API Technical Report 2503 First Edition PDF

API TR 2503 PDF

This technical report consolidates the industry available data for the thermal expansion coefficients and the modulus of elasticity of the typical metals used in the API MPMSsuite of documents. This document does not develop or calculate any of these properties.

The coefficient of thermal expansion is the relative amount by which the density of a material changes, per degree, due to a change in temperature. It describes how the size of an object changes with a change in temperature.

Specifically, it measures the fractional change in size per degree change in temperature at a constant pressure, such that lower coefficients describe lower propensity for change in size. Several types of coefficients have been developed: volumetric, area, and linear. The choice of coefficient depends on which dimensions are considered important for the application.

The volumetric coefficient of thermal expansion coefficient is the most common thermal expansion coefficient, and the most relevant for fluids. In general, substances expand or contract when their temperature changes, with expansion or contraction occurring in all directions. Substances that expand at the same rate in every direction are called isotropic. For isotropic materials, the area and volumetric thermal expansion coefficient are, respectively, approximately two and three times larger than the linear thermal expansion coefficient.