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. 22.30Steam Condensate Systems 22.32Gas Piping 22.35Fuel Oil Piping. 22.36HIS 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 pressure, if applica-ble, required to achieve the desired flow. Computerized methods arewell suited to handling the details of calculating
13、losses around anextensive 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
14、to chemical 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 theM
15、oody 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, b
16、ecause 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.
17、 The 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 (SI)Table
18、1 Common Applications of Pipe, Fittings, and Valves for Heating and Air ConditioningApplication Size, mm Material Type Joint Type Fitting MaterialClass (When Applicable)SystemgTemperature, CMaximum Pressure at Temperature,a,bkPaChilled water51 Steel Type F (CW) Schedule 40 Thread Cast iron 125 121 8
19、6262.5 to 305 Steel A or B, Type E (ERW)Schedule 40 Weld Wrought steel Standard 121 2758Flange Wrought steel 150 121 1724Cast iron 125 121 1207Cast iron 250 121 2758Copper, hard or soft Type K or L Solder Wrought or cast Cu 38 2586 Type K softFlared (soft) 4378 Type K hardRolled groove (51 to 203) 1
20、724 Type L softPress-connect (13 to 102) 2999 Type L hardPush connect (13 to 51)Mechanical formedBraze Wrought or cast Cu 38 1724 Type L softWeld 2586 Type K softCopper, hard Type M Solder Wrought or cast Cu 38 2724 Type M hardRolled groove (51 to 203)Press-connect (13 to 102)Push connect (13 to 51)
21、Mechanical formedBraze Wrought or cast Cu 38 1586 Type M softWeld10 to 25 PEX (barrier) SDR-9 Crimp Bronze 23 1000Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietary13 to 152 PE Schedule 40,f80, SDRThermal fusion, compressionPE 49 (60 limit for some applica-tions)Varies with
22、 pipe wall thickness, grade, schedule, size. Check manu-facturers documentation for design ratings 207 to 758 at 54CHeating and recirculating51 and smaller6 to 305Steel Type F (CW) Schedule 40 Thread Cast iron 125 121 862Steel B Type E (ERW)Schedule 40 Weld Wrought steel Standard 121 2758Flange Wrou
23、ght steel 150 121 1724Cast iron 125 121 862Cast iron 250 121 2758Copper, hard or soft Type K or L Solder Wrought or cast Cu 93 2069 Type K softBraze 4378 Type K hardFlared (soft) 1413 Type L softRolled groove (51 to 203) 2999 Type L hardPress-connect (13 to 102)Push connect (13 to 51)Mechanical form
24、edBraze Wrought or cast Cu 93 2069 Type K softWeld 1413 Type L soft6 to 305 Copper, hard Type M Solder Wrought or cast Cu 93 2724 Type M hardRolled groove (51 to 203)Press-connect (13 to 102)Push connect (13 to 51)Mechanical formedBraze Wrought or cast Cu 93 1379 Type M softWeld10 to 25 PEX (barrier
25、) SDR-9 Crimp Bronze 93 545Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietarySteam and condensate51 and smallerSteel Type F (CW) or SSchedule 40dThread Cast iron 125 621Thread Malleable iron 150 621Socket Forged steel 3000 621Steel B Type E (ERW) or SSchedule 40dThread Cast
26、 iron 125 690Thread Malleable iron 150 862Socket Forged steel 3000 2758Steel B Type E (ERW) or SSchedule 80 Thread Cast iron 250 1379SocketThread Malleable iron 300 1724Socket Forged steel 3000 275851 to 305 Steel B Type E (ERW) or SSchedule 40 Weld Wrought steel Standard 1724Flange Wrought steel 15
