Piping and plumbing fitting

The key point is that the plumbing term focuses on the degree of bend from the original straight pipe, not the resulting angle.

Long elbows are used in low-pressure gravity-fed systems and other applications where low turbulence and minimum deposition of entrained solids are of concern.

[15] This change may be intended to meet hydraulic flow requirements of the system or adapt to existing piping of a different size.

Throttling valves control the amount or pressure of a fluid allowed to pass through and are designed to withstand the stress and wear caused by this operation.

Valves are available in several types, based on design and purpose: Because they operate at low pressure and rely on gravity to move fluids (and entrained solids), drain-waste-vent systems use fittings whose interior surfaces are as smooth as possible.

The fittings may be "belled" (expanded slightly in diameter) or otherwise shaped to accommodate the insertion of pipe or tubing without forming a sharp interior ridge that might catch debris or accumulate material, and cause a clog or blockage.

[16] Freshly cut ends of pipe segments are carefully deburred to remove projecting slivers of material which may snag debris (such as hair or fibers) which can build up to cause blockages.

Minimum requirements are typically at the end of each branch in piping, just ahead of each water closet, at the base of each vertical stack and inside and outside the building in the main drain or sewer.

Threaded steel pipe may still be used in high-security or exposed locations because it is more resistant to vandalism, more difficult to remove, and its scrap value is much lower than copper or brass.

Pipes used to convey fuel gas are often made of "black iron", which has been chemically treated to reduce corrosion, but this treatment does not resist erosion from flowing water.

[citation needed][28] Where many connections must be made in a short period (such as plumbing of a new building), soldering is quicker and less expensive joinery than compression or flare fittings.

However, using an open flame for heating joints can present fire and health hazards to building occupants and requires adequate ventilation.

Skill is required to melt the joint sufficiently to ensure good fusion while not deforming or damaging the joined pieces.

Because of the skills required, welded pipe joints are usually restricted to high-performance applications such as shipbuilding, and in chemical and nuclear reactors.

Adequate ventilation is essential to remove metal fumes from welding operations, and personal protective equipment must be worn.

Because the high temperatures during welding can often generate intense ultraviolet light, dark goggles or full face shields must be used to protect the eyes.

The pipe end should be square, so it sits against the stop in the fittings and does not create turbulence, and needs to be a clean cut to avoid damaging the O-ring during insertion.

Two surfaces are joined tightly together with threaded bolts, wedges, clamps, or other means of applying high compressive force.

[30] Although a gasket, packing, or O-ring may be installed between the flanges to prevent leakage, it is sometimes possible to use only a special grease or nothing at all (if the mating surfaces are sufficiently precisely formed).

Although flange fittings are bulky, they perform well in demanding applications such as large water supply networks and hydroelectric systems.

However, mechanically fastened joints are sensitive to residual and thickness stresses caused by dissimilar metals and temperature changes.

If this was not possible due to position or some other constraint, the joint could be filled with lead wool or rope, which was forcibly compacted one layer at a time.

Quicker and lower-cost methods, such as rubber sleeve joints, have replaced mainly leaded hub connections of cast-iron piping in most new installations, but the older technology may still be used for some repairs.

[21]: 149  In addition, some conservative plumbing codes still require leaded hub joints for final connections where the sewer main leaves a building.

Cast iron DWV pipe and fittings are still used in premium construction because they muffle the sound of wastewater rushing through them,[21]: 149  but today they are rarely joined with traditional lead joints.

[21]: 149 [18]: 71  Optionally, the entire rubber sleeve may be jacketed with thin sheet metal, to provide extra stiffness, durability, and resistance to accidental penetration by a misplaced nail or screw.

An alternative design also allows the selective use of belled fittings made entirely of flexible rubber, including more-complex shapes such as wyes or tee-wyes.

An advantage of flexible rubber fittings is that they can accommodate small misalignments and can be flexed slightly for installation in tight locations.

[21]: 147, 149  A flexible fitting may be preferred to connect a shower or heavy tub to the drainage system without transmitting slight movements or stresses, which could eventually cause cracking.

Clamped fittings may occasionally need to be disassembled to provide access for "snaking" or "rodding-out" with a unique tool to clear blockage or clogs.