MG wrote:
A month ago I found a leak in the sprinkler.
No problem, you dig, splice and repair.
Apply the pressure and another elbow nearby blows open.
At this point I get a little suspicious and stress mildly all other joints
in the dig and got 2 more to fail nice an clean, you can tell that there was
no good bonding.

Also note that the cement used was a deep blue, not the usual transparent
stuff with the tell tale of the purple primer.

The blue cement appears to be like a thick paint, the failed joints can be
easily cleaned with steel wool and the cement residue does not seem to be
fused with the rest of the fitting as I would expect.

Same story, I stressed the stub and I got the entire valve assembly out. I
was able to break out the pipe stubs from the valve. All pretty poor joint,
little sign of cement.

Other notes. The water utility started adding free chlorine for the annual
flushing, this is a temporary thing. Could this be a factor?

I never had any problem with the transparent type of cement applied over the
purple primer.

Is this blue cement different? Incompatible with PVC?

I do not believe movement or stresses are a factor here.

Anyone can shed some insight?

Thanks MG



You pretty much described the problem. Whatever the blue cement was it
is clearly not compatible with the plastic pipe because it never
dissolved the plastic (what a solvent cement does) to form a bond.