Expansion Joints

U.S. Bellows, Inc., a subsidiary of Piping Technology & Products, offers a wide variety of expansion joint products and services. If you are replacing an existing joint which has performed for its expected life or if you have completed your design for a new application, we can fabricate and test the unit to your specifications. If you have an existing expansion joint which has not performed in a satisfactory manner, we can propose alternative designs for your consideration. When necessary we will build prototypes and conduct tests to help evaluate units prior to installation. Many of our expansion joints are custom-made for a particular application. The general categories we supply can be described by the materials used and the type of movement provided for.

32" Universal Metal Expansion Joint	78" Thick Wall Expansion Joint	81" x 18" Rectangular Fabric Expansion Joints

Metal Bellows fabricated Expansion Joints
The convolutions in the bellows provide for axial, lateral, and some angular movement in a system such as that of a pipeline connecting pumps and vessels. Flanged-end or welded-end expansion joints can be quickly fabricated using standard, off-the-shelf bellows. Ties, hinges, or other accessories can be added to provide for greater angular and lateral movements. Universal and double expansion joints each use two bellows in their design. The number and shape of the bellows, the metal used, and the degree to which the joint must be able to move are the main factors in determining the "wear-out" failure rate of these devices. Of course, one event, a force or pressure well beyond the design limits, could cause sudden failure.

Thick-wall Expansion Joints
These may be cost-effective for large-diameter piping systems which operate at low pressure. Metals can be selected to satisfy different temperature conditions. The distribution of axial, angular, and lateral forces will be different when thick-wall expansion joints are used. We can provide your design engineers with the potential forces and movements for proper design of the structural members supporting the system. These joints have a long life which justifies the initial investment.

Fabric Expansion Joints
These are often used in ducts which carry hot gases at low pressures. The major design parameters are the temperatures and flow rates of the gases and the amount and abrasiveness of solids suspended in the gases. Layers of different fabrics, insulation, and metal foils can be combined to accommodate the temperatures and pressures in the system. The fabric belt may need to be replaced periodically.

Slip-type Expansion Joints
These are used when the primary problem is a large axial movement. Materials can be selected to accommodate high temperatures and pressures. Design details include selection of packing and seals, and perhaps resistance to abrasive solids. Some applications may require special surfaces to minimize abrasive wear. Special features such as "wipers" can be included to prevent potential clogging of the space provided for slip movement.

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