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.
(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.
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.
* 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
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.
The zinc-plated (galvanized) steel plate is formed into a tube. The area burnt due to welding is repaired by metal thermal sprayed coating.
The non-galvanized steel tube is formed into a tube and the plate is then dipped in a galvanized bath.