IS 12427
Transmission Tower Bolts
Equivalent Standard: ISO 4016
The other type of transmission tower bolt known as step bolt is covered in IS 12427:2020 / IS 10238:2001 ‘Fasteners —
Threaded steel fasteners — Step bolts for steel structures — Specification @rst revision)’. The hexagon head
bolts intended for fabrication of general steel structures are covered in IS12427:2020 IS 6639:1972 ‘Hexagon bolts for steel structures’.
For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with 1S 2:1960, IS 12427:2020 ‘Rules for rounding off numerical values (revised)’. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard.
Transmission Tower Bolts IS 12427.
- Mushroom Head Square Neck Bolts/Cup Square Bolts
- Material Grade: 5.8, 8.8
- Finish: Hot Dip Galvanized
- Thread: METRIC
Technical Specification for IS 12427 Transmission Tower Bolts
| Dimensions of Hexagon Head Transmission Tower Bolts | ||||||
| Nom. Dia. (d) | M12 | M16 | M20 | (M22) | M24 | |
| Thread Pitch | 1.75 | 2 | 2.5 | 2.5 | 3 | |
| b (ref) | 20 | 23 | 26 | 28 | 30 | |
| C | Max. | 0.6 | 0.8 | 0.8 | 0.8 | 0.8 |
| Da | Max. | 14.7 | 18.7 | 24.4 | 26.4 | 28.4 |
| Ds | Max. | 12.7 | 16.7 | 20.84 | 22.84 | 24.84 |
| Min. | 11.3 | 15.3 | 19.16 | 21.16 | 23.16 | |
| Dw | Max. | 18 | 24 | 30 | 34 | 36 |
| Min. | 16.47 | 22 | 27.7 | 31.35 | 33.25 | |
| e | Min. | 19.85 | 26.17 | 32.95 | 37.29 | 39.55 |
| k | Nom. | 7.5 | 10 | 12.5 | 14 | 15 |
| Max. | 7.95 | 10.75 | 13.4 | 14.9 | 15.9 | |
| Min. | 7.05 | 9.25 | 11.6 | 13.1 | 14.1 | |
| k’ | Min. | 4.95 | 6.48 | 8.12 | 9.17 | 9.87 |
| r | Min. | 0.6 | 0.6 | 0.8 | 0.8 | 0.8 |
| s | Max. | 18 | 24 | 30 | 34 | 36 |
| Min. | 17.57 | 23.16 | 29.16 | 33 | 35 | |
| Length — Size Combinations and Grip Ranges | |||||||||||||||
| Thread | M12 | M16 | M20 | M22 | M24 | ||||||||||
| Size d | ls | Lg | Grip | ls | Lg | Grip | ls | Lg | Grip | ls | Lg | Grip | ls | Lg | Grip |
| Min. | Max. | Range | Min. | Max. | Range | Min. | Max. | Range | Min. | Max. | Range | Min. | Max. | Range | |
| 30 | 65 | 10 | 6-10 | – | – | – | – | – | – | – | – | – | – | – | – |
| 35 | 11.5 | 15 | 11-15 | 8 | 12 | 8-12 | – | – | – | – | – | – | – | – | – |
| 40 | 16.5 | 20 | 16-20 | 13 | 17 | 13-17 | 9 | 14 | 11-14 | 7 | 12 | 8-12 | – | – | – |
| 45 | 21.5 | 25 | 21-25 | 18 | 22 | 18-22 | 14 | 19 | 15-19 | 12 | 17 | 13-17 | 9 | 15 | 11-15 |
| 50 | 26.5 | 30 | 26-30 | 23 | 27 | 23-27 | 19 | 24 | 20-24 | 17 | 22 | 18-22 | 14 | 20 | 16-20 |
| 55 | 31.5 | 35 | 31-35 | 28 | 32 | 28-32 | 24 | 29 | 25-29 | 22 | 27 | 23-27 | 19 | 25 | 21-25 |
| 60 | 36.5 | 40 | 36-40 | 33 | 37 | 33-37 | 29 | 34 | 30-34 | 27 | 32 | 28-32 | 24 | 30 | 36-30 |
| 65 | 41.5 | 45 | 41-45 | 38 | 42 | 38-42 | 34 | 39 | 35-39 | 32 | 37 | 33-37 | 29 | 35 | 31-35 |
| 70 | 46.5 | 50 | 46-50 | 43 | 47 | 43-47 | 39 | 44 | 40-44 | 37 | 42 | 38-42 | 34 | 40 | 36-40 |
| 75 | 51.5 | 55 | 51-55 | 48 | 52 | 48-52 | 44 | 49 | 45-49 | 42 | 47 | 43-47 | 39 | 45 | 41-45 |
| 80 | 56,5 | 60 | 56-60 | 53 | 57 | 53-57 | 49 | 54 | 50-54 | 47 | 52 | 48-52 | 44 | 50 | 46-50 |
| 85 | 61.5 | 65 | 61-65 | 58 | 62 | 58-62 | 54 | 59 | 55-59 | 52 | 57 | 53-57 | 49 | 55 | 51-55 |
| 90 | 66.5 | 70 | 66-70 | 63 | 67 | 63-67 | 59 | 64 | 60-64 | 57 | 62 | 58-62 | 54 | 60 | 56-60 |
| 95 | 71.5 | 75 | 71-75 | 68 | 72 | 68-72 | 64 | 69 | 65-69 | 62 | 67 | 63-67 | 59 | 65 | 61-65 |
| 100 | 76.5 | 80 | 76-80 | 73 | 77 | 73-77 | 69 | 74 | 70-74 | 67 | 72 | 68-72 | 64 | 70 | 66-70 |
| 105 | 78 | 82 | 78-82 | 74 | 79 | 75-79 | 72 | 77 | 73-77 | 69 | 75 | 71-75 | |||
| 110 | 83 | 87 | 83-87 | 79 | 84 | 80-84 | 77 | 82 | 78-82 | 74 | 80 | 76-80 | |||
| 115 | 88 | 92 | 88-92 | 84 | 89 | 85-89 | 82 | 87 | 83-87 | 79 | 85 | 81-85 | |||
| 120 | 93 | 97 | 93-97 | 89 | 94 | 90-94 | 87 | 92 | 88-92 | 84 | 90 | 86-90 | |||
| 125 | 98 | 102 | 98-102 | 94 | 99 | 95-99 | 92 | 97 | 93-97 | 89 | 95 | 91-95 | |||
| 130 | 103 | 107 | 103-107 | 99 | 104 | 100-104 | 97 | 102 | 98-102 | 94 | 100 | 96- I00 | |||
| 135 | 108 | 112 | 108-112 | 104 | 109 | 105-109 | 102 | 107 | 103-107 | 99 | 105 | 101-105 | |||
| 140 | 113 | 117 | 113-117 | 109 | 114 | 110-114 | 107 | 112 | 108-112 | I04 | 110 | 106-110 | |||
| 145 | 118 | 122 | 118-122 | 114 | 119 | 115-119 | 112 | 117 | 113-117 | 109 | 115 | 111-115 | |||
| 150 | 123 | 127 | 123-127 | 119 | 124 | 120-124 | 117 | I22 | 118-122 | 114 | 120 | 116-120 | |||
| 155 | I28 | 132 | 128-132 | 124 | 129 | 125-129 | 122 | I27 | 123-127 | 119 | 125 | 121-125 | |||
| 160 | 133 | 137 | 133-137 | 129 | I34 | 130-134 | 127 | 132 | 128-132 | 124 | 130 | 126-130 | |||
