Answer Happy

kindly answer task 1 and 2 on pumps and network analysis problem, attached below is the PVC broucher tables needed
1 years An engineering company has been appointed to review the design of the water supply infrastructure for Taung in the North West Province. The review is based on data given in Table 1 and relevant values from The Neighbourhood Planning and Design Guide (Redbook). A brochure from the pipe supplier is also provided. Table 1: Design data for a Taung S/No. Design data Value Units Population growth rate 2.4 % 2 Design Horizon 15 3 Abattoir 120 Cattle 200 Sheep 4 Hospital 250 beds Day school 600 Students 6 Boarding School 450 students 7 Church 550 m2 Filling station 400 Standpipes 1050 9 Yard connections with full flush sanitation 2460 population Low-income housing connection 4000 Residential house connection 1200 10 Lodge 70 Single rooms Double rooms 11 Fruit processing industry 0.6 ML/day 12 Design Loss Factor (LF) 10 % 13 Summer Peak Factor (SPF): 1.4 5 8 m2 90 Figure 1 depicts the Water supply scheme from the treatment plant to the distribution system. Water is pumped from temporary storage contact tank) to the distribution reservoir and flows by gravity to consumers. The various consumer groups have been allocated to nodes (not required for this task).
1161 m asl 1155 m asl Reservoir A at 1120 m asl B 1093 m asl F Pump 1090 m asl Contact tank Figure 1: Schematic Layout of the Taung Water Supply System
Task 1 (a) Determine AADD, GAADD & SDD for Taung (use Table 1 and consumption figures from the Redbook) (b) Use GAADD to determine the pump head required if both the suction and delivery pipes have a diameter of 160 mm (uPVC pipes - see brochure for details). Select appropriate classes for both the pumping main and the gravity main. C) Use this calculated pump head to select the most suitable impeller size (a system characteristic curve is required). Determine the power at the duty point. (d) Check for cavitation. The pump characteristic curves for various impeller sizes as well as efficiency curves are given in Figure 2. E30% 50%-6 HE 60% 60 1702 LLLLLL 3% 75% H 50 (m) 70% 40 60% 200mm 90mm 30 1 Somm 20 0 0,01 0,02 0,03 0,04 0,05 Q (m/s) . . . Figure 2 Pump characteristic and efficiency curves Components of the water supply system Delivery line: 4 bends, 3 valves Suction line: 1 bend, 1 valve Water temperature = 20°C Pipe between the contact tank and pump: 15 m Pipe between the pump and the reservoir: 870 m (diameter 160 mm) Pipe between the reservoir the supply area: 200 m (diameter 160 mm) Elevations of the various points are indicated on the layout. Information not provided should be reasonably assumed and justified. Assume atmospheric pressure = 101.1 kPa; vapour pressure at 20°C. NPSHR= 4.2 m. Task 2 Use SDD to determine the pressure head at the inlet node (A). Investigations revealed that fire fighting requirements are well catered for within the summer daily demand. . .
