Products List
High Tensile Bolt Supplier in Kolkata
Most steel structures are fastened together on site by nuts and bolts. These come in a variety of sizes, from 6mm to 100mm in diameter. They can be soft (grade 4.6, 8.8, 10.9, 12.9): the figures refer to the ultimate strength and yield strength of bolts. For example a 4.6 has an ultimate strength of 400N/mm2 but yields at 60% of this, 240N/mm2; an 8.8 bolt has an ultimate strength of 800N/mm2, and yields at 80% of this, 640N/mm2. Bolts can act in tension (pulling) and in shear (being sliced by two sliding plates). Bolts can also be designed to work in friction, by squeezing plates so hard together that they cannot slip (these are called friction grip bolts, and sound good: but it is extremely hard to get them all to the right tension, and they should normally be avoided). In general, structural bolts are 8.8
High tensile bolt grades for load-bearing assemblies
High tensile bolts are specified where clamping force, shear capacity, and fatigue resistance matter. Buyers should not order only by size; the drawing grade, property class, thread length, nut class, washer type, and tightening method all affect performance.
| Common supply | HT hex bolts, HT nuts, hardened washers, socket head screws, and heavy-duty bolt sets |
|---|---|
| Grades handled | 8.8, 10.9, 12.9, ASTM A325/A490-type requirements subject to equivalent review |
| Reference standards | IS 1367, IS 3757, IS 6623, DIN 931, DIN 933, ISO 898-1 |
| Finishes | Black, zinc plated, phosphate, hot dip galvanised where suitable, and special coatings as specified |
| Use cases | Steel structures, cranes, machinery, heavy fabrication, rail work, earthmoving equipment, and plant maintenance |
Procurement checks before ordering
- Match bolt grade with nut grade and hardened washer requirement.
- For preloaded joints, confirm whether the job needs torque control, DTI washers, or project-specific tightening procedure.
- Do not hot dip galvanise high tensile bolts without checking hydrogen embrittlement and standard compatibility.
- Ask for test certificates where required by the consultant or client QA team.
Frequently asked questions
What is the difference between 8.8 and 10.9 bolts?
10.9 bolts have higher tensile and yield strength than 8.8 bolts, but the correct choice depends on the design and tightening requirement.
Do high tensile bolts need special nuts?
Yes. High tensile bolts should be used with compatible nuts and washers so the joint performs as designed.
Can you supply HT bolts with test certificates?
Documentation can be discussed during enquiry based on grade, size, source, and project requirement.
High Tensile Nuts & Bolts
High Tensile Nuts & Bolts
High Tensile Nuts & Bolts
