High-strength structural bolts are commonly used in construction and engineering projects to join heavy steel structures like bridges, buildings, and industrial frameworks. These bolts are designed to handle high loads and provide strong, secure connections between structural components.
To make sure these bolts perform properly and can withstand heavy stress, they need to follow IS 3757:1985, a standard set by the Bureau of Indian Standards. Obtaining BIS certification guarantees that these structural bolts have been properly tested and meet all required standards.
What is IS 3757:1985
This is the Indian Standard for high-strength structural bolts, which is set by the Bureau
of Indian Standards to ensure that these bolts are strong, durable, and suitable for
load-bearing applications.
This standard makes sure that the bolts are:
- Strong enough to handle high tensile loads and stress
- Made from proper material with required mechanical properties
- Accurate in size, threading, and overall dimensions
- Capable of maintaining tight and secure joints in structures
- Resistant to wear and suitable for long-term structural use
Testing and Inspection Requirements for Structural Bolts
To ensure proper strength, durability, and performance of these high-strength bolts, the
Bureau of Indian Standards has defined clear testing and inspection requirements under
the standard, which are carried out during manufacturing.
What are R and S
- R (Required): Test must be conducted in the manufacturer’s in-house laboratory
- S (Subcontracting Allowed): Test can be conducted in a BIS-approved external
laboratory
Physical and Dimensional Tests
- Dimensions and Tolerances (R) – Checks bolt size, length, diameter, and
compliance with standard limits
- Thread Requirements (R) – Ensures proper threading, pitch, and fit using
gauges
- Visual and Surface Check (R) – Ensures bolts are free from defects or surface
discontinuities
Material Tests
- Raw Material Test (S) – Confirms material meets specified grade as per IS
requirements
- Decarburization Test (R) – Ensures proper surface hardness and treatment
- Carburization Test (R) – Verifies material surface properties
- Retempering Test (R) – Checks heat treatment consistency
Mechanical and Strength Tests
- Tensile Strength Test (R) – Ensures bolts can withstand required load
- Proof Load Test (R) – Verifies bolts can handle specified stress without
deformation
- Torsion Test (R) – Checks resistance to twisting forces
- Head Soundness Test (R) – Ensures bolt head integrity under load
- Hardness Test (R) – Verifies strength and durability of the material
Finish and Coating Tests
- Finish Check (R) – Ensures proper surface finish like dull black or galvanized
- Galvanizing Test (R) – Verifies coating thickness and corrosion protection
- Anti-Seizing Test (R) – Ensures proper functioning of threads without sticking
Additional Component Tests
- Surface Discontinuity Test (R) – Detects cracks or defects on the bolt surface
- Nut Testing (S) – Ensures nuts meet required standards if supplied with bolts
- Washer Testing (S) – Verifies washers comply with relevant IS standards
Process for BIS Certification
The BIS certification process for High Strength Structural Bolts involves multiple steps, designed to thoroughly evaluate a product's compliance with the required standards. Here is a general overview of the certification process:
- Online Registration: Manufacturers register on the BIS Manak Online Portal by submitting company
details, factory information, and product specifications. Foreign manufacturers
must appoint an Authorized Indian Representative (AIR) in India.
- Testing at BIS-Approved Laboratory: Product samples are tested in BIS-approved laboratories to evaluate electrical
safety, insulation resistance, heating efficiency, durability, and overall
performance as per requirements.
- Application Submission: The application is submitted along with laboratory test reports, technical
documents, manufacturing process details, and factory information. Foreign
manufacturers must also provide AIR-related documents.
- Factory Inspection: BIS officials conduct an on-site inspection of the manufacturing unit to verify
production processes, quality control systems, safety measures, and compliance
with the standard.
- Grant of BIS License: If all requirements are successfully met, BIS issues the certification license under
Scheme-I, allowing the manufacturer to produce and sell certified products.
