T/CSEA 23-2022 Metal coating: Requirements and test methods for zinc plating on steel parts

Scope

Main technical content: **5 Requirements** 5.1 Appearance a) The surface of the zinc-plated layer shall be smooth and uniform upon visual inspection. Slight scratches caused by normal contact between parts during the zinc-plating process or during storage and transportation are acceptable. Surface unevenness of the zinc-plated layer due to sand holes or slag inclusions in the parts prior to zinc-plating shall not be considered an appearance defect. b) The surface of the zinc-plated layer shall be gray (dull or glossy). This standard does not specify requirements for the appearance of the zinc-plated layer after passivation or sealing treatments. c) There shall be no leakage of zinc-plating. d) The area of deep gray spots on the zinc-plated layer shall not exceed 5% of the total area of the zinc-plated layer. e) Unless otherwise agreed by both the supplier and the buyer, the surface of the parts shall not have orange-brown products upon delivery. Parts rejected due to the presence of orange-brown products on the surface shall be re-zinc-plated and inspected after obtaining the buyer's approval. **5.2 Thickness** 5.2.1 Thickness requirements This document classifies the zinc-plated layer thickness into eight grades (see Table 1), and the zinc-plated layer thickness for each grade shall not be less than the requirements specified in Table 1. **Table 1: Zinc-plated layer thickness** Zinc-plated layer grade Minimum local thickness (μm) Unit area zinc-plated layer mass (g/m2) 100 100 720 90 90 648 80 80 576 70 70 50 760 60 43 250 50 360 40 40 288 30 216 5.2.2 Pre-reserve clearance for threaded parts For threaded parts, sufficient clearance between the internal and external threads shall be considered before zinc-plating. The buyer shall discuss with the supplier the requirements for pre-reserve clearance. Guidelines for pre-reserve clearance are referenced in GB/T 19355.3. **5.3 Post-proces

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