GEORG FISHER +GF+ PP-H产品手册(英)

Beta (b) Polypropylene . . . the better PPBeta (b) Polypropylene Piping Systems• Pipe, Valves, Fittings and Flow Control• Sizes 16 mm (3/8") through 315 mm (12")• IR™/Butt and Socket Fusion JoiningTable of ContentsBeta (b)Polypropylene Piping Systems Introduction...............................................................................................................................................................................................5.4 Polypropylene Applications..............................................................................................................................................................5.10 Polypropylene Working Temperatures and Pressure for Pipe and Fittings........................................................................5.12 Flow Rate versus Friction Loss – PP pipe........................................................................................................................................5.13 Friction Loss through PP Fittings........................................................................................................................................................5.15 SDR11 Polypropylene vs. Schedule Pipe Dimensions...............................................................................................................5.15 Determining the Length Changes in PP Pipelines.......................................................................................................................5.16 The Incorporation of Expansion Joints...........................................................................................................................................5.22 The Installation of Pipework under Plaster or Embedded in Concrete...............................................................................5.22 Pipe Bracket Support Centers and Fixation of Plastic pipelines............................................................................................5.23Beta (b) Polypropylene Butt and IR™ (Infrared) Fusion Joining Technology Polypropylene Piping Specification for the Institutional, Pharmaceutical and Food Industries...................................5.25 Butt and IR Fusion Pipe and Fittings Dimensions.........................................................................................................................5.28 Butt and IR Polypropylene Valves....................................................................................................................................................5.43 Butt and IR Joining Machines...........................................................................................................................................................5.45Beta (b) Polypropylene Socket Fusion Joining TechnologyPolypropylene Piping Specification for the Chemical and Plating Industries...................................................................5.47 Socket Pipe and Fittings Dimensions..............................................................................................................................................5.50 Socket Valves.........................................................................................................................................................................................5.61 Socket Fusion Joining Machines......................................................................................................................................................5.63Good TemperatureResistanceThe George Fischer polypropylenepiping system is pressure rated to 150psi (10 bar) at 70°F (21°C) with a longterm safety factor of 2.1. The upper longterm temperature limit for polypropyleneis 176°F (80°C) and the temperature limitfor short term use is 212°F (100°C).However, as with all