STEAM_INTERACT is a FORTRAN90 program which allows the user to query the NBS steam tables.
The user can specify temperature and pressure, or temperature and density, and the program will return the computed values of a variety of quantities.
Most of these routines use a standard set of SI units. The original routines were written in FORTRAN77. This FORTRAN90 version has been extensively rewritten, with some additional routines for computing quantities such as the viscosity, thermal conductivity, and the Prandtl number.
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
STEAM_INTERACT is available in a FORTRAN90 version.
STEAM, a FORTRAN90 library which is based on the NBS steam table package;
TEST_VALUES, a FORTRAN90 library which stores selected values of various mathematical, statistical and physical functions, including some of the steam table functions.
You can go up one level to the FORTRAN90 source codes.