Physical Properties Major properties of PVC pressure and sewer and drain pipes are given in Table 2 Please note that as with all thermoplastics, properties are dependent on the operating temperature and the duration of the stress application. For example, working pressures of pipes used at higher temperatures should be lowered (or a higher class to be used) in order to maintain the long-term design life of the pipe Product Range PRODUCT PVC-U Pressure Pipes PVC-U Pressure Pipes PVC-U Pressure and Pressure Sewer PVC-M Mining Pressure Pipes High Impact Borehole Casings and Screens RANGE (ia) SPECIFICATION 20-500 mm SANS 966-1 50-500 mm SANS 966-2 20 - 500 mm ISO 1452-2 110 - 200 mm SANS 1283 50 - 315 mm DIN 4925 6 ASTM F480-88 UNITS kg/m2 % PVC-U 6x 10 14 x 10- 45 70-80 > 80 10x 10 014 PVC-M 6 x 10 1.4 x 10 45 70-80 > 80 10 x 10 0.14 *C 1/Kg/K W/m/K Product Properties PHYSICAL Co-Efficient of Linear Expansion Density Flammability (oxygen index] Shore Hardness (O) Softening Point [Vicat- minimum) Specific Heat Thermal Conductivity (O'C-50°C] MECHANICAL Elastic Modulus [long term: 50 years) Elastic Modulus (short term:100 seconds) Elongation at break (Minimum) Poisons Ratio Tensile Strength (50 year-extrapolated) Tensile Strength (short-term / Minimum] FRICTION FACTORS Manning Hazen Williams Ni kuradse Roughness (6) MPa MPa 1500 3300 45 04 26 45 1400 3000 45 04 26 45 MPa MPa 0.008-0009 0.008-0.009 150 150 003 0.03 mm
PIPES DIOS 2 th 20 ט ט lo 1 SANS 966 Part 1 PVC-U Pipes From the stress-time line (also known as the creep rupture regression line) the minimum required strength (MRS) at 50 years is determined and the design stress (s) is then obtained by applying a safety factor (C). The safety factor (or overall service design coefficient) Pipe Standards takes into account the properties of the material and the service conditions and Designation Standard MRS (MPa) Design Stress Safety Factor any unknown loading or environmental PVC-U (20mm-90mm SANS 966-1 25 10.0 2.5 conditions PVC-U [100mm-90mm) SANS 966-1 25 12.5 OS = MRS с Features and Benefits As can be determined from the stress line the MRS for PVC-U and for modified, high Manufactured from environment friendly virgin PVC & Lead free Impact PVC-M mine pipes is 25 MPa It is material does not affect water quality for human health. Important to note that since the design Excellent flow chorocteristics: reduces friction losses stress is the constant stress that the p pe wall can resist for at least 50 years, the - Best long-term strength/cost ratio of all pipe materials, serves in safety factor applies at 50 years. excess of 50 years. So cost effective with very low lifetime ownership cost ochieved The safety factors used in the design of PVC-U and PVC-M Pipes have been • Unique combination of mechanical properties: long-term strength. accepted by the water and mining toughness and stiffness, making it ideal for pressure, sewer and Industries after many years of excellent drainage pipes performance • Large bore and high flow capacity: lowers pumping costs and overall energy requirements • Durability and toughness: resistant to handling. transport and installation damage Resistant to abrasion and scouring and modern cleaning methods. Light mass: lower transport costs and easy handling and installation ideally suited for labour intensive projects - Elastomeric locked-in sealing ring system: resistant to most chemicals, long-term sealing performance and easy low cost Installation with unskilled labour • Inflammable. Does not support combustion FLOTEK BOW CLASS 16 PC-
