Link points to Internet Archive / others. Not hosted by InfraLens. Details
IS 3757:1985 is the Indian Standard (BIS) for high strength structural bolts. This standard specifies the requirements for high strength structural bolts of property classes 8.8 and 10.9 in the size range from M16 to M36. It details dimensions, material specifications, and mechanical testing requirements to ensure the reliability of these fasteners in structural friction-grip and bearing-type connections.
Specifies requirements for high strength structural bolts for use in steel structures.
EN 14399 seriesCEN (European Committee for Standardization), Europe
HighCurrent
High-strength structural bolting assemblies for preloading
Covers system-based bolting assemblies (bolt, nut, washer) with the same property classes (8.8, 10.9) for preloaded structural connections.
ASTM F3125/F3125M - 22ASTM International, USA
MediumCurrent
Standard Specification for High Strength Structural Bolts, Steel and Alloy Steel, Heat Treated, 120 ksi (830 MPa) and 150 ksi (1040 MPa) Minimum Tensile Strength, Inch and Metric Dimensions
Covers high-strength bolts for structural steelwork, but uses different grade designations (A325, A490) and dimensional standards.
ISO 898-1:2013ISO (International Organization for Standardization), International
HighCurrent
Mechanical properties of fasteners made of carbon steel and alloy steel — Part 1: Bolts, screws and studs with specified property classes
Defines the mechanical property classes (e.g., 8.8, 10.9) which form the technical basis for the strength requirements in IS 3757.
JIS B 1186:2013JSA (Japanese Standards Association), Japan
HighCurrent
Sets of high strength hexagon bolt, hexagon nut and plain washers for friction grip joints
Specifies sets of bolts, nuts, and washers for friction-grip joints, aligning closely with the intended application of IS 3757 bolts.
Key Differences
≠IS 3757 is a component-based standard (specifying the bolt), whereas modern equivalents like EN 14399 are 'system' standards, requiring the bolt, nut, and washer to be supplied and tested together as a matched assembly.
≠IS 3757 uses the ISO property class system (8.8, 10.9). In contrast, the primary US standard (ASTM F3125) uses Grade designations (e.g., Grade A325, Grade A490) which are roughly comparable in strength but not directly interchangeable.
≠Modern international standards like the EN 14399 series provide extensive detail on suitability tests for preloading and specific tightening procedures within the standard itself. IS 3757 is less detailed, with installation procedures typically covered in separate application codes like IS 4000.
≠While based on ISO standards, there can be minor dimensional differences in head sizes (width across flats) and thread lengths between IS 3757 bolts and those specified under different international norms like DIN or some EN parts.
Key Similarities
≈The fundamental basis for strength, using Property Classes 8.8 and 10.9, is identical to the system defined in ISO 898-1 and used widely in European and other international standards.
≈All standards cover the same fundamental application: bolts used for joining structural steel elements, particularly in connections requiring high tensile strength and often designed as slip-resistant (friction-grip) joints.
≈The required manufacturing route is conceptually the same, involving the use of medium carbon or alloy steel, which is then heat-treated (quenched and tempered) to achieve the specified high-strength mechanical properties.
≈The suite of mandatory mechanical tests to verify compliance, including tensile strength, proof load, hardness, and impact strength (Charpy), are common verification methods across IS 3757 and its international counterparts.
Parameter Comparison
Parameter
IS Value
International
Source
Tensile Strength (Min), Class 8.8
830 MPa (for diameters > 16mm)
800 MPa
ISO 898-1:2013
Yield Strength (Min), Class 8.8
640 MPa
640 MPa (or 660 MPa for dia > 16mm)
ISO 898-1:2013
Tensile Strength (Min), Class 10.9
1040 MPa
1040 MPa
ISO 898-1:2013
Yield Strength (Min), Class 10.9
940 MPa
940 MPa
ISO 898-1:2013
Elongation after fracture (Min), Class 8.8
12%
12%
ISO 898-1:2013
Bolt Head Marking
Manufacturer ID, 'HSFG', and Property Class (e.g., 8.8S)
Manufacturer ID, Property Class, and System ID (e.g., 'HR' or 'HV')
EN 14399-1:2015
Associated Nut for Class 8.8 Bolt
Property Class 8
Property Class 8
ISO 898-2:2022
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
tensile strength grade 8.8800 MPa
yield strength grade 8.8640 MPa
tensile strength grade 10.91040 MPa
yield strength grade 10.9940 MPa
bolt size rangeM16 to M36
minimum elongation grade 8.812%
Tables & Referenced Sections
Key Tables
Table 1 - Dimensions of High Strength Structural Bolts
What property classes of bolts are covered by IS 3757?+
It covers property classes 8.8 and 10.9.
What is the size range for high strength structural bolts per this code?+
The code specifies dimensions and requirements for sizes from M16 to M36.
What do the digits in grade 8.8 signify?+
The first digit represents 1/100 of the nominal tensile strength (800 N/mm2). The second digit represents 10 times the ratio of yield stress to nominal tensile strength (0.8).
Which code specifies the installation of these bolts?+
IS 4000 covers the design and installation of high strength friction grip (HSFG) bolting.