Zinc Plating Performance, Perfect Post Zinc

DAIWA STEEL TUBE INDUSTRIES
Perfect Post Zinc
Perfect Post Zinc (PPZ)

The interior of the Perfect Post Zinc (PPZ) steel tube is galvanized, and the exterior is finished with an epoch-making product called Post Zinc (already patented).
The Perfect Post Zinc tube is a follow-on product to the Post Zinc tube where the entire tube is coated with zinc and therefore is strong against corrosion. It has additional qualities in that the thickness of the zinc plating can be flexibly changed according to usage. Perfect Post Zinc has been granted the Construction Technology Evaluation Certification by the Public Works Research Center (Japan) as being equivalent in quality to dip coating because of its zinc plating thinness.

For details on the exterior zinc plating of Post Zinc, see the Post Zinc page.

Acquisition of the Construction Technology Evalutation Certification
Perfect Post Zinc has acquired the Construction Technology Evaluation Certification issued by the Public Works Research Center (Japan). The Certification is issued by the Ministry of Land, Infrastructure, Transport and Tourism's public corporation, the Public Works Research Center (Japan), to promote the development and use of new construction technology. The Center examines the new technology of applicant corporations using the academia and approves them when it judges them to be scientifically and technically sound.
It is registered in NETIS.
The product is registered as an excellent technology in the Ministry of Land, Infrastructure, Transport and Tourism's NETIS.*
(NETIS registration number: KK-100035-A)

* NETIS is a system in which the Ministry of Land, Infrastructure, Transport and Tourism evaluates the technology of the private sector and promotes its usage to the public and private sectors through the Ministry's nationwide agencies.

Comparison table -- Perfect Post Zinc and Dip Coating standards

It has been examined and proven by the Public Works Research Center (Japan) that the thickness of the pure zinc layer greatly affects the development of red rust on tubes. The Center has also recognized the fact that the PPZ tube although having a thinner pure zinc layer than that of dip coating, has a lower corrosion coefficient than the latter.

PPZ pipe standard / Hot dip galvanized coating (JIS H 8641)

* Example of how to read the Standard signs and the amount of zinc adhesion.
120Z: Exterior & Interior zinc adhesion amount 120g/m2 ±20g/m2
HDZ35: Exterior & Interior zinc adhesion amount 350g/m2 or more

Daiwa's manufacturing process - Perfect Post Zinc
Perfect Post Zinc

First, the plate surface that is to become the interior of the tube is galvanized, then the tube is formed and the seam is welded, and the exterior is galvanized, all in a continuous process.

Other manufacturers' process
Pre-coating

The zinc-plated (galvanized) steel plate is formed into a tube. The area burnt due to welding is repaired by metal thermal sprayed coating.

Plating ahead
Dip Coating

The non-galvanized steel tube is formed into a tube and the plate is then dipped in a galvanized bath.

Dip Coating
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