DESIGN OF SHAFTS DESIGN OF SHAFTS 14.17 REFERENCES Lingaiah, K., and B R Narayana Iyengar, Machine Design Data Handbook, Engineering College Cooperative, Bangalore, India, 1962 Lingaiah, K., and B R Narayana Iyengar, Machine Design Data Handbook, Vol I (SI Units and Customary Metric Units), Suma Publishers, Bangalore, India, 1986 Lingaiah, K., Machine Design Data Handbook, Vol II (SI Units and Customary Metric Units), Suma Publishers, Bangalore, India, 1986 Soderberg, C R., ‘‘Working Stresses,’’ J Appl Mechanics, Vol 57, p A-106, 1935 ASME Code for Design of Transmission Shafting, Standard ANS/ASME B106.1M, 1985 Shigley, J E., Machine Design, McGraw-Hill Publishing Company, New York, 1956 Kececioglu, D B., and V R Lalli, Reliability Approach to Rotating Component Design, Technical Note TND-7846, NASA, 1975 Davies, V C., H T Gough, and H V Pollard, Discussion to the Strength of Metals under Combined Alternating stresses, Proc of the Inst Mech Eng., 131(3), pp 66–69, 1935 Loewenthal, S H., Proposed Design Procedure for Transmission Shafting under Fatigue Loading, Technical Note TM-7802, NASA, 1978 10 Gough, H J., and H V Pollard, The Strength of Metals under Combined Alternating stresses, Proc of the Inst Mech Eng., 131(3), pp 3–103, 1935 BIBLIOGRAPHY Berchard, H A., ‘‘A Comprehensive Method for Designing Shafts to Insure Fatigue Life,’’ Machine Design, April 25, 1963 Black, P H., and O Eugene Adams, Jr., Machine Design, McGraw-Hill Publishing Company, New York, 1983 British Standards Institution Deutschman, A D., W J Michels, and C E Wilson, Machine Design—Theory and Practice, Macmillan Publishing Company, New York, 1975 Maleev, V L., and J B Hartman, Machine Design, International Textbook Company, Scranton, Pennsylvania, 1954 Marks’ Standard Handbook for Mechanical Engineers, 8th ed., McGraw-Hill Publishing Company, New York, 1978 Vallance, A., and V L Doughtie, Design of Machine Members, McGraw-Hill Publishing Company, New York, 1951 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website DESIGN OF SHAFTS 14.18 CHAPTER FOURTEEN TABLE 14-1 Empirical shafting formulas Power capacity, P Load factors considered Kind of service Torsion, Kt Bending, Kb kW hp Transmission shafts in torsion only Line shafting with limited bending Head or main shafts with heavy bending loads 1.0 1.0 1.0 1.0 1.5 2.5 54,831D3 n0 34,532D3 n0 20,715D3 n0 1:225 Â 10À6 D3 n 7:715 Â 10À7 D3 n 4:628 Â 10À7 D3 n TABLE 14-2 Shock and endurance factors Nature of loading Stationary shafts Gradually applied load Suddenly applied load Rotating shafts Steady or gradually applied loads Suddenly applied loads, minor shocks only Suddenly applied loads, heavy shocks TABLE 14-3 Values of constant c Kb Kt 1.0 1.5–2.0 1.0 1.5–2.0 1.5 1.5–2.0 1.0 1.0–1.5 2.0–3.0 1.5–3.0 Type of shaft loading Shaft heavily loaded, subjected to shock, or reversed under full load Line shafts and countershafts, loaded in bending but not reversed Line shafts or bar with pulleys close to the bearings MPa kpsi 0.82 17 2.5 1.1 27 4.0 1.56 44 6.4 TABLE 14-4 Shock load factorsa for use in Eq (14-81) Nature of load Ksb , Kst Gradually applied load Loads applied with minor shocks Loads applied with heavy shocks Allowable stress Coefficient c in Eq (14-61) 1.00 1.0–1.5 1.5–2.0 a Data from Berchard, H A., ‘‘A Comprehensive Method for Designing Shafts to Insure Fatigue Life,’’ Machine Design, April 25, 1963 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website DESIGN OF SHAFTS DESIGN OF SHAFTS 14.19 TABLE 14-5 Spacinga for fine shaft bearings Transmission shaft stressed in torsion only, mm Line shaft carrying pulleys or gears and subjected to usual bending loads, mm Diameter of shaft, mm 1–250 rpm 251–400 rpm 1–250 rpm 251–400 rpm 36.5 49.0 62.0 74.5 87.5 100.0 112.5 274.5 305.0 335.5 366.0 396.0 427.0 457.0 244.0 274.5 305.0 335.5 366.0 396.0 427.0 213.5 229.0 244.0 259.0 274.5 289.5 305.0 198.0 213.5 228.5 244.0 259.0 274.5 289.5 a Center-to-center distance in millimeters TABLE 14-6 Sizes of shafts Diameters, mm (in) (0.16) (0.20) (0.24) (0.28) (0.32) (0.36) 10 (0.4) 12 15 17 20 25 30 35 (0.48) (0.60) (0.68) (0.80) (1.0) (1.2) (1.4) 40 (1.6) 45 (1.8) 50 (2.0) 55 (2.2) 60 (2.4) 65 (2.6) 70 (2.8) 75 (3.0) 80 (3.2) 85 (3.4) 90 (3.6) 95 (3.8) 100 (4.0) 105 (4.2) 110 (4.4) 120 (4.8) 130 (5.2) 140 (5.6) 150 (6.0) 160 (6.4) 170 (6.8) 180 (7.2) 190 (7.6) 200 (8.0) 220 (8.8) 240 (9.6) 260 (10.4) 280 (11.2) TABLE 14-7 Load factors for various machines, kl a Driver Driven machinery Factor, kl Steam turbine Electric generator, steady load; turbine blower Electric generator, uneven load; centrifugal pump Induced-draft fan; line shaft; gear drive Rolling mill, gear drive Turbine blower; metalworking machinery Centrifugal pump; wood working machinery Line shaft; ship propeller; double acting pump Triplex single-acting