It is very important for a piping engineer to study ASME Remember that this code covers a wide spectrum of piping engineering-design, stress, materials, construction.
If you are a specialist piping engineer, then there are sectors of this code you will rarely, if ever, use. Even so, it is important to know what the information is and who will use it. It is not essential to memorize the text and data, but it is very important to know what information is held within the pages of code and be able to access it and interpret it accurately.
Committee Personnel. Summary of Changes. Chapter I, Scope and Definitions. Chapter 11, Design. Part 1, Conditions and Criteria. Part 2, Pressure Design of Piping Components. Part 6, Systems. Chapter , Materials. Chapter V, Fabrication, Assembly, and Erection. Part 1,Conditions and Criteria. Part 5, Flexibility and Support. Part 7, Materials. Part 8, Standards for Piping Components. Part 9, Fabrication, Assembly, and Erection. Part 10, Inspection, Examination, and Testing. Part 7, Metallic Materials.
Parts 11 through 20 correspond to Chapter VII. Part 11, Conditions and Criteria. Part 15, Flexibility and Support of Nonmetallic Piping. Part 16, Nonmetallic and Nonmetallic Lined Systems.
Part 17, Nonmetallic Materials. Piping components are defined as pipe, pipe fittings, valves, gaskets, and bolts. These international standards and specifications cover 0 Materials-chemical composition, mechanical strength, and testing.
Dimensions and tolerances. Testing of piping systems and valves. The purpose for the publication of these standards and specifications is to standardize the dimensions, tolerances, and the materials of con- struction of piping components to make the fabrication and erection less complex. Procedures and inspection standards and specifications ensure that the quality of the material and the completion of a piping system are to a level acceptable to the relevant code.
These docu- ments are essential, and without them, the industry would be anarchic. Next, we discuss the scopes of most commonly used ASME standards that include mechanical and dimensional data, which allows the standardization of piping systems and is beneficial for both design and construction personnel. The B1. The inclusion of dimen- sional data in this standard is not intended to imply that all the products described are stock production sizes.
Consumers must con- sult with manufacturers concerning availability of products. Metric, general purpose, semitubular rivets purchased for government use conform to this standard and, additionally, to the requirements of Appendix I. 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 mate- rials. Also included in this standard are requirements and recommen- dations regarding flange bolting, flange gaskets, and flange joints.
It covers fittings of any produc- ible wall thickness. This standard does not cover low-pressure, corro- sion-resistant, butt-welding fittings.
Its purpose is to assure installation interchangeability for valves of a given material, type, size, rating class, and end connection. These gaskets are dimensionally suitable for use with the flanges described in the reference flange standards ASME B This standard covers spiral-wound metal gaskets and metal-jacketed gaskets for use with raised face and flat face flanges. These gaskets are dimen- sionally suitable for use with flanges described in the referenced flange standards.
Wafer or flangeless valves, bolted or through-bolt types, which are installed between flanges or against a flange, are treated as flanged-end valves. Coverage is lim- ited to the following: 1 welding neck flanges classes , , , , , and and 2 slip-on and threaded class Flanges may be of cast, forged, or plate for blind flanges only mate- rials, as listed in Table 1A. Requirements and recommendations regarding bolting and gaskets are included. The dimensions are suitable for blanks made of materials listed in Table 1.
The word pipe is used as distinguished from tube to apply to tubular products of dimensions commonly used for pipeline and piping systems. In contrast, the outside diameters of tubes are numerically identical to the size number for all sizes.
The word pipe is used as distin- guished from tube to apply to tubular products of dimensions com- monly used for pipeline and piping systems.
Pipe dimensions of sizes 12 and smaller have outside diameters numerically larger than the corresponding size. The suffix S in the schedule number is used to differentiate B Standards Std. Publications Publ. The standards published by the ASTM include test procedures for determining or verifying character- istics, such as chemical composition, and measuring performance, such as tensile strength and bending properties.
The standards cover refined materials, such as steel, and basic products, such as machinery and fabricated equipment. The standards are developed by commit- tees drawn from a broad spectrum of professional, industrial, and commercial interests. Many of the standards are made mandatory by reference in applicable piping codes. The ASTM standards are pub- lished in a set of 67 volumes divided into 16 sections. Each volume is published annually to incorporate new standards and revisions to existing standards and to delete obsolete standards.
