1、22.1CHAPTER 22PIPE DESIGNFUNDAMENTALS. 22.1Codes and Standards . 22.1Design Considerations. 22.1General Pipe Systems 22.1Design Equations. 22.5Sizing Procedure 22.10Pipe-Supporting Elements . 22.10Pipe Expansion and Flexibility 22.11Pipe Bends and Loops 22.12PIPE AND FITTING MATERIALS 22.14Pipe 22.1
2、4Fittings . 22.18Joining Methods . 22.18Expansion Joints and Expansion Compensating Devices 22.20APPLICATIONS. 22.22Water Piping 22.22Service Water Piping 22.23Steam Piping 22.29Low-Pressure Steam Piping. 22.33Steam Condensate Systems 22.34Gas Piping 22.37Fuel Oil Piping. 22.38HIS CHAPTER discusses
3、pipe systems, materials, design, in-Tstallation, supports, stress calculations, pipe expansion andflexibility, bends and loops, and application of pipe systems com-monly used for heating, air conditioning, refrigeration, and servicewater. When selecting and applying components; applicable localcodes
4、, state or provincial codes, and voluntary industry standards(some of which have been adopted by code jurisdictions) must befollowed. Further details on specific piping systems can be found inapplication-specific chapters of the ASHRAE Handbook.1. FUNDAMENTALS1.1 CODES AND STANDARDSThe following org
5、anizations in the United States issue codes andstandards for piping systems and components:ASME American Society of Mechanical EngineersASTM American Society for Testing and MaterialsNFPA National Fire Protection AssociationICC International Code CouncilMSS Manufacturers Standardization Society of t
6、he Valve and Fittings Industry, Inc.AWWA American Water Works AssociationParallel federal specifications also have been developed by gov-ernment agencies and are used for many public works projects.Chapter IV of ASME Standard B31.9 lists applicable U.S. codes andstandards for HVAC piping. In additio
7、n, it gives requirements forsafe design and construction of piping systems for building heatingand air conditioning. ASME Standard B31.5 gives similar require-ments for refrigerant piping.1.2 DESIGN CONSIDERATIONSPipes are conduits in which fluids compressible (e.g., air, steam)and noncompressible (
8、e.g., water) flow in a system, in response toa pressure differential. Piping system designers should assess thefollowing aspects: Code requirements.Load: the amount of energy or fluid to be moved through the pipeto where it is needed; determination of load is not covered in thischapter (see Chapters
9、 16 to 18 for information on load calcula-tions).Working fluid and fluid properties in the pipe.Pressure and temperature of the fluid.External environment of the pipe: outdoor installations deal withtemperature extremes, environmental contaminants, and ultravio-let radiation. Other environments coul
10、d contain caustic chemicals.Soil can contain elements that can be corrosive to undergroundpipe systems.Installation cost.Pipes resistance to chemical attack from the fluid.When designing a fluid flow system, two related but distinct con-cerns emerge: sizing the pipe and determining the flow/pressure
11、 rela-tionship. The two are often confused because they can use the sameequations and design tools. Nevertheless, they should be determinedseparately.This chapter focuses on sizing the pipe during the design phase,and to this end presents design charts and tables for specific fluids inaddition to th
12、e equations that describe fluid flow in pipes. Once asystem has been sized, it should be analyzed with more detailedmethods of calculation to determine the pump head, if applicable,required to achieve the desired flow. Computerized methods are wellsuited to handling the details of calculating losses