Pipe Dimensions All pipes are made to provide an effective length of 6.0 meters from 20 mm - 250 mm and 58 meters from 315 mm - 500 mm after Installation, the outside diameters are the same for all pressure classes of the same size and there are 6 classes of pipes. The minimum wall thickness and mass per meter are given in the table below. SANS 966-1 PVC-U PRESSURE PIPE MINIMUM WALL THICKNESS AND MASS PER METER OF RUBBER RING SOCKET PIPE FOR EACH SIZE S CLASS EFFECTIVE CLASS 6 CLASS 9 CLASS 12 CLASS 16 ks NOMINAL SIZE CLASS 4 LENGTH CLASS 20 ITTI ITI KG NG kg 50 0.16 0.25 6.0 60 OUTSIDE DIAMETER Min Max 20 20 2 25 25.2 32 32.2 40 40.2 SO 50.2 53 63.2 75 75.2 90 90.3 18 23 即叫即时乃四 20 25 32 40 SO 63 75 90 四四四四四四 60 6.0 6.0 60 60 on GOWE 18 22 27 32 39 15 19 24 30 3.7 4.7 56 6.7 033 051 080 113 155 Kg 013 021 034 053 084 134 191 275 1.8 19 22 27 1.9 23 29 3.7 45 5.a 6.9 82 026 041 0.65 104 149 213 0.42 057 0.79 116 ON . MT 0.40 0.64 1.02 152 2.30 3.30 28 36 43 52 15 1.8 054 0.78 110 125 140 160 200 110 125 140 160 200 250 315 355 400 450 SOD 1103 125.3 1404 160.4 200,5 250.6 315.5 355.7 400.7 450.8 500.9 NOTE: ABOVE WALL THICKNESS BASED ON OS OF 10 Mpo(SAFETY FACTOR 25) 50 22 117 26 137 39 204 51 253 6.7 6.0 2.5 1.51 3.0 1 BD 261 5.8 340 76 6.0 28 1.89 3.3 2 22 49 3.26 55 427 85 6.0 3.2 248 38 293 56 4.27 74 S.57 9.7 60 39 378 47 454 70 568 92 8.68 121 6.0 49 5.99 59 718 10.45 115 13.67 151 5.8 6.2 9.59 74 1141 110 15.76 145 21.83 190 5.B 70 12.25 84 1465 124 21 37 163 27.78 24 5.8 78 15.45 94 18.55 140 2730 184 35 47 241 5.8 8.9 19.83 106 23.53 15.7 34 45 20.7 14.89 5.8 9.8 24.27 118 29.10 174 4242 229 5519 NNNNNN rum MONO 342 439 5.50 7.20 1124 1767 28.18 35.92 45.75 82 9.3 10.4 119 149 18.6 411 5.30 6.64 8.70 13.63 2145 250 87 315 355 400 450 500 GO NOTE: ABOVE WALL THICKNESS BASED ON OS OF 125 Mpo. [SAFETY FACTOR 2)
2 SANS 966 Part 2 PVC-M Pipes PVC-M has been used successfully in Southern Africa, Australia and New Zealand for over 15 years and is proven as one of the most cost effective and energy efficient piping materials. The reason for this is the lower long-term safety factor which may be used with tough materials. Toughness can be defined as resistance to impact and resistance to cracks, Le toughness prevents cracks from starting initiation) and also prevents the propagation of cracks through the pipe wall. Cracks or notches may be initiated during handling or installation or during service due to bending stresses and point loads on the pipe. Brittle failure does not occur with tough materials having predictable failure properties: therefore the material's toughness bears a direct relationship with the long-term safety factor It is now accepted by pipe standards authorities and by the water industry that the 50 year safety factor depends as much on strength as it does on Pipe Standards toughness. Tough materials fail by predictable ductile yielding and hence Designation allow the use of lower safety factors. Thus PVC-M [50mm-500mm) SANS 966-2 25 Standard MRS (Mpa) Design Stress Safety Factor the 50 year safety factor relates to the 18.0 1.4 type of material and its properties, HDPE has much lower strength than PVC-u but has higher toughness, hence a safety Features and Benefits factor of 125 - Modified polymers achieve The increased internal diameter The excellent long-term hydrostatic strength properties of PVC-U are improvement in resistance to for a given external diameter maintained as shown in the stress-time cracking than PVC-U and ductile iran. line figure, and toughness Improved to - Minimization of the effect of Depending on size and class. the extent that ductile failure modes are stress concentrators such os weight savings in excess of 10% achieved according to the most rigorous scratches test procedures detailed in SANS 966 over PVC-U. Part 2 - Reduction in the factor of + PVC-M pipes will not affect the For PVC-M, a design stress of 18 MPa is safety toste, smell, appearance or used for the calculation of wall thickness Higher wall stresses are health aspects of drinking water and is derived from the MRS of 25 MPa and the application of a 50 year safety allowable, which lead to reduced factor of 14 wall thickness