Volume Section 2, Nonferrous Metal Products. Section 4, Construction. Section 6, Paints, Related Coatings, and Aromatics. Section 7, Textiles. Section 8, Plastics. Section 9, Rubber. Section 10, Electrical Insulation and Electronics.
Section 11, Water and Environmental Technology. Responses; Waste Management; Biological Effects. Section 12, Nuclear, Solar, and Geothermal Energy. Section 14, General Methods and Instrumentation. Section 00, Index. Referenced documents. Ordering information. Chemical composition. Mechanical requirements-tensile strength, yield strength, elongation. Heat treatment.
Workmanship, finish, and appearance. Additional supplementary requirements. These standards guarantee that, if the base material used is manufac- tured to a set of well defined rules, then the various characteristics of that material will be predictable and the materials of construction can be specified with confidence. Supplementary Requirements Sl Product analysis.
S2 Transverse tension test. S3 Flattening test. S5 Carbon equivalent. S6 Heat treated test specimens. S 7 Internal cleanliness-government orders. S8 Requirements for carbon steel pipe for hydrofluoric acid alkylation service. Q, , E-Standard. The specifi- cations for filler metals are in the AWS A5 series.
The filler metal spec- ifications usually are cited in design documents. The welding procedures are in the D10 series. The AWS handbook is published in five volumes and intended to be an aid to the user and producer of welded products.
Volume 2, Welding Processes. Volume 3, Welding Processes. Volume 4, Engineering Applications-Materials. AWS A3. AWS A5. AWS D AWS D1O. Conformance to AWWA standards is required either by being referenced in the codes governing the con- struction of water systems piping or by the enforcement authorities having jurisdiction over the water systems piping.
C, Rubber-Seated Butterfly Valves. C, Fiberglass Pressure Pipe. The relevant CGA publication is G The CSA works in Canada and around the world to develop standards that address real needs, such as enhancing public safety and health. The relevant CSA publication is EJMA was founded in to establish and maintain quality design and manufacturing standards.
Compliance to the standard practices of MSS is required by reference in a code, specifica- tion, sales contract, law, or regulation. Its members work in corporations, educational institu- tions, research facilities, and federal governments. The requirements contained in these volumes have been judged suitable for legal adoption and enforcement.
Volumes 9 through 11 contain recommended practices and guides considered to be good engineering practices. Volume 12 contains formal interpreta- tions, tentative interim amendments, and errata that relate to the documents in Volumes 1 through The PFI standards contain minimum requirements; however, the designer or fabricator may consider specifying addi- tional requirements beyond the scope of PFI publications. The use of PFI standards or bulletins is voluntary.
ES-3, Fabricating Tolerances. ES-5, Cleaning of Fabricated Piping. ES, Tool Calibration. ES, Painting of Fabricated Piping. The society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others.
Its stan- dards also are used outside these industries. This chapter deals with the numerous types of piping components that make up a process piping system. The selection of the design and the materials of construction is extremely important and should be based on the past performance of the piping component in similar or more extreme design conditions. Rarely will a piping engineer or designer be faced with selection decisions that have not occurred on a previous project somewhere in the world.
It is essential that the indi- vidual is fully aware of the limitations of the component and all of the design conditions. The chapter is divided into the following sections: 2. Introduction to Piping Components 2. Pipe 2. Piping Fittings 2. Flanges 2. Valves 2. This chapter introduces the reader to these components and explains their design function and how they are specified, manufactured, and installed.
All components have their own characteristics, both posi- tive and negative, and it is essential to be aware of their strengths and weaknesses. Specifymg them can become complex, especially for valves and piping special items. The individual components necessary to complete a piping system are Pipe.
Piping fittings. Bolts and gaskets fasteners and sealing. Piping special items, such as steam traps, pipe supports, and valve interlocking. These pressure-containing and non-pressure-containing components combine to form the ingredients of a piping system.
I introduce each category and outline the general international stan- dards and specifications that apply to that particular group of compo- nents.
Although individual components have different commercial values and availability, all are of equal importance in a piping system that is to function safely and efficiently see Figure 2 1.
For example, you could have a very expensive valve held in position by two, comparatively less expensive flanges, two gaskets, and a set of bolting worth a fraction of the cost but no less important. The specifi- cation and the correct installation procedure of mating flanges, gas- kets, and bolts are essential for the valve to be installed and function efficiently within a piping system.
I start with the least complex component within a process piping system. Although it can be consid- ered to be the least complex component within a piping system, it is not without its peculiarities.
