Steel casing pipe protects one or many of various types of utilities such as water mains, gas pipes, electrical power cables, fiber-optic cables, etc. The utility lines that are run through the steel casing pipe are most commonly mounted and spaced within the steel casing pipe by using "casing spacers" that are made of various materials, including stainless steel or carbon steel and the more economical plastic versions.  The ends of a steel casing pipe "run" are normally sealed with "casing end seals", which can be of the "pull-on" or "wrap-around" rubber varieties. Steel casing pipe is also used in the construction of deep foundations.