pump; elevator; crane Compressor, air or ammonia Rolling mill; rubber mill Values for electric-motor drive multiplied by 1.2–1.5 Values for electric-motor drive multiplied by 1.3–1.6 the factor depending on the coefficient of steadiness of the flywheel 1.00 1.25 1.50 2.00 1.25 1.50 1.75 1.75 1.75 2.50 Electric motor Steam engine Gas and oil engines a To be used also in Eqs (5–9) and (19–79) Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website Source: MACHINE DESIGN DATABOOK CHAPTER 15 FLYWHEELS SYMBOLS1,2 a A b Cf d dh D Do E Fc Fc g h i ko I J kt Mtm Mt m n n1 n2 r t T1 T2 v v1 v2 W Z major axis of ellipse, m (in) negative acceleration or deceleration, m/s2 (ft/s2 ) cross-sectional area of the rim, m2 (in2 ) minor axis of ellipse, m (in) width of rim, m (in) coefficient of fluctuation of rotation diameter of shaft, m (in) hub diameter, m (in) flywheel diameter, m (in) outside diameter of rim, m (in) excess energy, J (ft lbf ) centrifugal force, kN (lbf ) centrifugal force per unit width of rim, kN (lbf ) acceleration due to gravity, 9.8066 m/s2 (32.2 ft/s2 ) depth of rim, m (in) number of arms polar radius of gyration of the rim, m (in) mass moment of inertia, N s2 m (lbf s2 ft) polar second moment of inertia, m4 (in4 ) torsional stiffness of shaft, N m/rad (lbf in/rad) mean torque, N m (lbf ft) transmitted torque, N m (lbf ft) coefficient of steadiness mean speed, rpm maximum speed, rpm minimum speed, rpm mean radius of the flywheel, m (in) time, s tension in belt on tight side, kN (lbf ) tension in belt on slack side, kN (lbf ) mean rim velocity, m/s (ft/min) maximum rim velocity, m/s (ft/min) minimum rim velocity, m/s (ft/min) rim weight, kN (lbf ) specific weight of material or weight density, N/m3 (lbf/in3 ) sectional modulus of the arm cross section at the hub, m3 (in3 ) 15.1 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website FLYWHEELS 15.2 1 , 2 ! !1 , !2 CHAPTER FIFTEEN stress (also with subscripts), MPa (psi) maximum and minimum angular displacement of flywheel from constant speed deviation, rad (deg) average angular speed, rad/s maximum and minimum angular speed, respectively, rad/s Particular Formula The equation of motion of ith rotor of Ii inertia in a multirotor system connected by (i À 1) number of shafts of various inertias subjected to external torque Ii i ẳ Mti Mti 1ị ð15-1Þ The equation of motion of a flywheel, which is mounted on a shaft between two supports and rotates with an angular velocity and subjected to an input external torque Mti I ¼ Mti À Mto ¼ kt ð2 À 1 ị 15-2ị where Mto ẳ output torque, N m (lbf ft) ¼ angular displacement of flywheel, rad (deg) KINETIC ENERGY Kinetic energy (Fig 15-1) Wv2 K ¼ mv2 ¼ ¼ I! 2g 2 For variation of torque with crank angle for twocylinder engine Refer to Fig 15-1 ð15-3Þ FIGURE 15-1 Torque-crank shaft angle curve for a two-cylinder engine The kinetic energy of flywheel at an angular displacement 1 and at angular velocity !1 during one cycle Wv2 K1 ¼ I!2 ¼ 2g ð15-4Þ The kinetic energy of flywheel at an angular displacement 2 and at angular velocity !2 Wv2 K2 ẳ I!2 ẳ 2g 15-5ị The change in kinetic energy or energy fluctuation due to change in angular velocity !1 to !2 in one cycle Wv2 v2 ị E ẳ K2 K1 ẳ I!2 !2 ị ẳ 2 2g ẳ I!2 !1 ị!2 ỵ !1 ị ẳ I!2 !1 ị! ẳ Wv2 v1 Þ v g Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website ð15-6Þ FLYWHEELS FLYWHEELS Particular The coefficient of fluctuation of speed or rotation The change in kinetic energy or excess energy 15.3 Formula Cf ¼ !2 À !1 v2 À v1 n2 À n1 ¼ ¼ ! v n E ¼ K2 À K1 ¼ I!2 Cf ¼ ð15-7Þ Wv2 Cf g ð15-8Þ FLYWHEEL EFFECT OR POLAR MOMENT OF INERTIA Wk2 ¼ The mean angular velocity !¼ !2 ỵ !1 15-10ị The coecient of steadiness mẳ Cf ð15-11Þ 182:40gE n2 À n2 ð15-9Þ Refer to table 15-1 for Cf STRESSES IN RIM (Figs 15-2 and 15-3) The component of the centrifugal force normal to any diameter of the flywheel Fc ¼ 2bhr2 !2 g ð15-12Þ The tangential force due to hoop stress in the flywheel rim (Fig 15-3) F ¼ bhr2 !2 g ð15-13Þ The tensile stress created in each cross section of the rim by the centrifugal force ¼ 0:01095 The centrifugal force per unit width of rim (Fig 15-3) 2 r n g Fc ¼ 0:01095 SI SI r2 n2 h g ð15-14Þ ð15-15Þ TABLE 15-1 Coefficient of fluctuation of rotation, Cf Driven machine Type of drive Cf AC generators, single or parallel AC generators, single or parallel DC generators, single or parallel DC generators, single or parallel Spinning machinery Compressure, pumps Paper, textiles, and flour mills Woodworking and metalworking machinery Shears and pumps Concrete mixers, excavators, and compressors Crushers, hammers, and punch presses Direct-coupled Belt Direct-coupled Belt Belt Gears Belt Belt Flexible coupling Belt Belt 0.01 0.0167 0.0143 0.029 0.02–0.015 0.02 0.025–0.02 0.0333 0.05–0.04 0.143–0.1 0.2 