An expansion joint is sometimes referred to as a movement joint, and it is designed for purposes such as absorbing thermal expansion and contraction of various materials, or absorbing pressures which can sometimes be minor, and in other cases can be as powerful as huge natural forces.
Engineers make liberal use of expansion joints in applications such as piping, buildings, and bridges. They are also often used to protect expensive equipment around them from the harm that would otherwise result from grinding, pounding, or expansion and contraction. Without expansion joints to absorb pressures and compensate for expansion and contraction of various structures, there would be rampant cracking and breaking of components used in all components of civil infrastructure.
Hinged Expansion Joints
Hinged expansion joints are used in applications where it is desirable to allow angular rotation in a single plane. This is accomplished by using a pair of pins through hinge plates that are attached at both ends to the expansion joint, and all hardware and pins comprising the hinge joint are designed to absorb whatever pressures may be exerted upon them.
Generally used in sets of two or three, hinged expansion joints have the ability to transmit loads and support hinged piping systems. Hinged expansion joints can be used at almost any point along a piping system without interfering with the free movement of that system, so they become an organic part of the whole system.
They have great versatility, in that they can be used in situations other than 90° bands, and they are very compact yet have great structural rigidity. They can also virtually eliminate torsion and twisting along the longitudinal axis. Since they transmit the pressure load so well, hinged expansion joints exert minimum forces on piping anchors, so the integrity of the local environment in which they are installed remains intact, even under severe stresses.
High-Pressure Expansion Joints
High-pressure expansion joints are often used in applications such as pipelines, which are under high pressure to maintain desired fluid flow through a pipeline. The bellows element of a high-pressure expansion joint is often made of a durable, high-quality metal like stainless steel, and the flanged ends which connect to the piping on either side are also constructed of high-quality metal for best performance. Typical design of a high-pressure expansion joint would include an internal sleeve intended to focus and streamline the flow of water through the expansion joint, and also to reduce any erosion of the bellows component itself from the inside.
Since the fluids being moved are under pressure, they occupy the entire volume of the piping they move through, and one of the functions of a high-pressure expansion joint is to maintain a relatively constant volume by having the bellows component compensate for volume changes in the line. The expansion joint facilitates fluid movement, while at the same time minimizing any transfer of force to components in the system which might be sensitive to high pressure.
ASME expansion joints
The American Society of Mechanical Engineers (ASME)is an organization that promotes various aspects of engineering, including continuous education, research, training, professional development, and standards. It also regularly publishes materials related to its own activities and on many different aspects of the materials and methods to be used in engineering applications. One of those areas of interest for the ASME is expansion joints, and their usage in applications like pipelines.
Expansion joints which are designed to ASME specifications follow the guidelines set forth by that organization as being in accordance with best design and engineering practices. When designing and building expansion joints to ASME code, manufacturers will generally have their products inspected by a third party agency whose function is specifically to ensure that ASME guidelines are adhered to before approval will be granted.
The specific ASME standards which govern the construction of expansion joints are listed in Section 8, Division I, Appendix 26, and these refer to shell and tube type heat exchangers. In addition, ASME piping codes are established in sections B31.1 and B31.3, so metal expansion joints can be manufactured to these specific pipeline application standards as well. When inspected by a third party agency, approval will be indicated by stamping the letter 'R', which indicates authorization to repair unfired pressure vessels, or the letter 'U', which indicates the registration of new equipment.
For time-proven design and quality you can count on in even the highest pressure situations, have all your expansion joint needs covered by contacting Badger Industries. Badger works with all types of industries from power generation to steel mills, providing the utmost reliability for over ten years. If you’re ready to get started, contact Badger Industries for a quote today and start extending the life of your expansion joints.