ΠΑΡΑΡΤΗΜΑ 1 ΠΙΝΑΚΕΣ ΓΙΑ ΙΑΤΡΗΤΙΚΑ ΣΤΕΛΕΧΗ & ΣΥΝ ΕΣΜΟΥΣ

ΠΑΡΑΡΤΗΜΑ 1 ΠΙΝΑΚΕΣ ΓΙΑ ΙΑΤΡΗΤΙΚΑ ΣΤΕΛΕΧΗ & ΣΥΝ ΕΣΜΟΥΣ

diameter Wall thickness Πίνακας Π1.1. Γεωµετρικά χαρακτηριστικά διατρητικών στελεχών D Crosssection (mm 2 ) Polar moment of inertia (mm 4 ) Polar modulus (mm 3 ) Upset and grade Type of tool Tool OD Tool D Approximate including tool (kg/m) 2 3/8 (60.33 mm) 2 7/8 (73.03 mm) 3 1/2 (88.90 mm) 4 (101.60 mm) 4.85 4.83 1.995 50.67 842 653 421 21 662 6.65 7.11 1.815 46.11 1 189 856 775 28 403 6.85 5.51 2.441 62.01 1 169 1 340 977 36 724 10.40 9.19 2.151 54.65 1 843 1 916 866 52 495 9.50 6.45 2.992 76.00 1 671 2 856 744 64 269 13.30 9.35 2.764 70.20 2 337 3 747 837 84 316 11.85 6.65 3.476 88.30 1 984 4 492 846 88 442 14.00 8.38 3.340 84.84 2 454 5 374 730 105 802 EU E NC26 (F) 85.7 44.5 7.89 5.30 EU E WO 85.7 50.8 7.59 5.10 EU E OH 79.4 50.8 7.29 4.90 EU E SL-H90 82.6 50.8 7.44 5.00 EU E NC26 (F) 85.7 44.5 10.43 7.01 EU E OH 82.6 44.5 10.27 6.90 U E PAC 73.0 34.9 10.12 6.80 EU X NC26 (F) 85.7 44.5 10.57 7.10 EU X SL-H90 82.6 46.0 10.42 7.00 EU G NC26 (F) 85.7 44.5 10.57 7.10 EU G SL-H90 82.6 46.0 10.42 7.00 EU E NC31 (F) 104.8 54.0 11.16 7.50 EU E WO 104.8 61.9 10.86 7.30 EU E OH 95.3 61.9 10.27 6.90 EU E SL-H90 98.4 61.9 10.57 7.10 EU E NC31 (F) 104.8 54.0 16.21 10.90 EU E OH 98.4 54.8 15.78 10.60 EU E SL-H90 98.4 54.8 15.78 10.60 U E XH 108.0 47.6 16.67 11.20 U E NC26 85.7 44.5 15.48 10.40 U E PAC 79.4 39.1 15.33 10.30 EU X NC31 (F) 104.8 50.8 16.50 11.09 EU X SL-H90 98.4 54.8 16.22 10.90 EU G NC31 (F) 104.8 50.8 16.50 11.09 EU G SL-H90 101.6 50.8 16.22 10.90 EU S NC31 (F) 111.1 41.3 17.19 11.55 EU S SL-H90 104.8 41.3 16.82 11.30 EU E NC38 (F) 120.7 68.3 15.38 10.34 EU E NC38 (WO) 120.7 76.2 15.33 10.30 EU E OH 114.3 76.2 14.88 10.00 EU E SL-H90 117.5 76.2 15.18 10.20 EU E NC38 (F) 120.7 68.3 20.76 13.95 EU E OH 120.7 68.3 20.76 13.95 U E XH 120.7 61.9 21.13 14.20 U E NC31 (SH) 104.8 54.0 20.24 13.60 EU X NC38 (F) 127.0 65.1 21.75 14.61 EU X SL-H90 120.7 65.1 21.13 14.20 EU G NC38 (F) 127.0 61.9 21.89 14.71 EU G SL-H90 120.7 65.1 21.13 14.20 EU S NC38 (F) 127.0 54.0 22.21 14.92 EU S SL-H90 127.0 54.0 22.21 14.92 EU S NC40 (4FH) 136.5 61.9 22.77 15.30 EU E NC38 (F) 127.0 65.1 24.65 16.57 EU X NC38 (F) 127.0 61.9 25.05 16.83 EU G NC38 (F) 127.0 54.0 25.37 17.05 EU S NC40 (FH) 139.7 57.2 26.47 17.78 EU E NC46 (F) 152.4 82.6 20.09 13.50 EU E NC46 (WO) 146.1 87.3 19.79 13.30 EU E OH 133.4 88.1 18.10 12.10 U E H90 139.7 71.4 19.50 13.10 EU E NC46 (F) 152.4 82.6 23.64 15.89 EU E OH 139.7 82.6 