Questions regarding cable ducting
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Our company is currently manufacturing cable trays as well as conduit for wiring. In the past, hot-dip galvanized pipes were used for this purpose, but the client here said that cold-dip galvanized pipes are also fine, as they do not rust as easily. So the question is: can cold galvanizing be used for wire ducts? Are there any specifications that detail this, or is hot galvanizing the standard practice?
Give myself a push – is there anyone who can help answer this? I haven’t paid much attention to this issue before
HGT 20512-2014 Code for Design of Instrument Piping and Wiring 8.4.1 Galvanized welded steel pipes are recommended for protective pipes. It seems that there is no requirement to use hot-dip galvanizing. Cold galvanizing is a form of electro-galvanizing; the galvanized layer is relatively thin, and it depends on the corrosion conditions at the site.
This post was last edited by feng*aosa on 2019-7-24 21:12. The specification requires the use of galvanized pipes, and the standard for such pipes is GBT 3091-2015: Welded steel pipes for low-pressure fluid transport. The standard specifies that \"hot-dip galvanizing shall be used for the galvanization of steel pipes.\" Cold galvanizing is a form of galvanization achieved through electroplating; it is an outdated process that results in a very thin galvanized layer which is prone to damage and corrosion. For small pipe diameters, it is difficult to ensure and verify the quality of the internal electroplating. It is recommended not to use it. The Ministry of Construction has issued regulations prohibiting the use of electro-galvanized pipes for water and gas pipelines in new buildings.
GB50093-2002 Code for Construction and Acceptance of Automatic Instrumentation Projects also specifies that galvanized pipes should be used as wire conduit through threaded connections, without mentioning electroplated or hot-dip plated pipes.
If cold-galvanized materials are used, they won’t pass the inspection upon arrival; in such cases, one should not look to construction standards, but rather to regulations regarding material procurement and inspection upon arrival
So, in what areas are cold-galvanized materials generally used?
Cold galvanizing is rarely used; for chemical processing applications, hot galvanizing is what we use, as the galvanizing layer obtained through cold galvanizing is too thin
In explosion-proof areas, standards require the use of welded steel pipes for low-pressure fluid transport
AQ3009-2007 Safety Code for Electrical Explosion Protection in Hazardous Areas 6.1.1.3 Conduit Wiring 6.1.1.3.1 Permissible Conduits a) The wiring conduits shall be galvanized welded steel pipes for low-pressure fluid transportation, as specified in GB T 3091-2015 Welded Steel Pipes for Low-Pressure Fluid Transportation, Section 5.9 Galvanizing Coating; 5.9.1 Galvanizing Method Hot-dip galvanizing shall be used for galvanizing the steel pipes.