Too much care cannot be exercised in the running and supporting of soil pipes. They are generally made tight by caulked lead joints, which are easily made defective when moved in any way, owing to the great weight and leverage of the pipe. Few plumbing systems that have been in use for a number of years would show perfect joints under test, and in many cases this condition is due to imperfect supporting of the pipe.
When a vertical line drops to the cellar bottom, it should rest upon a thick flagging or upon a brick or stone foundation, as in Fig. E.
Plate XIV. Supporting And Running Of Soil Pipe
Supporting of Soil Pipe
Fig. D Poor Practice
Care should be taken in building such a pier during the winter season that there is no frost beneath it, which would allow the pier and stack to settle when it thawed.
Brick or stone piers should also support a horizontal line running above the cellar bottom, particularly at points where vertical stacks enter it. The use of piers to support horizontal lines running below the cellar timbers is preferable to long hangers, as in the use of the latter the pipe would be inclined to swing if subjected to side pressure.
There are now on the market pipe-supporting fittings, as shown in Fig. G, which can be made to support piping running at any given grade. When there is no firm cement cellar bottom, these supporting fittings should rest on wide flaggings.
Equal care should be used on overhead piping, some ordinances calling for overhead running of all pipes.
In supporting overhead pipes, hangers of the pattern shown in Fig. A should be used, and the pipe should be supported once in each five feet. Some ordinances call for a support in each ten feet, but the above provision is better.
Fig. D shows a practice, generally prohibited, of using hooks for the supporting of pipe.
The hanger is firmly supported at each end, the pipe resting between the two supporting points; in the use of pipe hooks, however, the weight of the pipe, owing to the form of the support, will cause it to sag, and though the sag may often be very slight, it will generally be sufficient to cause defective joints.
All vertical lines of soil pipe should be supported at each floor by iron bands placed just below the hub or under the branch of a fitting.
These bands are made of flat wrought iron, and should have the strength of 1/2-in. round iron, and should be securely fastened to the timber with screws.
The support should be made on a vertical timber if possible, as the danger of settling or sagging of a horizontal timber is greater.
A practice sometimes followed is to cut the pipe in such a manner that it supports itself on a hub at each floor, as shown in Fig. C.
For hangers for 2- and 3-in. soil pipe, 3/8-in. wrought-iron rod should be used; and 1/2-in. rod for 4- and 5-in. pipe.
That there is great need of every precaution in running and supporting soil pipe may be seen when it is considered that a 4-in. stack in almost any ordinary residence or dwelling will weigh at least 550 lbs., without taking into account any branches or fittings, and pipe of larger size will weigh very much more.
Furthermore, when the entire system is filled with water during the water test, this weight is raised to a much higher amount.
Stacks passing through the roof and carried several feet above it in order that their upper ends may be above all roof openings or above adjoining windows, should be given special support, as the pressure of the wind against them is at times very strong.
When roofs of tenement houses are occupied and used by tenants, as often happens, there is the additional danger of blows against the pipe. Such pipes should be supported by three or four stout wrought-iron rods firmly secured to the soil pipe, run off at an angle and secured to the roof. A wrought-iron collar placed around the pipe and above a hub, provides a good means of attaching the rods to the soil pipe. Another method is to tap the pipe and secure the rods by bolts.
Vent pipes from cesspools when required to run vertically in the open for a number of feet should also receive special support.
A very good method of providing such support is to set in the ground, close to the cesspool, a heavy pole which will not sway under the pressure of the wind, and run the pipe vertically against it, supporting the pipe under each hub by wrought-iron bands.
The present excellent practice of connecting main lines of vent pipe to their main soil and waste stacks above the highest fixtures, and below the lowest fixtures, is a good practice, as it ties the work together, giving rigidity to it, and, in the event of settling, allows both lines to settle evenly without resulting in an unequal strain on the two lines that would result to a greater extent if not thus connected. The settling of a line of cast-iron pipe often results in pulling apart the caulked lead joints, especially if the line is not properly supported. For instance, a vertical line that may happen to be well supported in its upper sections, but poorly supported at lower points, is very liable to pull apart from the section that is securely fastened. This sometimes results in pulling the caulked lead joint entirely out of the hub.
The great necessity will thus be apparent, of securing vertical lines firmly throughout their course, and of providing support at the foot of each stack which cannot possibly settle. One of the chief advantages to be gained in the use of wrought-iron drainage and vent piping, in the construction of the Durham system of plumbing, is that the screw joints of such pipes will not pull apart in the settling of stacks, as the caulked joints of cast-iron piping will do when the pipe is not properly supported. As far as a vertical pull on a vertical line of screwed pipe is concerned, it will have no more effect on the joint than on the pipe itself in pulling it apart.
However, if proper precautions are taken, vertical lines of cast-iron pipe may be installed even in high buildings without danger of pulling apart.