thermoplasticpiping systems, an increase in tempera-ture is combined with a decrease inoperating pressure.Chemical ResistanceThe chemical resistance properties ofpolypropylene are excellent. It is resistantto aqueous solutions of acids, alkalisand salts and to a large number oforganic solvents. This wide range ofchemical resistance allows this materialto be used for many piping systems thathandle different chemicals includingcaustics, acids and solvents. Polypro-pylene is not suitable for handlingconcentrated oxidizing acids andhalogens.IntroductionPolypropylene is one of the mostcommon, fastest growing and versatilethermoplastics currently used. Eachyear many tons of this material areconverted into diverse products rangingfrom plastic bags through automobileparts to tanks and chemical pipingsystems.From a chemical standpoint, polypro-pylene is closely related to polyethyl-ene. As members of the group ofmaterials known as “polyolefins”, bothof these plastics are composed of onlycarbon and hydrogen. This contrastswith other commonly used plasticmaterial such as PVC and PTFE whichcontain chlorine and flurorine respec-tively.Physical PropertiesThe physical properties of polypropy-lene combine strength, low weight,abrasion resistance, impact strengthand a wide operating temperaturerange, making it a very suitable mate-rial for use in load bearing products.Combined with excellent all roundchemical resistance and low waterabsorption, these properties combine toprovide a material that meets all of therequirements for use in a piping system.PurityGeorge Fischer polypropylene complieswith guidelines listed in the FederalRegister, CFR Title 21, chapter 1, §177.1520 a (1) for polypropylene and c(1.1) for compounds. George Fischerpolypropylene is suitable for transportof potable water, foodstuffs, and highpurity deionized water.Beta (b) Polypropylene Piping for Industrial ApplicationsDaplen Beta (b )-PP ... the Greater Safety and EconomyDaplen Beta (β)-PP is a polypropylene homopolymer with an exceptionally homogeneous, fine structure and significantly higher impact strength.The high degree of crystallinity of these substances ensures an excellent resistance to chemicals. This is further improved by the titanium dioxide pigment used.The long-term creep strength was assured by endurance tests inaccordance with ISO TR 9080 and certified with the value MRS 10(minimum required strength).Conventional PP homopolymer surface magnified 200 timesDaplen Beta (b )-PP surface magnified 200 timesImpact Bending Test to DIN 8078Hammer 50 J instead of 15 J Pipe 110 mm x 10 mBehavior of Daplen Beta (b )-PPRegression curves to ISO TR 9080LTHS LCLTest interruptedMeasurements andcalculations (SEM) from TGM plastics technologyDaplen Beta (b PPPP-H conven-tionalIn contrast with conventional PP homopolymers, Beta (b )-PP possesses a superior impact strength – both at room temperature and also at low temperatures.C o m p a r a t i v e s t r e s s (N /m m 2)We offer a complete range of plasticpiping components, including pipes,fittings (socket and butt-fusion fittings),manually operated valves andactuated valves in one material.In addition to the outstandingcharacteristics of polypropylene homo-polymer, this also provides unlimitedcompatibility for the mutual weldabilityof various PP types for users and finalconsumers.Beta (β)-PP combines all the requiredfavorable properties for modernindustrial pipeline construction,including:• Excellent resistance to chemicals• High impact strength• High thermal resistance• High stress crack resistance• Excellent fusion capability• Homogeneous, fine structureThe pipes comply in all features withDIN 8077/8078 type 1.The many years of process know-howacquired by the two companiesGeorge Fischer Piping Systems andDEKA Pipe Systems provides the idealproduct package from an outstandingraw material for