Pipe Dimensions All pipes are made to provide an effective length of 6.0 meters from 50 mm - 250 mm and 5.8 meters from 315 mm - 500 mm after installation the outside diameters are the same for all pressure classes of the same size and there are 6 classes of pipes. The minimum wall thickness and mass per meter are given in the table below. SANS 966-2 PVC-M PRESSURE PIPE MINIMUM WALL THICKNESS AND MASS PER METER OF RUBBER RING SOCKET PIPE FOR EACH SIZE S CLASS EFFECTIVE NOMINAL SIZE mm 50 53 75 90 110 125 140 160 200 OUTSIDE DIAMETER Min Mak 50.0 50.2 63.0 63.2 75.0 75.2 900 90.3 110.0 110.3 125.0 125.3 140.0 140.4 160.0 1504 2000 2005 250.0 250.6 315.0 315.6 355.0 355.7 400.0 400.7 450.0 450.8 5000 500.9 LENGTH CLASS 6 CLASS 9 CLASS 12 CLASS 16 CLASS 20 CLASS 25 KE ke KS RE KO XOX 150 0.36 170 0240 220 051 2.70 0.62 XOX 1.50 045 1.50 048 210 0.62 2.70 0.80 3.40 0.99 1.50 0 54 190 0.68 2.50 0.89 320 113 DO 1.39 OK 1.80 078 220 095 3.00 1 29 390 1.55 480 201 XX XOX 220 117 270 1.43 3.60 1.89 470 244 5.80 298 720 3.64 2.50 1.51 310 186 410 2.44 540 318 6.50 385 XX XOX 2.80 1.89 350 235 450 3.07 6.00 3.96 740 483 XX XOX 3.20 248 400 3.08 5.20 3.97 6.90 5.21 8.50 6.36 10:40 768 6 390 3.78 490 473 6.50 5.22 860 814 10.60 9.92 13.00 12.02 4.90 5.98 6 10 741 810 9.75 10.70 12.75 13.20 15.58 16.30 18.98 58 6 20 959 7.70 11 86 10 20 15 58 13.50 20 39 16.60 24.32 OX 58 7.00 1226 870 15.16 11 50 19.87 15 20 25.99 18.70 31 54 XOX 5.B 780 15.45 9 80 19.32 13.00 25.42 | 1710 33 09 21.10 40.39 XOX 5.8 8.90 19.83 11.00 2439 14.50 32 11 1920 42.78 23.70 5104 XX OK 5.8 9.80 2427 12.20 30.06 16.20 39.59 21 30 5251 26.40 53 15 XX XOX NOTE: ABOVE WALL THICKNESS BASED ON OS OF 18 Mpo. (SAFETY FACTOR 1.4) oooooooooo CE 250 315 355 400 450 500 XOX DANGER OF CRUSHING A 11
resistance to the most corrosive resistant joints provide advantages in the of environments. way of minimising anchor thrust blocks Johannesburg Water has used this pipe In addition, because they are poor system since the early 1980's and today conductors of heat they offer an ideal this pipe is being used to replace the pipe for the conveyance of chilled water very problematic asbestos pipes which In underground mines in order maintain are now falling in many cities and towns a reasonable, safe working environment. in Southern African countries. A typical Modified PVC pipes are also self installation is shown below. extinguishing hence improving safety. Given harsh mining environments, rough handling and installation, as well as strict safety considerations, it is necessary to produce a toughened, impact resistant High impact PVC-M pipes are made to the PVC pipe by the incorporation of impact SANS 1283 specification which ensures modifiers in addition as the pipes are consistent, high quality products. The suspended in the haulage ways and not result of the high speed impact test from 9 buried; an end thrust resistant joint is a height of 20m (carried out according required to prevent pipes from pulling to the procedure detailed in SANS 966 apart under pressure Part 2 and SANS 1283) illustrates the Applications A Victaulic shouldered and produced from toughness properties exhibited by - Underground Mining Pipe cast and machined SG iron is fitted to the PVC-M pipes. Note the ductile nature of Systems end of each pipe and joined by standard the failure' where a hole is formed with Victaulic clamps and rubber seals. stress whitening as opposed to brittle- type failure The steel Victaulic stub end is precision machined with gripping teeth on the inside to provide a mechanical interference fit with the pipe that is resistant to high pressures. The shouldered and is galvanised to provide protection against corrosion Pipe Standards The toughened PVC-M pipe and Victaulic Designation Standard jointing system has been used in the MRS (Mpa) Design Stress Safety Factor ( mining industry since the late 1970's and PVC-M (110mm, 160mm SANS 1283 25 12.5 2.0 proven itself over the past 30 years as a 6 200mm 12 Pipe Dimensions All pipes are made to provide an effective length of 9.0 meters after installation the outs de diameters are the same for all pressure classes of the same size and there are 6 classes of pipe The minimum wal thickness (as per the applicable SABS standard) and mass per meter are given