Caustic and Caustic Rinse Tanks
Caustic and caustic rinse tanks are constructed of 1/4″ mild steel plate and reinforced at the lip with steel channel and at the girth with angle. In addition, the lower portion of the sidewall and the bottom is reinforced with T bar and/or I beam.
The tanks are heated by immersion tube burners fabricated of schedule 40 steel pipe and fired with atmospheric type burners. Temperature control of the solution is manual, and the necessary burners are furnished. The stacks extend approximately one foot above the tank lip. After fabrication, the caustic and caustic rinse tanks are painted with an epoxy coating suitable for the operating environment.
Acid, Acid Rinse and Flux Tanks
Acid, Acid Rinse and Flux Tanks are constructed of 1/4″ mild steel plate and are reinforced at the lip with steel channel and at the girth with angle. In addition, the lower portion of the sidewall and the bottom are reinforced with T bar and/or I beam.
The tanks are then lined with 1″ welded polypropylene copolymer sheet. The tank liner bottom is in turn covered with acid brick. After fabrication, the tanks are painted with an epoxy coating suitable for the operating environment.
Free standing fc tanks constructed of structural steel encapsulated with polypropylene sheet are also available
Furnace Efficiency Comparison
Furnace design & kettle life are closely related, and this comparison will outline what UCS recommends & why we make these recommendations. We have been working in the industry for more than twenty five years, and our experience has taught us that several furnace designs are useful.
Kettle life depends entirely on the amount of heat transferred through the kettle wall and the design of the furnace and its ability to transfer the heat efficiently with minimum damage to the kettle. Without a lot of boring detail, the furnace that is most efficient & produces the best kettle life is the one that produces the most even radiation of heat onto the outer surface of the kettle wall. The inner kettle wall is kept at the lowest most uniform temperature and erosion of the wall is minimized. Historically, the industry has undersized and over fired the galvanizing furnace, and as a result, short kettle life has been the rule. UCS builds all commonly used furnace designs and our advice is based on our desire to reduce your overall cost as much as possible.
End Fired Furnaces
End fired furnaces are an excellent choice for specific plant applications with moderate production rates, and they are easy to run and maintain. They are also less expensive to build. However, end fired furnaces must be carefully designed and the kettle wall must be protected with insulation for the first few feet from the burner or rapid erosion of the kettle inner wall will occur. The major portion of heat transfer through the kettle wall occurs in the next several feet (where the flame is radiant). This can easily be seen during meltdown of longer end fired furnaces when the zinc in this region of the kettle is the first to melt.
Even though there has been a lot of conversation about the higher efficiency of the burner itself, it is the overall furnace efficiency that we are interested in. There is also a current myth about the amount of heat transferred to the kettle by the circulating hot gases. All that is needed to expose this myth is a reading of any basic thermodynamics text. It is particularly important that this type of furnace not be over fired, as several of our clients have found at some expense. UCS is careful to choose the proper size burner so that the furnace can not be damaged by increasing the heat output from the burner as has been the case with some designs.
Flat Flame Furnaces
For the highest production rate applications, a well designed side fired “flat flame” furnace is a good choice. No other furnace design, excepting electric furnaces, allows the even radiation of heat through the kettle sidewall. Each burner is positioned at the proper spacing from its neighbor so that the kettle will not be overheated, and if the kettle is properly sized for the desired production rate, kettle life will be much improved over industry average.
Naturally Aspirated or “Inspirator” Furnace
A third furnace design that is much less expensive uses multiple small burners along both sides of the furnace near the kettle bottom. These small burners are normally aspirated (drawing their own air supply through a venturi) and do not require a combustion blower. The control system is also quite simple, but electronic flame safeguards are not practical because of the large number of burners. Another advantage of this furnace system is that it will continue to run without electrical power. The fuel efficiency of this type furnace is about 7 – 10% less than the powered furnaces described above.
Electric furnaces are the most reliable and maintenance free of all, and the cost is about the same as a flat flame furnace. However, the cost of electricity usually makes this furnace economically unattractive.
Hot dip galvanizing kettles are fabricated from steel plate specially formulated for galvanizing kettle construction, along with state-of-the-art welding techniques that are nearly identical to our special steel plate chemistry. We can provide either flat bottom or round bottom kettles, both of which are commonly used in the hot dip galvanizing market today, and offer identical service life regardless of length, width or depth.
In addition, we can support any customer-specific requirements such as kettle size, thickness, shape, lifting lugs, additional flanges or stainless steel heat shields.
Kettles for continuous strip galvanizing are fabricated the same way as hot dip kettles. They can be fabricated from special carbon steel in thicknesses up to 2.5 inches, or stainless steel in thicknesses up to 2.25 inches, and are available with optional spouts or extensions based on customer needs.