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India - Member - New Member

Join Date: May 2007
Posts: 34

Explanation of hot dip galvanisation

05/29/2007 11:17 AM

hi,can you pl explain me briefly hot dip galvanisation .Surface preparation before galvanisation , and how to ensure the purity and composition of zinc in the bath.Instrument to mesure the coating thickness.and Pl explain me how can i ensure the uniformity of the coating thickness.

eg structure -ERW Pipe(od=244.5)with coupler welded to 50 mm ms plate.

Looking forward for your kind response.

Thanking you.

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Guru

Join Date: Nov 2006
Location: OH USA
Posts: 549
Good Answers: 27
#1

Re: Explanation of hot dip galvanisation

05/30/2007 9:56 AM

The information you need is available from the American Galvanizers Association (www.galvanizeit.org). Also search this forum for previous discussions related to HDG. There have been several.

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Guru

Join Date: Jul 2006
Location: "Dancing over the abyss."
Posts: 4942
Good Answers: 243
#2

Re: Explanation of hot dip galvanisation

05/30/2007 11:11 AM

Bluestone has given great advice.

Cleaning prior to process is essential. The hot dip process is more sensitive to the preliminary cleaning than it is to the deposition procedures.Your choice of alkaline cleaning, Best for oily soils on product; mineral acid cleaning Sulphuric or hydrochloric, Best for removal of oxide soils; and anodic or cathodic electrocleaning. Or combination of the above.

So my question is why hot dip for pipe? HEat requirements would seem to make electro deposited a much lower cost choice.

Heat loss from zinc bath= 5000 Btu. ft^2/ hour;

heat needed to raise product temp approx 110,000Btu / 1000# of steel;

Plus heat needed to melt zinc

MEasurement of coating thickness - make sample section mounts and examine under microscope.

How ensure uniformity of coating thickness? How do you expect to apply coating to product. Its not like you will be pulling a mile long strand of wire through at a given rate.

Again. Why hot dip?

milo

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