- Use of ISI Mark: After certification approval, the manufacturer is permitted to use the ISI mark
along with a CM/L number on the product, confirming compliance with the
standard.
documents required for bis certification
| Basic Details | - GST Certificate
- Email ID & Contact Number
- Factory & Office Address
- Rent Agreement / Lease Deed (if applicable)
|
| Legal Documents | - Partnership Deed (if partnership firm)
|
| Manufacturing Details | - List of machinery
- Process flow chart
- Layout Plan of Factory
|
| Raw Material Details | - List of Raw Materials
- Supplier Details
- Raw Material Invoices
- Raw Material Test Certificates
|
| Testing & Quality Control | - List of Testing Equipment
- Calibration Certificates
- QC / Lab In-charge Appointment Letter & Qualification
|
| Production Details | - Annual Installed Capacity
- Last Year Production Value
|
| Product & Packaging Details | - Quantity per Package
- Nature of Packing
- Nature of Printing / Marking on Product
|
| Management Details | - Top Management Details
- Concerned Person for BIS Communication
|
| Brand & Certification Documents | - Trademark / Brand Certificate
- Consent Letter from BIS Recognized Laboratory
|
| Additional Documents | - Weekly Off Details
- Hygiene Document (if applicable)
- Relaxation Letter (if applicable)
- Any Other Relevant Document
|
Additional documentation may be required based on product specifications and environmental regulations.
Marking Requirements & License Validity
Marking Requirements
When a manufacturer obtains the BIS license, the ISI mark for high-strength bolts must
be applied clearly and permanently on the product or its packaging. In addition to the ISI
Mark, other important details must also be provided on the product or packaging, as
specified in the table below. This ensures the product meets all quality and safety
standards.
| Requirement | Details |
|---|
| ISI Mark | Indicates that the product is BIS certified and follows to the standard |
| Standard Number | IS 3757 |
| CML Number | Certification Marks Licence (CML) number issued by BIS |
| Manufacturer Details | Name of manufacturer or registered trademark |
| Batch / Date | Batch number, heat number, or manufacturing date for traceability |
Note:
Marking is typically applied using durable stamping, tagging, or permanent printing to
ensure clear identification during handling, storage, and transportation, as per BIS
marking requirements.
Validity of BIS licenses for structural bolts
After obtaining BIS certification for structural bolts, the license is valid for a fixed period
and must be maintained by following BIS rules and standards.
| Particulars | Details |
|---|
| Initial Validity | Typically 1 to 2 years, depending on BIS approval conditions |
| Renewal | Must be renewed before expiry by submitting the application along with the prescribed fee and updated documents |
| Surveillance | Includes periodic factory inspections and market sample testing conducted by BIS |
| Compliance | Continuous following to standard and applicable Quality Control Orders (QCOs) is mandatory |
| Risk | Non-compliance or failed sample testing may lead to suspension or cancellation of the BIS license |
BIS Certification Cost for high-strength bolts
The cost of BIS certification includes charges for application, inspection, license, testing,
and marking. These fees are paid to BIS as per Scheme I guidelines.
Cost Breakdown
Indian Manufacturers
| No. | Major Charges | Particulars | Amount | Remark |
| 1 | BIS Fees | Application Fee | INR 1,000 | — |
|
| Audit / Inspection Fee | INR 7,000 | — |
|
| License Fee | INR 1,000 | — |
|
| Marking Fee | Depends on product | Discount as per MSME |
| 2. | Testing Charges | Sample Testing Fee | As Applicable | Payable to a BIS-approved laboratory. |
| 3. | EVTL India Service Fee | Consultancy & Support | As per actual | Depends on product type and factory location. |
Foreign Manufacturers
| No. | Major Charges | Particulars | Amount | Remark |
| 1. | BIS Fees | Application Fee | USD 15 | Payable via SWIFT to BIS. SAARC countries can pay INR with 18% GST. |
|
| Audit Charges | USD 3,200 – 5,900 | Depend on Country |
|
| License Fee | USD 15 | — |
|
| Marking Fee | Depends on product | — |
| 2. | Testing Charges | Sample Testing Fee | As Applicable | Payable to a BIS-approved laboratory. |
| 3. | EVTL India Service Fee | Consultancy & Support | As per actual
| Based on product and manufacturing location. |
cOST AND TIMELINE OF CERTIFICATION
to know the process in detail,please visit
Under BIS Registration Products ISI and CRS
Conclusion
BIS certification for high-strength structural bolts, as per IS 3757:1985, ensures that the
product meets all required strength, dimensional accuracy, and performance standards
for use in construction and structural applications. It guarantees that the bolts are
properly tested for tensile strength, load-bearing capacity, threading accuracy, and
durability, making them reliable for heavy-duty use in buildings, bridges, and industrial
structures.
With the support and guidance of an experienced BIS consultant like EVTL India,
manufacturers can complete the certification process smoothly, minimize errors, and
obtain approval faster for market compliance.