27、0 1379Pipe Design 22.3Cast iron 125 690Steel B Type E (ERW) or SSchedule 80 Weld Wrought steel XS 4826Flange Wrought steel 300 3448Cast iron 250 1379Ground-source heat pump6 to 51 Copper, hard or softType L or ACR Flared or brazed Wrought or cast Cu 93 1413 Type L soft, 2999 Type L hard, 4655 ACR so
28、ft, 3448 ACR hard10 to 25 PEX (barrier) SDR-9 Crimp Bronze 82 690Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietaryRefrigerant Steel B Type E (ERW)Schedule 40 Weld Wrought steel10 to 105 Copper, hard Type L or ACR Braze Wrought or Forged Cu93 2999 Type L hard, 4655 ACR soft
29、Natural gas and LP6 to 305 Copper, hard or soft Type K or L Solder Wrought or cast Cu 38 2551 Type K softRolled groove (51 to 203) 4378 Type K hardPress-connect (13 to 102) 1724 Type L softPush connect (13 to 51) 2999 Type L hardMechanically formedBraze Wrought or cast Cu 38 2551 Type K softWeld 172
30、4 Type L soft10 to 105 Copper, hard ACR Solder Wrought or cast Cu 38 3448 Type ACR hardBraze Wrought or cast Cu 38 2000 Type ACR Soft10 to 25 PEX SDR-9 Crimp Bronze 23 1000Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietary13 to 152 PE Schedule 40, 80, SDRThermal fusion, com
31、pressionPE 49 (60limit for some applica-tions)Depends on pipe, grade, schedule, size. Generally 207 to 758 at 54C13 to 152 HDPE SDR Thermal fusion, compressionHDPE 49 Depends on pipe, grade, schedule, size. Generally 441 for SDR 11 at 49CFuel oil, aboveground51 to 305 Black Steel, B Type E (ERW) or
32、S (seamless)Schedule 40 Thread or weld Black malleable iron 150Wrought steel weldForged steel flanges 1506 to 305 Copper, hard or softType K or L Solder Wrought or cast Cu 38 2069 Type K softFlared (soft) 4378 Type K hardRolled groove (51 to 203) 1724 Type L softPress-connect (13 to 102) 2999 Type L
33、 hardPush connect (13 to 51)Mechanical formedBraze or weld Wrought or cast Cu 38 2069 Type K soft, 1724 Type L softCopper, hard Type M Solder Wrought or cast Cu 38 2724 Type M hardBrazeRolled groove (51 to 203)Press-connect (13 to 102)Push connect (13 to 51)Mechanical formed 6 to 305 ABS Schedule 40
34、,f80, SDRSolvent weld, thread, flangeABS 71 limit Depends on pipe class: approxi-mately 345 at 71C13 to 152 HDPE SDR-9 Thermal fusion, compressionHDPE 49 Depends on pipe, grade, schedule, size. Generally 441 for SDR 11 at 49CCompressed air62.5 and smallerBlack steel Schedule 40 Thread Black malleabl
35、e iron 150 17762.5 Black steel Schedule 40 Flange or weld Black malleable iron 150 17710 to 105 Copper, hard ACR Solder Wrought or cast Cu 93 4655 ACR softFlared (soft) 3448 ACR hardMechanical formedBraze 93 4655 ACR hard13 to 102 ABS Schedule 40 Solvent weld ABS 23 1276HDPE Schedule 40, 80, SDRHDPE
36、Table 1 Common Applications of Pipe, Fittings, and Valves for Heating and Air Conditioning (Continued)Application Size, mm Material Type Joint Type Fitting MaterialClass (When Applicable)SystemgTemperature, CMaximum Pressure at Temperature,a,bkPa22.4 2017 ASHRAE HandbookFundamentals (SI)10 to 25 PEX
37、 SDR-9Potable water, inside build-ing6 to 305 Steel, galvanized Schedule 40 Thread Galv. cast iron 150 38 862Galv. cast iron 150 38 1034Copper, hard or softType K or L SoldercWrought or cast Cu 38 2551 Type K softFlared (soft) 4378 Type K hardRolled groove (51 to 203) 1724 Type L softPress-connect (
