Why is type M- L- K pipe called this?

grindog

they have different hardnesses. Mis softest and k is hardest. In massachusetts we use L for all water piping in the building and type K for the water service coming in from the street. M is used for heating unless otherwise specified.

John@Reliable_5

Copper pipe markings

Anyone know why copper pipe is rated like this. Is it because of drill size (thickness) or some other reason.I hate it when someone asks me a question I can't answer. John

brucewo1b

Type M is thin-walled, system pressure as in water boiler runs to baseboard. Type L is medium-walled usually used for street pressse ie hot and cold water pressure and Type K is thick-walled

Mike T., Swampeast MO

According to www.copper.org the K-L-M designation refers to wall thickness:

"Types K (heaviest), L (standard), and M (lightest) wall thickness schedules as classified by ASTM B88"

Am still searching for the origin of those designations. I've found that the origins of nomenclature are EXTREMELY difficult to find on the web and almost never mentioned in printed trade references. You have to find the "weird facts" sort of sources...

Mike T., Swampeast MO

It doesn't help that even when quoted "K-L-M" Google returns hits for "KLM". KLM is both an airline and a major mining company...

"M-L-K" gets almost nothing besides typos for "milk"

bob_50

Copper Tube

is availabel (ASTM B 88) in K,L,M,DWV,Medical Gas,ACR and G. Wall thickness varies from .025"-3/8"M to .405"-12"K. There are other types available from the mill on special order. The letter designation has nothing to do with hardness. I have no idea where the designations came from. The first documented use of copper tube to convey water was 5,000 years ago. It was used to supply water to Pharaoh Cheops bath. It is still in usable condition. I wonder what 5,000 year old PEX will look like. bob

brucewo1b

If your pulling them out of a concrete slab I'll wager that the PEX wins