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website FLYWHEELS 15.4 CHAPTER FIFTEEN Particular The bending stress The combined tensile stress Formula b ¼ 0:2146 r3 n2 ghi2 SI R ẳ 0:75 ỵ 0:25b 15-16ị 15-17ị STRESSES IN ARMS (Fig 15-2) The stresses in the arm 1 ẳ Mt D dh ị iZD 15-18ị FIGURE 15-2 Flywheel FIGURE 15-3 Centrifugal force acting on the rim of a flywheel When the flywheel is used as a belt pulley, the stresses at the hub 2 ¼ ðT1 À T2 ÞðD À dh Þ 2iZ ð15-19Þ In case of thin-rim flywheel, the stress 02 ¼ ðT1 À T2 ÞðD À dh Þ iZ ð15-20Þ Stress due to centrifugal force 3 ¼ 0:01095 r2 n2 g The maximum tensile stress in an arm is at hub max ¼ 1 þ 2 þ 3 The force necessary to stop the ywheel Fẳ SI Wa g 15-21ị 15-22ị 15-23ị RIM DIMENSIONS (Fig 15-2) The relation between ko in cm and the outside diameter D of the rim in m Cross-sectional area of the rim k2 ẳ 0:125ẵD2 ỵ Do 2hị2 o o A¼ W 2k Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website ð15-24Þ ð15-25Þ FLYWHEELS FLYWHEELS Particular 15.5 Formula The relation between depth and width of rim b ẳ 0:65 to h 15-26ị The outside diameter of rim Do ẳ 2ko ỵ h approx:ị 15-27ị The hub diameter in m dh ẳ 1:75d ỵ 6:35 103 ẳ 2d 15-28ị The hub length l ¼ 2d to 2:5d ð15-29Þ rffiffiffiffiffiffiffiffiffi 64Z ð15-30Þ ARMS (Fig 15-2) The major axis in case of elliptical section can be computed from the relation a¼ where z ¼ ba2 32 and a ¼ 2b ð15-31Þ REFERENCES Lingaiah, K., and B R Narayana Iyengar, Machine Design Data Handbook, Vol I (SI and Customary Metric Units), Suma Publishers, Bangalore, India, 1986 Lingaiah, K., Machine Design Data Handbook (SI and U.S Customary Units), McGraw-Hill Publishing Company, New York, 1994 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website Source: MACHINE DESIGN DATABOOK CHAPTER 16 PACKINGS AND SEALS SYMBOLS1;2 A Ag A1 , A2 b c d d1 d2 da di Dm Dam E Fb F Fo g h hi h i l l1 , l2 (dl) Mt Mti area of seal in contact with the sliding member, m2 (in2 ) gasket area over which the bolt loads are distributed, m2 (in2 ) area of cross section of unthreaded and threaded portions of bolt, m2 (in2 ) width of U-collar, m (in) gland width or depth of groove, m (in) radial clearance between rod and the bushing, radial deflection of the ring, m (in) nominal diameter of the bolt, m (in) diameter of sliding member, m (in) outside diameter of packing material, m (mm) outside diameter of seal ring (Fig 16-3), m (in) minor diameter of bolt, m (in) actual diameter of wire, m (in) inside diameter of packing material, m (in) estimated mean diameter of conical spring, m (in) actual mean diameter of conical spring, m (in) modulus of elasticity, GPa (psi) bolt load, kN (lbf ) frictional force, kN (lbf ) frictional force of the stuffing box when there is no fluid pressure, kN (lbf ) acceleration due to gravity, 9.8066 m/s2 (9806.6 mm/s2 ) (32.2 ft/s2 ) radial ring wall thickness, m (in) uncompressed gasket thickness, m (in) loss of head, m/m (in/in) number of bolts depth of U-collar (Fig 16-2a), m (in) length of joint, m (in) incremental length in the direction of velocity [Eq (16-15)], m (in) bolt elongation [Eq (16-24)], m (in) twisting moment, N m (lbf in) initial bolt torque, N m (lbf in) 16.1 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS 16.2 CHAPTER SIXTEEN fluid pressure, MPa (psi) flange pressure on the gasket, MPa (psi) minimum per cent compression to seal pressure differential in the direction of velocity [Eq (16-15)], MPa (psi) discharge, m3 /s (cm3 /s, mm3 /s) (in3 /s) equivalent radius, m (in) velocity, m/s (ft/min) nominal packing cross section, m (in) deflection of spring, m (in) absolute viscosity of fluid, Pa s (cP) design stress, MPa (psi) coefficient of friction p pf Ps (dp) Q r v w y d Particular Formula ELASTIC PACKING1–3 Frictional force exerted by a soft packing on the reciprocating rod F ẳ kpd 16-1ị where k ẳ 0:005 and p ¼ 0:343 MPa SI k ¼ 0:2 and p ¼ 50 psi USCS FRICTION Friction resistance F ẳ Fo ỵ Ap 16-2ị where ẳ 0:01 for rubber and soft lubricated leather ¼ 0:15 for hard leather Torsional resistance in a rotary motion friction F d kd p ¼ 2 where k ¼ 0:005 SI k ¼ 0:2 USCS Mt ẳ 16-3ị c ẳ 0:2d ỵ mm if d 100 mm pffiffiffi c ¼ 0:08 d if d > 0:1 mm pffiffiffi c ¼ 0:5 d if d > ð16-4Þ METALLIC GASKETS (Fig 16-1) The empirical relations3 hẳ SI 16-5aị USCS 16-5bị d ỵ 12:54 mm or 0:5 in 16-6ị a ẳ d ỵ 2c 16-7ị ẳ 108 to 158 16-8ị p d2 ẳ 0:2d ỵ 0:102ị= i p d2 ẳ 0:2d ỵ 4ị= i SI ð16-9aÞ USCS ð16-9bÞ Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS TABLE 16-10 Dimensions for oil seals (Cont.) Nominala b Ỉ 0:2, mm Shaft bore diameter Types A diameter d1 , of housing, mm mm and B Type C cb min, mm 35 0.4 47 50 52 62 47 50 52 62 38 52 55 62 40 36 — Nominala b Ỉ 0:2, mm Shaft bore diameter diameter d1 , of housing, Types A mm mm and B Type C cb min, mm 