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Protection of pipes against freezing.

If a pipe can be covered with some good insulating material, so that frost cannot come in contact with it, there is little danger of it freezing. The great difficulty in providing such insulation is the expense attached, in protecting long lines.

Some of the materials that may be used for this purpose, and that are often used on short sections of exposed pipe, are rubber or gutta percha covering, wax, rosin, pitch, etc. Sometimes a heavy covering of paper, wound onto the pipe, and tied on, may be used to advantage, if the paper covering is given a heavy coat of varnish to keep out the moisture.

Sawdust is often used as a protection, but the great objection to its use is, that it absorbs moisture, and in time very often becomes a source of danger to the piping rather than a protection. When water pipe is to be laid underground, and above the freezing point, horse manure may be used to surround the pipe, it generally being used in rough wooden boxing. The heat of the manure provides an excellent protection, but after being used through a winter it must be renewed the following winter. Probably the most satisfactory protection under many conditions is that shown in Fig. 23. This method consists in surrounding the piping by a line of boxing, made up of several boxes. The ends of the boxing should also be closed to prevent any possible circulation of air through the air spaces. The stagnant air contained between the boxes forms the protection for the pipe to a much greater extent than does the boxing. It is well known that stagnant air is a strong protection against freezing, and that pipe located where the air is not in motion, can withstand a much lower temperature than when exposed to currents of air. The boxing mentioned above may be made of any rough lumber at hand, but if to be laid underground, chestnut boxing will be found most durable. Mineral wool and hair felt may also be included in the list of insulating materials.

Very often water pipes are brought up through the floor from the cellar, through holes somewhat larger than the pipe. Cold air being drawn up through such a hole, constitutes a source of danger from freezing, and should be guarded against. The necessary points then, in protecting water pipes against freezing, are that they should be protected against dampness, and against currents of air. In laying underground piping, additional protection against freezing can be secured, if the earth that is filled into the trench is not tamped down. Tamping naturally reduces the amount of air spaces between the particles of earth, and these air spaces represent a considerable protection to the pipe. Water pipes should always be kept from contact with cold walls, and when necessary to so run them, they should be insulated from the wall. A good method under such conditions is to run the pipe on strips of board attached to the wall.

This was taken from the book "Questions and Answers on the Practice and Theory of Sanitary Plumbing, Volume III, Practical Wrinkles" which was published in 1919.

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