|
| Types of Pipes | Lead plumbing was prevalent in old buildings. Towards the end of the 1800s it was ousted principally by galvanized iron water equipment, connected with threaded fittings. Around 1950 copper with soldered fittings became widely applicable, despite the fact that it had been used as far back as 1900. Plastic feed pipes have become ever more widespread since about 1970, with an assortment of materials and fittings in employment.
 As a general rule galvanized iron feed pipes are brought into being with inner diameters from 1/2" to 2". The largest part of domestic systems however will not involve any delivery pipes larger than 3/4". (Note that iron is frequently used in DWV systems as well.) In the USA pipes have NPT (National Pipe Thread) standard thread, which conjugate with internal threads on bend pieces, couplers and other fittings. Galvanized iron (known also as "galv" or "iron" in the plumbing trade circles) is of moderate cost, hard to work with (because of weight and need for a thread-cutting machine), and experience difficulties caused by mineral dregs accumulated within the pipe. It is still common for restoration of presented "galv" systems and to satisfy non-combustibility requirements of building specifications habitually found in hotels, apartment houses and other commercial applications. It is amazingly durable by the way.
Copper pipes were established in about 1900, but didn't develop into accepted until approximately 1950 (according to local building norms). (Note that some copper and brass are used as DWV pipes too.) We have three common classes of copper plumbing tube: "Type K", "Type L" and "Type M". Type M is comparatively cheap and thin-walled and appropriate by and large for residential use, with a lower water working pressure (WWP) thereafter. Type L is more often used in above-ground commercial applications, and has a thicker pipe wall section. Type K is ordinarily used for underground burial, with a proper corrosion-resistant covering or continuous polyethylene sleeve as required by code. Besides it has the thickest wall section of the three types of pressure rated tubing. Generally Type K is available only in hard drawn quantities of 20'-0" "sticks", whereas M and L Types are commonly available in both hard drawn "sticks" and in rolls of soft annealed tubing. The outside diameter (OD) of plumbing tube is 1/8" larger than the nominal diameter as a standard wall thickness of an early plumbing pipe was 1/16". To avoid changing the design of fittings the OD was conserved, when improved metallurgy made thinner walled tube possible.
|
|