63 85 90 10 12 0.5 65 85 90 100 10 12 0.5 68 90 100 10 12 0.5 70 90 100 10 12 0.5 72 95 100 10 12 0.5 75 95 100 10 12 0.5 78 100 100 10 12 0.5 80 100 110 10 12 0.5 85 110 120 12 15 0.8 90 110 120 12 15 0.8 95 120 125 12 15 0.8 100 120 125 130 12 15 0.8 105 130 140 12 15 0.8 110 130 140 12 15 0.8 115 140 150 12 15 0.8 120 150 160 12 15 0.8 — 0.4 — 0.4 52 55 62 72 — 0.4 42 55 62 72 — 10 0.4 45 60 62 65 72 — 10 0.4 48 62 72 — 10 0.4 50 65 68 72 80 — 10 0.4 68 72 70 72 80 85 70 72 80 85 58 72 80 — 10 0.4 125 150 160 12 15 0.8 60 80 85 90 — 10 0.4 130 160 170 12 15 0.8 62 85 90 10 12 0.5 135 140 145 170 170 175 11 15 15 15 15 15 0.8 1 52 55 56 — 10 0.4 — 10 0.4 — 10 0.4 16.18 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS TABLE 16-10 Dimensions for oil seals (Cont.) Nominala b Ỉ 0:2, mm Shaft bore diameter Types A diameter d1 , of housing, mm mm and B Type C 150 160 170 180 190 200 210 220 230 240 250 260 180 190 200 210 220 230 240 250 260 270 280 300 15 15 15 15 15 15 15 15 15 15 15 20 15 15 15 15 15 15 15 15 15 15 15 20 cb min, mm Nominala b Ỉ 0:2, mm Shaft bore diameter diameter d1 , of housing, Types A mm mm and B Type C cb min, mm 1 1 1 1 1 1 280 300 320 340 360 380 400 420 440 460 480 500 1 1 1 1 1 1 320 340 360 380 400 420 440 460 480 500 520 540 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 a For limits of housing, see Tables 16-11 and 16-12 The edges may be chamfered or rounded according to the manufacturer’s discretion Source: Bureau of Indian Standards: 5129, 1969 b TABLE 16-11 Press-fit allowances and tolerancesa for type A seals Possible press-fit variation, mm Nominal bore diameter of housing, mm Housing bore, mm Outside diameter of seal, mm High limit Low limit High limit Low limit Maximum interference Minimum interference 25 25–55 55–125 125–200 !200 þ0.03 þ0.03 þ0.03 þ0.04 þ0.05 À0.03 À0.03 À0.03 À0.04 À0.05 þ0.20 þ0.25 þ0.30 þ0.38 þ0.48 þ0.10 þ0.15 þ0.20 0.22 0.32 0.23 0.28 0.33 0.42 0.53 0.07 0.12 0.17 0.18 0.27 a All tolerances are relative to nominal bore diameter of housing Source: IS 5129, 1969 TABLE 16-12 Press-fit allowances and tolerances’ for types B and C seals Possible press-fit variation, mm Nominal bore diameter of housing, mm Housing bore, mm Outside diameter of seal, mm High limit Low limit High limit Low limit Maximum interference Minimum interference 50 50–90 90–115 115170 170215 215230 ! 230 Nominal Nominal ỵ0.03 ỵ0.03 ỵ0.04 þ0.04 þ0.04 À0.03 À0.03 À0.03 À0.03 À0.04 À0.04 À0.04 þ0.12 þ0.14 þ0.18 þ0.20 þ0.23 þ0.25 þ0’30 þ0.04 þ0.06 þ0.08 þ0.10 þ0.13 þ0.15 þ0.20 0.15 0.17 0.21 0.23 0.27 0.29 0.34 0.04 0.06 0.05 0.07 0.09 0.11 0.16 a All tolerances are relative to nominal bore diameter of housing Source: IS 5129, 1969 16.19 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS 16.20 CHAPTER SIXTEEN TABLE 16-13 Depth of the housing bore (all dimensions in mm) b t (0.85b) Min t2 (b to 0.3) Min 10 12 15 20 5.95 6.80 7.65 8.50 10.30 12.75 17.00 7.3 8.3 9.3 10.3 12.3 15.3 20.3 Source: Indian Standards 5129, 1969 TABLE 16-14 Types of hollow, metallic O-rings8,9 FIGURE 16-14 Fully confined hollow-metal O-ring: (a) before bolting and (b) after bolting down Source: Wes J Ratelle, ‘‘Seal Selection, Beyond Standard Practice,’’, Machine Design, Jan 20, 1977 and, ‘‘Packings and Seals’’ Issue, Machine Design, Jan 1977 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS PACKINGS AND SEALS 16.21 TABLE 16-15 Recommended groove dimensions for metallic Q-ring sealing inside pressure Nominal O-ring OD Nominal tubing OD mm 0.8 Actual O-ring dimensions Min B, mm Incremental increase, I, mm Tubing OD, O-Ring B, OD, mm mm 6.30 0.8 up to 25 0.74–0.96 1.6 11.0 1.6 thereafter 0.14–0.16 2.4 19 1.6 0.20–0.24 3.2 44 1.6 0.30–0.31 4.0 75 1.6 0.37–0.40 4.8 100 1.6 0.44–0.48 6.3 125 1.6 0.59–0.81 9.5 250 No limit 0.900.95 12.7 250 No limit 1.201.25 B ỵ 0:075 0.000 B ỵ 0:075 0.0006 B ỵ 0:100 0.000 B ỵ 0:125 0.000 B ỵ 0:150 0.000 B ỵ 0:175 0.000 B ỵ 0:200 0.000 B ỵ 0:300 0.000 B ỵ 0:400 À 0.000 Open-groove dimensions Maximum ID of closed groove, Y, mm Maximum, radius of groove corner, R, mm B À 2:160 B À 3:000 0.125 B À 3:600 B À 4:825 0.255 B À 5:665 B À 6:860 0.510 B À 7:495 B À 8:635 0.760 B À 9:245 B À 10:410 0.760 B À 11:170 B À 12:190 0.760 B À 14:730 B À 16:000 0.760 B À 22:600 B À 23:110 0.760 B À 30:480 B À 30:480 0.760 Depth, C, mm Groove OD, Minimum X, groove ID, mm Y, mm 0.510– 0.500 1.066– 1.145 1.0650– 1.750 2.290– 2.415 2.920– 3.050 3.685– 3.810 4.955– 5.080 7.495– 7.620 9.910– 10.160 B ỵ 0:0105 to 0.01525 B ỵ 0:0105 to 0.01525 B ỵ 0:0127 to 0.0225 B ỵ 0:0178 to 0.0305 B ỵ 0:0203 to 0.0355 B ỵ 0:0228 to 0.0380 B ỵ 0:0280 to 0.0480 B ỵ 0:0355 to 0.0735 B ỵ 0:0510 to 0.0965 Source: Wes J Ratelle, ‘‘Seal Selection Beyond Standard Practice,’’ Machine Design, Jan 20, 1977, and ‘‘Packings and Seals’’ Issue, Machine