processors and plantoperators.Extruded pipes and precisionmolded fittingsAn innovative extrusion process ensuresoptimum conversion of the rawmaterial potential to a high-grade pipeproduct with minimum internal stresses.The special method of processingachieves extremely smooth internalsurfaces in the pipes, which are in noway inferior in topography to injectionmoldings.Your benefit in applicationComprehensive tests bear witness tothe special barrier effect of ahomogeneous and fine-crystalline pipewall construction with regard tointeraction with a wide range ofmedia. The significantly improvedinternal surface further substantiallyincreases the resistance of the pipes tochemicals. The resulting optimized flowbehavior reduces the danger oferosion and deposition.All in one material -Daplen® Beta (b)-PPOptimum processing for thebetter materialLow internal stressMicrotome section magnified40 timesRa measuring curve for the pipeinternal surface measured by anon-contact laser process in theextrusion directionPipes after a test series withchromic acid magnified 600times under the scanningelectron microscope.Conventional PP-HDEKAPROP Beta (b)-PPComplete System of Pipe,Valves and FittingsThe George Fischer polypropylenepiping system is available in sizes from3/8" to 12". The system includes valvesthrough 12."This system includes all commonlyrequired pressure pipe fittings, includingthreaded adaptors and flanges forease of mating to equipment or otherpiping materials. Ball valves areavailable in sizes 3/8" to 6", dia-phragm valves from 1/2" to 6" andbutterfly valves in sizes 2 1/2" to 12".Other valves including check valvesand metering valves are also availablein this system.Fusion Joining ReliablityAssembly and joining of this system isperformed by heat fusion. Fusion jointsare made by heating and melting thepipe and fitting together. This type ofjoint gives a homogeneous transitionbetween the two components withoutthe lowering of chemical resistanceassociated with solvent cement joiningand without the loss of integrity andloss of pressure handling ability of athreaded joint.Three different fusion methods forpolypropylene are available andcommonly used in today's demandingapplications. These include socketfusion, regular butt fusion, and Infrared(IR) fusion.Socket Fusion Joining can be used tojoin socket fusion fittings available insizes 16-110mm (3/8"-4"). The socketfusion method of joining uses a heatednon-stick “female” bushing to melt theoutside of the pipe end and a heatednon-stick “male” bushing to heat theinside of the corresponding size offitting. After several seconds, when theoutside of the pipe and the inside ofthe fitting are melted, the bushings areremoved and the pipe is pushed intothe fitting. Due to the large area ofpipe to fitting contact (3-5 times thecross sectional area of the pipe), theresulting joint is actually several timesstronger than the pipe itself. The pipeand fittings for this system are alsomanufactured to have an interferencefit; because of this interference it is notpossible to slide a fitting over the pipewithout the use of heat to melt thesurface to be joined. This featureprevents the possibility of inadvertentlyleaving a joint unfused, and moreimportantly causes displacement ofsome material during fusion therebyguaranteeing a high strength, reliable,reproducible joint.Acid neutralization facilityuses George Fischerpolypropylene piping andvalves in overheadinstallation.For a complete guide toproper installation techniques,the George Fischer factorysponsored installer certifica-tion program is recommended.It teaches a basic understand-ing of plastics and fusiontechnology. For moreinformation, contact yourGeorge Fischer representative.smaller and lower stresses due to very uniform heating. This method is available for pipe sizes 1/2" (20mm) through 9"(225mm).IR Plus™ Advantages:• Non-contact heating• Smaller internal and external beads repeatability • Low stress joint• Ease of operation due to fully automated fusion machinery• Automatic fusion joining record (if desired) using optional printerPiping System DesignAs with all piping systems, proper selection and design is necessary to ensure that a successful installation can be made. Before using this polypro-pylene piping system, the user should ensure that the polypropylene issuitable for contact with the liquids to be handled. This information may be readily found in a chemical resistance chart. If polypropylene is chemically compatible and the operating tem-perature and pressure are within the previously discussed limits, then the system may be used. However it should be designed to include allowances for expansion andcontraction, pressure drops and proper pipe support.Length changes in plastic pipelines are commonly caused by thermal expansion due to changes in ambienttemperature and changes in the tem-perature of the media being handled.The length change for polypropylene will be 0.0000837 inches per inch of length per degree Fahrenheit tempera-ture change. So if the temperature of a 100 foot straight length of pipe is raised from 30°F (-1°C) to 80°F (27°C)it would grow by 5 inches. The pipe-line must be installed in such a way that this expansion can be accounted for. Common practice is to use either expansion loops or change of direction to achieve this. In both of these cases,a length of pipe running perpendicular to the change in length is used to absorb the expansion by being bent.IR Plus ™ Infrared Butt Fusion Joining is an ideal method to join IR fusion fittings in the size range of 20-225mm (1/2"-9") to achieve the maximum joint consistancy. Regular butt fusion can also be used to join IR and butt fusion fittings in the size range of 20mm and up.Butt fusion pipe and fittings both have the same inside and outside diameters.To make a butt fusion joint, the pipe and fitting are clamped so that the ends to be joined are facing each other. The ends are then "faced" flat and parallel. A flat heating plate is used to simultaneously heat both faces to be joined. When each end is molten the heating plate is removed and the pipe and fitting are brought together. Joining is achieved by fusion between the molten materials.George Fischer is constantly searching for and developing new joining proce-dures to improve mechanical strengths,ensure repeatability, and simplifyoperation. A recent development is the George FischerIR Plus™ (Infrared) Fusion System Using the new, fully automated, digital indicating fusion machinery, highstrength butt fusion joints can be made with many advantages over the con-ventional, pressure type butt fusion methods. A non-contact, IR heating plate is used, along with apredetermined overlap to join the pipe (or fitting) ends together to eliminate operator error and provide a reliable,reproducible, high strength joint withFor a complete guide toproper installation techniques,the George Fischer factory sponsored installer certifica-tion program is recom-mended. It teaches a basic understanding of plastics and fusion technology. For more information, contact your George Fischer representative.George Fischer polypropylene is used at a caustic handling facility.Polypropylene ApplicationsWasteOver a period of many years, polypro-pylene has become a preferredmaterial for handling many differenttypes of liquid waste. This material’swide range of chemical resistancemakes it very suitable for handling thewide range of different chemicals andmixtures that are found in differentwaste streams. The unsuitability ofpolypropylene for use with concen-trated oxidizing acids is generally nota problem because these acids willusually be diluted before they aredisposed of. The high resistance