Link points to Internet Archive / others. Not hosted by InfraLens. Details
IS 4000:1992 Part 2 is the Indian Standard (BIS) for hot-dip galvanized coatings (mass, thickness and uniformity) on fasteners. IS 4000 provides comprehensive guidelines for the design, assembly, and tightening of high-strength friction grip (HSFG) bolts in steel structures. It covers critical parameters like slip factors for various faying surfaces—including the effects of hot-dip galvanizing—and standardizes installation methods such as the turn-of-nut and calibrated torque control techniques.
Specifies requirements for hot-dip galvanized coatings on fasteners.
Quick Reference — Top IS 4000 Part 2:1992 Values
Key requirements for hot-dip galvanized coatings on fasteners, including mass, thickness, thread allowances, and test criteria.
✓ Verified 2026-04-27
Reference
Value
Clause
Min Zinc Grade for Galvanizing— Conforming to IS 209:1992.
Zn 98.5
Cl. 3.2
High Purity Zinc Grade— Optional higher purity grade, conforming to IS 209:1992.
Zn 99.95
Cl. 3.2
Mean Coating Mass (>10mm Fasteners)— Applies to bolts, screws, studs, and nuts with thread dia > 10 mm.
380 g/m²
Cl. 4.1 (Table 1)
Min Individual Coating Mass (>10mm Fasteners)— Minimum for any single specimen from the test sample.
305 g/m²
Cl. 4.1 (Table 1)
Mean Coating Mass (≤10mm Fasteners & Washers)— Applies to fasteners ≤ 10 mm dia and all washers.
305 g/m²
Cl. 4.1 (Table 1)
Min Individual Coating Mass (≤10mm Fasteners & Washers)— Minimum for any single specimen from the test sample.
245 g/m²
Cl. 4.1 (Table 1)
Mean Coating Thickness (>10mm Fasteners)— Equivalent to the mean mass requirement of 380 g/m².
53 µm
Cl. 4.2.1
Mean Coating Thickness (≤10mm Fasteners & Washers)— Equivalent to the mean mass requirement of 305 g/m².
43 µm
Cl. 4.2.1
Coating Mass to Thickness Conversion— Approximate conversion factor for zinc coating.
1 g/m² ≈ 0.14 µm
Cl. 4.2.1
Nut Threading Rule— Threads must be subsequently oiled for corrosion protection.
Tapped oversize AFTER galvanizing
Cl. 5.2
Oversize Tapping Allowance (M12)— Minimum diametral allowance for nut threads.
0.30 mm
Cl. 5.2.1 (Table 2)
Oversize Tapping Allowance (M16-M22)— Minimum diametral allowance for nut threads.
0.40 mm
Cl. 5.2.1 (Table 2)
Oversize Tapping Allowance (M24-M30)— Minimum diametral allowance for nut threads.
0.50 mm
Cl. 5.2.1 (Table 2)
Oversize Tapping Allowance (M36)— Minimum diametral allowance for nut threads.
0.60 mm
Cl. 5.2.1 (Table 2)
Uniformity Test Dips (>10mm Fasteners)— Preece test (copper sulphate solution) without showing bright, adherent copper.
4 one-minute dips
Cl. 4.3.1
Uniformity Test Dips (≤10mm Fasteners & Washers)— Preece test (copper sulphate solution) without showing bright, adherent copper.
3 one-minute dips
Cl. 4.3.1
Preece Test Solution Sp. Gravity— For uniformity test. Solution to be neutralized with excess cupric hydroxide.
1.186 @ 18°C
Annex B, B-2.1
Preece Test Solution Min pH— Checked with methyl orange indicator before use.
4.0
Annex B, B-2.1
Embrittlement Test Applicability— Required for high-strength bolts susceptible to hydrogen embrittlement.
UTS ≥ 1000 MPa
Cl. 6.5.1
Embrittlement Test Sustained Load— Load to be applied and held for the test duration.