Design, Jan 20, 1977 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS 16.22 CHAPTER SIXTEEN TABLE 16-16 Rectangular groove dimensions for O-ring gaskets O-ring nominal cross section, mm Actual O-ring cross section, mm Maximum groove depth, V, mm 1.6 1.6 1.6 1.6 1.6 2.4 3.2 4.8 6.4 0.100 Ỉ 0.0075 0.125 Ỉ 0.0075 0.150 Ỉ 0.0075 0.175 Æ 0.0075 0.175 Æ 0.0075 0.260 Æ 0.0075 0.350 Æ 0.0100 0.530 Ỉ 0.0125 0.700 Ỉ 0.0150 For Flange Gaskets (Axial) 0.070–0.0050 0.160 Ỉ 0.0050 0.090–0.0050 0.185 Ỉ 0.0075 0.110–0.0050 0.210 Ỉ 0.0075 0.130–0.0100 0.240 Ỉ 0.0075 0.125–0.0100 0.240 Ỉ 0.0075 0.205–0.0105 0.270 Ỉ 0.0125 0.280–0.0200 0.470 Ỉ 0.0125 0.445–0.0250 0.725 Ỉ 0.0125 0.585–0.0250 0.960 Ỉ 0.0125 1.6 1.6 1.6 1.6 1.6 2.4 3.2 4.8 6.4 0.100 Ỉ 0.0075 0.125 Æ 0.0075 0.150 Æ 0.0075 0.175 Æ 0.0075 0.175 Æ 0.0075 0.260 Ỉ 0.0075 0.350 Ỉ 0.0100 0.530 Ỉ 0.0125 0.700 Ỉ 0.0150 For Nonflange Gaskets (Radial) 0.075–0.0025 0.140 Ỉ 0.0050 0.095–0.0025 0.160 Ỉ 0.0075 0.115–0.0025 0.190 Ỉ 0.0075 0.135–0.0025 0.230 Ỉ 0.0075 0.130–0.0050 0.230 Ỉ 0.0075 0.210–0.0075 0.315 Ỉ 0.0125 0.290–0.0100 0.430 Ỉ 0.0125 0.455–0.0125 0.600 Ỉ 0.0125 0.595–0.0150 0.800 Ỉ 0.0125 TABLE 16-17 Triangular groove dimensions for O-ring flange gaskets Groove width, b, mm Minimum diametral squeeze mm Bottom radius, R1 , mm 0.025 0.030 0.035 0.040 0.045 0.050 0.060 0.075 0.100 0.0125 0.0200 0.0300 0.0380 0.0380 0.0500 0.0750 0.1250 0.1500 0.0175 0.025 0.030 0.035 0.038 0.043 0.050 0.065 0.090 0.0125 0.0200 0.0300 0.0380 0.0380 0.0500 0.0750 0.1250 0.1500 TABLE 16-18 Packing sizes recommended for various shaft diameters Shaft diameter, mm O-ring nominal cross section, mm Actual O-ring cross section, mm Width, h, mm 1.6 2.4 3.2 4.8 6.4 0:175 Ỉ 0:0075 0:260 Ỉ 0:0075 0:350 Ỉ 0:0100 0:530 Ỉ 0:0125 0:700 Ỉ 0:0150 Packing size, mm 12.70–15.85 17.45–38.10 39.70–50.80 52.40–63.50 65.10–76.20 77.80–101.60 7.95 9.50 11.10 12.70 14.30 15.85 0:240 ỵ 0:0075 0:000 0:345 ỵ 0:0125 0:000 0:470 ỵ 0:0175 0:000 0:710 ỵ 0:0255 0:000 0:950 ỵ 0:0375 0:000 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS PACKINGS AND SEALS 16.23 TABLE 16-19 Temperature limits for gasket materials Maximum sustained temperature Material K 8C Asbestos fiber and rubber Cellulose-fiber and rubber Cork and rubber Synthetic rubber Cork composition 673 423 393 393 393 400 150 120 120 120 TABLE 16-21 Selection of shaft piston seals Type name Distributor External-fitted to piston, sealing in bore Internal-fitted in housing, sealing on piston or rod Simple housing design Low wear rate High stability Low friction Resistance to extrusion Availability in small sizes Availability in large sizes Bidirectional sealing U-Ring Cup O-Ring Good Very good Good Fair Good Fair Good Good Good Fair Fair Good Good Fair Single acting only Poor Good Very good Fair Good Poor Good Very good Poor Poor Good Fair Very good Good Effective but usually used in pairs FIGURE 16-15 Nomenclature of gasketed joint (J E Shigley and C R Mischke, Standard Handbook of Machine Design, McGraw-Hill, 1986.) Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website 0.34–2.94 50–425 27.46–48.05 4000–7000 0.29–0.53 17.16–20.59 2500–3000 0.49–4.90 Acrylic Polyester Polyurethane-bitumen modified Butyls—mastic type Butyls—curing type Polybutene Olcoresin a 8.33–24.02 Epoxy–modified 5–20 5–150 650–800 250–400 100–270 3–15 10–20 50–750 250–350 75–125 325 3.0–6.0 150–500 0.17–0.27 0.34–0.69 0.15–0.44 0.34–0.59 0.44–0.69 Elongation %, ASTM D412 MPa 24.5–40 50–100 15–65 50–85.5 65–100 psi Adhesion in tension, ASA 1161-1960 1.03–1.873 150–270 10.79–23.54 1500–3400 1500–2750 40–100 125–175 1500–3500 0.27–0.69 0.85–1.20 10.29–24.0 10.29–19.1 80–175 240–350 150–200 psi 0.55–1.20 1.72–2.40 1.03–1.37 MPa Shear strength, ASTM D1002 Compounds built specifically for plotting and molding, where high strength and abrasion resistance are required 70–710 42–75 1200–3500 56.5–125 1000–3000 285–780 1000–1500 500–600 1210 4000–13000 0.39–0.86 6.86–20.50 1.96–5.39 6.86–10.29 3.43–4.11 8.33 27.46–89.73 Polysulfide Polyurethanea Silicone Ncoprene Hypalon Viton Epoxy psi MPa Tensile strength, ASTM D412 Sealant base test method TABLE 16-20 Properties of sealants 0.5–5.0 0.25–1.5 0.75–1.50 1.0–5.0 0.25–0.75 0.27–0.50 0.25–1.5 1–3.0 0–1–0.25 0.5–1.5 1.0–5.0 0–3.0 0.04–0.10 Good Good Good Good Good Fair to good Good Good to excellent Fair to good Excellent Fair to good Excellent Excellent Fair to good Good to excellent Moisture resistance, % Abrasion ASTM D570 resistance –30 to 120 –25 to 95 –20 to 95 –60 to 150 –35 to 95 –25 to 150 –55 to 150 –35 to 150 –50 to 120 –55 to 205 –75 to 370 –40 to 150 –40 to 150 –55 to 230 –35 to 150 Operating temperature 8C 20–40 5–70 5–70 15–75 0–3.0 l5–45 15.0–15.0 0–3.0 5.0–15.0 2.0–10.0 0–3.0 0–3.0 Shore ‘‘D’’ 40–60 Shore ‘‘D’’ 40–100 10–70 Shore ‘‘D’’ 10–45 