Chemical Analysis — Zinc & Zinc Alloy Coated Prestressed Strands(IS 14268:2022 · ASTM A475/A641 Reference)
Base-strand chemical composition testing of galvanized prestressing strand — verifying the IS 14268:2022 base-strand steel beneath the zinc or zinc-alloy coating applied per international galvanizing practice.
What is Zinc-Coated Strand Chemical Analysis?
Zinc and zinc-alloy coated prestressing strand uses hot-dip galvanizing (or zinc-aluminium alloy coating) over a base strand for sacrificial corrosion protection, an alternative to epoxy coating for aggressive exposure conditions. There is currently no dedicated Indian Standard for galvanized prestressing strand specifically — the base strand is expected to meet IS 14268:2022, while the zinc coating itself is typically specified against international references such as ASTM A475 (zinc-coated steel wire strand) or ASTM A641 (zinc-coated carbon steel wire), per project specification.
Global Lab verifies the base-strand chemistry beneath the galvanizing using OES per IS 228 methods on a locally de-galvanized wire section, reporting carbon, manganese, sulphur and phosphorus against IS 14268:2022 requirements — we report the standard actually applicable to each layer rather than citing a single Indian Standard that doesn't fully cover the galvanized product.
Chemical Analysis — Zinc & Zinc Alloy Coated Prestressed Strands — Site Images
How the Chemical Analysis — Zinc & Zinc Alloy Coated Prestressed Strands is Conducted
- 1
Sample Selection
A representative galvanized strand length is sampled, with coating specification (ASTM A475/A641 reference) reviewed alongside the declared base-strand grade. - 2
Local De-Galvanizing
The zinc coating is chemically or mechanically stripped from a small section of one wire to expose bare base steel, without disturbing the surrounding coating. - 3
OES Spark Analysis
Optical Emission Spectroscopy determines carbon, manganese, sulphur, phosphorus and silicon on the exposed steel, calibrated against certified reference material. - 4
Compliance Check
Measured composition is checked against IS 14268:2022 base-strand requirements. - 5
Reporting
Base-strand composition is compiled into a NABL-accredited report confirming compliance, issued via Autovity QLMS.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| IS 14268:2022 | Uncoated Stress Relieved Low Relaxation Seven-Wire Strand — Specification | Base-Strand Chemical Composition | Indian Standard |
| ASTM A475 / A641 | Zinc-Coated Steel Wire Strand / Zinc-Coated Carbon Steel Wire | Zinc Coating Reference (No Dedicated IS Standard Yet) | ASTM Standard |
| IS 228 (Various Parts) | Methods for Chemical Analysis of Steels | Elemental Analysis Methods | Indian Standard |