The Four Standard Systems in Indian Procurement
India's industrial history has created a multi-standard environment. British colonial engineering introduced BSW threads; German machinery brought DIN standards; American oil & gas installations specified ASTM; and Indian BIS developed IS standards. Today, procurement teams must navigate all four.
IS (BIS — Bureau of Indian Standards)
Key IS fastener standards:
- IS 1367: Technical supply conditions for threaded fasteners (the foundational Indian standard)
- IS 3757: High strength structural bolts (HSFG)
- IS 6623: Nuts for HSFG connections
- IS 6755: Washers for HSFG connections
- IS 5624: Anchor bolts
- IS 6639: Hexagonal bolts for flanged joints
When to specify IS standards:
- Government tenders (PWD, CPWD, Railways, NHAI)
- Public infrastructure where BIS ISI mark is required
- Projects where the tender documents specify IS standards
IS 1367 is technically equivalent to ISO 898 for bolts and ISO 898-6 for nuts — so a DIN 933 Grade 8.8 bolt and an IS 1367 Grade 8.8 bolt have the same mechanical properties and very similar dimensions (minor differences in some head sizes above M24).
DIN (Deutsches Institut für Normung)
Key DIN fastener standards:
- DIN 933: Fully threaded hex bolt
- DIN 931: Partially threaded hex bolt
- DIN 934: Hexagon nut
- DIN 912: Socket head cap screw
- DIN 985: Nyloc lock nut
- DIN 125: Flat washer
- DIN 127: Spring lock washer
When to specify DIN standards:
- Private engineering projects importing German machinery or equipment
- Projects where DIN dimensions are critical for equipment compatibility
- Fabrication shops used to DIN part numbers
- Most standard engineering applications where IS standards aren't mandatory
DIN standards are widely understood in India and used interchangeably with IS for most applications. The key difference is that DIN fasteners don't carry ISI mark — not suitable for IS-marked government procurement.
ISO (International Organisation for Standardisation)
Many DIN standards have been adopted or superseded by ISO standards:
- DIN 933 → ISO 4017 (fully threaded hex bolt)
- DIN 931 → ISO 4014 (partially threaded hex bolt)
- DIN 934 → ISO 4032 (hex nut)
In practice, the ISO-equivalent and DIN original are dimensionally identical for most sizes. Both are specified in Indian engineering. ISO references appear more in multinational project specifications.
ISO 898-1: The thread fastener mechanical property standard (grade designation 4.6, 8.8, 10.9, 12.9) — used as the basis for IS 1367 and widely referenced in India.
ISO 3506: Stainless steel fastener properties (A2-70, A4-80) — universally used in India for stainless specifications.
ASTM (American Society for Testing and Materials)
Key ASTM fastener standards used in India:
- ASTM A325/A490: High-strength structural bolts (often used per BS EN 14399-3 equivalent in India)
- ASTM A193 B7: Alloy steel stud bolts for high-temperature service
- ASTM A194 2H: Heavy hex nuts for pressure bolting
- ASTM A307: General purpose anchor bolts
- ASTM F1554: Anchor bolts for structural support
When to specify ASTM standards:
- Oil, gas, and petrochemical projects (B7 stud bolts, A194 nuts)
- Projects designed to ASME/ANSI codes (American flanging standards)
- American or multinational EPC contractors' specifications
- Projects where ASTM product is imported from the USA
Practical Decision Guide
For infrastructure and construction in India:
- Use IS 1367 for government projects
- Use DIN 933/931 for private construction — equivalent quality, wider availability in India
- Specify grade (8.8, 10.9) explicitly regardless of standard
For oil & gas and petrochemical:
- Use ASTM A193 B7 and A194 2H — this is the global standard for pressure bolting and all Indian refinery specifications follow this
For structural steel (HSFG):
- Use IS 3757 for IS-marked procurement
- BS EN 14399 series is equivalent and widely used for international projects
For stainless steel fasteners:
- Specify ISO 3506 grade A2-70 (SS304) or A4-80 (SS316) — universally understood
- Both DIN and IS fasteners follow this stainless grade designation
Bottom line: For most Indian private engineering procurement, DIN standards provide the widest product availability and are equivalent to IS in practice. For government projects and critical structural applications, specify IS 1367 with BIS ISI mark. For oil & gas pressure equipment, specify ASTM A193/A194.
Contact PGS Fasteners for guidance on standard selection for your specific project requirements.