ofpolypropylene to solvents is particu-larly important, because many solventsdo not mix in water and often end upfloating in a concentrated form nearthe top of the pipe. Thus, eventhough a waste stream may containonly 1% of a solvent, it is often notpossible to regard this dilution be-cause most of the solvent will oftenfloat to the top of the pipe. Thematerial’s high temperature capabilitiesare also important in enabling it tohandle any exothermic reactions thatmay occur when different chemicalsmix.Pressure drop calculations are used toensure correct pipe and pump sizing.By summation of pressure drop figuresthrough each length of pipe, fittingand valve, a total value for the systemcan be found.This value can be used to help inpump selections. If the value is toohigh for the available pumps, then useof larger diameter pipe, fittings andvalves should be recommended todecrease the allowed pressure dropfor the chosen flow rate.Correct support is also necessary toprevent sagging and damage to thepipe. The distance between the pipebrackets depends upon the pipediameter and the specific gravity of themedia as well as the maximumworking and ambient temperatures. Ifthe media to be handled is hot, then itis often advantageous to providecontinuous horizontal support by layingthe pipe within V or U shapedchannels, made of metal or a heatresistant plastic. Pipe clamps shouldpreferably be made of plastic, andshould allow longitudinal movement ofthe pipe. Pipe clamps that clamptightly onto the outside of the pipe donot allow proper expansion and maycause damage to the pipe.Butt fusion fittings areavailable in sizes 1/2”through 12”.Deionized WaterLarge volumes of distilled or deionized water are used by a wide range of different industries. This water is often used for diluting chemicals, washing and rinsing. Polypropylene is commonly used as a piping material for conveying this water. Although it does not have the ultra-purity of PVDF, polypropylene piping systems are able to maintain the purity required in all but the most demanding installations. Fusion joining gives fast reliable joining without the use of hazardous and noxious solvents that may contaminate the water. The total quantity of added lubricants and organic materials in polypropylene is far less than found in many other plastic piping materials. The use of a pig-mented material is recommended to reduce degradation of the pipe material from ultraviolet light. The pigmented pipe wall will prevent the transmission of ambient light into the pipe material. This prevents possible degradation of the pipe wall and corresponding particulation of plastic into the water stream.Caustic SolutionsThe chemical resistance of polypro-pylene to caustic solutions such as potassium hydroxide and sodium hydroxide is very good. The fusion joining method gives strong joints that are resistant to attack by these strongly caustic solutions. This contrasts to solvent cemented joints which may be attacked by some caustic solutions. For these reasons polypropylene is often used to trans-port caustic soda used for neutralizing acidic waste streams.General Chemical HandlingThe wide range of chemical resistance of polypropylene makes it suitable for use in applications where a piping system may be required to carry different chemicals or mixtures of chemicals. In this case polypropylene is often found to be one of the most suitable materials for handling combi-nations of many chemicals.Polypropylene Working Temperatures and Pressures for Pipe and FittingsBased on 25-year service life. Design factor C=2.0Flow V ∆H ∆P V ∆H ∆P V ∆H ∆P V ∆H ∆P V ∆H ∆P Flow Rate Rate (GPM) 16 mm 20 mm 25 mm 32 mm 40 mm (GPM)1 1.72 3.23 1.40 1.00 .88.38.63.29.12.35.09.0412 3.4311.64 5.04 2.01 3.16 1.37 1.27 1.03.45.70.32.142 58.5863.5427.51 5.02 17.257.47 3.17 5.63 2.44 1.93 1.72.75 1.22.57.255 