MDMT is one of the design conditions for

pressure vessel A pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure. Construction methods and materials may be chosen to suit the pressure application, and will depend on the size o ...

s engineering calculations, design and manufacturing according to the

ASME The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via " continuing ...

Boilers and Pressure Vessels Code. Each pressure vessel that conforms to the ASME code has its own MDMT, and this temperature is stamped on the vessel nameplate. The precise definition can sometimes be a little elaborate, but in simple terms the MDMT is a temperature arbitrarily selected by the user of type of fluid and the temperature range the vessel is going to handle. The so-called ''arbitrary'' MDMT must be lower than or equal to the CET (which is an environmental or "process" property, see below) and must be higher than or equal to the (MDMT)_M (which is a material property). Critical exposure temperature (CET) is the lowest anticipated temperature to which the vessel will be subjected, taking into consideration lowest

operating temperature An operating temperature is the allowable temperature range of the local ambient environment at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the de ...

, operational upsets, autorefrigeration, atmospheric temperature, and any other sources of cooling. In some cases it may be the lowest temperature at which significant stresses will occur and not the lowest possible temperature. (MDMT)_M is the lowest temperature permitted according to the metallurgy of the vessel fabrication materials and the thickness of the vessel component, that is, according to the

low temperature embrittlement Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile str ...

range and the

charpy impact test In materials science, the Charpy impact test, also known as the Charpy V-notch test, is a standardized high strain rate test which determines the amount of energy absorbed by a material during fracture. Absorbed energy is a measure of the ma ...

requirements per temperature and thickness, for each one of the vessel's components.

References

*ASME, Boilers and Pressure Vessels Code *Dennis R. Moss, ''Pressure Vessel Design Manual'', 1997 (2nd ed.) Pressure vessels Threshold temperatures {{Mech-engineering-stub