On Tue, 11 Oct 2011 22:57:23 +0100, David Billington
wrote:

Gunner Asch wrote:
On Tue, 11 Oct 2011 06:09:12 -0700, Larry Jaques
wrote:


Why black pipe? We're not doing nat. gas here. I used all 3/4"
galv steel for my main and 3/4 x 3/4 x 1/2 tee's UP, then two 90 deg
street el's and 1/2" down to my outlet, ball valve and Q/C.

Galv flakes a lot. I hope you use a FLR on each drop, with or without
lube. F'rinstance http://goo.gl/2yi3z .


Indeed. Ive made a point to NEVER use Galvanized pipe in any of the 100
or so air systems Ive designed and installed. This after repeatedly
having to unchoke or replace air solenoids that were
filled/blocked/ruined by flakes..sometimes BIG flakes of Galv.

Black pipe is cheaper, and while it may rust a bit more internally..it
reaches a point where little comes out of it..and when it does..is dust
that passes through such devices nicely. Particularly when one does
moisture control before the air reaches the plumbing.

Copper is best..but as Larry indicated...figure out which kid you like
the least, then sell him/her for the bucks to install it.

When a joint of 3/4 black, 20 feet long is $11 or less...its the most
viable candidate for most folks.

Gunner

"In the history of mankind, there have always been men and women who's goal
in life is to take down nations. We have just elected such a man to run our
country." - David Lloyyd (2008)

Why does the galv flake and is that inside or outside or both. I put
galv pipe handrails at my mothers place over ten years ago and the
external surface, while a bit weathered, is otherwise still perfect, I
tinned the cut ends with solder so no rust there either.

Inside tends to flake off as the pipe expands at the pressures used in
air systems..often 150-175psi




Does remind me of my dad building some boats in the early to mid 1970s
and the local hardware stores in Huntington Long Island, NY were having
difficulty getting decent hot dipped galvanised nails, most that came in
from cheap sources you would hit and the galv would flake off at the
first strike and their days were numbered, I think they were poor hot
dip or plated. The good ones you could hammer fully home and no problems
and you could rely on them lasting.


"In the history of mankind, there have always been men and women who's goal
in life is to take down nations. We have just elected such a man to run our
country." - David Lloyyd (2008)