712.01118.4951.307.03 32.1613.92 4.4410.50 4.55 2.63 3.21 1.39 1.67 1.07.467 1017.16229.3899.3010.04 62.2626.95 6.3420.338.80 3.86 6.22 2.69 2.44 2.07.9010 1515.06131.9357.119.5043.0818.65 5.7913.18 5.71 3.67 4.38 1.9015 2012.6773.4031.777.7222.469.72 4.897.47 3.2320 259.8233.9614.70 6.2211.29 4.8925 3011.7547.5920.607.4415.83 6.8530 358.6721.069.1235 409.8926.9711.6840 4511.1133.5414.5245Flow V ∆H ∆P V ∆H ∆P V ∆H ∆P V ∆H ∆P V ∆H ∆P Flow Rate Rate (GPM)50 mm 63 mm 75 mm 90 mm 110 mm (GPM) 1122 5.78.19.08.49.06.03.35.03.0157 1.06.36.16.67.12.05.47.05.02710 1.56.69.30.99.23.10.69.10.04.48.04.02.32.02.011015 2.34 1.47.64 1.48.49.21 1.04.20.09.72.08.03.48.03.011520 3.12 2.51 1.09 1.97.82.35 1.39.35.15.96.14.06.64.05.022025 3.97 3.79 1.64 2.51 1.23.53 1.77.53.23 1.22.21.09.82.08.032530 4.75 5.31 2.30 3.00 1.73.75 2.11.74.32 1.46.30.13.98.11.053035 5.537.07 3.06 3.50 2.30 1.00 2.46.98.42 1.70.40.17 1.14.15.063540 6.319.05 3.92 3.99 2.94 1.27 2.81 1.26.55 1.94.51.22 1.30.19.0840 457.0911.26 4.87 4.48 3.66 1.58 3.15 1.57.68 2.18.64.28 1.46.24.1045 507.8713.69 5.93 4.98 4.45 1.93 3.50 1.90.82 2.42.78.34 1.62.29.1350 609.5019.188.30 6.01 6.24 2.70 4.23 2.67 1.16 2.93 1.09.47 1.96.41.1860 7011.0625.5211.05 6.998.30 3.59 4.92 3.55 1.54 3.41 1.45.63 2.28.54.2370 807.9810.62 4.60 5.61 4.64 2.01 3.89 1.85.80 2.60.70.3080 908.9713.21 5.72 6.31 5.65 2.45 4.37 2.30 1.00 2.92.87.3890 10010.0016.06 6.957.03 6.87 2.97 4.87 2.80 1.21 3.26 1.05.45100 1258.7710.39 4.50 6.07 4.23 1.83 4.06 1.59.69125 15010.5414.56 6.307.29 5.93 2.57 4.88 2.23.97150 1758.517.89 3.42 5.69 2.97 1.29175 2009.7410.11 4.38 6.51 3.80 1.65200 25012.1615.28 6.618.13 5.74 2.48250 3009.758.05 3.48300 35011.3910.71 4.64350Hazen and Williams EquationV=Fluid velocity, ft/sec∆H=Head loss, ft H2O per 100 ft pipe∆P=Head loss, psi per 100 ft pipeC=150ID=Inner Diameter of pipe in inchesFlow Rate versus Friction Loss - Polypropylene Pipex)V=4 Q (.1337)60π D 212(∆P=∆GPM1.852ID4.8655()1.852∆H=.2083100C()Flow Rate versus Friction Loss – Polypropylene PipeFlow V∆H∆P V∆H∆P V∆H∆P Flow Rate Rate (GPM)160 mm200 mm225 mm(GPM) 25 .39 .01 .01 .25 .00 .00 .19 .00 .00 25 50 .77 .05 .02 .49 .02 .01 .39 .01 .00 50 100 1.54 .17 .07 .98 .06 .03 .78 .03 .01 100 150 2.31 .36 .16 1.48 .12 .05 1.17 .07 .03 150 200 3.08 .62 .27 1.97 .21 .09 1.56 .12 .05 200 260 4.01 1.00 .44 2.56 .34 .15 2.02 .19 .08 260 300 4.62 1.31 .57 2.95 .44 .19 2.34 .25 .11 300 360 5.55 1.84 .79 3.55 .62 .27 2.80 .35 .15 360 400 6.16 2.23 .97 3.94 .75 .33 3.11 .42 .18 400 450 6.93 2.77 1.20 4.43 .93 .40 3.50 .53 .23 450 500 7.70 3.71 1.46 4.92 1.14 .49 3.89 .64 .28 500 550 8.47 4.02 1.74 5.42 1.35 .59 4.28 .77 .33 550 600 9.24 4.73 2.05 5.91 1.59 .69 4.67 .90 .39 600 70010.78 6.29 2.72 6.89 2.12 .92 5.45 1.20 .52 700 80012.328.05 3.49 7.88 2.71 1.17 6.23 1.53 .66 800 900 8.86 3.37 1.46 7.01 1.90 .82 900 1000 9.85 4.10 1.77 7.79 2.31 1.001000 120011.82 5.74 2.49 9.34 3.24 1.401200 140010.90 4.32 1.871400160012.46 5.53 2.391600 250 mm280 mm315 mm100 .63.02.008.5.011.005.4.006.003100 150 .95 .041.018 .75.024.01.6.013.006150 200 1.26 .07.03 1.01.041.018.79.023.01200 300 1.89.149.065 1.51.086.037 1.19.048.021300 400 2.52.254.11 2.01.146.063 1.59.082.036400 500 3.15.384.166 2.51.221.096 1.99.125.054500 600 3.79.539.233 3.02.31.134 2.38.175.076600 700 4.42.717.31 3.52.412.178 2.78.233.101700 800 5.05.918.397 4.02.528.229 3.18.298.129800 900 5.68 1.141.494 4.52.657.284 3.57.37.16900 1000 6.31 1.387.601 5.03.798.345 3.97.45.1951000 1200 7.57 1.944.842 6.03 1.119.484 4.77.631.2731200 1400 8.83 2.587 1.12 7.04 1.488.644 5.56.839.3631400 160010.09 3.313 1.434 8.04 1.906.825 6.361.075.4651600 180011.36 4.12 1.784 9.05 2.371.0267.151.337.5791800 200012.62 5.008 2.16810.05 2.8811.2477.941.625.7032000 240015.147.019 3.03912.06 4.0381.7489.532.278.9862400 280017.679.339 4.04314.07 5.3722.32611.12 3.031.3122800 320020.1911.959 