As a field foreman speaking, blue dope/Super dope is very hard to break loose.
Please note these pipe dopes are expensive. Fab shops only apply dope on the
threads with a fitting. Many older fitters apply dope only on the fitting side
using the Rigid 300. I mean Argo plain white dope. Leave blue dope for
plumbers,
and chill water fitters. NEVER use blue dope on branch lines, as they may have
to be broke loose years later during tenant finish, or add and relocates. Blue
dope, or Superdope is only acceptable for Glycol antifreeze systems. You don't
want your field hands using a 36" Rigid steel pipe wrench to breaks loose a 1"
nipple drop that spins the branch line and makes the heads behind it crooked.
You can apply regular Argo white dope on threads, heads, plugs, and it will not
leak at 250 psi. I have done jobs with underground static psi at 250, and had
no
leaks with dope only. BLUE DOPE is never acceptable in sprinkler work. Its for
the lazy fitter that wants to hand turn his pipe and "eyeball" the fitting so
his armovers, and drops are crooked. If you can't wrench pipe in tight enough
to
hold 250 psi, get another trade. I've had 0'2" nipples that were tight as ever,
once I put a 4' armover they were loosy goosy and held 200 psi.
Dope and tape is good, but I always use dope on the outside of threads over
tape
for close nipples, and unions. I also use dope second for shallow threads as it
allows for superior makeup into the fitting. I have had shallow threads, and
ran
a fitting over the threads on the Ridgid 300, removed the fitting, then I
installed the pipe with major makeup. I stretched the threads. Its the same
when
you reuse an old 90, you make the 90 in on the Ridgid 300 where there was no
makeup on the machine, then install the armover, or drop nipple on the old made
up threads, ensuring 2 or 3 threads show, and accurate precision in cutting the
sprinkler head in so a eschuteon will fit with no problem.
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