13、 around an exten-sive system.Not discussed in detail in this chapter, but of potentially greatimportance, are physical and chemical considerations such as pipeand fitting design; materials; and joining methods appropriate forworking pressures and temperatures encountered, as well as resis-tance to c
14、hemical attack by the fluid. For more information, see Esh-bach (2009), Heald (2002), and Nayyar (1999).For fluids not included in this chapter or for piping materials ofdifferent dimensions, manufacturers literature frequently suppliespressure drop charts. The Darcy-Weisbach equation, with theMoody
15、 chart or Colebrook equation, can be used as an alternative topressure drop charts or tables.1.3 GENERAL PIPE SYSTEMSMetallic Pipe SystemsEach HVAC system and, under some conditions, portions of asystem require a study of the conditions of operation to determinesuitable materials. For example, becau
16、se the static pressure of waterin a high-rise building is higher in the lower levels than in the upperlevels, a heavier pipe or different materials may be required for dif-ferent vertical zones.Table 1 lists some typical systems and materials used for heatingand air-conditioning metallic piping. The
17、 list is not all inclusive,because piping systems are constantly being developed. The pres-sure and temperature rating of each component selected must beThe preparation of this chapter is assigned to TC 6.1, Hydronic and SteamEquipment and Systems.22.2 2017 ASHRAE HandbookFundamentals Table 1 Common
18、 Applications of Pipe, Fittings, and Valves for Heating and Air ConditioningApplication Size, in. Material Weight Joint Type Fitting MaterialClass (When Applicable)SystemgTemperature, FMaximum Pressure at Temperature,a,bpsiChilled water2 Steel Type F (CW) Schedule 40 Thread Cast iron 125 250 1252.5
19、to 12 Steel A or B, Type E (ERW)Schedule 40 Weld Wrought steel Standard 250 400Flange Wrought steel 150 250 250Cast iron 125 250 175Cast iron 250 250 400Copper, hard or soft Type K or L Solder Wrought or cast Cu 100 370 Type K softFlared (soft) 635 Type K hardRolled groove (2 to 8 in.) 250 Type L so
20、ftPress-connect (0.5 to 4 in.) 435 Type L hardPush connect (0.5 to 2 in.)Mechanical formedBraze Wrought or cast Cu 100 250 Type L softWeld 370 Type K softCopper, hard Type M Solder Wrought or cast Cu 100 395 Type M hardRolled groove (2 to 8 in.)Press-connect (0.5 to 4 in.)Push connect (0.5 to 2 in.)
21、Mechanical formedBraze Wrought or cast Cu 100 230 Type M softWeld0.375 to 1.0 PEX (barrier) SDR-9 Crimp Bronze 73 145Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietary0.5 to 6 PE Schedule 40,f80, SDRThermal fusion, compressionPE 120 (140 limit for some applications)Varies w
22、ith pipe wall thickness, grade, schedule, size. Check man-ufacturers documentation for design ratings 30 to 110 at 130FHeating and recirculating2 and smaller0.25 to 12Steel Type F (CW) Schedule 40 Thread Cast iron 125 250 125Steel B Type E (ERW)Schedule 40 Weld Wrought steel Standard 250 400Flange W
23、rought steel 150 250 250Cast iron 125 250 125Cast iron 250 250 400Copper, hard or soft Type K or L Solder Wrought or cast Cu 200 300 Type K softBraze 635 Type K hardFlared (soft) 205 Type L softRolled groove (2 to 8 in.) 435 Type L hardPress-connect (0.5 to 4 in.)Push connect (0.5 to 2 in.)Mechanica
24、l formedBraze Wrought or cast Cu 200 300 Type K softWeld 205 Type L soft0.25 to 12 Copper, hard Type M Solder Wrought or cast Cu 200 395 Type M hardRolled groove (2 to 8 in.)Press-connect (0.5 to 4 in.)Push connect (0.5 to 2 in.)Mechanical formedBraze Wrought or cast Cu 200 200 Type M softWeld0.375
25、to 1.0 PEX (barrier) SDR-9 Crimp Bronze 200 79Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietarySteam and condensate2 and smallerSteel Type F (CW) or SSchedule 40dThread Cast iron 125 90Thread Malleable iron 150 90Socket Forged steel 3000 90Steel B Type E (ERW) or SSchedule
