Summary for automatic pipe galvanizing Discussion
automatic pipe galvanizing is the focus keyphrase here, and Dr. Thomas H. Cook explains that galvanizing pipes and tubes is far more difficult than general after-fabrication work because kettle times can be only about a minute, so the flux must be very good. He says poor fluxing is a major reason the inside diameter of pipes can end up with much thicker zinc than the outside. Flux temperature also matters: too hot can corrode the outside surfaces of pipes in bundles and create black spots, while too cold can cause zinc spatter in the kettle. He also stresses that handling equipment is critical, recommending walking beams over end-on rollers because rollers can rub off the flux. On aluminum, Cook recommends keeping it between 0.001% and 0.003% in the zinc and properly alloyed, warning that higher levels cause many problems.
Q. Hello everyone,
I am working in a small galvanizing plant which is 20 years old. We produce pipes & tubes per ASTM A53
[affil. link] / BS standard. Can you people help me in complete galvanizing process (chemical related) like procedure to calculate baumé/acids and all, how much % of AL is to be added in zinc bath etc.
Please help me
Thanks in advance.
Javed
factories for steel products ltd – Jeddah, Saudi Arabia
April 3, 2012
A. Hi, Javed. We have hundreds of threads about galvanizing topics including baumé, acids, % of aluminum, etc. Please use the search engine to locate relevant threads. You’re certainly welcome to start new threads whenever you wish, but asking for “complete galvanizing process” is hopeless; people can’t possibly summarize the subject in a paragraph or two :-)
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
April , 2012
April 6, 2012
A. Sir:
Automatic pipe galvanizing is about 10 times more difficult than general after fab galvanizing. Part of this is due to short kettle times (e.g. 1 minute or so). Thus the flux must be “GOOD.” Also the inside diameter of the pipes are many times four times thicker in zinc than the outside diameter. This is mainly due to bad flux. Temperature of the flux is critical also. Too hot causes corrosion on the outside diameter of the pipes in the bundles and then black spots. Too cold of flux causes much zinc spatter in the kettle. Pipes handling equipment is also extremely important. Walking beams are best– end-on rollers are worst because they rub off the flux.
For aluminum, I like between 0.001% to 0.003% in the zinc and properly alloyed into the zinc. Higher than this causes many problems.
Regards,
Dr. Thomas H. Cook
Galvanizing Consultant – Hot Springs, South Dakota, USA