Galvanizing Kettle melted -- why?

A. Thanks Mr. Doug Theall for your reply.

As mentioned by you, temp. controller fails....

There is also chances of poor quality of materials as it's not easy to erode steel plate so fast at initial stage. Better check quality of steel plate also.

If temperature goes up, you will notice that by visualizing also but you couldn't know quality of steel plate without inspecting.

A. How much life are you getting out of your current kettle and how much due you hope to get? Improving your burner system would probably be the best way to extend kettle life. I assume your kettle is made from steel with the proper steel chemistry (kettle steel). Impressing a current to the kettle may not be possible with the high temperatures.

A. Regular dross removal and agitation is essential (every 2 weeks minimum). Kettle must be ultra low Si content. Low iron level in flux solution (<1%) helps.

A. X-Ray

A. Buckets are NOT a safe way to empty a kettle. You need a pump and if you have holes it needs emptying quickly.

Its a specialist job, and several such specialists exist, some advertise on this site.

And don't cool molten zinc with water. You risk lives being lost!

Q. Thank you so much for the kind reply sir. Our kettle has been emptied and now we are planning to replace it with the new one. You told me not to solidify zinc with water, apart from the blasts and splashes, is there any other effect on the zinc quality by doing so? Can you kindly refer some book/literature about this very issue (regarding maintenance in HDP) I am a very new person in galvanizing industry and would really love to learn from you. Thanks a lot again for your kind help!

Q. Sir:

How many years did your galvanizing kettle last?

Regards,

A. The reason to not solidify molten zinc with water is to avoid trapping water beneath zinc where it can explosively vapourise, forcing the zinc to violently splash.

Zinc so cooled by water is not damaged, and is reuseable, but there are much higher losses due to the higher surface area, and resultant oxidation on re-melting.

So the reason not to solidify with water is mostly a safety one not so much a metallurgical one.
After solidification, water could be used very carefully to speed up cooling, but not too cold or you risk water inclusion in the ingot, and on re-melting this could explode.

A. There's not enough information in the question to give a meaningful answer.
What tonnage galvanized by this kettle?
What operating temperature?
How many times frozen? For how long?
What actual grade of steel was the kettle?
What material being galvanized? At what rate?
How long a life did the kettle give?
What drossing procedure? (how often, how much)
What flux type?
How heated?
What furnace design?

All this info is relevant, but even then an answer might not be obvious. Answering these "might" reveal a suggested cause.

Your questions appear straightforward, but actually are quite difficult to answer.

1. what is an estimate quantity of LPG (Liquefied Petroleum Gas as source of heating the zinc kettle) required to melt the evacuated zinc and new zinc ingots that will be added?
Many factors can influence this. The efficiency of your burners; insulation effectiveness of furnace, insulation effectiveness during meltout of the surface of the zinc;

2. how long (days) will it take to melt the zinc for production to start sine we are starting all over again?

This is the wrong question, and that you are asking suggests a reason for the kettle leak.
You should be asking what rate of temperature increase should I maintain in a melt-out profile. The answer might be somewhere in the region of 5-17 °C per hour, but with some stopping (hold) points at the two main critical temperatures during this operation.

3. what is the expected life span of this repaired zinc kettle if we galvanize 40 tons of steel per day?

That's like asking "How long will my tyre now last with the puncture repaired? There are so many variables involved that the answer could be from weeks to years.
For example these factors: Residual kettle thickness; zinc chemistry; flux practice, hours of operation; temperature of normal operations; chemistry of typical steel; drossing practice; ashing practice; rate of immersion; rate of withdrawal; stability of temperature; shape of burner flame; existence of protection plates; layout of kettle insulation inside the furnace and so on...

A. Dear Mr. Farooq
Superficially it looks that the Zinc Kettle has gone from its bottom welding. The kettle manufacturing and first few firing is a very sensitive issue. Sometimes Furnace design is also faulty, maybe made localized heating.
My submission:
1. The Zinc Kettle has to be made by [deleted by editor] only.
2. in such a deep furnace, advise to use Flat Flame Burners better to take Furnace from [deleted by editor]. Do not try here and there.
3. Hire a consultant.

Thank you for your generous suggestions, Mr. Dalela, they are a continuing help. You are welcome to your belief that there is but one competent kettle manufacturer and but one competent furnace manufacturer in all the world, and they're welcome to advertise anywhere they wish, including here, but comment spam is a curse and we cannot post testimonials to, nor slams of, vendors in this forum for a long list of reasons (why?) which we've bored our readers to tears with :-)

Thanks again for the other help.

Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 2017

A. Dear Mr. Mohammed Farouk Abdallah

As mentioned by you, your Kettle Punctured within couple of days, it means Either Furnace Design or Manufacturing of Galvanizing kettle plate or its Design or Welding electrodes or workmanship was too poor.

Better you should consult some of better consultant for the same or hire some better supplier of Galvanizing Kettle and Furnace Constructor.

Dear Sir.

It looks like your furnace design or Materials for Kettle may be wrong.

Otherwise it will not happen so fast.

 Hi cousin Gubendiran. Unfortunately, I don't think your question is actually reasonable...

As a professional engineer I spent 40 years designing metal finishing plants & equipment but, because I don't have experience specifically in hot dip galvanizing, I would not attempt to design galvanizing equipment. Most galvanizing equipment lead designers and consultants have decades of experience in that specific field. And even they encounter problems, as you are reading on these pages.

I think realistically you will need to buy your equipment from a proven source or retain an experienced galvanizing consultant because it isn't possible to compress decades of experience into the 2 or 3 paragraphs appropriate for a public forum. But you can get a few galvanizing books from the library for starters, and we'll leave your question on line and see if readers can suggest starting points. Good luck.

Regards,

A. Dear Gubendiran Singaram.

Better you consult some good consultant for Plant and machinery designing of galvanizing Plant.

Its difficult for you to design and do the job -- it's not easy job.