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IS 2629 : 1985Recommended Practice for Hot-Dip Galvanizing of Iron and Steel

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ISO 1461 · ASTM A123/A123M · BS EN ISO 1461
CurrentFrequently UsedCode of PracticeMaterials Science · Fencing, Gates and Barriers
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Link points to Internet Archive / others. Not hosted by InfraLens. Details
OverviewValues5InternationalTablesFAQ4Related

IS 2629:1985 is the Indian Standard (BIS) for recommended practice for hot-dip galvanizing of iron and steel. This standard details the recommended practice for hot-dip galvanizing of iron and steel to protect them against corrosion. It comprehensively covers the required surface preparation (degreasing, pickling, fluxing), zinc bath temperature maintenance, and dipping processes.

Describes procedures for hot-dip galvanizing of iron and steel articles, related to corrosion protection for fencing and barriers.

Overview

Status
Current
Usage level
Frequently Used
Domain
Materials Science — Fencing, Gates and Barriers
Type
Code of Practice
Amendments
Amendment 1 (1990); Amendment 2
International equivalents
ISO 1461:2022 · ISO (International Organization for Standardization)ASTM A123/A123M-23 · ASTM International (US)BS EN ISO 1461:2022 · BSI (UK) / CEN (Europe)AS/NZS 4680:2006 · Standards Australia / Standards New Zealand (Australia/New Zealand)
Typically used with
IS 209IS 2633IS 4759IS 6745
Also on InfraLens for IS 2629
5Key values4FAQs
Practical Notes
! Fabricators must ensure proper venting and draining holes are provided in tubular and hollow sections to prevent explosive pressure build-up during dipping.
! IS 2629 covers the galvanizing 'process' and best practices; however, engineers must refer to IS 4759 for the actual specified coating thickness and mass requirements.
! Special care must be taken against hydrogen embrittlement when galvanizing high-tensile steel (referencing IS 6158).
Frequently referenced clauses
Cl. 4Requirements of Base MetalCl. 5Surface Preparation (Degreasing and Pickling)Cl. 6FluxingCl. 7Galvanizing ProcessCl. 8Post-Treatment
Pulled from IS 2629:1985. Browse the full clause & table index below in Tables & Referenced Sections.
Updates & Amendments2 amendments
1990Amendment 1 (1990)
Amendment 2
Consolidated list per BIS. For the text of each amendment, refer to the BIS portal link above.
ironsteelzincgalvanized steel

