Copper tubing
Soft copper is the most popular choice for refrigerant lines in split-system air conditioners and heat pumps.
If heated and allowed to cool in a process called annealing, rigid copper will become soft and can be bent/formed without cracking.
Solder-connected rigid copper is the most popular choice for water supply lines in modern buildings.
In situations where many connections must be made at once (such as plumbing of a new building), solder offers much quicker and much less expensive joinery than compression or flare fittings.
The filler metal is brought slightly above its melting (liquidus) temperature while protected by a suitable atmosphere, usually a flux.
A disadvantage in compression connections is that they take longer to make than sweat and sometimes require re-tightening over time to stop leaks.
Thousands of pounds-force per square inch of pressure are used to deform the fitting and compress the sealant against the inner copper tubing, creating a water-tight seal.
Note: Types "L"& "M" are often mistakenly identified as purposed for "hot" or "cold" applications by novice home repairers by their red and blue printing.
The printing only references the gauge thickness of the pipe, which may affect application choice and address quality/durability concerns for the product selected.
In both the U.S. and Canada, copper pipe and fittings are sold in imperial units only as metric sizes are not manufactured for use in North America.
Building codes throughout the U.S. and the Safe Drinking Water Act Amendments of 1986 require the use of virtually "lead-free" (<0.2% lead) solder or filler metals in plumbing fittings and appliances.
Correctly installed plumbing appliances will have a copper bonding jumper cable connecting the interrupted pipe sections.
Pinhole leaks from stray current corrosion can result in high plumbing bills and require the replacement of the entire water line.
The impressed DC voltage causes dissolved ions in the water within the piping to move carrying charge as they do.
Electrical current is carried by dissolved ions across a non-conductive section (a plastic filter housing, for example), to the pipe on the opposite side.
Pitting occurs at the electrically positive side (the anode), which may happen to be either upstream or downstream with respect to the water flow direction.
Detection is accomplished using a simple DC voltmeter, with test probe leads placed in various locations in the plumbing.
The measured electrical potential father away is diminished by the electrochemical reaction that causes pipe corrosion.
The missing bond is often located near the cold water inlet to the building where filtration and treatment equipment are usually added.
The problem can be corrected by installing bronze ground clamps on the plumbing on either side of the dielectric gap and joining them with a copper cable #6 AWG in diameter or larger.
See NFPA 70, the U.S. National Electrical Code Handbook (NEC), for the correct bonding conductor wire size for a particular building.
A failure if the building’s grounding electrode(s) can also result in the earth current being carried to the buried natural gas service pipe.
