So, you need to make a round tank out of metal to store or transport a supply of liquid or powder. How would you even begin? Fortunately, Revolution Machine Tools provides exactly the right sort of equipment to help you out.
Pick Your Metal
The first step in tank construction is the design and planning stage. You need to determine the specifications of the tank, including dimensions, materials, and thickness of the plate. Choose the appropriate metal plate based on the tank’s intended use and environmental conditions. While it’s most likely that you will choose carbon steel or stainless steel for the task—since you probably aren’t reading this if you are producing a lot of high-end tanks for corrosive chemicals—it is important to note that other metals or alloys might be used depending on need, such as titanium, Monel, Inconel, or Hastelloy.
Low carbon steel—commonly called mild steel—contains between 0.05% to 0.25% carbon and up to 0.4% manganese. This makes it malleable and ideal in plate form for rolling. It is a low-cost alloy that is readily available, and it meets the basic requirements for a high percentage of storage situations, including for water, fuel, oil, and many chemicals. It can be lined with polyurethane or other materials to deter leakage or corrosion, and its surface hardness can be increased through carburizing. A commonly used type of mild steel used for plate fabrication is A36 steel, a hot-rolled steel. It has a minimum yield strength of 36 KSI.
While more expensive, stainless steel contains chromium, making it extremely resistant to rust. More corrosive liquids may require stainless steel for storage and transportation. The most common grade of stainless steel is 304, and it is used in kitchen appliances, cookware, and sinks. It is ideal for the storage of chemicals like liquid fertilizer or in the construction of a pasteurizing tank. 304 stainless steel that has been given a “sanitary finish” (No. 4 finish) is considered food-grade because it doesn’t have any surface irregularities, so it will resist the growth of bacteria and is easily cleaned. The second most common grade is 316 stainless, which contains a small amount of molybdenum, making it even more corrosion resistant (and perfect for substances like sulfuric acid).
Prepare Your Plate
The next step is getting your metal cut down to the required size. Various types of plate metal cutting machines are available on the market for doing this, with shearing machines being the most common. Shears cut metal sheets and plates by moving two heavy blades past each other under great pressure. The lower blade is usually stationary and attached to a short table that helps support the plate in position, while the upper moves downward under mechanical or hydraulic power.
Revolution Machine Tools offers 42 models of metal-cutting shears across three different styles:
- C-FAB™ series of high-speed mechanical direct drive shears, featuring a dozen 10 HP machines that range from a 3’6″ shear with a quarter inch cutting capacity (in mild steel) to a 10′ shear with a 12-gauge capacity.
- C-SMART™ series of hydraulic swing beam shears in six different thickness capacities, ranging from 1/4″ to 3/4″ (mild steel), each available in either 10’2″ or 12’2″ models.
- C-GENIUS™ series of hydraulic variable rake shears in 18 different models, with cutting capacities up to 1″ (mild steel) and cutting lengths up to 20′.
While doing edge preparation on metal sheets and plates less than 1/8″ isn’t really feasible, it is often advised for larger plates that the connecting edges on either side of the workpiece be beveled prior to rolling. Beveling the edges not only allows the welding electrode access to the root of the weld, but it also provides more surface area to which the weld can adhere.
RMT carries three models of plate beveling machines in their PVB-FAB™ series, accommodating plates from 4″ to infinite length, with thicknesses of 0.12″ to 1.58″.
Roll, Roll, Roll Your Tank
The first step in rolling the main body of the tank is to adjust your plate roll machine settings according to the thickness and type of metal. Ensure the rolls are clean and properly aligned. Then feed the metal plate by inserting its edge into the plate roll, clamping it into position between the top roll and a bottom roll (plate rolls typically have three or four rolls; the top roll applies pressure while the bottom rolls rotate to feed the plate through). Gradually increase the pressure on the top roll as you feed the plate through multiple passes. This will start to bend the plate into a curved shape. Continue rolling until the plate forms the desired curvature or diameter for the tank.
Depending on how your plate roll is equipped (such as with a CNC control and an overhead support), you may be able to roll ovals and other shapes that can be used as tanks.
Revolution Machine Tools carries a vast selection of 145 different models of plate and sheet rolling machines, including the R-ECO™ series of motorized initial pinch three rolls, the R-SMART™ series of planetary type hydraulic four rolls, the R-GIANT™ series of rectilinear type hydraulic four rolls, and the R-HYBRID™ series of planetary type hydraulic three rolls.
Once the plate has been rolled into a cylindrical shape, bring the edges together. Depending on the thickness and type of material, you may need to use clamps or apply tack welds to hold the edges in place temporarily. Then perform a full weld along the seam where the edges meet. This can be done using various welding techniques such as MIG, TIG, or stick welding. Ensure the weld is strong and free from defects, as this will be a critical part of the tank’s integrity.
Revolution Machine Tools can help you source welding equipment for your tank preparation. RMT also carries three models of LightWELD™ handheld laser welding and cleaning systems, as well as a large-scale chassis beam welding system for structural steel work.
Head Them Off (After) the Pass
Once you’ve rolled and welded your tank body, you need to cut and form the end caps or heads of the tank. These can be flat, dished, or hemispherical, depending on the design requirements.
A fiber laser like one of the 13 models in the KYSON™ series carried by Revolution Machine Tools would be perfect to cut the end caps of the tank, while RMT’s FC-FAB™ dishing-flanging-cutting machine would work great if you needed to put a curvature in the outside surfaces of the tank heads.
Once formed, position the heads on each end of the cylindrical shell and weld them in place. Ensure the welds are continuous and defect-free to prevent leaks.
Finishing Your Tank
Inspect all welds and the overall structure for defects. Perform non-destructive testing (NDT) such as ultrasonic testing, X-ray, or dye penetrant testing to ensure weld integrity. Clean the tank to remove any slag, debris, or contaminants. Apply a protective coating or paint to prevent corrosion, especially if the tank will be exposed to harsh environments. If required, secure the tank to a vehicle or trailer and weld in place. Attach any additional components such as nozzles, flanges, or fittings as per the design specifications.
Perform quality control steps, such as hydrostatic testing: fill the tank with water or another non-compressible fluid to check for leaks and ensure it can withstand the designed pressure. Conduct a thorough final inspection to verify that the tank meets all design and safety standards.
Call RMT Today
Check with Revolution Machine Tools for more tips on tank construction and request competitive quotes from them for all the equipment you will need for the job.