in the tables below OUTSIDE DIAMETER Min Max 105.0 105.3 110.0 110.3 SANS 1283 PVC-M MINING AND HIGH IMPACT PRESSURE PIPE MINIMUM WALL THICKNESS AND MASS PER METER FOR EACH SIZE AND PRESSURE CLASS EFFECTIVE CLASS CLASSS CLASS 12 LENGTH CLASS 16 CLASS 20 CLASS 25 Kg kg Ke 9 2.50 1.226 3.70 1793 4 BD 2301 6.40 3019 7 BO 3.527 9.50 4340 9 9 2.60 1336 390 1979 5.10 2559 6.70 3.311 820 3.993 10.00 4.784 9 3.60 2607 5.40 3.864 710 5.023 9.40 6.547 11.50 7.894 1410 9.504 9 3.80 2.839 5.60 4 136 740 5402 9.70 6.974 11.90 8.431 14.60 10.155 9 4.70 4391 700 6463 9.20 8.397 12 10 10.875 1490 13 193 18.20 15.828 9 5.00 4903 730 7078 9.70 9294 12.70 11 987 15 60 14.507 19 10 17442 9 9 5.90 6.889 8.70 10.042 1250 13120 15.10 16.968 16.968 18.50 20.589 2280 24.780 9 9 740 10.889 11.00 15.997 14.50 20.844 15.10 15 10 21 100 XOX xx XX XX 155.0 1554 160.0 160.4 200.0 200.5 210.0 2105 250.0 315.0 250.6 315.6 NOTE: NOTE ABOVE WALL THICKNESS BASED ON as of 12 5 MPa (SAFETY FACTOR 2] Features and Benefits → Modified polymers achieve improvement in resistance to cracking → Minimization of the effect of stress concentrators such as scratches - Higher wall stresses are allowable - Best long-term strength (serves in excess of 50 years) - Long-term strength, toughness and stiffness - Large bore and high flow capacity - Durability and toughness. • Resistant to acids and alkalis •
- PVC-M pipes will not affect the taste, smell, appearance or health aspects of drinking water - Environment-friendly & Lead- free material • Excellent flow characteristics reduces friction losses. - Resistant to acids and alkalis - Resistant to obrosion scouring and modern cleaning methods. Light mass: for easy handling and installation - Inflammable: Does not support combustion 13 O C O 4. BOBS ISO 1452-2 PVC-U Pipes Flo-Tek pipes and fabricated fittings are intended for below groundwater supply drainage and sewerage under pressure applications in which continuous temperatures between 25°C and 45°C are encountered Pipe Standards Flo-Tek's pressure pipe produced under this standard covers pressure sewer pipes, where as there is no standard in SABS to cover pressure sewer pipe. Designation Standard MRS (Mpa) Design Stress Safety Factor PVC-U (20mm-90mm) ISO 1452-2 25 10.0 25 PVC-U (110mm-500mm ISO 1452-2 25 120 20 Features and Benefits - Buried and sewerage under pressure application - Environment-friendly & Lead- free material - Excellent flow characteristics: reduces friction losses. * Best long-term strength (serves in excess of 50 years] • Long-term strength, toughness and stiffness - Durability and toughness. Resistant to acids and alkalis. Resistant to obrosion, scouring and modern cleaning methods. - Light mass. for easy handling and installation Elastomeric locked-in sealing ring system - Inflammable: Does not support combustion
Pipe Dimensions All pipes are made to provide an effective length of 6.0 meters from 20 mm - 250 mm and 58 meters from 315 mm - 500 mm after installation, the outside diameters are the same for all pressure classes of the same size and there are 7 classes of pipe. The minimum wall thickness (as per the applicable BOBS ISO standard) and mass per meter are given in the tables below. DIMENSIONS & WEIGHT OF PVC-U PRESSURE PIPES AS PER ISO 1452-2 MINIMUM WALL THICKNESS AND MASS PER METER FOR EACH SIZE AND PRESSURE CLASS NOMINAL SIZE mm OUTSIDE EFFECTIVE LENGTH NOMINAL (MINIMUM) WALL THICKNESS DIAMETER (METERS) S 20 [SDR 41) PNS PRE 35[SDR 11) PN 25 mm Kg מח Kg Б 190 0.166 1 252 25 Б 230 32 Б 2.90 316 (SDR 33) $12.5 (S0R25) $10 (SOR 21 Sa (SOR 17 56.3 SDR 13.6) PN 10 PN 125 PN 15 PN 20 Kg Kg kg Kg mm Kg NOMINAL PRESSURE PN BASED ON DESIGN COEFFICIENT C=2.5 15 0133 150 0169 19 210 1.50 1.219 1.50 1.223 290 0.274 24 2.340 1.50 0.276 160 0.294 190 0.346 240 0432 3 3531 1.50 0.378 200 1469 240 0.558 3.00 0.689 3.7 0.837 200 0.596 2.50 0.739 3.00 0879 3.80 1099 4.7 1 338 230 0.820 2.90 1025 3.60 1.250 4.50 1.556 56 1906 280 1 202 350 1491 1814 540 2.249 2.748 516 (SDR 35) 512.5 [SOR26) 510 (SDR 21 sa(SOR 17) 56.3 [SOR 13.6) PNB PN 10 PN 125 PN 16 PN 20 1.405 0.646 40 Б 3.70 四四%mm西亚 Б 4.60 1024 63 6 5.80 1629 75 Б 2.284 6.80 8.20 90 Б 430 67 3.314 520 (SOR41) PNG 3 [SOR 11) PN 25 m M m Kg Kg 4064 110 6 BI 10.00 11.40 4.943 6398 125 6 9.2 5.245 140 6 103 6.577 12.70 7.991 6 150 200 NOMINAL PRESSURE PN BASED ON DESIGN COEFFICIENT C = 2 kg mm Kg mm kg mm Kg mm Kg 2.70 1.425 3.40 1784 4 20 2188 5.30 2.732 5.50 3.360 3.10 1.860 3.90 2325 4.80 2.841 6.00 3.515 7.40 4.294 3.50 2352 30 2873 5.40 3.578 6.70 4.397 8.30 5.382 4.00 3.080 4.90 3751 6.20 4.706 270 5.788 9.50 7.056 4.726 6.20 5999 7.70 7319 9.60 9.035 11 90 11.065 6.20 7.532 770 9.297 9.50 11.500 11.90 14 119 14.80 17345 770 11.856 9.70 14.838 1210 18.364 1500 22547 18.70 27.752 8.70 15.158 10.90 18.870 13.50 23 360 15.90 28.747 21 10 35.446 9.80 19.318 12.30 24.090 15.30 29.734 19 10 36.752 23.70 45.053 11.00 24.395 1380 30.409 17.20 37605 21.50 45.540 26.70 57095 1230 30 304 15 30 37.453 1910 46.401 2390 57483 29.70 70562 4,90 5 . 118 8 630 14.50 10.513 147 13.465 18 20 16.41 18.5 21 235 23 2 33.920 250 315 6 5.8 355 26.1 43.189 5.8 5.8 400 294 55.042 450 5.8 331 69.711 36.8 86.111 500 58 15
DESIGN CONSIDERATIONS Durability and the Short-Term Safety Factor Long-Term Safety Factor The question is often asked, "how do PVC-U and PVC-M pressure pipes withstand It should be noted that the stress – time sudden surges in pressure caused, for example by water hammer? The short answer line does not indicate a loss of strength is extremely well". The question usually results from a consideration of the safety with time rather that the material can factors of 20 and 14 applied in the design of the two materials, PVC-U and PVC-M. support lower stresses for longer times respectively. However, it should be noted that these are long-term, i.e. 50 year safety With each new loading, for example, factors, while their short-term safety factors are much greater water hammer or pressure surges, the The polymer molecular structure ensures that the more rapid the pressure increase material acts according to the short-term the greater the strength exhibited by these materials: the molecular structure reacts strength properties Short-term strength so as to resist the stress is independent of how much time has passed since the first loading the pipe The short-term safety factors of PVC-U and PVC-M are over 3 times the design acts as a new pipe operating pressure and can be as high as 4 or 5 times depending on the rate of the Numerous studies conducted on PVC-U pressure surge pipes excavated at various times up to 60 years service, have shown the exceptional durability of these 'old' pipes, with little Long-Term Hydrostatic Strength Properties and or no difference in mechanical properties to recently manufactured pipes. Tenslie The Long-Term Safety Factor strength. Impact strength, burst pressure the strength of plastics pipes can be defined in terms of the maximum stress to and elastic modulus show virtually no cause failure in a given time, usually 50 years, and is determined at various extended change with time in service A study times according to the procedure described in ISO 9080. The results are graphically conducted on 60 year old PVC-U pipes illustrated by plotting the haap stress against the time to fall on a log scale, as shown states: 'although the plastics industry is a relatively young materials segment PVC-U below. pipe is now about 70 years old, which is more than the predicted service lifetime of 50 years for PVC pipe applications 100 Years 50 Years As per pipe Standards 38BR# Hoop Stress (MPa) 10 1000 100000 10000 1000000 Time (Hours) Stress-Time line for PVC-U ond PVC-M at 20°C. (1) PVC-U and PVC-M regression line as per SANS 966 Parts 1 and 2 PVC-M design stress, SANS 966-2 [18 MPa] PVC-U design stress, SANS 966-1 [125 MPa] 16