75% of min ultimate tensile load
Cl. 6.5.2
Embrittlement Test Duration— The bolt must not fracture during this period.
24 hours
Cl. 6.5.3
⚠ Verify against the latest BIS/IRC publication and project specifications. Amendment Slips may modify values.
Overview
Status
Current
Usage level
Essential
Domain
Structural Engineering — Fasteners, Bolts and Anchors
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Never reuse fully tensioned HSFG bolts; they must be discarded once tightened to their minimum bolt tension.
! Faying (contact) surfaces must be strictly free of dirt, oil, paint, or loose scale, as these severely reduce the slip factor and compromise joint capacity.
! Standard hot-dip galvanized surfaces significantly lower the joint's slip factor (down to ~0.10) unless properly treated (e.g., light grit blasting or wire brushing) before assembly.
RCSC Specification for Structural Joints Using High-Strength Bolts, 2020RCSC / AISC (US)
HighCurrent
Specification for Structural Joints Using High-Strength Bolts
Both are primary codes of practice for the design, installation, and inspection of high-strength bolted connections in steel structures.
EN 1993-1-8:2005CEN (European Union)
HighCurrent
Eurocode 3: Design of steel structures — Part 1-8: Design of joints
Covers design principles for bolted connections, including categories, resistance calculations, and detailing, within a broader steel design code.
AISC 360-22AISC (US)
MediumCurrent
Specification for Structural Steel Buildings
Chapter J (Connections) extensively covers bolted joint design and references the RCSC specification for installation and inspection.
BS 5950-1:2000BSI (UK)
MediumWithdrawn
Structural use of steelwork in building - Part 1: Code of practice for design - Rolled and welded sections
The previous British standard containing design rules for bolted connections before the adoption of Eurocodes.
Key Differences
≠Bolt Grades: IS 4000 primarily uses IS 1367 property classes 8.8 and 10.9. The RCSC Specification is based on ASTM F3125 grades, historically known as A325 (now Grade A325) and A490 (now Grade A490), which have different specified tensile strengths and material properties.
≠Installation Methods: The RCSC specification details four pretensioning methods: Turn-of-Nut, Calibrated Wrench, Twist-Off Type Bolts, and Direct Tension Indicators (DTIs). IS 4000 focuses primarily on the Turn-of-Nut and Calibrated Wrench methods, with less comprehensive coverage of DTIs or Twist-Off bolts.
≠Prying Action: The RCSC and AISC 360 specifications provide more rigorous and detailed analytical procedures for calculating the effects of prying action on bolts in tension than the more simplified guidance offered in IS 4000:1992.
≠Surface Preparation and Slip Factors: While both standards specify slip factors (coefficients of friction) for slip-critical/friction-type joints, the RCSC specification provides a more detailed classification of faying surface conditions (Class A, B, etc.) with corresponding slip coefficients, which may not directly align with the values in IS 4000 for similar surfaces.
Key Similarities
≈Fundamental Joint Types: Both standards are fundamentally based on the same two mechanisms for load transfer in shear connections: 'Bearing-type' (where bolts bear against the plate) and 'Friction-type' or 'Slip-critical' (where load is transferred by friction generated by bolt pretension).
≈Bolt Pretensioning: For friction-type/slip-critical connections, both IS 4000 and the RCSC specification mandate that bolts must be tightened to a specified minimum pretension (clamping force) to enable the friction mechanism.
≈Turn-of-Nut Method: The principle and application of the 'Turn-of-Nut' pretensioning method, which involves applying a specific rotation from a snug-tight condition to achieve the required tension, are conceptually identical in both standards.
≈Combined Loading Rules: Both codes provide interaction equations or design checks for bolts subjected to a combination of shear and tensile forces, ensuring the combined stress state does not exceed the bolt's capacity.
Parameter Comparison
Parameter
IS Value
International
Source
Primary Bolt Grade (Medium Strength)
Property Class 8.8 (Ultimate Tensile Strength: 800-830 MPa)