Steel structures and buildings
Fasteners for steel structures and buildings
Preloaded structural bolting for steel frames and buildings. TUFF® heavy hex bolts are made in Gr. 8.8S and 10.9S to IS 3757, to EN 14399-3 and EN 14399-4, and to ASTM F3125 Gr. A325 / A490, in M12 – M36 and ½″ – 1½″, with tension control bolts, DTI washers, hardened washers, shear connectors and anchor bolts.
TUFF products for this work
Heavy Hex BoltIS 3757, EN 14399-3, EN 14399-4 · M12 – M36, ½″ – 1½″
Tension Control BoltEN 14399-10, ASTM F3125, IS 3757 · M12 – M36
DTI WasherEN 14399-9, ASTM F959, BS EN 14399-9 · M12 – M36- Chamfered / Machined WasherDIN 125-B, ISO 7090, IS 6649 · M8 – M100
Shear ConnectorISO 13918, AWS D1.1, EN ISO 14555 · Ø10 – 25 mm
Foundation BoltIS 5624, DIN 529, ASTM F1554 · M8 – M72
Heavy Hex NutIS 6623, ASTM A194, ASTM A563 · M12 – M100, ¼″ – 4″
Testing and inspection
Every lot is tested before dispatch to the applicable standard and the order's inspection plan, in our in-house laboratory accredited by NABL to ISO/IEC 17025:2017 for the tests in its scope. Lots have been inspected on customer orders by agencies including TÜV SÜD, TÜV NORD, Lloyd's Register, DNV, SGS, BVQI, RITES and EIL.
In an independent test by Element Materials Technology, Singapore (report T24-56832R, November 2024), one TUFF M22 class 10.9 HSFG bolt reached 1,221 MPa tensile strength against the ISO 898-1 minimum of 1,040 MPa. This is one sample; results vary by size, grade and lot, and the test certificate of each supplied lot governs. Read the test summary.
Test certificates
We issue test certificates with every lot. State the certificate type your order needs, for example EN 10204 3.1 or 3.2, in the enquiry.
Shipping terms
FOB, CIF or other terms, as agreed for the order.
Send an enquiry
Send the standard, grade, size, quantity, finish and the certificate type your order needs. Open the enquiry form or write to sales@tuffbolt.com.
Where TUFF fasteners have been used
- Steel structuresStructural bolting for heavy steel structures.
- BuildingsFasteners for critical building structures.
Questions
What is an HSFG bolt?
A high-strength friction-grip (HSFG) bolt is pretensioned so that the joint carries shear by friction between the clamped plates. In India the bolts are made to IS 3757 (8.8S and 10.9S), with nuts to IS 6623 and washers to IS 6649; installation follows IS 4000. Faying surfaces must be free of oil, paint and loose scale.
How are HSFG and structural bolts tightened?
IS 4000 and the RCSC Specification use the part-turn (turn-of-nut) and calibrated-wrench methods; RCSC also allows tension control bolts and direct tension indicators. In each method the joint is first brought to snug-tight and then pretensioned. A torque value alone is unreliable, because thread friction varies from lot to lot.
Can structural bolts be reused?
Under the RCSC Specification, A490 bolts and galvanized A325 bolts must not be reused. Plain A325 bolts may be reused only if the Engineer of Record approves. Retightening bolts loosened by the tightening of neighbouring bolts is not considered reuse.
About the maker
- Fasteners since 1996Pioneer Nuts & Bolts Pvt. Ltd., brand TUFF®. Forging, heat treatment, machining and finishing in-house.
- 50 yearsMetallurgy and heat treatment, since 1976.
- IATF 16949:2016Certified quality management system.
- NABL labIn-house laboratory accredited by NABL to ISO/IEC 17025:2017 for the tests in its scope. Lots tested to the applicable standard.
- Japanese collaborationTechnical collaboration with Japanese fastener companies.
- 150+ testimonialsMore than 150 customer testimonials.