38、13 to 102) 2999 Type L hardPush connect (13 to 51)Mechanical formedBraze Wrought or cast Cu 38 2551 Type K softWeld 1724 Type L soft6 to 305 Copper, hard Type M SoldercWrought or cast Cu 38 2724 Type M hardRolled groove (51 to 203)Press-connect (13 to 102)Push connect (13 to 51) Mechanical formedBra
39、ze Wrought or cast Cu 38 1586 Type M softWeld13 to 203 CPVC Schedule 40,f80 CPVC 99 Limit, 93 operating10 to 25 PEX SDR-9 Crimp Bronze 38 1000Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietary13 to 152 PE Schedule 40,f80, SDRThermal fusion, compressionPE 49 (60 limit for so
40、me applica-tions)Depends on pipe, grade, schedule, size generally 207 to 758 at 54C13 to 152 PP Schedule 40,f80, SDRThermal fusion, flange, ThreadePP 82 345Water ser-vices, under-groundThrough 152Ductile iron Class 50 Mechanical joint Cast iron 24 17246 to 305 Copper, hard or softType K or L Solderc
41、Wrought or cast Cu 38 2551 Type K softFlared (soft) 4378 Type K hardRolled groove (51 to 203) 1724 Type L softPress-connect (13 to 102) 2999 Type L hardPush connect (13 to 51)Mechanical formedBraze Wrought or cast Cu 38 2551 Type K softWeld 1724 Type L softFlange Bronze 386 to 305 Copper, hard Type
42、M SoldercWrought or cast Cu 38 2724 Type K hardRolled groove (51 to 203)Press-connect (13 to 102)Push connect (13 to 51)Mechanical formedBraze Wrought or cast Cu 38 1586 Type M softWeld10 to 25 PEX SDR-9 Crimp Bronze 23 1000Clamp BrassExpansion CopperCompression Engineered plasticPush fitProprietary
43、6 to 508 PVC Schedule 40, 80, 120, SDRSolvent weld, thread,fthermal weldPVC 66 limit, 60 operating545 to 724, depending on schedule and sizeDrainage, waste, and vent (DWV)32 to 203 Copper, hard DWV Solder Wrought or cast Cu 38 1724 DWV hard32 to 305 ABS Schedule DWV, 40,f80, SDRSolvent weld, thread,
44、 flangeABS 71 limit Depends on pipe class: approxi-mately 345 at 71C32 to 508 PV Schedule 40,f80, 120, SDRSolvent weld, thread, thermal weldPVC 66 limit, 60 operating545 to 724, depending on schedule and sizeaMaximum allowable working pressures have been derated in this table. Higher systempressures
45、 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, class, and schedule.cLead- and antimony-based solders are prohibited for potable water system
46、s. 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 to have a 689 kPa at82C rating.fThreads are not recommended on Schedule 40 plastic pipe.gDes
47、igner 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, mm Material Type Joint Type Fitting MaterialClass (When Applicable)SystemgTemperature, CMaximum P
48、ressure at Temperature,a,bkPaPipe Design 22.5considered; the lowest rating establishes the operating limits of thesystem.Nonmetallic (Plastic) Pipe SystemsNonmetallic pipe is used in HVAC and plumbing. Plastic is light,generally inexpensive, and corrosion resistant. Plastic also has a low“C” factor
49、(i.e., its surface is very smooth), resulting in lower pump-ing power requirements and smaller pipe sizes. Plastic pipes disad-vantages include rapid loss of strength at temperatures aboveambient and a high coefficient of linear expansion. The modulus ofelasticity of plastics is low, resulting in a short support span. Somejurisdictions do not allow certain plastics in buildings because oftoxic products emitted during fires. Plenum-rated plastic and insu-lation may be used to achieve a plenum rating; check with theauthority having jurisdiction (AHJ).Table 2 lists non