Pipe used within a process plant designed to one of the ASME B31 codes generally is of a metallic construction, such as carbon steel, stainless steel, duplex, copper, or to a lesser degree, one of the more exotic metals like Monel or titanium. Nonmetallic pipe such as one of the plastics, like PVC, glass- reinforced epoxy, or glass-reinforced plastic, are not prohibited, and each has its own set of characteristics.
Glass-reinforced plastic GRP , is a plastic reinforced by fine fibers of glass. The plastic most com- monly used is polyester or vinylester, but other plastics, such as epoxy, can be used to make glass-reinforced epoxy GRE.
Circular in shape, pipe is identified in the various industry codes, standards, and specifications as a nominal pipe size NPS , in U. Carbon steel pipe in schedules, Sch 20, 30, 40, 60, 80, , Stainless steel pipe in schedules, Sch 5. Calculated wall thickness in U.
Steel pipe is generally made by one of the following methods: seam- less, longitudinally welded, or spirally welded. The first two are the most commonly used with seamless pipe available up to 24"; and lon- gitudinally welded pipe generally is specified for sizes above 16", but it can be manufactured in smaller sizes. Seamless pipe is formed by passing a solid billet with a mandrel through a metal bar that is at an elevated temperature.
The bar is held between sizing rollers that dictate the outside diameter O. Seam- less pipe has a quality factor E of 1. Longitudinally welded pipe is created by feeding hot steel plate through shapers that roll the plate into a hollow circular section. The two edges of the pipe are squeezed together and welded. Longitudinally welded pipe has a quality factor E of 0. Initially, longitudinal pipe has a lower integrity than seamless pipe; however, if the longitudinal weld is radiographically x-rayed success- fully, then it is considered equal to seamless pipe with a quality factor E of 0.
Class Appendix A Description No. Seamless pipe 1. Electric resistance welded pipe 0. Electric fusion welded pipe, 0. Furnace butt welded 0. A53 Types Seamless pipe 1. Type E Electric resistance welded pipe 0. Type F Furnace butt welded pipe 0. Forgings and fittings 1. Seamless tube 1. Seamless and welded fittings 1. Electric fusion welded pipe, 1. Electric fusion welded pipe, as 0. A 12, 22, 32, Electric fusion welded pipe, 1. Electric fusion welded tube, 0. Class Description No: for Type Seamless fittings 1.
Welded fitting, double butt 0. Welded fitting, single butt 0. Steel castings 0. Electric fusion welded, double 0. Electric fusion welded, single 0. Welded fittings, double butt 0. Seamless water tube 1. Seamless pipe and tube 1. B OO 16 B Welded pipe 0. Nickel alloy forgings 1. B All Welded pipe 0. Electric fusion welded pipe Ck80 B Electric fusion welded pipe 0. Class AppendixA Description No.
Welded fittings, single butt 0. Welded pipe, double butt 0. Welded pipe, single butt seam 0. Printed with the permission of the ASME. Spiral welding is the least common method of manufacturing pipe. It is formed by twisting strips of metal into a spiral pattern. This type of pipe is the cheapest, and it generally is used only for piping systems in nontoxic service, such as cooling water at atmospheric or very low pressures and for very large sizes.
Spirally welded pipe has a quality factor E of 1. The quality factor E is used in the formula in ASME B31 codes to cal- culate the wall thickness of pressure containing pipe. So that a higher E factor in the calculation results in a thinner and therefore lighter pipe. D is the outside diameter of pipe as listed in tables of standards or specifications or as measured. S is the stress value for material from Table A E is the quality factor from Table A-1B.
P is the internal design gauge pressure. Y is the coefficient from Table The value of Y may be interpolated for intermediate temperatures. This increases the amount of material required for the pipe and increases its weight. Radiography comes at a price, but it raises the quality factor E to 1. The general option is to radiograph the longitudinal pipe. All three methods have advantages and disadvantages, both commer- cially and technically. Longitudinal pipe can be manufactured to closer tolerances than seamless pipe, but it requires additional radiog- raphy to bring it up to the same quality factor as seamless pipe.
Taken from API 5L, Specification for Line Pipe, nominal lengths of 20 ft 6 m formerly were designated single random lengths and those of 40 ft 12 m double random lengths. If long runs are anticipated, as on a pipe rack, DRL is preferred, because it will result in fewer field welds.
