Expansion Tanks

A reliable source for Pressure Vessel information and leading Pressure Vessel Companies & Manufacturers.

Modern tanks are called diaphragm expansion tanks and are attached and hang down from the boiler piping on the supply side of the system. Older models were larger, horizontal and connected from above the system. Read More…

Expansion Tanks Expansion tanks are small vessels containing pressurized air that are components of closed water heating systems for both residential and commercial buildings.

Leading Manufacturers

Oak Lawn, IL  |  800-282-1574

If you are looking for innovative pressure vessels, you’ve come to the right place! We actively manage your project every step of the way. We keep you informed of what we are doing to ensure we keep up to your standards and delivery times. We will deliver our products on time-every time! Contact us today or visit our website to find out more!

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Midwest Imperial Steel Fabricators, LLC $$$

Gladwin , MI  |  989-426-4768

Gladwin Tank Manufacturing specializes in custom designed and built ASME tanks and ASME jacketed weldments of any shape or size made from carbon steel, stainless, duplex and nickel alloys.

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Gladwin Tank Mfg., Inc. $$$

Berea, OH  |  440-243-6800

Alloy Engineering is ASME code vessel certified and offers extensive expertise in the mechanical design of pressure vessels that will meet rigorous quality standards and procedures. High expertise in the design of vessels fabricated from high-nickel and exotic alloys. Our designs are frequently used in applications with design process conditions up to 1700°F. We also specialize in redesigning current applications to provide more cost-effective and higher performance with longer life.

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Alloy Engineering Company $$$

Beverly, OH  |  866-984-8265

Since 2006, Waterford Tank and Fabrication, LTD has been a manufacturer of quality pressure vessels. We offer personalized service, flexibility, competitive prices and excellent customer service. If you need a customized solution then you have come to the right place. Please give us a call today!

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Waterford Tank and Fabrication, LTD $$$

Garden City, GA  |  912-233-8902

We serve the chemical processing, pulp & paper, pharmaceutical, food, and coatings industries with high quality, on-time delivery and competitive pricing. Our pressure vessels meet today’s demanding market, fabricated to ASME tank standards. We offer carbon, stainless, alloy 20, monel, inconel, hastelloy and 904L; thicknesses up to 1” and pressures up to 1000 PSIG; non-destructive testing options.

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Savannah Tank & Mfg., Inc. $$$

Chattanooga, TN  |  423-266-7118

Chattanooga Boiler and Tank Company is certified to design, shop fabricate, or field erect ASME Section VIII Div 1 pressure vessels that require "R", "S", or "U" Code Stamps. Through the years, we have built a vast array of pressure vessels that range in wall thicknesses of 3/16" to over 2", in diameters up to 30 feet, and weights up to 150 tons.

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Chattanooga Boiler & Tank Company, Inc. $$$
placeholder image Midwest Imperial Steel Fabricators, LLC Gladwin Tank Mfg., Inc. Alloy Engineering Company Waterford Tank and Fabrication, LTD Savannah Tank & Mfg., Inc. Chattanooga Boiler & Tank Company, Inc.

Expansion tanks are easy to maintain, and if they are pre-charged, these tanks are literally maintenance free. All repairs should be done by a certified plumber. These pressure tanks ensure constant pressure within the piping system, and act as a safety device. Without them, the boiler may explode, the pipes could burst and overflowing is a major concern.

They are typically composed of a stainless steel tank, blue or green exterior paint and a rubber spacer called a diaphragm located on the inside of the tank. This diaphragm provides an air-tight seal and divides the tank in half-the bottom is pressurized air, while the top is left open for excess water from the boiler.

Plasite Lined Tank Expansion Tanks - Gladwin Tank Mfg., Inc.

Since they occasionally hold drinking water, expansion tanks, like boilers or other food processing tanks and water pressure tanks, must be sanitary, non-contaminating and conform to health standards. The interior walls of the tanks need to be smooth and groove free. Besides domestic and commercial closed heating systems, most vehicles contain smaller expansion tanks for their heating systems.

The purpose of expansion tanks is to absorb excess water pressure in a closed water heating system. Any water heated in a closed space will expand. Therefore, heating systems need additional space for the increased water volume when it is at a high temperature. The excess water enters the expansion tank, which is filled halfway with pressurized air at 12 psi and divided by a rubber diaphragm spacer.

While the water volume is up, the extra water fills the tank. The top half of the tank is directly connected with the heating system, and when the temperature decreases, the pressurized air on the bottom half of the expansion tank pushes the water back into the boiler system. This ensures there will be no pipe damage because of too much pressure.

Water heating systems without expansion tanks risk the internal boiler pressure increasing beyond the release setting of the pressure release valve (PRV). When the PRV opens, the water leaves the system and creates pressure that is too low. Expansion tanks are always properly charged with air, which shouldn't exceed 12 psi, or the water will boil and this consistency is a major benefit to using expansion tanks.

Expansion Tanks Informational Video