric system or pounds per square inch of cross section in U. Modulus of Elasticity Young's Modulus The modulus ofezasticity is defined as the ratio of normal stress to cor- responding strain for tensile or compressive stresses.
Content is organized and presented for quick-reference on- the-job or for systematic study of specific topics. KEY TOPICS: Presents general concepts and principles of plant layout -- from basic terminology and input requirements to deliverables; deals with specific pieces of equipment and their most efficient layout in the overall plant design configuration; addresses the plant layout requirements for the most common process unit equipment; and considers the computerized tools that are now available to help plant layout and piping designers.
Process Plant Layout and Piping Design. Get Books. For mechanical and chemical engineers working for engineering construction as well as process manufacturing companies with responsibility for plant layout, piping, and construction; and for engineering students. Based on the authors' collective 65 years of experience in the engineering construction industry, this profusely illustrated, comprehensive guidebook presents tried-and-true workable methods.
This book fills a training void with complete and practical. Process Plant Layout. Process Plant Layout, Second Edition, explains the methodologies used by professional designers to layout process equipment and pipework, plots, plants, sites, and their corresponding environmental features in a safe, economical way. It is supported with tables of separation distances, rules of thumb, and codes of practice and standards.
Pipe Diameter 2. Pipe Thickness 3. Area 4. Velocity 5. Fanning friction factor 6. Losses 7. Pipe Length 8. Total Head 9. Power Requirement. For turbulent flow, the equation for pipe diameter is given by Plant Design and Economics by Peters and Timmerhaus. To solve for losses for gate valve, and elbow. Kf value for wide open gate valve is 0. Total Losses: 0. From table 2. Use: 1. Open navigation menu. Close suggestions Search Search.
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Explore Audiobooks. Bestsellers Editors' Picks All audiobooks. Explore Magazines. Editors' Picks All magazines. Explore Podcasts All podcasts. Difficulty Beginner Intermediate Advanced. Explore Documents. Piping Design by Karl Joshua Raymundo. Uploaded by Mahathir Che Ap. Document Information click to expand document information Description: -To identify and briefly discuss the parts of a piping system -To determine design consideration of an engineer in a piping system -To enumerate and identify several underlying principles in a piping system through its parts -To design a water piping system.
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SYSTEMS The flow rate of fluids is a critical variable in most chemical engineering applications especially in flows in the process industries Flow is defined as mass flow or volume flow per unit of time at specified temperature and pressure conditions for a given fluid. To slow down or stop the flow of a fluid To reduce or increase the flow rate of a fluid. To control the direction of a flow To regulate process pressure. Two of these equations follow: For smooth pipe or tubes, 0.
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