22.32 15.00 U E NC40 (FH) 139.7 71.4 22.39 15.04 U E SH 117.5 65.1 21.43 14.40 EU X NC46 (F) 152.4 82.6 24.09 16.19 U X NC40 (FH) 133.4 68.3 22.73 15.27 U X H90 139.7 71.4 23.22 15.60 EU G NC46 (F) 152.4 82.6 24.09 16.19 U G NC40 (FH) 139.7 61.9 23.59 15.85 U G H90 139.7 71.4 23.22 15.60 EU S NC46 (F) 152.4 76.2 24.43 16.42 U S NC40 (FH) 139.7 50.8 24.00 16.13 U S H90 139.7 81.4 23.22 15.60 mm x 0.0394 = in mm 2 x 0.00155 = in 2 mm 3 x 6.10 10 5 = in 3 mm 4 x 2.4 10-6 = in 4 1

diameter Wall thickness Πίνακας Π1.1. Γεωµετρικά χαρακτηριστικά διατρητικών στελεχών D Crosssection (mm 2 ) Polar moment of inertia (mm 4 ) Polar modulus (mm 3 ) Upset and grade Type of tool Tool OD Tool D Approximate including tool (kg/m) 4 1/2 (114.30 mm) 13.75 6.88 3.958 100.54 2 322 6 725 300 117 678 16.60 8.56 3.826 97.18 2 844 8 000 523 139 992 20.00 10.92 3.640 95.46 3 547 9 581 665 167 658 EU E NC50 (F) 161.9 95.3 22.37 15.03 EU E NC50 (WO) 155.6 98.4 22.03 14.80 EU E OH 146.1 100.8 20.98 14.10 U E H90 152.4 82.6 22.62 15.20 EU E NC50 (F) 161.9 95.33 26.77 17.99 EU E OH 149.2 95.3 17.10 EU E NC46 (F) 158.8 82.6 27.33 18.37 EU E FH 152.4 76.2 26.99 18.14 EU E H90 152.4 82.6 26.64 17.90 EU E NC38 (SH) 127.0 68.3 25.00 16.80 EU X NC50 (F) 161.9 95.3 27.33 18.36 EU X NC46 (XH) 158.8 76.2 27.70 18.61 EU X FH 152.4 76.2 27.02 18.16 EU X H90 152.4 82.6 26.79 18.00 EU G NC50 (F) 161.9 95.3 27.33 18.36 EU G NC46 (XH) 158.8 76.2 27.70 18.61 EU G FH 152.4 76.2 27.02 18.16 EU G H90 152.4 82.6 26.79 18.00 EU S NC50 (F) 161.9 88.9 27.71 18.62 EU S NC46 (XH) 158.8 69.9 28.02 18.82 EU S FH 158.8 63.5 28.30 19.02 EU S H90 152.4 76.2 27.02 18.16 EU E NC50 (F) 161.9 92.1 32.19 21.63 EU E NC46 (XH) 158.8 76.2 32.91 22.12 EU E FH 152.4 76.2 32.94 21.66 EU E H90 152.4 76.2 32.24 21.66 EU X NC50 (F) 161.9 88.9 32.883 22.09 EU X NC46 (XH) 158.8 69.9 33.66 22.62 EU X FH 152.4 63.5 33.25 22.35 EU X H90 152.4 82.6 32.29 21.70 EU G NC50 (F) 161.9 88.9 32.88 22.09 EU G NC46 (XH) 158.8 63.5 33.94 22.81 EU G FH 152.4 63.5 33.25 22.35 EU G H90 152.4 76.2 32.59 21.90 EU S NC50 (F) 168.3 76.29 34.31 23.06 EU S NC46 (XH) 158.8 57.2 34.20 22.98 5 (127 mm) 19.50 9.19 4.276 108.62 3 401 11 873 714 186 988 EU E NC50 (XH) 161.9 95.3 31.06 20.87 EU E 5 1/2 FH 177.8 95.3 33.19 22.30 EU X NC50 (XH) 161.9 88.9 31.83 21.39 EU X 5 1/2 FH 177.8 95.3 33.58 22.56 EU G NC50 (XH) 165.1 82.6 32.55 21.87 EU G 5 1/2 FH 177.8 95.3 33.58 22.56 25.60 12.70 4.000 101.60 4 560 15 078 604 237 458 EU S NC50 (XH) 168.3 69.9 33.57 22.56 EU S 5 1/2 FH 184.2 88.9 34.86 