Type K. Typical uses are applications, such as underground water services, plumbing, heating, steam, gas, oil, oxygen, and industrial piping where codes, installation, and service conditions necessitate the use of a heavy wall tube. Type K is commonly used with solder-type, flared, and compression fittings.

Type L. Typical uses are applications, such as interior plumbing, heating air-conditioning, steam, gas, and oil piping and for underground drainage lines. Type L is commonly used with solder-type, flared, and compression fittings.

Type M. Typical uses are applications, such as interior heating and pressure lines when suggested by engineering design. Type M is commonly used with solder-type fittings.