Search our quarter-million Q&As

Home of the finishing HOTLINE since 1989

-----

Serious peeling problems with galvanizing

2004

Dear sirs,

We faced peeling problem with our production in Hot dip galvanizing line and we tried many times to solve this problem but we can't with adusting all parameters like exit strip , AL % in Zinc pot, H2 % inside furnace if you have any solution tell me please.

Regards

Hussein Zeinhom
- Cairo, Egypt

---

Peeling or barespots are one of the hardest defects to overcome in a CGL . There are so many things that can attribute to this . After seeing some of the steps you have takin in tracking it down all I can suggest would be to do a furnace tuning and make sure that mixtures are still to specs. After doing this as a short term fix try adjusting line speed to give more soak time in the furnace . This should allow more oxides to burn away . Another thing to keep an eye on is when this defect occurs . Is it on G80 FH and anneal both . If it seems to be mostly on G80 I suggest that more alkaline be added to the cleaning section ( since the temps are usually lower in the furnace and the speeds higher : not allowing the furnace to act as a " cleaning section " ) and a few feet per minute drop in normal speed in addition to the raised H2 that you have already tried .... hopefully this helps you out . I hope to hear good news from you about this pending issue .

Mark Postema
- Rancho Cucamonga , CA , USA
2004

Sorry! Finishing.com is temporarily Read-Only.
Ted Mooney is retiring but I have several offers to take it over.
We're working hard to make sure we find it the best new home.