23.42 EU E NC50 (XH) 161.9 95.3 40.00 26.88 EU E 5 1/2 FH 177.8 95.3 42.12 28.30 EU X NC31 (F) 104.8 50.8 16.50 11.09 EU X SL-H90 98.4 54.8 16.22 10.90 EU G NC31 (F) 104.8 50.8 16.50 11.09 EU G SL-H90 101.6 50.8 16.22 10.90 EU S NC31 (F) 111.1 41.3 17.19 11.55 5 1/2 (139.70 mm) 21.90 9.175 4.778 121.36 3 760 16 096 385 24.70 10.54 4.670 118.621 4 277 17 955 483 230 442 257 058 EU E FH 177.8 101.6 35.40 23.79 EU X FH 177.8 95.3 36.33 24.41 EU G FH 184.2 88.9 37.59 25.26 EU S FH 190.5 76.2 39.24 26.37 EU E FH 177.8 101.6 39.16 26.31 EU X FH 184.2 88.9 41.29 27.75 EU G FH 184.2 88.9 41.29 27.75 EU S FH 190.5 76.2 42.94 28.86 6 5/8 (168.28 mm) 25.20 8.38 5.955 151.22 4 210 26 981 773 320 667 EU E FH 203.2 127.0 40.63 27.30 mm x 0.0394 = in mm 2 x 0.00155 = in 2 mm 3 x 6.10 10 5 = in 3 mm 4 x 2.4 10-6 = in 4 2

diameter Πίνακας Π1.2. Μηχανικά χαρακτηριστικά διατρητικών στελεχών Class Grade Tensile yield (1) (10 3 dan) Torsional (2) (dan.m) Burst pressure Collapse pressure E 43.5 650 72.4 76.1 X95 55.1 820 91.7 96.4 G105 61.0 900 101.3 106.6 S135 78.3 1 160 130.0 131.5 E 34.2 510 66.2 58.9 2 3/8 4.85 Premium X95 43.3 640 83.8 70.0 G105 47.9 710 92.7 75.1 S135 61.6 910 119.1 89.1 E 29.7 440 57.9 47.2 X95 37.6 550 73.4 55.1 G105 41.5 610 81.1 58.5 S135 53.4 790 104.2 66.6 E 61.5 850 106.7 107.5 X95 77.9 1 070 135.1 136.2 G105 86.1 1 190 149.3 150.6 S135 110.7 1 530 192.0 193.6 E 47.9 650 97.6 92.2 2 3/8 6.65 Premium X95 60.7 830 123.5 116.9 G105 67.1 910 136.6 129.1 S135 86.2 1 180 175.6 166.0 E 41.3 560 85.3 83.7 X95 52.3 710 108.1 106.0 G105 57.8 780 119.5 117.1 S135 74.4 1 010 153.6 150.6 E 63.5 1 100 68.3 72.2 X95 76.6 1 390 86.5 89.1 G105 84.7 1 530 95.6 96.6 S135 108.9 1 970 122.9 117.6 E 47.6 860 62.5 52.9 2 7/8 6.85 Premium X95 60.3 1 090 79.1 62.0 G105 66.6 1 200 87.4 66.3 S135 85.7 1 550 112.4 77.3 E 41.3 744 54.6 41.7 X95 52.3 940 69.2 48.0 G105 57.8 1 040 76.5 50.6 S135 74.3 1 340 98.4 56.0 E 95.4 1 570 114.0 113.8 X95 120.8 1 990 144.3 144.2 G105 133.5 2 190 159.5 159.3 S135 171.7 2 820 205.1 204.9 E 74.1 1 200 104.2 98.0 2 7/8 10.40 Premium X95 93.8 1 520 132.0 124.2 G105 103.7 1 680 145.8 137.3 S135 133.4 2 160 187.5 176.5 E 63.9 1 030 91.2 89.2 X95 80.9 1 300 115.5 113.0 G105 89.4 1 440 127.6 124.9 S135 114.9 1 850 164.1 160.6 E 86.4 1 920 65.6 69.2 X95 109.5 2 430 83.2 83.1 G105 121.0 2 680 92.0 90.0 S135 155.6 3 450 118.2 108.8 E 68.1 1 500 60.0 48.9 3 1/2 9.50 Premium X95 86.2 1 910 76.0 47.0 G105 95.3 2 110 84.0 60.7 S135 122.5 2 710 108.1 59.8 E 59.1 1 300 52.5 38.2 X95 74.8 