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Waste Plumbing in House
Galvanized steel plumbing on the waste system is used in some areas solely for vent pipes. Vents carry air but do not carry water. The galvanized vent piping is not, therefore, subject to the same rusting problems as galvanized steel supply piping. Its life expectancy is very long, easily more than fifty years.
In other areas, galvanized drain and waste pipes were used. These have a relatively short life expectancy since the steel corrodes and the rough inner surface created by the corrosion can cause blockages as solids get hung up.
Copper waste plumbing was used commonly after World War II, up until the mid 1960’s. Copper piping was used for branch drain lines, main stacks, and vent piping. It performs all of these functions very well. In single family residential use, it has become rare, since plastic waste plumbing is much less expensive to purchase and install. In multi-family construction, copper waste plumbing is sometimes used where authorities will not allow combustible plastic piping.
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Figure 11. Soil Stack versus Waste Stack
The joints in copper piping are soldered and an indefinite life expectancy is projected under single family residential conditions.
Since the 1960s, ABS plastic piping has become almost the exclusive waste plumbing material. It is used for drains, wastes and vents and is connected by using a plastic cement (glue). The piping is inexpensive, easy to work with and as far as we know, very durable. Its only disadvantage is that it is somewhat noisy when water is running through it. Efforts to control the noise include wrapping it with fiber glass insulation.
Cast iron piping was used for the main stack in houses up until the 1950s. Its life expectancy is projected to be fifty years and up. It employs a bell-and-spigot connection traditionally with oakum packed into the joint and caulked with lead to seal it. There is also hubless cast iron pipe joined with neoprene sleeves clamped over the joint. Cast iron is expensive and awkward to work with, because it is very heavy.
Cast iron waste piping generally fails in one of two ways. The pipe can rust through, often in a pin hole pattern. It is also prone to splitting along a seam, particularly on horizontal runs.
Lead waste plumbing was used up until the 1950s, to connect plumbing fixtures to a main cast iron or copper drain. Lead was used because of its resistance to corrosion, and its workability. A piece of lead pipe can be bent fairly easily by hand.
Lead piping, because of its age, is prone to leakage, usually at the connections. It is typically replaced with ABS plastic pipe. Lead waste lines are usually replaced during any major plumbing work, whether problems are being experienced or not. Lead waste plumbing does not create a health hazard in terms of lead content, since it only contacts the waste water.
Lead Suspected: Since the sections of lead piping used are relatively small, they are often not visible. In houses built before the 1960s, where substantial updating has not been done, it is reasonable to assume that concealed lead waste plumbing exists. Where this is the case, the plumbing system is considered susceptible to leakage. The lead should be replaced, of course, when leaks appear or during any other work in the area.
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Figure 12. Cast Iron Waste Pipe
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