30 Pressure Variation The Effect of Temperature Expansion and Contraction and Surge Pressures Changes on Working Ali plastics have high co-efficients of The stress-time lines are derived using Pressure expansion and contraction, several times constant stresses: pipelines the The pressure classes of PVC pipes carrying in any installation by the use of expansion thase of metals. This must be allowed for stress on the material is rarely constant the SABS mark have been allocated on jaints, expansion loops etc varying as the pressure varies and as superimposed loads vary. The latter the basis of design at 20°C PVC pressure stabilise fairly quickly usually within pipes perform well at temperatures MATERIAL below 20°C and can withstand higher CO-EFFICIENT OF the first year or two of the network EXPANSION (K) life, but pressure variations are there pressures at lower temperatures Pipes PVC 8x 10 forever As with any other pipe material, used in applications where operating due allowance for this must be made in temperatures exceed 25C should be HDPE 20 x 10 designing a water reticulation network de-rated to ensure that the 50 year LDPE 20 x 10 with PVC pipes design life is not adversely affected The following pressure reduction factors Steel 12x 10 Anti-surge devices such as air vessels, should be applied non-return valves, programmed use of Copper 20 x 10 pumps etc, should be incorporated where WORKING necessary. Lower surge pressures develop TEMPERATURE MULTIPLICATION Examples based on the above are as (C) FACTORS In PVC pipes as a result of lower surge follows wave velocities and this has enabled PVC 25 10 A PVC pipe wil expand or contract by pipes to be used in areas where water hammer has caused pipes manufactured 0.9 0.06mm per metre per 'c change in temperature from other materials to fracture Above 35 0.8 all. It enables ane to operate with lower • A HDPE pipe will expand or contract 40 0.7 pressure classes for PVC. by 0.2mm per metre per *C change in temperature 45 0.6 Considerable research has been done on A 30-rise in temperature will cause an the fatigue properties of plastic pipelines 5D 0.5 increase in length of 10.8mm (0.06 Recently work has been published on 55 04 30 x 6] on a 6m length of PVC pipe and fatigue properties of PVC-M related to an increase of 36mm (0.2 x 30 x 6jon actual site conditionsin water distribution 60 0.3 systems. It concludes that PVC-M pipes a 6m length of HOPE pipe will not fall under conditions of dynamic and static stress within 50 years provided the total stress does not exceed 18 MPa Calculating Water Hammer and the stress amplitude over one million pressure cycles (equal to 55 cycles per The Wave Celerity for PVC-U and CLASS PVC-M which is used in the ca culation PVC-U PVC-M day for 50 years) is below 3,0MPa. of water hammer in pipelines is given in 6 263 249 the table below. 9 325 270 Higher wave ceerty values result in higher levels of water hammer. Each 12 378 312 class of pipe has a constant value of wave cel arty. By comparison the wave 16 439 363 Ce erities for materials such as steel 20 495 407 and fibre cement are much higher-by multiples of 3 or more 25 559 458 DO 17
DESIGN CONSIDERATIONS ... Resistance to Weathering Flow Rates, Velocities and Friction Losses (Ultraviolet Light) The flow velocities in pressure pipelines should fall in the range 0.8 to 25 m/s, the Mast plastics are affected by UV light lower rate to maintain self-cleansing flow and assist in the removal of air and the upper PVC pressure pipes have pigments and limit to maximise air release at high points Approximate flow rates, flow velocities and light stabilisers incorporated in their friction losses in straight PVC pressure pipelines without fittings can be read off the formulation and if pressure pipes have following Nomogram. to be exposed for an indefinite period, they should be painted, preferably with How to use a Nomogram: one coat of white alkyd enamel ar PVA 1. You need a straight edge and at least two of the four values. or suitable covering should be provided Paint containing solvent thinners should 2. Place the straight edge across all four columns so that it intersects the two known be avoided values 3. Read off the other two values. Long-term exposure (more than 4 - 6 months, but dependent on climatic conditions) to UV light can cause discolouration of the pigments in the pipe and, in severe cases, lead to some embrittlement. Such embrittlement affects the ability to withstand impacts but does not reduce pressure handling capabilities It is recommended that pipes should be buried wherever possible, Bater Flow Woche Hydraulle reden m/100m 15 20 001 002 BOS 03 0.00 . 