1 650 66.5 43.4 G105 82.7 1 820 73.6 45.5 S135 106.3 2 350 94.6 49.2 E 120.8 2 520 95.1 97.3 X95 153.1 3 190 120.5 123.3 G105 169.2 3 520 133.2 136.2 S135 217.5 4 530 171.2 175.1 E 94.4 1 950 87.0 82.9 3 1/2 13.30 Premium X95 119.6 2 470 110.2 104.9 G105 132.2 2 720 121.7 116.0 S135 170.0 3 510 156.6 149.1 E 81.6 1 680 76.1 74.9 X95 103.3 2 120 96.4 94.8 G105 114.2 2 350 106.6 103.7 S135 146.8 3 020 137.0 126.9 (1) Based on uniform wear of 20% for Premium Class and 30% for Class. (2) Based on shear of 57.7% of minimum yield and uniform wear of 20% for Premium Class and 30% for Class. Based on uniform wear of 20% for Premium Class and 30% for Class. dan x 2.25 = lb dan.m x 7.38 = lb.ft MPa x 145 = psi 3

diameter Πίνακας Π1.2. Μηχανικά χαρακτηριστικά διατρητικών στελεχών Class Grade Tensile yield (1) (10 3 dan) Torsional (2) (dan.m) Burst pressure Collapse pressure E 143.6 2 860 116.1 115.6 X95 181.9 3 620 147.0 146.5 G105 201.1 4 000 162.5 161.9 S135 258.5 5 150 209.0 208.1 E 111.5 2 190 106.1 99.8 3 1/2 15.50 Premium X95 141.2 2 770 134.4 126.4 G105 156.1 3 060 148.6 139.7 S135 200.6 3 960 191.0 179.6 E 96.1 1 870 92.9 90.8 X95 121.7 2 370 117.6 115.0 G105 134.5 2 620 130.0 127.2 S135 172.9 3 370 167.2 163.5 E 102.7 2 640 59.3 58.0 X95 130.1 3 340 75.1 68.7 G105 143.8 3 700 83.0 73.8 S135 184.8 4 750 106.7 87.2 E 81.0 2 080 54.2 39.5 4 11.85 Premium X95 102.6 2 630 68.7 44.7 G105 113.4 2 910 75.8 47.0 S135 145.8 3 740 97.6 51.5 E 70.3 1 800 47.4 29.7 X95 89.1 2 280 60.1 32.4 G105 98.5 2 520 66.4 33.6 S135 126.6 3 240 85.4 37.5 E 127.0 3 160 74.7 78.2 X95 160.8 4 000 94.6 99.1 G105 177.8 4 420 104.5 109.6 S135 228.6 5 680 134.4 139.1 E 99.8 2 470 68.3 62.3 4 14.00 Premium X95 126.4 3 120 86.5 74.3 G105 139.7 3 450 95.6 80.0 S135 179.6 4 440 122.9 95.6 E 86.5 2 130 59.7 50.3 X95 109.5 2 700 75.7 59.1 G105 121.0 2 990 83.6 63.0 S135 155.6 3 840 107.5 72.5 E 120.2 3 510 54.5 49.6 X95 152.2 4 450 69.0 57.9 G105 168.2 4 920 76.3 61.7 S135 216.3 6 320 98.1 71.1 E 94.9 2 770 49.8 32.5 4 1/2 13.75 Premium X95 120.2 3 500 63.1 35.6 G105 132.8 3 870 69.8 36.8 S135 170.8 4 980 89.7 40.7 E 82.5 2 400 43.6 23.4 X95 104.5 3 040 55.2 26.5 G105 115.5 3 360 61.0 27.7 S135 148.4 4 320 78.5 29.6 E 147.1 4 180 67.8 71.6 X95 186.3 5 290 85.8 87.9 G105 205.9 5 850 94.9 95.3 S135 264.8 7 520 122.0 115.8 E 115.7 3 270 62.0 52.0 4 1/2 16.60 Premium X95 146.6 4 150 78.5 61.0 G105 162.0 4 580 86.7 65.2 S135 208.3 5 890 111.5 75.8 E 100.4 2 830 54.2 41.0 X95 127.2 3 590 68.7 47.1 G105 140.6 3 970 75.9 49.5 S135 