26、 40dThread Cast iron 125 100Thread Malleable iron 150 125Socket Forged steel 3000 400Steel B Type E (ERW) or SSchedule 80 Thread Cast iron 250 200SocketThread Malleable iron 300 250Socket Forged steel 3000 4002 to 12 Steel B Type E (ERW) or SSchedule 40 Weld Wrought steel Standard 250Flange Wrought
27、steel 150 200Pipe Design 22.3Cast iron 125 100Steel B Type E (ERW) or SSchedule 80 Weld Wrought steel XS 700Flange Wrought steel 300 500Cast iron 250 200Ground-source heat pump0.25 to 2 Copper, hard or softType L or ACR Flared or brazed Wrought or cast Cu 200 205 Type L soft, 435 Type L hard, 240 AC
28、R soft, 500 ACR hard0.375 to 1.0 PEX (barrier) SDR-9 Crimp Bronze 180 100Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietaryRefrigerant Steel B Type E (ERW)Schedule 40 Weld Wrought steel0.375 to 4.125Copper, hard Type L or ACR Braze Wrought or Forged Cu200 435 Type L hard, 2
29、40 ACR softNatural gas and LP0.25 to 12 Copper, hard or soft Type K or L Solder Wrought or cast Cu 100 370 Type K softRolled groove (2 to 8 in.) 635 Type K hardPress-connect (0.5 to 4 in.) 250 Type L softPush connect (0.5 to 2 in.) 435 Type L hardMechanically formedBraze Wrought or cast Cu 100 370 T
30、ype K softWeld 250 Type L soft0.375 to 4.125Copper, hard ACR Solder Wrought or cast Cu 100 500 Type ACR hardBraze Wrought or cast Cu 100 290 Type ACR Soft0.375 to 1.0 PEX SDR-9 Crimp Bronze 73 145Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietary0.5 to 6 PE Schedule 40, 80,
31、 SDRThermal fusion, compressionPE 120 (140 limit for some applications)Depends on pipe, grade, schedule, size. Generally 30 to 110 at 130F 0.5 to 6 HDPE SDR Thermal fusion, compressionHDPE 120 Depends on pipe, grade, schedule, size. Generally 64 for SDR 11 at 120FFuel oil, aboveground2 to 12 Black S
32、teel, B Type E (ERW) or S (seamless)Schedule 40 Thread or weld Black malleable iron 150Wrought steel weldForged steel flanges 1500.25 to 12 Copper, hard or softType K or L Solder Wrought or cast Cu 100 300 Type K softFlared (soft) 635 Type K hardRolled groove (2 to 8 in.) 250 Type L softPress-connec
33、t (0.5 to 4 in.) 435 Type L hardPush connect (0.5 to 2 in.)Mechanical formedBraze or weld Wrought or cast Cu 100 300 Type K soft, 250 Type L softCopper, hard Type M Solder Wrought or cast Cu 100 395 Type M hardBrazeRolled groove (2 to 8 in.)Press-connect (0.5 to 4 in.)Push connect (0.5 to 2 in.)Mech
34、anical formed 0.25 to 12 ABS Schedule 40,f80, SDRSolvent weld, thread, flangeABS 160 limit Depends on pipe class: approxi-mately 50 at 160F0.5 to 6 HDPE SDR-9 Thermal fusion, compressionHDPE 120 Depends on pipe, grade, schedule, size. Generally 64 for SDR 11 at 120F Compressed air2.5 and smallerBlac
35、k steel Schedule 40 Thread Black malleable iron 150 3502.5 Black steel Schedule 40 Flange or weld Black malleable iron 150 3500.375 to 4.125Copper, hard ACR Solder Wrought or cast Cu 200 240 ACR softFlared (soft) 500 ACR hardMechanical formedBraze 200 240 ACR hard0.5 to 4 ABS Schedule 40 Solvent wel
36、d ABS 73 185HDPE Schedule 40, 80, SDRHDPETable 1 Common Applications of Pipe, Fittings, and Valves for Heating and Air Conditioning (Continued)Application Size, in. Material Weight Joint Type Fitting MaterialClass (When Applicable)SystemgTemperature, FMaximum Pressure at Temperature,a,bpsi22.4 2017
37、ASHRAE HandbookFundamentals 0.375 to 1.0 PEX SDR-9Potable water, inside build-ing0.25 to 12 Steel, galvanized Schedule 40 Thread Galv. cast iron 150 100 125Galv. cast iron 150 100 150Copper, hard or softType K or L SoldercWrought or cast Cu 100 370 Type K softFlared (soft) 635 Type K hardRolled groo