If this is not an issue, the shorter SRL are an option. The size identified the approximate inside diameter of the pipe in inches. For example IPS 6 pipe has an inside diameter of approximately 6 inches. As the oil and gas industry developed and more sophisticated new materials were developed and became available, such as carbon steel in its various guises, low and intermediate alloys, and corrosion- resistant alloys CRA like stainless steel, the original dimensional system required updating to accommodate the improved characteris- tics that these new materials brought.
Corrosion-resistant alloys meant that corrosion allowances could be reduced and, in many cases, dispensed with, resulting in a reduction of the wall thicknesses and less weight. These thinner walls required a new method to identify the size and the wall thickness of this expanded range of pipes.
Essentially, nominal pipe size is a dimensionless designator of pipe size. It identifies a pipe size without an inch symbol. For example, NPS 2 indicates a pipe whose outside diameter is 2. The NPS 12 and smaller pipes have outside diameters greater than the size designator 2, 4, 6, 8, 10, However, the outside diameter of NPS 14 and larger pipes is the same as the size designator in inches. For example, NPS 14 pipe has an outside diameter equal to 14 in.
The inside diameter depends on the pipe-wall thickness specified by the schedule number. Dium2tre nominu2 is the dimensionless designator of pipe size in the metric unit system, developed by the International Standards Organization ISO. Table is a cross reference between NPS U. DimensionalSpecifications Pipes used within a plant designed to one of the various ASME B31 codes generally are manufactured to a set of requirements specified in one of two American Society for Mechanical Engineers standards, depending on the materials of construction: B Standard B The word pipe, as distinguished from tube, is used to apply to tubular products of dimensions commonly used for pipeline and piping systems.
The word pipe, as distinguished from tube, is used to apply to tubular prod- ucts of dimensions commonly used for pipeline and piping systems. The size of pipes, fittings, flanges and valves are given in either millimeters as DN metric units or inches as NPS U.
Information to be Supplied by the Purchaser. Process of Manufacture and Material. Material Requirements. Couplings PSL 1 Only. Inspection and Testing. Coating and Protection. Pipe Loading. Both versions of carbon steel combine strength and a basic level of resistance to corrosive services. In slightly more corrosive ser- vice, an additional calculated allowance can be added to the wall thickness of the pipe, called a corrosion allowance CA.
The Corrosion Allowance Increments Process piping also can be supplied in a variety of corrosion-resistant alloys, such as stainless steel or nickel alloy and various other mate- rials with specialized chemical compositions.
These lesser-used nickel alloys are called exotic materials because of their rarity; they are used for very special services that have particularly corrosive characteristics at both ambient and elevated temperatures. Material not on this list, known as unlisted material, can be used, but there is a require- ment to authenticate the material data sheet. Pipe can be manufactured using various processes; however, the most commonly specified that satisfy the requirements of ASME B The method of manufacturing depends on size, process require- ments, and economics.
Threaded end TE , usually pipe 2" and below. Butt weld BW or weld end WE , all sizes. Dimensional Standards for Pipe Ends Plain end pipe is simply a cut 90" perpendicular to the outside diam- eter of the pipe that passes through the centerline of the pipe to the opposite side. It is also called a square cut, because of the 90" angle. Plain end pipe can be reprepared, also called reprepped for short, to form either threaded or butt-weld ends.
There is no standard for plain end pipe, because of its simple geom- etry: however, threaded end and butt-weld ends are more complex and the geometry, dimensions, and tolerances of these two examples are covered in the following ASME standards. Threaded Ends A threaded end joint also has a specific geometry, depending on the wall thickness of the pipe; and this is specified in ASME B1. To connect to lengths of straight pipe, a coupling with matching threads is required.
This American National Standard covers dimensions and gauging of pipe threads for general purpose applications. The general pur- pose types are available to satisfy particular requirements, and manu- facturers should be consulted for special requirements. The inclusion of dimensional data in this standard is not intended to imply that all of the products described are stock production sizes. The standard covers the following areas: 1.
Gauging of Taper Pipe Threads. Gauging of Straight Pipe Threads. Correspondence with the B16 Committee. Transition Contours. Welding Bevel Design. Preparation of Inside Diameter of Welding End. Mandatory Appendices. Nonmandatory Appendix. This covers straight pipe; however, to facilitate the mechanical jointing, the changes of direction, changes in O.
Pipe fitting components are used for one or more functions: Change of direction" and 45" elbows. Change of direction-equal tee. Printed with the permission of ASME.
