Properly, soil pipe is any pipe through which the waste from a water closet passes, and waste pipe is any pipe receiving waste from any fixture or group of fixtures other than the water closet. The term soil pipe is often used to designate cast-iron pipe of any size and for any purpose in connection with the plumbing system.

The latter is the sense in which it will be referred to in the consideration of the present subject.

Plate XIII. Soil Pipe And Soil Pipe Connections

Soil Pipe

Soil Pipe And Soil Pipe Connections 41

Fig A

Soil Pipe And Soil Pipe Connections 42

Fig b.

Poor Practice

Soil Pipe And Soil Pipe Connections 43

Fig C.

Soil Pipe And Soil Pipe Connections 44

Fig D.

Soil Pipe And Soil Pipe Connections 45Soil Pipe And Soil Pipe Connections 46

Fig F.

Soil pipe is of two weights, "Standard," and extra heavy, the latter being far preferable in general, owing to the fact that it may be cast more evenly, with fewer defects, sand holes and cracks, and that it may be cut and caulked with less liability of cracking pipe and fittings.

Weights Per Foot Of Cast-Iron Pipe


Extra Heavy



Extra Heavy


2 in... .

5 1/2 lbs.

3 1/2 lbs.

6 in. . . .

20 lbs.

10 lbs.

3 in....

9 1/2 lbs.

4 1/2 lbs.

7 in... .

27 lbs.

4 in... .

13 lbs.

6 1/2 lbs.

8 in... .

33 1/2 lbs.

5 in....

17 lbs.

8 lbs.

10 in....

45 Ibs.

It is sometimes required by plumbing ordinances to use soil pipe that is plain and uncoated, it being usually coated inside and outside with asphaltum or tar. The coating often covers defects, which in the uncoated pipe would appear and be remedied. If plain pipe is used it should be coated after being tested. The joints on cast-iron soil pipe should be made of molten soft lead poured onto a firm body of caulked oakum, the lead being caulked even with the top of the hub.

The approximate weights of lead necessary for each joint are, viz.:

2-in. caulked joint............. 1 lb. 8 oz.

3-in. " " ............. 2 " 4 "

4-in. " " ............. 3 "

5-in. " " ............. 3 "12 "

6-in. " " ............. 4 " 8 "

7-in- " " ............. 5 " 4 "

8-in. " " ............. 6 " io-in. " " ............. 7 " 8 "

It is generally unsatisfactory to give such a table as the above, of the amount of lead necessary for caulked joints of different size, as one workman may use much more oakum than another, and a correspondingly less amount of lead. Therefore it will no doubt be found that the table published will not agree always with the practice of different workmen. There is a rule, sometimes used in estimating the amount of caulking lead, calling for one pound of lead for each inch in size of the respective joints; thus, 3 lbs. for a 3-in. joint, 4 lbs. for a 4-in. joint, etc. In estimating the total amount of lead to be used on the cast-iron piping, it is necessary simply to estimate the number of hubs on fittings of different sizes, and the number of lengths of pipe of different sizes, adding the amounts of each size together and multiplying by the weight of lead used per joint.

Thus a Y or tee would call for two joints, the third joint on the spigot end, being estimated on the straight pipe.

An allowance for waste, shrinkage, and extra fittings, should always be added to the estimated amount of lead.

It is sometimes necessary to make a rust joint on soil pipe. This should be done by caulking into the hub a ring of oakum, and filling the remaining space with a putty made by mixing together sulphur, iron filings, and sal ammoniac.

Connections between cast-iron pipe and lead pipe should be made by connecting the lead pipe to a brass ferrule by means of a wiped solder joint, the ferrule being caulked into the cast-iron hub.

Overcast and cup joints are often weak and imperfect, and should not be used.

Connections between cast-iron pipe and wrought-iron or brass pipes should be made by means of a caulked or screw joint. All horizontal soil pipes, whether for drainage or venting, should, when possible, have a uniform fall of 1/2 in. to the foot, but never less than

1/4 in. to the foot. A less amount of pitch brings the pipe nearly level, and stoppage and sluggish flow of waste is liable to result. A grade on vent pipes is necessary in order that condensation may be carried off.

All changes in direction of soil pipe used on the drainage system should be made by means of Y-branches and sixth, eighth, or sixteenth bends.

This connection is shown in Fig. A, Plate 13, and applies whether the change in direction is made vertically or horizontally. A clean-out should always be used in the end of the Y in order to control that section of the piping. The change in direction made in Fig. B is entirely wrong, the quarter bend not being permissible on any part of the drainage system.

It is allowed, however, on the fresh-air inlet, vent lines, rain leaders, and floor and yard drains.

The tee should not be used on any part of the drainage system; the T-Y being allowed on vertical lines when it is impossible to use the Y-branch, but not being allowed on the horizontal piping.

The object in restricting the use of these fittings on the drainage system is to secure for the waste flowing through the drainage system as natural and unimpeded a passage as possible.

Double hubs should not be used on the drainage piping, as in their use a rough end of pipe is always exposed where the pipe was cut off, and on this end, lint, paper, etc., in the sewage is liable to be caught.

The use of double-hub pipe will often avoid the use of double hubs.