180.6 5 100 97.6 54.6 E 183.5 5 000 86.5 89.3 X95 232.4 6 340 109.5 113.2 G105 256.9 7 010 121.1 125.1 S135 330.3 9 010 155.7 160.8 E 143.7 3 890 79.1 75.7 4 1/2 20.00 Premium X95 182.0 4 930 100.1 95.8 G105 201.2 5 440 110.6 105.8 S135 258.7 7 000 142.3 129.9 E 124.3 3 360 69.2 66.4 X95 157.5 4 250 87.6 80.0 G105 174.1 4 700 96.8 86.3 S135 223.8 6 040 124.5 103.6 (1) Based on uniform wear of 20% for Premium Class and 30% for Class. (2) Based on shear of 57.7% of minimum yield and uniform wear of 20% for Premium Class and 30% for Class. Based on uniform wear of 20% for Premium Class and 30% for Class. dan x 2.25 = lb dan.m x 7.38 = lb.ft MPa x 145 = psi 4

diameter Πίνακας Π1.2. Μηχανικά χαρακτηριστικά διατρητικών στελεχών Class Grade Tensile yield (1) (10 3 dan) Torsional (2) (dan.m) Burst pressure Collapse pressure E 176.0 5 580 65.5 68.9 X95 223.0 7 070 83.0 82.8 G105 246.4 7 810 91.7 89.6 S135 316.9 10 500 118.0 108.2 E 138.6 4 380 59.9 48.7 5 19.50 Premium X95 175.6 4 540 75.8 56.7 G105 194.1 6 130 83.8 60.4 S135 249.5 7 880 107.8 69.3 E 120.3 3 790 52.4 38.0 X95 152.4 4 800 66.4 43.2 G105 168.4 5 310 73.4 45.2 S135 216.5 6 830 94.3 48.9 E 239.9 7 090 90.4 93.1 X95 298.8 8 980 114.6 117.9 G105 330.3 9 920 126.7 130.3 S135 424.6 12 750 162.8 167.5 E 184.5 5 500 82.7 79.0 5 25.60 Premium X95 233.7 6 960 104.8 1000.0 G105 258.3 7 700 115.8 110.6 S135 332.2 9 900 148.9 141.6 E 159.6 4 740 72.4 71.3 X95 202.1 6 000 91.7 87.1 G105 223.4 6 630 101.4 94.4 S135 287.2 8 530 130.3 114.4 E 194.5 6 880 59.4 582 X95 246.4 8 710 75.2 68.9 G105 272.3 9 630 83.1 74.0 S135 350.1 12 380 106.9 87.6 E 153.4 5 410 54.3 39.7 5 1/2 21.90 Premium X95 194.3 6 850 68.8 45.0 G105 214.8 7 570 76.0 47.3 S135 276.2 9 730 97.8 51.8 E 133.2 4 720 47.5 29.9 X95 168.8 5 940 60.2 32.6 G105 186.5 6 560 66.5 33.8 S135 239.8 8 440 85.5 37.7 E 221.3 7 670 65.8 72.1 X95 280.3 9 720 86.5 89.1 G105 309.8 10 740 95.6 96.5 S135 398.3 13 810 122.9 117.5 E 174.1 6 010 62.4 52.9 5 1/2 24.70 Premium X95 220.6 7 610 79.1 62.0 G105 243.8 8 410 87.4 66.3 S135 313.4 10 810 112.4 77.2 E 151.0 5 200 54.6 41.7 X95 191.3 6 590 69.2 48.0 G105 211.4 7 290 76.5 50.5 S135 271.9 9 370 98.3 56.0 E 217.8 9 570 45.1 33.2 X95 275.9 12 120 57.1 36.6 G105 304.9 13 400 63.1 37.8 S135 392.1 17 230 81.1 41.6 E 172.0 8 200 41.2 20.2 6 5/8 25.20 Premium X95 218.0 10 440 52.2 22.4 G105 242.0 11 520 57.7 23.1 S135 310.0 14 800 74.2 23.6 E 150.0 6 580 36.1 15.4 X95 190.0 8 330 45.7 16.2 G105 210.0 9 210 50.5 16.2 S135 270.0 11 840 64.9 16.2 (1) Based on uniform