0–3.0 0–3.0 0–10.0 0–10.0 0–10.0 10–20 Shrinkage 15–60 45–90 25–80 30–80 30–80 40–60 40–100 Shore A hardness ASTM 676 PACKINGS AND SEALS Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS PACKINGS AND SEALS TABLE 16-22 Recommended maximum temperature for materials (supplement to Table 16-2) TABLE 16-22 Recommended maximum temperature for material (supplement to Table 16-2) Temperature 8F Material Coil spring material Phosphor-bronze ASTM B159 Silicon bronze ASTM B99 Ni-span C902 Music wire ASTM A228 Hard-drawn spring wire ASTM A227 Oil-tempered wire ASTM A229 Valve spring wire ASTM A230 Beryllium-copper ASTM B197 Chrome-vanadium alloy steel AISI 6150 Silicon-manganese alloy steel AISI 9260 Chrome-silicon alloy steel AISI 9254 Martensite AISI 410 Martensite AISI 420 Austenitic AISI 301 Austenitic AISI 302 17-7 PH Stainless Steel Inconel6OO Nickel-chrome alloy steel A286 Inconel 7l8 Inconel X-750 L-605 S-816 Rene 41 Flat spring material Ni-span C902 Phosphor-bronze ASTM B103 High-carbon AISI 1050 High-carbon AISI 1065 High-carbon AISI 1075 High-carbon AISI 1095 Beryllium-copper ASTM B194 Austenitic AISI 301 Austenitic AISI 302 17-7 PH Stainless Steel Inconel 600 Beryleo-nickel Titanium 6-6-2 Sandvik 11 R51 Duranickel 301 Permanickel Elgiloy Havar Inconel 7l8 Inconel X-750 Rene 41 8C 200 200 200 250 250 300 300 400 425 450 475 500 500 600 600 590 700 950 1200 1300 1400 1400 1400 93 93 93 121 121 149 149 204 218 232 246 260 260 315 315 311 371 510 649 704 760 760 760 200 200 200 200 250 250 400 600 600 700 700 700 750 800 800 800 900 900 1200 1300 1400 16.25 Temperature 93 93 93 93 121 121 204 315 315 371 371 371 399 427 427 427 482 482 649 704 760 Material Formed metal bellows materials Brass CDA 240 Phosphor-bronze CDA 510 Beryllium-copper CDA 172 Monel 404 Unstabilized 300 series stainless steel Inconel 600 Inconel X-750 Welded metal bellows materials Ni-span C AM-350 Stainless Steel 410 Stainless Steel Commercially pure titanium Stabilized 300 series Stainless Steel Inconel X-750 Inconel 625 Hastelloy-C Rene 41 8F 8C 300 300 350 450 500 750 800 149 149 177 232 260 399 427 500 800 800 800 1220 1500 1500 1800 1800 260 427 427 427 659 815 815 982 982 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS 16.26 CHAPTER SIXTEEN TABLE 16-23 pv values for seal face material (life of 8000 h) pv Value Unbalanced Product Water Oil Water Oil Water Oil Water Oil Water Water Oil Combination face material Stainless steel Carbona Lead bronze Carbona Stellite carbona Tungsten carbide Carbonb Solid ceramic Sprayed ceramic o o o Balanced MPa, m/s kpsi fpm MPa, m/s kpsi fpm 0.9 1.8 1.8 3.5 3.5 9 15 15 20 25.5 51.0 51.0 100 100 Seldom used Seldom used Seldom used Seldom used 10 70 25 150 Seldom used 90 150 Seldom used Seldom used Seldom used Seldom used 285 2000 710 4280 Seldom used 2570 4280 255 255 430 430 560 a Metal-impregnated carbon Retain impregnated carbon Source: Courtesy M J Neale, Tribology Handbook, Butterworths, London, 1973 b TABLE 16-24 Spring arrangements for various sizes of shaft and speeds Spring arrangement Stationary Rotary Shaft diameter, mm Speed, rpm Single Multiple Single Multiple 100 >100 75 100 >100 3000 3000 4500 >4500 >4500 Yes No Yes Yes No Yes Yes Yes Yes Yes Yes No Yes No No Yes Yes Yes No No Source: Courtesy of M J Neale, Tribology Handbook, Butterworths, London, 1973 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS PACKINGS AND SEALS 16.27 TABLE 16-25 Types of static and dynamic seals Dynamic seals Clearance seals Static seals Reciprocating Fibrous gasket Metallic gasket Elastomeric gasket Plastic gasket Sealant, setting Sealant, nonsetting O-ring Inflatable gasket Pipe coupling Bellows a Labyrinth (Fig 16-8) Fixed bushing Floating bushing Contact seals Rotary Reciprocating Rotary Labyrinth (Fig 16-8) Viscoseal Fixed bushing Floating bushing Centrifugal seal U-ring (Fig 16-11) O-ring (Table 16-15) Lobed O-ring Rectangular ring Packed gland Piston ring Bellows Diaphragm (Fig 16-12) Lip seal (Fig 16-4) Face seal (Fig 16-9a) Packed gland (Fig 10-10) O-ringb (Fig 16-14) Felt ring a Usually for steam or gas Only for very slow speeds Source: Courtesy M J Neale, Tribology Handbook, Butterworths, London, 1973 b TABLE 16-26 Operating conditions of lip seals Shaft diameter and housing Particular TABLE 16-27 Types of seals for reciprocating shafts Type of packing Remarks Remarks Cups and hats Maximum pressure of fluid 75 mm diameter 60 kPa (8.7 psi) >75 mm diameter 35 mm diameter Maximum speed Surface finish Eccentricity 30 kPa (4.35 psi) 8000 rpm 75 mm diameter >75 mm diameter Housing Shaft 4000 rpm 15 m/s Fine-turned Grind and polish to better than 0.5 mm 0.25 mm total indicator reading Depends on speed, 0.25 mm Varies from À208C to 2008C (À688F to 2668F) Housing Shaft Temperature Semiautomatic, leather and rubber/ fabric