38、ve (2 to 8 in.) 250 Type L softPress-connect (0.5 to 4 in.) 435 Type L hardPush connect (0.5 to 2 in.)Mechanical formedBraze Wrought or cast Cu 100 370 Type K softWeld 250 Type L soft0.25 to 12 Copper, hard Type M SoldercWrought or cast Cu 100 395 Type M hardRolled groove (2 to 8 in.)Press-connect (
39、0.5 to 4 in.)Push connect (0.5 to 2 in.) Mechanical formedBraze Wrought or cast Cu 100 230 Type M softWeld0.5 to 8 CPVC Schedule 40,f80 CPVC 210 Limit, 200 operating0.375 to 1.0 PEX SDR-9 Crimp Bronze 100 145Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietary0.5 to 6 PE Sche
40、dule 40,f80, SDRThermal fusion, compressionPE 120 (140 limit for some applications)Depends on pipe, grade, schedule, size generally 30 to 110 at 130F 0.5 to 6 PP Schedule 40,f80, SDRThermal fusion, flange, ThreadePP 180 50Water ser-vices, under-groundThrough 6 Ductile iron Class 50 Mechanical joint
41、Cast iron 75 2500.25 to 12 Copper, hard or softType K or L SoldercWrought or cast Cu 100 370 Type K softFlared (soft) 635 Type K hardRolled groove (2 to 8 in.) 250 Type L softPress-connect (0.5 to 4 in.) 435 Type L hardPush connect (0.5 to 2 in.)Mechanical formedBraze Wrought or cast Cu 100 370 Type
42、 K softWeld 250 Type L softFlange Bronze 1000.25 to 12 Copper, hard Type M SoldercWrought or cast Cu 100 395 Type K hardRolled groove (2 to 8 in.)Press-connect (0.5 to 4 in.)Push connect (0.5 to 2 in.)Mechanical formedBraze Wrought or cast Cu 100 230 Type M softWeld0.375 to 1.0 PEX SDR-9 Crimp Bronz
43、e 73 145Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietary0.25 to 20 PVC Schedule 40, 80, 120, SDRSolvent weld, thread,fthermal weldPVC 150 limit, 140 operating79 to 105, depending on schedule and sizeDrainage, waste, and vent (DWV)1.25 to 8 Copper, hard DWV Solder Wrought
44、or cast Cu 100 250 DWV hard1.25 to 12 ABS Schedule DWV, 40,f80, SDRSolvent weld, thread, flangeABS 160 limit Depends on pipe class: approxi-mately 50 at 160F1.25 to 20 PV Schedule 40,f80, 120, SDRSolvent weld, thread, thermal weldPVC 150 limit, 140 operating79 to 105, depending on schedule and sizea
45、Maximum allowable working pressures have been derated in this table. Higher systempressures can be used for lower temperatures and smaller pipe sizes. Pipe, fittings, joints,and valves must all be considered.bTemperature and pressure relationships can vary based on pipe material composition,size, cl
46、ass, and schedule.cLead- and antimony-based solders are prohibited for potable water systems. Brazingshould be used.dPiping codes typically require thicker-walled pipe for threaded joints to maintaincorrosion allowance and pressure ratings.eAll plumbing codes require both hot and cold water piping t
47、o have a 100 psi at180F rating.fThreads are not recommended on Schedule 40 plastic pipe.gDesigner should confirm that all materials are suitably rated for intended opera-tion.Table 1 Common Applications of Pipe, Fittings, and Valves for Heating and Air Conditioning (Continued)Application Size, in. M
48、aterial Weight Joint Type Fitting MaterialClass (When Applicable)SystemgTemperature, FMaximum Pressure at Temperature,a,bpsiPipe Design 22.5considered; the lowest rating establishes the operating limits of thesystem.Nonmetallic (Plastic) Pipe SystemsNonmetallic pipe is used in HVAC and plumbing. Pla
49、stic islight, generally inexpensive, and corrosion resistant. Plastic alsohas a low “C” factor (i.e., its surface is very smooth), resulting inlower pumping power requirements and smaller pipe sizes. Plasticpipes disadvantages include rapid loss of strength at temperaturesabove ambient and a high coefficient of linear expansion. Themodulus of elasticity of plastics is low, resulting in a short supportspan. Some jurisdictions do not allow certain plastics in buildingsbecause of toxic products emitted during fires. Plenum-rated plas-tic and insulation may be used to a
