Organizer：Materials Division

Co-organizer：Environmental Division

Date, Time & Venue

Date:  14 September 2024 (Saturday)

Time: 9:30 am to 12:00 noon

Assembly time and place: 9:15 am at MTR Long Ping Station (exit A)

Speakers:

Representatives from Yau Sang Galvanizing (Hot-Dip) Co. Ltd.

Programme Highlights

Yau Sang Galvanizing (Hot-Dip) Co., Ltd. was founded in 1978 specializing in hot-dip galvanizing, with factories set up in Hong Kong and Dongguan, and with renowned project references through the past decades of operation.

Registration & Enquiries

The visit is limited to 30 persons. For registration, please fill the online form: 

https://docs.google.com/forms/d/e/1FAIpQLSdj6Mtfz_V_TdzFAV6XMNy3Ubt7vQNih-yWcunjnU0JWjwdzA/viewform

on or before 6 September 2024. Late applicants may only be accepted subject to available vacancy.

The technical visit will be cancelled if No. 8 or higher Tropical Cyclone Warning Signal or Black Rainstorm Warning is issued/ still in effect within two hours before the starting time.

For enquiry, please contact Ir Dr Kenneth Pak at 92700130 or Ir Dr PL Ng at 95875310. Attendancecertificate will be issued after attending the technical visit.

Applicants please fill the following form for online registration.

Technical Visit to Yau Sang Galvanizing (Hot-Dip) Company Limited – By Ir Chris MAK

In September 2024, the HKIE Materials Division organized a technical visit to Yau Sang Galvanizing (Hot-Dip) Company Limited in Yuen Long Industrial Estate. As a result of the impressive level of interest in the technical visit, 94 individuals were enrolled, and the visit was split into two sessions with two separate visits to cater for the number of participants on 14 and 21 September 2024.

This event was arranged so that interested members could better understand the hot-dip galvanizing (HDG) process and its application in Hong Kong. Visiting the factory and witnessing the process first hand enabled the participants to gain a better and more in depth understanding of HDG.

Founded in 1978, Yau Sang is an approved Contractor for HKSAR Government Projects to provide Hot Dip Galvanizing (Class V). Yau Sang has provided HDG services to Hong Kong for nearly half a century. We were delighted to be hosted by Mr. Billy Wong, the marketing manager of Yau Sang, to share the background, technology, general process, quality management plus practical considerations with us.

Background:

HDG has grown almost continuously since it was first used to protect corrugated iron sheets 150 years ago. Its ability to grow in the face of sophisticated and more modern competition is the result of the simplicity of the process, together with unique advantages. HDG is very common in construction projects near coastal areas, corrosion is one of the major concerns of long-term maintenance and is a problem that HDG can mitigate very effectively.

There were 4 companies providing HDG services in Hong Kong 30 years ago but, Yau Sang is the last remaining provider and became the only one in recent years.

Technology:

HDG is a process used to apply a thin, sacrificial protective coating of zinc to steel or iron substrates. It involves immersing the cleaned, pre-fabricated and pre-treated steel or iron products into a bath of molten zinc at a temperature of approximately 435 to 455 degrees Celsius.

General Process

HDG is a multi-stage process where the first stage (cleaning) uses a hot alkaline solution to remove dirt, oil and grease from the product to be coated. This is followed by pickling (using dilute hydrochloric acid solution to remove rust) and then fluxing (using zinc ammonium chloride solution to remove oxide). Following these three preliminary stages, the product is ready for galvanizing by immersing in a bath of molten zinc between 435-455 degrees Celsius. The zinc metallurgically bonds to the steel, creating a series of highly abrasion-resistant zinc-iron alloy layers, commonly topped by a layer of impact-resistant pure zinc. Lastly, air cooling would be applied.