used U-packing Used for piston rod application up to 10 MPa (1.5 kpsi) (rubber) or 20 MPa (3.0 kpsi) (rubber/fabric) Nylon-supported Used up to 25 MPa (3.6 kpsi) Composite Used with rubber sealing lips, rubber/ fabric supporting portions and nylon wearing portions—used for pressure varying from 15 to 20 MPa (2.2 to 3.0 kpsi) Source: M J Neale, Tribology Handbook, Butterworths, London, 1973 Source: M J Neale, Tribology Handbook, Butterworths, London, 1973 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS 16.28 CHAPTER SIXTEEN TABLE 16-28 Materials for lip seals (rubber) Resistance to Temperature 8F 8C Type of rubber Trade names Mineral oil Chemical fluids Acrylate Thiacril Cyanacryl Viton Fluorel Silastic Silastomer Hycar Polysar Excellent Fair 68 to ỵ266 20 to ỵ130 Excellent Excellent 77 to ỵ392 25 to ỵ200 Fair Poor 158 to ỵ392 70 to ỵ200 Excellent Fair 104 to ỵ212 40 to ỵ100 Fluoropolymer Polysiloxane Nitrile Source: Courtesy M J Neale, Tribology Handbook, Butterworths, London, 1973 TABLE 16-29 Seal materials for reciprocating shafts Material Remarks Rubber (nitrile) Highest scaling efficiency; low cost; easily formed to shape; limited to a pressure of 10 MPa (1.5 kpsi); excellent wear resistance RubberGreat toughness; resistance to extrusion impregnated and cutting; wear resistance inferior to fabric rubber Leather Good wear and extrusion resistance; poor resistance to permanent set; limited shaping capability Nylon Resist extrusion; provide a good bearing surface Source: Courtesy M J Neale, Tribology Handbook, Butterworths, London, 1973 TABLE 16-30 Extrusion clearance for reciprocating shafts—dimensions in mm (in) 10 MPa (1.5 kpsi) 10–20 MPa (1.5–3.0 kpsi) >20 MPa (3.0 kpsi) Material Normal Short life Normal Short life Normal Short life Rubber Rubber/fabric leather Polyurethane Nylon support 0.25 (0.01) 0.40 (0.015) 0.40 (0.015) — 0.50 (0.02) 0.60 (0.025) 0.60 (0.025) — — 0.25 (0.01) 0.25 (0.01) 0.25 (0.01) — 0.50 (0.02) 0.50 (0.02) 1.00 (0.04) — 0.10 (0.005) 0.10 (0.005) 0.10 (0.005) — 0.25 0.01) 0.25 (0.01) 0.25 (0.01) Source: Courtesy M J Neale, Tribology, Handbook, Butterworths, London, 1973 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website 250 300 300 0.700 0.525 7.000 1.750 2.100 2.100 Graphited asbestos with latern ring and jacket cooling arrangement—rotary type Graphited asbestos with PTFE antiextrusion ring hand surface replaceable sleeve, jacket cooling arrangement—rotary type Graphited asbestos and PTFE yarn with PTFE antiextrusion ring, jacket cooling arrangement—rotary type Reciprocating, steam-graphited asbestos Reciprocating, water-greased cotton packing Reciprocating, oil-graphited hemp yam Source: Courtesy M J Neale, Tribology Handbook, Butterworths, London, 1973 1000 0.280 Graphited asbestos with latern ring cooling arrangement—rotary type 75 100 40 15 0.105 Graphited asbestos—rotary type psi MPa Pressure Type of gland TABLE 16-31 Operation conditions of packed glands (Fig 16-1) 500 500 200 545 290 320 240 200 8F 260 260 93 285 143 160 115 93 8C Temperature 0.75 0.75 0.75 (150) 5.5 (1080) 306 (6100) 17.75 (4000) 17.75 (4000) 17.75 (4000) Velocity, m/s (fpm) Steam Water Oil No latern or jacket ring cooling required Cooling liquid used below 34.5 kPa sealing pressure Latern ring cooling liquid and water to jacket cooler used below sealing pressure of 34.5 kPa Cooling as per type 3; special packing and accurate assembly is required Water to jacket coolant used Remarks PACKINGS AND SEALS Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website 16.29 PACKINGS AND SEALS 16.30 CHAPTER SIXTEEN TABLE 16-32 Axial stress in packed glands TABLE 16-33 Selection of number of sealing rings Minimum axial stress required for seal packing Type of packing MPa psi Teflon-impregnated braided asbestos Plastic Braided vegetable fiber, lubricated Plaited asbestos, lubricated Braided metallic 1.40 200 1.12 1.75 2.8 3.5 160 255 405 505 Pressure MPa psi Number of sets of sealing rings 1.0 1.0–2.0 2.0–5.0 3.5–17.0 7.0–15.0 >15.0 150 (150–250) 250–500 500–1000 1000–2000 above 2000 9–12 Source: Courtesy M J Neale, Tribology Handbook, Butterworths, London, 1973 Source: Courtesy M J Neale, Tribology Handbook, Butterworths, London, 1973 TABLE 16-34 Selection of packing materials Material Hardness of rod, HB Axial clearance, mm Lead bronze 250 0.08–0.12 (0.003–0.005 in) Flake graphite gray cast iron White metal (Babbitt) 400 0.08–0.12 Filled PTFE 400 Reinforced pf resin Carbon-graphite Graphite/metal sinter 0.08–0.12 0.4–0.5 0.25–0.5 400 0.030–0.06 250 0.08–0.12 Application Optimum material with good lubricated bearing property High thermal conductivity; used where chemical condition exists and suited for pressure up to 300 MPa (50 kpsi) Cheaper suitable up to a pressure of MPa (1.0 kpsi) Used where lead-bronze and flake