跨距计算原理.doc

2.按强度条件计算允许跨距一般工业管道按强度条件计算允许跨距，如表2-2所示，表2-2 按强度条件计算允许跨度序号项目内容1计算原则管道自重弯曲应力不应超过管材的许用外载弯曲应力值，以保证管道的安全，根据这原则确定管道允许跨距，称为按强度条件计算的管道允许跨距2计算方法对于连续敷设、均布荷载的水平直管，如图2-1所示，管道（或管架）的最大允许跨距，可按下列公式计算，即式中，管道或管架最大允许跨度m，管道单位长度计算荷载（N/m），=管材重+保温重+附加重，如表2-4、表2-5所示。管道截面抗弯截面系数（cm3,）如表15-15（726/709）所示，管道横向焊缝系数，如表2-6所示钢管热态许用应力（N/mm2），如图15-8（717/700）所示。3.按刚度条件计算允许跨距一般工业管道按刚度条件计算允许跨距，如表2-3所示，表2-3 按刚度条件计算允许跨度序号项目内容1计算原则管道在一定跨度下总有一定的挠度，由管道自重产生的弯曲挠度不应超过管道跨距的0.005（当疏水、放水坡度=0.002时）。根据对挠度的限制所确定的管道允许跨距叫做按刚度条件计算的管道允许跨距。2计算方法对于连续敷设、均布荷载的水平直管，如图2-1所示，管道（或管架）的最大允许跨距，可按下列公式计算，即式中，管道或管架最大允许跨度m，管道单位长度计算荷载（N/m），=管材重+保温重+附加重，如表2-4、表2-5所示。在计算温度下钢材弹性模量（N/mm2），如表4-20所示，管道截面惯性距，如表15-15所示管道放水坡度，。表2-4 不保温管道单位长度计算荷载序号公称通径/mm外壁壁厚/mm管道重/（kg/m）凝结水重/（kg/m）管内充满水重/（kg/m）不保温管单位计算荷载气管体/（N/m）液管体/（N/m）11518*222.30.7891.410.0400.040.200.208.1314.229.7015.7922025*2.528*31.391.850.0620.0660.310.3314.2418.8316.6721.3832532*332*3.52.152.460.110.100.530.4922.1625.1026.2828.9343238*338*3.52.592.980.160.150.800.7626.9730.6933.2536.6754045*345*3.53.113.580.240.2241.201.1332.8537.3142.2746.1965057*3.557*44.625.190.390.381.961.8849.1354.6364.5369.3476573*3.573*46.006.810.680.663.423.3265.5173.2592.3899.3388089*48.381.035.1592.28132.689100108*410.261.187.85112.19177.6010125133*412.731.8412.27142.88245.1711150159*4.517.152.6517.67194.17341.4612200219*631.525.0533.65358.62639.0913250273*745.927.9052.69527.79967.0314300325*862.5411.2574.99723.621348.6915350377*7377*8377*963.8772.8081.6815.5215.3515.15103.5102.1101.0778.54864.45949.571641.321718.111791.4616400426*7426*8426*972.3382.4792.5520.019.8019.61133.3132.0130.70905.441002.921099.912016.522103.212189.3217450487*7478*8478*981.3192.73104.1025.1025.2025.0208.30206.70205.101190.121312.201433.522926.373035.213143.1918500500*7500*8500*990.11102.81115.1231.2531.0030.76208.30206.70205.101190.121312.201433.522926.373035.213143.1919600630*9630*10630*11137.81152.89167.9144.1043.8043.52294.0292.0290.01783.911928.852073.404234.574362.844490.52注：表中，不保温管计算荷载为气管体=（管材重+凝结水重）*9.81液管体=（管材重+管内充满水重）*9.81表2-5 保温管道保温结构单位长度重量序号公称通径/mm外壁壁厚/mm保温结构单位长度重量/（kg/m）质量密度150kg/m3质量密度250kg/m310015020025030010015020011522*30.870.871.941.942.601.451.453.2322028*30.960.962.072.783.571.601.603.4132532*30.991.022.812.883.721.652.584.8043238*31.111.113.063.063.891.752.785.1054045*31.201.203.264.134.132.002.985.4365057*3.51.572.013.594.525.732.283.357.5376573*41.592.335.046.156.153.885.238.4088089*41.832.635.856.758.014.385.8511.259100108*42.12.996.207.478.494.986.612.4010125133*42.523.458.409.8911.455.757.5814.0011150159*4.53.955.169.3910.9812.686.588.618.3012200219*65.096.5711.6615.4517.5710.9813.6328.8513250273*76.127.5815.8318.020.3413.0816.1830.0814300325*87.079.0818.0320.5525.7315.1318.6334.1815350377*98.0610.2920.2425.828.6616.5621.0842.9516400426*98.9411.4522.3125.3531.4417.5823.3847.1817450478*99.9612.6827.7131.0537.8621.1330.7551.6818500529*910.9213.8830.1133.6040.9823.1355.5056.0819600630*1112.8319.8034.9043.047.227.139.071.63（续）序号公称通径/mm外壁壁厚/mm保温结构单位长度重量/（kg/m）质量密度250kg/m3质量密度350kg/m325030010015020025030011522*34.335.62.223.157.849.8412.0822028*35.955.952.423.4310.4012.6715.1932532*36.157.682.313.6110.7513.0615.6143238*38.058.053.895.3911.2716.2818.9054045*38.488.484.175.7814.3517.0519.9565057*3.59.2311.14.696.4415.5421.4224.6876573*412.2314.385.439.4520.1323.3530.4588089*413.3515.638.1910.525.2728.9132.739100108*417.2519.79.2411.7627.5835.3539.7310125133*419.0021.8510.6116.7634.6938.8548.3411150159*4.524.124.8515.1218.4138.1547.657.8912200219*629.2532.90190827.2051.3162.6574.3913250273*738.042.1822.6531.9265.1078.0591.5614300325*843.047.4831.1936.4077.094.3106.6915350377*952.7557.9535.2817.2588.59103.95120.5416400426*957.7568.3338.9652.1596.64121.8139.8617450478*963.069.0542.9557.05114.0132.3151.3118500529*968.2581.1846.8762.30123.0142.43172.9419600630*1185.7893.154.6472.24151.41173.39196.28注：计算依据：1.100150为室外架空热水采暖管道； 2.200300为室外架空蒸汽管道；表2-6 管子强度焊缝系数横向焊缝系数纵向焊缝系数焊接情况焊接情况手工有垫环对焊0.9手工无垫环对焊0.7直缝焊接钢管0.8手工双面加强焊0.95螺旋焊接钢管0.6自动双面焊1.0无缝钢管1.0自动单面焊0.8表4-20常用钢材的弹性模量和线膨胀系数钢号Q235A102020g16Mn16Mng15MnV15MnVg弹性模量/*105（N/mm2）线膨胀系数设计温度20100150表15-15管道计算数据P49表2-16水平管及