015 MW so 02 3 OS 3 70 2 8888 TTT a 04 & Compressed Air Normal forms of PVC pipes should NOT be used for the reticulation of compressed air Bending An important feature of PVC pipes is that they may be deliberately bent, within limits, thus eliminating the need, in some cases, for separate bend fittings. As a rule of thumb the radius of such a bend must not be less than 300 times the pipe diameter In addition each rubber ring joint can accammodate a further 21 of bend. This feature significantly reduces costs and speeds up installation times when compared to some traditional pipe materials 25 150 RRS SO 2010 250 300 350 200 1000 10 10 2000 பட்ட 20 SO 2000 5000 Diagram for water at 1c Approximate values only 18
PIPE JOINTING JOINTING METHODS 1. Cutting 4. Chamfering PVC pipes can be easily cut using a number of different cutting the spigot end of all rubber ring jointed pipes is chamfered at tools, such as proprietary cutting tools which cut deburr and the time of manufacture Chamfering facilitates the insertion of chamfer in one operation Circular saws or hand saws may be the spigot end into the socket of the next pipe without damaging used. It is important to ensure that after cutting the pipe end or dislodging the rubber ring. If however, the chamfering has is thoroughly deburred. been cut off it is important to re-chamfer the end correctly. Re-chamfering can easily be done using a file that leaves na 2. Rubber Ring Joints sharp edges which may cut the rubber ring. A rubber ring socket is integrally moulded on one end of the pipe it should be at an angle of about 12° -15° and the length of and incorporates a factory fitted rubber sealing ring which is the chamfer should be such that at least half the wall of the retained in position. The opposite end of the pipe (spigot end) is thickness is removed the chamfering should not be done to suitably chamfered and has a depth of entry mark near its end such an extent that a sharp edge is made at rim of the bore. Each joint is capable of handling expansion and contraction as well as angular deflection of up to 2°C and a pressure of up to 75 kPa below the ambient atmospheric pressure. The seal 5. Lubricant ring is designed to provide a watertight joint at high and low pressures It is the most important to use correct lubricant when making a joint. The lubricant considerably reduces the effort required to 3. Depth of Entry insert the spigot inta the socket and at the same time minimizes The depth of entry mark is a guide to ensure correct depth of the possibility of dislodging the rubber ring. The lubricant should insertion of the spigot into the socket of the next pipe. If pipes be water soluble, non-toxic and of a gel consistency. Alternative are cut to measure an site it is necessary to remark the depth of lubricants such as oil, grease, diesel , dish-washing liquid, etc, entry according to the dimensions given in the following table ar must under no circumstances be used as per the pipe being installed at the same time. Re-marking can be done with a permanent felt tipped marker Joints Per Lubricant pen. The correct depth of entry allows for expansion and contraction of the pipes in the pipeline. PIPE SIZE (mm) JOINTS /2kg JOINTS/ Skg 290 725 PIPE SIZE (mm) DEPTH OF ENTRY (mm) 625 50 75 220 550 63 180 130 125 130 325 300 160 140 200 188 160 250 50 125 250 225 315 400 240 150 70 400 250 500 450 500 50 63 250 110 120 90 110 450 350 140 75 90 110 125 140 275 135 150 160 165 175 200 120 110 75 60 150 200 315 355 230 BB 75 355 35 30 25 25 60 265 275 24