What Does Creep Resistance Mean?
Creep resistance is a term used in materials science that refers to a solid material’s ability to resist “creep,” which refers to the tendency of a material to slowly deform over a long period of exposure to high levels of stress.
Creep resistance is affected by a material’s properties, the length of time it is exposed to a stressor, the temperature at which it is exposed to the stressor, and the power of the stressor (e.g., the weight of the load that the stressor places upon the material being considered). A specific material’s creep resistance can be generally defined in terms of the amount of creep that is produced by a specific amount of strain placed on a material for a specific amount of time.
Safeopedia Explains Creep Resistance
A material’s creep resistance is an important consideration for workplaces in which the structural integrity of an apparatus, such as an engineered safety control, is important to workplace safety. Because creep resistance is lowered by exposure to high temperatures, workplaces must consider whether a material that is safe to use in one setting might become unsafe to use if transported into a higher-temperature setting.
Creep occurs to materials that are placed under strain. Most materials that are or were used in building structures are heavily resistant to creep while at room temperature, with materials such as glass and lead being notable exceptions. However, a material’s creep resistance can be significantly lowered due to exposure to heat (thermal creep).
The creep resistance of a material changes over time, according to a “creep curve.” The initial “primary creep” stage is relatively rapid, whereas the secondary creep stage occurs at a slower, constant rate. The final stage, tertiary creep, is marked by the re-acceleration of creep, which occurs until the material fails.
Creep is considered dangerous because it reduces the structural integrity of the buildings, vehicles, and equipment that it affects, thus increasing the risk of a safety incident. For instance, containers that hold material under high levels of pressure and heat, such as boiler tanks, must be able to avoid creep in order to prevent a rupture. The risk that creep could damage the integrity of a joint weld or other seal is a particular concern.
Occupational settings where creep poses a significant safety challenge include the power generation and process manufacturing industries, and creep is also a significant concern in ensuring safe airplane design. As creep is accelerated by heat, building and equipment designs may also take creep into account when assessing the risk of potential fire hazards. In general, any occupational setting in which materials will be held under stress is one in which the creep resistance of a material is a safety concern.