We price tank fabrication by fabricated weight, because we buy plate, pipe and flanges by the kilogram. Volume alone does not set the price; two tanks of the same volume can have completely different weights and prices depending on pressure, material and dimensions.
The weight of any tank is the sum of the weights of its shell plates, its heads or bottom and roof, and its accessories. The weight of each plate is area times thickness times density. The density of carbon steel is about 7,850 and that of stainless steel about 7,900 to 8,000 kilograms per cubic metre.
The thickness is set by the design calculations: pressure or liquid head, diameter, the plate's allowable stress, joint efficiency and corrosion allowance. In small and medium water tanks the minimum fabrication thickness governs; in pressure vessels and large tanks, pressure does.
The relations that set the weight, and therefore the price:
Full radiography raises the joint efficiency and lowers the required thickness. In large tanks, the saving in plate weight is often greater than the extra cost of testing.
A tank's price can be lowered without reducing its life or safety:
For a given volume there is a diameter-to-height ratio that gives the lowest weight. The site's calculators suggest the optimal dimensions.
Do not set the design pressure higher than you really need. Every extra bar makes the plate thicker.
Stainless steel is not needed everywhere. For industrial water, coated or galvanized steel is often enough and much cheaper.
Reducing thickness below the calculated value or dropping tests makes the tank cheaper but more dangerous.
A transparent method both sides can check
Plate makes up the largest share of a metal tank's price. We buy plate, pipe and flanges by the kilogram, and fabrication is directly related to weight too: heavier plate means more cutting, rolling and welding. That is why the most logical and transparent way to price a tank is by its fabricated weight.
Consider two 20,000-litre tanks: one stores water at atmospheric pressure and the other holds compressed air at 10 bar. Their volume is the same, but the second needs thicker plate and stronger heads and may weigh several times as much as the first. Their prices differ in the same proportion.
Examples to show how weight changes; the thicknesses are assumed and the real thickness is set by calculation
2.5 m diameter and 4.1 m high, carbon steel, atmospheric. 5 mm shell, 6 mm bottom and 5 mm roof. The minimum fabrication thickness governs, not the water pressure.
1.2 m diameter and 3 m shell length, 10 mm plate and two elliptical heads. One fifth of the water tank's volume, but close to its weight.
A stainless tank weighs about the same as a carbon steel tank of the same size, but each kilogram of stainless plate costs several times more and welding it takes more care and time.
Anything that increases plate thickness or area raises the price
From an online estimate to a firm price
Two quotations can only be compared when they are for the same weight and the same specification. If one price is much lower than the others, first ask about the weight and plate thickness. Reducing thickness is the easiest way to make a tank cheaper, and the easiest way to shorten its life.
The same method is used for all Behineh Ab products
Send the tank specifications to have the weight calculated and a quotation prepared at the current price.
The most common questions about tank fabrication prices
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