International Equivalents

Similar International Standards
ISO 1461:2022ISO (International Organization for Standardization)
HighCurrent
Hot-dip galvanized coatings on fabricated iron and steel articles — Specifications and test methods
Specifies general properties and test methods for hot-dip galvanized coatings on fabricated iron and steel, directly comparable to IS 2629's recommendations for practice and quality.
ASTM A123/A123M-23ASTM International (US)
HighCurrent
Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products
Covers zinc coatings applied by the hot-dip process on various iron and steel products, providing detailed specifications and testing requirements similar to the scope of IS 2629.
BS EN ISO 1461:2022BSI (UK) / CEN (Europe)
HighCurrent
Hot dip galvanized coatings on fabricated iron and steel articles. Specifications and test methods
As the British and European adoption of ISO 1461, it provides identical specifications and test methods for hot-dip galvanized coatings, widely used and directly comparable.
AS/NZS 4680:2006Standards Australia / Standards New Zealand (Australia/New Zealand)
HighCurrent
Hot-dip galvanized (zinc) coatings on fabricated ferrous articles
Details specifications for hot-dip galvanized coatings on fabricated ferrous articles, including properties and test methods, aligning closely with IS 2629's scope and principles.
Key Differences
≠IS 2629:1985 is titled 'Recommended Practice,' indicating a guidance-oriented approach, whereas international standards like ISO 1461 and ASTM A123 are more prescriptive 'Specifications' detailing mandatory requirements.
≠ASTM A123/A123M-23 specifies a slightly higher minimum average coating thickness (100 µm) for structural shapes over 6.4 mm thick, while IS 2629:1985 and ISO 1461:2022 both specify 85 µm for steel over 6 mm thick.
≠IS 2629:1985 references older Indian standards (IS 209:1979) for zinc ingot purity, while modern international standards like ISO 1461:2022 refer to contemporary international or European standards (e.g., EN 1179, ISO 752), which may reflect updated classifications and impurity limits.
≠The steel thickness categories used to define coating thickness requirements vary slightly; for instance, IS 2629 and ISO 1461 use '>6mm' and '3mm to 6mm', whereas ASTM A123 uses '>6.4mm' and '>3.2mm to 6.4mm', potentially leading to minor differences in application for borderline thicknesses.
≠Being an older standard, IS 2629:1985 may not explicitly cover or provide recommendations for certain modern practices like specific post-treatment passivation techniques (e.g., chromium-free), advanced coating repair methods, or detailed environmental/safety considerations during the galvanizing process, which are often addressed or influenced by more recent international standards.
Key Similarities
≈All standards prescribe the fundamental hot-dip galvanizing process, encompassing essential pre-treatment steps such as degreasing, pickling, and fluxing, followed by immersion in molten zinc.
≈A core objective shared across all standards is to provide robust corrosion protection for iron and steel products through the creation of a metallurgically bonded zinc coating.
≈The appearance requirements are largely consistent, demanding a galvanized coating that is continuous, smooth, and free from major defects like bare spots, flux stains, blisters, and gross dross inclusions.
≈All standards correlate the required coating thickness or mass to the thickness of the steel article, acknowledging that thicker steel substrates generally necessitate and achieve thicker protective coatings.
≈The adhesion of the zinc coating to the steel substrate is considered paramount for long-term performance, with all standards specifying test methods, commonly the paring or knife test, to assess coating adhesion.
Parameter Comparison
ParameterIS ValueInternationalSource
Minimum Average Zinc Purity in Bath98.5% (or 99.95%) as per IS 209:1979Generally 98.5% or higher (e.g., 99.99%)ISO 1461:2022 (referencing EN 1179/ISO 752), ASTM A123/A123M-23 (referencing ASTM B6)
Min. Average Coating Thickness for Steel >6mm (>6.4mm for ASTM)85 µm85 µm (ISO 1461:2022, AS/NZS 4680:2006); 100 µm (ASTM A123/A123M-23)ISO 1461:2022, ASTM A123/A123M-23, AS/NZS 4680:2006
Min. Average Coating Mass for Steel >6mm (>6.4mm for ASTM)610 g/m²610 g/m²ISO 1461:2022, ASTM A123/A123M-23, AS/NZS 4680:2006
Min. Average Coating Thickness for Steel 3mm to 6mm (3.2mm to 6.4mm for ASTM)70 µm70 µm (ISO 1461:2022, AS/NZS 4680:2006); 85 µm (ASTM A123/A123M-23)ISO 1461:2022, ASTM A123/A123M-23, AS/NZS 4680:2006
Adhesion Test MethodParing TestParing Test (or Knife Test)ISO 1461:2022, ASTM A123/A123M-23, AS/NZS 4680:2006
Coating Appearance RequirementsContinuous, smooth, free from bare spots, flux stains, blisters, dross, lumps, and other inclusions.Continuous, smooth, free from bare spots, flux stains, blisters, gross dross inclusions, non-adherent particles.ISO 1461:2022, ASTM A123/A123M-23, AS/NZS 4680:2006
⚠ Verify details from original standards before use

Key Values5

Quick Reference Values
recommended zinc bath temperature445°C to 465°C
hydrochloric acid concentration for pickling10% to 15% by mass
sulfuric acid concentration for pickling5% to 15% by mass
sulfuric acid pickling temperature60°C to 80°C
minimum zinc purityConforming to IS 209 (typically 98.5% to 99.95%)

Tables & Referenced Sections

Key Tables
No tables data
Key Clauses
Clause 4 - Requirements of Base Metal
Clause 5 - Surface Preparation (Degreasing and Pickling)
Clause 6 - Fluxing
Clause 7 - Galvanizing Process
Clause 8 - Post-Treatment

Related Resources on InfraLens

Cross-Referenced Codes
IS 209:1992Zinc Ingots - Specification
→
IS 2633:2002Methods for Testing Electroplated Coatings
→
IS 4759:1996Hot-Dip Zinc Coatings on Structural Steel and...
→
IS 6745:1994Method for Determination of Density of Harden...
→

Frequently Asked Questions4

What is the correct temperature for the zinc galvanizing bath?+
The bath temperature should be maintained strictly between 445°C and 465°C for optimal coating.
How is mill scale and rust removed prior to galvanizing?+
Through a pickling process using either dilute Hydrochloric Acid (ambient temp) or Sulfuric Acid (heated to 60-80°C).
Does this standard specify the required thickness of the zinc coating?+
No, this standard covers the procedure. Coating mass and thickness requirements are specified in IS 4759.
Why is fluxing required before dipping into molten zinc?+
Fluxing (typically with zinc ammonium chloride) prevents oxidation of the cleaned steel surface and promotes smooth wetting of the steel by the molten zinc.

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