Reduction in pipe size-eccentric and concentric reducers, swages. Reinforced branch fitting-Weldolet, Sockolet, Threadolet. Mechanical joints-flanges. Pipe fittings used for projects designed to ASME B31 code are made to standard dimensions, based on their size and wall thickness.
These fixed dimensions are essential to allow a piping designer to lay out or route the piping system efficiently. All these piping components can be joined together by several welding and mechanical methods: butt-weld, socket weld or threaded ends, flanges bolts and gaskets , or proprietary mechanical joints Victaullic, hub ends.
At the beginning of the welding process the two butt-weld ends are place together with a root gap. This gap is occupied with the first pass or filler material. Nondestructive examination NDE can be carried out to guarantee that this weld is sound and defect free. Butt-weld fittings include elbows, tees full and reducing , and eccen- tric and concentric reducers covered in ASME B It covers fittings of any producible wall thickness.
The standard covers the following subjects: 1. Pressure Ratings. Fitting Dimensions. Surface Contours. End Preparation. Design Proof Test. Production Tests. To give added confidence, this fillet weld can be subjected to NDE to raise the level of confidence in the weld.
Threaded connec- tions are limited to low pressures and should not be used at elevated temperatures, where bending moments are expected, or cyclic condi- tions, because the geometry of the threaded connection might become distorted.
Socket-weld and threaded fittings include elbows, tees full and reducing , eccentric and concentric reducers, couplings, and the like that are covered in ASME B The B This document covers the following subjects: Committee Roster. It is a mechanical joint that, if assembled correctly, using the correct components and the right bolting procedure, results in a leak- free connection that can be dismantled and reassembled, if necessary.
A flange is an integral fitting with two distinct areas; The flange blade with the bolt holes and the sealing face. The flange hub with the pipe connection ends. The flange blade is the circular area through which there is a standard bolting pattern, based on the O. It has a seal face accurately machined to a predeter- mined finish, on which the gasket sits and a flange back on which the nut sits. The hub is located on the back of the blade and it receives the pipe.
Socket weld flanges-attached by one socket weld, medium integrity. Threaded flanges-attached by one threaded end, low integrity. Slip-on flanges-attached by one or sometimes two fillet welds, medium integrity. Lap joint n stub end flanges-attached by one butt-weld on the stub end, high integrity. Blind flanges-attached by a mechanical bolt up to any mating flange. Weld Neck Flanges Weld neck WN flanges are available at all sizes and ratings, and they offer the best alternative for combined high integrity, medium instal- lation cost, and standardization.
They come in a variety of flange fac- ings, including the three most commonly available: raised face RF , with low-, medium-, and high-pressure classes; flat face FF , with a low-pressure class; and ring-type joint RTJ , with low-, medium-, high-, and very high-pressure classes. The weld neck flange is an integral one-piece component, with two distinct parts: the hub and the blade.
The blade has a drilling pattern that allows it to be mated against other compatible flanges. The weld neck design and the high- integrity butt-weld make this the most robust option for a flange that will be subjected to elevated temperatures and pressures.
The butt-weld can be examined using magnetic particle inspection MPI , dye penetrant inspection DPI , radiography, or ultrasonic inspection. The flat-face or "full-face" flange has a gasket surface in the same plane as the bolting circle face. Applications using flat-face or full-face flanges frequently are those in which the mating flange or flanged fitting is made from a casting and the flush mating means no possibility for the flange blade to bow and crack or deform.
Raised and flat flange facings are machined, and they may be either phonographic spiral serrated or concentric serrated. Phonographic means that the finishing groove spirals in toward the center of the flange blade and a concentric grooving means a series of unconnected concentric grooves on the face of the flange. The industry norm is a phonographic serrated finish. The facing finish is measured by visual comparison with roughness average Ra standards.
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. Ayush, Can you please send the article related to dynamic analysis on Singh. Sir please send me piping handbook with isometric drawings or refer someone piping book…manickammechndt12 Gmail.
Your email address will not be published. Save my name and email in this browser for the next time I comment. Thermal relief valves are also known as thermal safety valves, temperature relief valves, or thermal expansion relief valves.
It is a safety device employed in liquid piping and pipeline systems to Air Relief Valves works as a safety device by releasing the air pockets that may be generated at each high point of a fully Skip to content. Join us on Telegram. Sir, please send some piping related material use for interview…. Sir can you please suggest a book to understand dynamic analysis. I need it urgently. Respected Sir, Pl. Dear Sir,Please send me the Mechanical piping engineer or Project engineer notes on my mail id.
Regards Hussain.
0コメント