In this article we discuss a model for an 80 K liner system for the beam tube vacuum of the Superconducting Super Collider (SSC). The liner is a coaxial perforated tube fitting inside the similar to 4.2 K bore tube of the SSC magnet cryostats. A liner of this type is useful for pumping the gas desorbed by synchrotron radiation out of the view of the synchrotron radiation and for decoupling the beam current from the 4.2 K refrigeration plant capacity. Addition of cryosorber on the bore tube, e.g., charcoal, greatly increases the H-2 sorption capacity compared to the bare metal surface, thus lengthening the time between beam tube warmups. The model equations are useful for estimating the performance of the beam tube vacuum and for defining the experimental information necessary to make a prediction. Some analysis is also presented for 4.2 and 20 K liners and a simple 4.2 K beam tube without a liner.