5.17716.08 6.8792.97812.71 3.88 1.683200Friction Loss through Polypropylene FittingsIn equivalent length of pipe, feetPipe outside3/8"1/2"3/4"1"11/4"11/2"2"21/2"3"4"6"8"9" diameter16mm20mm25mm32mm40mm50mm63mm75mm90mm110mm160mm200mm225mm 90° elbow0.9 1.52 2.7 3.5 4.2 5.57811162022.5 45° elbow0.50.81 1.3 1.7 2.1 2.7 3.54 5.581011.2 Tee with0.6 1.0 1.4 1.7 2.3 2.7 4.3 5.1 6.38.31316.518.6 flow through runTee with flow 1.8 4.0 5.1 6.0 6.98.112.014.316.322.1324045 through branchReducer bushing – 1.0 1.1 1.2 1.4 1.7 2.6 3.6 4.4 5.271011.2 (one reduction)Male/Female0.5 1.0 1.3 1.6 2.2 2.6 3.5––––––AdaptorSDR 11 Polypropylene vs Schedule Pipe DimensionsSDR 11 PP O.D.I.D.cross section area area ratioOD ID area SDR 11Sch 40Sch 80SDR 11Sch 40Sch 80SDR 11Sch 40Sch 80SDR 11 vs.closest mm mm cm2inch inch inch inch inch inch inch2inch2inch2Sch 40Sch 80inch size 16 12.4 1.208 .630 .675 .675 .488 .493 .423 .187 .191 .141 .979 1.3263/820 16.2 2.061 .787 .840 .840 .638 .622 .546 .320 .304 .234 1.053 1.3681/225 20.4 3.269 .984 1.050 1.050 .803 .824 .742 .506 .533 .432 .949 1.1713/432 26.0 5.309 1.260 1.315 1.315 1.024 1.049 .957 .824 .864 .719 .954 1.146140 32.6 8.347 1.575 1.660 1.660 1.283 1.380 1.278 1.293 1.496 1.283 .864 1.008 1 1/450 40.813.074 1.969 1.900 1.900 1.606 1.610 1.500 2.026 2.036 1.767 .995 1.147 1 1/263 51.420.750 2.480 2.375 2.375 2.024 2.067 1.939 3.217 3.356 2.953 .959 1.089275 61.2 29.417 2.953 2.875 2.875 2.409 2.469 2.323 4.558 4.788 4.238 .952 1.076 2 1/290 73.6 42.545 3.543 3.500 3.500 2.898 3.068 2.900 6.596 7.393 6.605 .892 .9993110 90.0 63.617 4.331 4.500 4.500 3.543 4.026 3.826 9.85912.73111.497 .774 .8574 125102.282.034 4.921** 4.024**12.718** *** 140114.4102.79 5.512 5.563 5.563 4.504 5.047 4.81315.93320.00518.193 .796 .8765 160130.8134.37 6.300 6.625 6.625 5.150 6.065 5.76120.83128.89026.066 .721 .7996 200163.6210.217.8748.6258.625 6.4417.9817.62532.58350.02745.663 .651 .7148 225184.0265.908.858** 7.244**41.214****9250 **204.4328.139.84310.75010.7508.04710.0209.56450.85878.85471.840.645.70810*No U.S. equivalent size** For Reference onlymin. distance = ∆ I max. +5 mm .20 in.Allowing for length changes in PP pipelinesGeneralVariations in temperature cause greater length changes in thermoplastic materials than in metals. In the case of above-ground, wall or duct mounted pipework,particularly where subjected to varying working temperatures, it is necessary to make suitable provision for length changes in order to prevent additional stresses.Length changes can be taken up by the following means:a. Flexible sections b. Expansion jointsThe flexible section is used most frequently,as it is the simplest and most economical method. The calculation and positioning of flexible sections are, therefore, de-scribed in detail.Coefficient of linear expansion δ of various materialsx10 - 6 St Cu GFK AI PVC PP PEFundamentalsIt is possible to take advantage of the very low modulus of elasticity of PP by includ-ing special sections of pipe which com-pensate thermal length changes. The length of the flexible section mainly de-pends upon the pipe diameter and the extent of the length change to be com-pensated. In order to simplify planning and installation, the third influencing fac-tor—the pipe wall temperature —is not taken into account, particularly as instal-lation usually takes place in the tempera-ture range between 5° and 25°C (41° and 77°F).Where the pipework changes direction or branches off there is always a natural flex-ible section. Movement of the flexible sec-tion a caused by the length change ∆ l must not be impeded in the area con-cerned by too tightly mounted pipe brack-ets, jutting brickwork, girders or similar.St Cu AI GFK PVC PP PECalculation and Positioning of Flexible SectionsModulus of elasticity of various materials E x103kp/cm 2min. distance = ∆ I max. +5 mm .20 in.。