IAPWS

The International Association for the Properties of Water and Steam (IAPWS) is an international non-profit association of national organizations concerned with the properties of water and steam,{{cite book | last1=Reynolds | first1=William C. | last2=Colonna | first2=Piero | title=Thermodynamics | publisher=Cambridge University Press | publication-place=New York, NY, USA | date=2018-09-20 | isbn=978-0-521-86273-8 | pages=119–120}} particularly thermophysical properties and other aspects of high-temperature steam, water and aqueous mixtures that are relevant to thermal power cycles and other industrial applications.{{cite book | author=Kirk-Othmer | title=Kirk-Othmer Concise Encyclopedia of Chemical Technology, 2 Volume Set | publisher=Wiley | year=2007 | isbn=978-0-470-04748-4 | url=https://books.google.com/books?id=BYQfEAAAQBAJ | access-date=2024-12-25 | page=913}}

The organization publishes a range of 'releases.' Specifically, these relate to the thermal and expansion properties of steam.

Both free software and commercial software implementations of the IAPWS correlations are available.