4145h 钻铤 drill collar number and connection label outside diameter inside diameter length bevel diameter reference bending strength ratio (mm) (mm) (mm) (mm) (mm) (mm) nc23-31 79.4 3 1/8 31.8 1 1/4 9150 76.2 2.57:1 nc26-35(2 3/8if) 88.9 3 1/2 38.1 1 1/2 9150 82.9 2.42:1 nc31-41(2 7/8if) 104.8 4 1/8 50.8 2 9150 100.4 2.43:1 nc35-47 120.7 4 3/4 50.8 2 9150 114.7 2.58:1 nc3850(3 1/2if) 127.0 5 57.2 2 1/4 9150 121.0 2.38:1 nc44-60 152.4 6 57.2 2 1/4 9150or9450 144.5 2.49:1 nc44-62 158.8 6 1/4 57.2 2 1/4 9150or9450 149.2 2.91:1 nc46-62(4if) 158.8 6 1/4 71.4 2 13/16 9150or9450 150.0 2.63:1 nc46-65(4if) 165.1 6 1/2 57.2 2 1/4 9150or9450 154.8 2.76:1 nc46-65(4if) 165.1 6 1/2 71.4 2 13/16 9150or9450 154.8 3.05:1 nc46-67(4if) 171.4 6 3/4 57.2 2 1/4 9150or9450 159.5 3.18:1 nc50-67(4 1/2if) 171.4 6 3/4 71.4 2 13/16 9150or9450 159.5 2.37:1 nc50-70(4 1/2if) 177.8 7 57.2 2 1/4 9150or9450 164.7 2.54:1 nc50-70(4 1/2if) 177.8 7 71.4 2 13/16 9150or9450 164.7 2.73:1 nc50-72(4 1/2if) 184.2 7 1/4 71.4 2 13/16 9150o