wear of 20% for Premium Class and 30% for Class. (2) Based on shear of 57.7% of minimum yield and uniform wear of 20% for Premium Class and 30% for Class. Based on uniform wear of 20% for Premium Class and 30% for Class. dan x 2.25 = lb dan.m x 7.38 = lb.ft MPa x 145 = psi tensile yield = όριο ελαστικότητας ή αντοχή σε εφελκυσµό torsional = αντοχή σε στρέψη burst pressure = πίεση διάρρηξης collapse pressure = πίεση αστοχίας 5

ΣΥΝ ΕΣΜΟΙ Το Αµερικάνικο Ινστιτούτο Πετρελαίου (American Petroleum nstitut AP) έχει καθιερώσει ένα σύστηµα ταξινόµησης και κωδικοποίησης των συνδέσµων. Στον Πίνακα Π1.3 παρουσιάζονται οι συντµήσεις που χρησιµοποιούνται διεθνώς για την περιγραφή των διαφόρων τύπων συνδέσµων. Πίνακας Π1.3. Επεξήγηση συντµήσεων που χρησιµοποιούνται διεθνώς για το χαρακτηρισµό των διαφόρων τύπων συνδέσµων Σύντµηση Επεξήγηση F nternal Flush Εσωτερικά λείος, χωρίς αλλαγή διαµέτρου EH Extra hole SH Slim hole OH Open hole SL-H-90 Slime line Hughes - 90º thread (σπείρωµα) FH Full hole H-90 Hughes - 90º thread (σπείρωµα) WO Wide open NC Numbered connection U nternal upset EU External upset EU nternal external upset Για την άµεση αναγνώριση του κάθε συνδέσµου χαράσεται στη βάση του πείρου µια σειρά κωδικών. Στο σχήµα Π1.1 παρουσιάζεται ένα χαρακτηριστικό παράδειγµα κωδικοποίησης συνδέσµου. Σχήµα Π1.1. Χαρακτηριστικό παράδειγµα κωδικοποίησης συνδέσµου Παράδειγµα κωδικοποίησης συνδέσµου που χαράσσεται στη βάση του πείρου: 1 2 3 4 5 (D) 9 76 A E 1. Σύµβολο εταιρείας κατασκευής 2. Μήνας συγκόλλησης συνδέσµου στο στέλεχος (9=Σεπτέµβριος) 3. Έτος συγκόλλησης συνδέσµου στο στέλεχος (76 = 1976) 4. Εργοστάσιο κατασκευής (D = Dalmine SPA, taly) 5. Κατηγορία χάλυβα στελέχους (Ε = στέλεχος κατηγορίας χάλυβα Ε) 6

Οι κωδικοί που χρησιµοποιούνται για να περιγράψουν το εργοστάσιο κατασκευής και την κατηγορία του χάλυβα παρουσιάζονται στους Πίνακες Π1.4 και Π1.5, αντίστοιχα. Πίνακας Π1.4. Κωδικός που χαράσεται στη βάση του πείρου και συµβολίζει το εργοστάσιο κατασκευής ενός συνδέσµου Συµβολισµός A J N P Y D F T K V M S W R B Εργοστάσιο κατασκευής Armco J Σ L Steel US Steel Wheeling, Pittsburgh Youngstrom Dalmine SPA, taly Falck, taly Tamsa Nippon Kokan Kabrushiki Vallourec Mannesmannrohren-Werke Sumitomo Metal nd. Balcock and Wilcox Republic British Steel Πίνακας Π1.5. Κωδικός που χαράσεται στη βάση του πείρου και συµβολίζει την κατηγορία του χάλυβα από τον οποίο είναι κατασκευασµένος ένας σύνδεσµος Συµβολισµός Κατηγορία χάλυβα Ν N-80 D D E E C C-75 X X-95 G G-105 S S-135 V V-150 U Used (χρησιµοποιηµένα) 7