graphite gray cast iron are not suitable because of chemical condition; used up to a maximum pressure of 35 MPa (5.0 kpsi) and maximum temperature 1208C (2508F) Suitable for unlubricated; very good chemical resistance; suited above 2.5 MPa (400 psi) Used with sour hydrocarbon gases and where lubricant may be thinned by solvents in gas stream Used with carbon-graphite piston rings; must be kept oil free; used up to 3508C (6608F) Alternative to filled PTFE and carbon-graphite Source: Courtesy M J Neale, Tribology Handbook, Butterworths, London, 1973 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS TABLE 16-35 Minimum recommended seating stresses for various gasket materials (Supplement to Table 16-8) Material, mm (in) Flat Stainless steel Jacketed metalasbestos Flat with rubber beads Flat 241–655 Aluminum (soft) Copper (soft) Carbon steel (soft) Stainless steel Aluminum Copper Carbon steel Stainless steel Aluminum Copper Carbon steel Stainless steel Aluminum Copper Carbon steel Stainless steel Stainless steel Corrugated Corrugated Corrugated Corrugated Profile Profile Profile Profile Plain Plain Plain Plain Corrugated Corrugated Corrugated Corrugated Spiral-wound Minimum seating stress range (psia) MPa Flat Carbon steel Metallic Asbestos fiber sheet 3.125 (1 in) thick 1.563 (16 in) thick 0.78 (32 in) thick Asbestos fiber sheet 0.78 (32 in) thick Asbestos fiber sheet 0.78 (32 in) thick Asbestos fiber sheet 0.78 (32 in) thick Cellulose fiber sheet Cork composition Cork-rubber Fluorocarbon (TFE) 3.125 (1 in) thick 1.563 (16 in) thick 0.78 (32 in) thick Nonasbestos fiber sheets (glass, carbon, aramid, and ceramics) Rubber Rubber with fabric or metal reinforcement Aluminum Copper Nonmetallic Gasket type Flat with metal grommet Flat with metal grommet and metal wire Flat Flat Flat Flat Flat Flat Flat with reinforcement Flat Flat (1400–1600) 9.7–11.0 (3500–3700) 24.1–25.5 (6000–6500) 41.4–44.8 (1000–1500 lb/in) on beads 175–263 kN/m (3000–4000 lb/in) on grommet 525.4–700.5 kN/m (2000–3000 lb/in) on wire 350.2–525.4 kN/m (750–1100) 5.2–7.6 (400–500) 2.8–3.5 (200–300) 1.4–2.1 (1500–1700) 10.3–11.7 (3500–3800) 24.1–26.2 (6200–6500) 42.8–44.8 (1500–3000) depending on composition 10.3–20.7 (100–200) 0.7–1.4 (300–500) 2.1–3.5 (10,000–20,000) 68.9–137.9 (15,000–45,000) 103.4–310.3 depending on hardness (30,000–70,000) 207–483 depending on alloy and hardness (35,000–95,000) 241–655 depending on alloy and hardness (1000–3700) 6.9–25.5 (2500–4500) 17.2–31.0 (3500–5500) 24.1–37.9 (6000–8000) 41.4–55.2 (25,000) 172.4 (35,000) 241.3 (55,000) 379.2 (75,000) 517.1 (2500) 17.2 (4000) 27.6 (6000) 41.4 (10,000) 68.9 (2000) 13.8 (2500) 17.2 (3000) 20.7 (4000) 27.6 (3000–30,000) 20.7–206.8 a Stresses in pounds per square inch except where otherwise noted Source: J E Shigley and C R Mischke, Standard Handbook of Machine Design, McGraw-Hill Book Company, New York, 1986 16.31 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PACKINGS AND SEALS 16.32 CHAPTER SIXTEEN TABLE 16-36 Safety factors for gasketed joints, n, for use in Eq (16-39) Safety factor, n When to apply 1.2 to 1.4 For minimum-weight applications where all installation factors (bolt lubrication, tension, parallel seating, etc.) are carefully controlled; ambient to 2508F (1218C) temperature applications; where adequate proof pressure is applied For most normal designs where weight is not a major factor, vibration is moderate and temperatures not exceed 7508F (3998C); use high end of range where bolts are not lubricated For cases of extreme fluctuations in pressure, temperature, or vibration; where no test pressure is applied; or where uniform bolt tension is difficult to ensure 1.5 to 2.5 2.6 to 4.0 Source: J E Shigley and C R Mischke, Standard Handbook of Machine Design, McGraw-Hill Book Company, New York, 1986 FIGURE 16-16 Packing assembly for a mechanical piston rod (M J Neale, Tribology Handbook, Butterworths, London, 1973.) FIGURE 16-17 Ratio of retained stress to origins versus shape factor for, various materials: A—asbestos sheet; B— cellulose; C—cork-rubber (J E Shigley and Mischke, Standard Handbook of Machine Design, McGraw-Hill, 1986.) 16.32 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website ... 0.3 19 22 24 26 32 35 40 47 10 11 22 26 0.3 24 — 0.3 12 22 24 28 30 0.3 35 37 40 47 25 — 0.4 24 28 30 35 35 40 42 47 52 26 7 — 0.4 24 26 30 32 35 37 42 47 28 40 47 52 — 0.4 16 28 30 32 35 0.3... 320 340 360 380 400 420 440 460 480 500 1 1 1 1 1 1 320 340 360 380 400 420 440 460 480 500 520 540 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 a For limits of housing,... Baume ´ Fuel oil, 24 8 Baume Spindle oil Machine oil Castor oil 29 3 29 3 27 3 29 3 29 3 29 3 29 3 29 3 29 3 29 3 29 3 20 20 20 20 20 20 20 20 20 20 0.0097 0.018 1.79 1.0 0.6 2. 7 5.0 40 20 –35 20 0–500 1000 0.0097