Soldered Joints involves the process of joining pipe by melting a filler metal, which has a low melting point, into a joint. As the filler metal cools, it bonds the two pieces of metal together. This method is most common with copper piping and can be used for water, waste, and vent piping.
The science behind this method is very old and has been able to withstand the test of time. Soldered joints are fairly strong and water tight when done correctly. The learning curve for this method is average and it is fairly easy to learn. However, when this method is used on larger diameter copper piping (3″ and up) there is quite a bit of room for human error.
The piping has to be cleaned properly (using flux) and the person installing has to have enough experience using heat or torch control. If not, you run the risk of the joint getting too hot and drawing solder down the bottom of the joint which leaves a gap at the top and softening the copper itself. In addition, piping materials and filler are expensive. With everyone being so cost conscious, using copper can become cost prohibitive.
Brazing is similar to soldered joints, but it is used primarily on water piping (specifically water services or large diameter piping), and is much more forgiving. It also uses a filler metal with a melting point lower than the base metal it is being joined to.
As with soldered joints, this is a mature technology. The result is that the joint ends up being stronger than a soldered joint because of the way the filler metal reacts to the metal being brazed. The drawbacks of brazing are similar to that which you would find in soldered joints.
Threaded Fittings will always be used for repairs or on specialized fittings (flange fittings), but as threaded pipe and fittings relate to galvanized water piping, it is a dying joining option. Galvanized pipe and fittings can be very difficult to repair.
As they start to break down, sediment and rust begin to build up inside the piping which shrinks the inside diameter of the piping, often a significant amount of the piping must be replaced for repair. The plumbing contractor must have the proper equipment available to cut and thread the pipe.
If this equipment is not available, the plumbing technician must have the skill set to measure correctly and relay these measurements to a wholesaler with the capability to cut and thread the piping. If either of these two things are incorrect, the end effect is a shutdown of the entire building.
A Fuse Seal (Polypropylene piping) is the process of melting a thin layer of the polypropylene plastic, using a specialized tool and heated to a specific temperature, which will then fuse into one piece after about 15 or 20 seconds.
Although this technology has been around since the 60s it’s had an extremely tough time gaining widespread use. Using a fuse seal will save about 20% in material when compared to copper. While there is a learning curve to this method, it is far more forgiving than it’s copper counterpart.
This material has very little contraction or expansion (eliminating worries for freezing or thawing), it is not an efficient conductor of heat (very little condensation or sweating), there is zero electrolysis (negligible electrical conductivity), and is naturally acid resistant (no hard water worries). There are some new products that offer pipe and fittings that are joined to be green friendly.
Some drawbacks are that, traditionally, the fittings are not full port. Anything over a 4″ I.D. piping must be a mechanical joint. Also, because of the lack of rigidity, more pipe hangers (some say double the amount) must be used. Although a large percentage of plumbing technicians have handled this material at some point, the use in the United States is minimal compared to other methods and materials, which makes it less than efficient in terms of labor costs.
A Mechanical Joint is any method of joining piping or fittings using coupling of a compressed rubber gasket to ensure a water tight seal (such as flanged pipe and fittings or grooved pipe with couplings or fittings). In theory, repairs on these applications are easier to perform.
The tolerances are high because they are high pressure fittings and can be installed in large diameter pipe and fittings. It does require a fairly high skill lever to prepare and install this pipe and accompanying fittings.
Installing the mechanical fittings for grooved pipe can be fairly simple, but measuring and grooving of the pipe takes some know-how. To install or repair flanged pipe, spool pieces, and flanged fittings, the plumbing technician has to have a very high skill level. Costs can be saved on material, but the repairs and installation can become intensive and fittings are heavy and expensive.