On Wed, 16 Sep 2015 19:08:19 -0400, Stormin Mormon
wrote:

On 9/16/2015 3:41 PM, J Burns wrote:
I was unable to slide a piece of 1/2" PEX onto an elbow. I've found the
reason. Virtually all fittings that seal against the inside of PEX are
designed for SDR-9, the industry standard. The walls of my SharkBite
pipe are .02" too thick. The ID is .04" too small. It's SDR-7.

A purchaser should know if he is being sold pipe that is not standard.
The SharkBite site doesn't mention any SDR standard for their pipe. The
only dimensions are nominal. How would the purchaser know it wasn't
standard?

A Home Depot search for 1/2 PEX pipe brings up 47 items. The first three
are SharkBite pipe for potable water. The store lists the nominal
dimensions to three decimal places as if they were actual. Even if they
were, they would be outside the industry standard. The only other choice
for potable water comes at the end. That manufacturer provides
dimensions proving it's SDR-9.

SharkBite may have set their wholesale price to take most of the market
at Home Depot. The unsuspecting consumer discovers that only
premium-priced SharkBite fittings will work. Lowes, where professionals
shop, doesn't sell SharkBite pipe. If plumbers find that they must
resort to heating to get SharkBite pipe onto fittings, they'll complain.


Of course, there are different grades of water
copper, K, L, M, and not sure if any other.
Those might be different OD, not sure.
K L and M have the same external zise but different thickness - and
therefore different IDs