Metal Expansion

Metal Expansion is a phenonium caused by heat to make metal expand. The heat causes atoms to vibrate, which causes the surface area of metal to grow. This is called thermal expansion. Grains in the metal will grow as metal is heated, causing metal expansion. This is also called kinetic energy. The metal expansion causes kinetic energy. One object’s movement causes another object’s movement. A great example of this is wind causing a windmill to turn. Imagine molecules and atoms growing a causing metal expansion.

When designing a piping system, you must consider the metal expansion of the pipe. A pipe bellow is part of expansion joint. The different metal expands at different rates. The metal properties must be known, and the temperature and mass of the pipe. Without knowing the dynamic thermal factors, the metal expansion can cause tremendous damage to buildings, supports, pumps, valves, and other ancillary parts of the process. Ball Joints help with metal expansion. Bellows expand when heated.

Metal Expansion Joints

The complete pipe system must be analyzed, including pipe bellows, pipe supports, clamps, variable and constant springs. Not only can there be metal expansion, but other materials such as PFC, HDPE, Plastic, Teflon, PVC, and Rubber also have their unique growth properties. A rule of thumb for steel and metal expansion joints. For each 100F rise in temperature, steel will grow up to .07 inches in length. Pipe seals are often used on a line with rubber expansion joints. That could mean an over 9-inch increase in a 100-foot pipe. That increase in length could damage structures and fracture the piping system.

The question that comes up the most “is how do you determine metal expansion? To calculate how much the length of steel will increase, you need to know how much the temperature increases and the original length of the steel. Like most materials, steel expands when the surrounding temperature increases. Duplex strainers and temporary strainers can be part of the metal expansion. Each material has a different response to the heat, characterized by its thermal expansion coefficient. The thermal expansion coefficient represents the amount that steel expands per degree increase.

  1. Use a thermometer to measure the change in temperature in degrees Fahrenheit. For example, if the original temperature was 70 degrees Fahrenheit and the final temperature was 75 degrees Fahrenheit, you would have a temperature increase of five degrees.

Multiply the temperature change by 7.2 x 10-6, which is the expansion coefficient for steel. Continuing the example, you would multiply 0.0000072 by 5 to get 0.000036. Next, multiply the product of the expansion coefficient and the temperature increase by the original length of the steel. Finishing this example, if the steel rod were originally 100 inches long, you would multiply 100 by 0.000036 to find that the steel would be 0.0036 inches longer when subjected to heat. Wye Strainers are part of pipe valves and fittings.

The easy way is to google pipe expansion rates, and there are several sites to refer to get metal expansion rates.

Metal expansion is a fundamental property of metals that occurs due to changes in temperature. As temperatures increase, metals tend to expand, while contracting when cooled. This natural behavior can cause complications in various industries, particularly in large-scale engineering projects where temperature fluctuations are common. Metal expansion joints play a crucial role in managing these expansions and contractions to maintain the structural integrity of the system.

Metal Expansion and Its Effects

Metals expand because their atoms vibrate more rapidly as temperature increases, causing the atomic bonds to stretch and the overall size of the material to increase. The degree of expansion varies depending on the type of metal, with some metals expanding more than others due to their unique atomic structures.

When structures made of metal are subjected to temperature fluctuations, the expansion and contraction can cause stress in the material. Over time, this stress can lead to deformation, cracks, and even failure of the structure. This is particularly relevant in industries like power generation, petrochemical, and aerospace, where temperature changes are not only frequent but also extreme.

Metal Expansion Joints: A Solution to Expansion-Related Problems

To mitigate the issues associated with metal expansion, engineers have developed metal expansion joints. These joints are specifically designed to accommodate the thermal expansion and contraction of metal structures. They are typically installed in piping systems, ductwork, and various equipment where temperature fluctuations are expected.

Types of Metal Expansion Joints

There are several types of metal expansion joints, each designed to address specific expansion-related problems. Some of the most common types include:

  1. Axial Expansion Joints: These joints are designed to absorb axial movement in a straight line. They are often used in pipelines and duct systems to accommodate linear expansion and contraction.
  2. Lateral Expansion Joints: Lateral expansion joints are used to absorb lateral or sideways movement. They are commonly installed in systems where pipes change direction or are subjected to external forces that cause side-to-side movement.
  3. Angular Expansion Joints: These joints are designed to absorb angular movement, such as bending or twisting, in a piping or duct system. They can handle a combination of axial, lateral, and angular movements, making them versatile and suitable for complex systems.
  4. Hinged Expansion Joints: These joints are designed to allow angular movement in a single plane while restraining other types of movement. They are often used in systems that require controlled flexibility, such as in bridges or piping systems with specific directional changes.
  5. Gimbal Expansion Joints: Gimbal expansion joints are designed to allow angular movement in multiple planes, providing flexibility and stability to complex piping systems.


Metal expansion and contraction due to temperature fluctuations can pose significant challenges to the structural integrity of various systems. Metal expansion joints offer a practical solution to these challenges by accommodating expansion and contraction, reducing stress on the structure, and ensuring its longevity. By understanding the various types of metal expansion joints and their applications, engineers can optimize the design of systems to minimize potential problems associated with thermal expansion.