OK to drill and tap a 3/4\" main vent hole on a 3\" iron main?

bob young

YEAH, Dave baby.......for a small fee.

Mike K_12

OK to drill and tap a 3/4\" main vent hole on a 3\" iron main?

On my one-pipe steam system I have a long main with no vent. The options for adding a vent seem to be drilling and tapping, or else adding a "T". The main is one long pipe, so I'm guessing that adding a T would involve cutting and threading, which I'd like to avoid. AS my question indicates, I'm assuming that a 3/4" nipple off the main would be the proper size for the main vent. Thanks!

Unknown

drill and tap a 3/4\" main vent

I`ve seen it done, but personally I`m leery of-it without having a "boss" arc-welded to the pipe.
I have D&T smaller holes up to 1/2" in 3" pipe though.

Dave

bob young

weld it

weld -o-let [ boss ] as dave suggested is the way to go. a first class permanent job.

The Steam Whisperer (Formerly Boilerpro)

You can tap much smaller than 3/4 inch.

You can tap a 1/8 inch hole and then increase to 1/2 or 3/4 for a main vent. A short 1/8 inch pipe flows the same amount of air as the largest main vent avialable... the Gorton #2.

Boilerpro

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Steamhead (in transit)

I'd use

several smaller tappings- 3/4" is getting big enough that the walls of the pipe being tapped might not be thick enough to provide enough threads to support the vent pipe. If you must use a single 3/4" tapping, have a thread-o-let welded on as Dave and Bob suggest.

But several 1/2" tappings would probably work great.

I'd use something bigger than 1/8" for the Gorton #2. I prefer 1/2" for this vent to keep the steam velocity in the vent pipe down. But when using a Gorton #1, which is smaller, 1/4" or even 1/8" would be fine.

How long is your 3" main?

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Mike K_12

The main is approx. 25' long. Thanks for these answers!

Steamhead (in transit)

A Gorton #2

will vent that main quickly, at just over an ounce of pressure. You only need to tap 1/2" for it.

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Mike Kehoe_4

I'm an idiot, the main is actually 2\", not 3\". Does that change

the answer?

Unknown

2\" is pretty small to tap \"period\".

you may get away with a 3/8" hole,, or 2 different 1/4" ones.
It gets touchy with 2"!
With a 4 wheel pipe-cutter, a pro can install the proper size fitting you need. :-).

Dave

Unknown

bob,

"IF" it was my house, I would no-doubt try-it,,, but then again, I have the tools to fix-it if things didn`t work out.
As you know,, 2" can be very touchy to D&T if not experienced. ;-)

Dave

Steamhead (in transit)

In that case

use two Gorton #1 or Hoffman #75 vents (though the Hoffmans are more expensive). The 1/2" pipe mentioned above will do nicely. I've drilled and tapped for installations like this many times with no problem.

"Steamhead"

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bob young

[ the edge factor. ]

YEAH but you got the edge, dave 'cause you know if you can't fix it me & paul bunyan will come over to your house & slap in a new main F.O.C. [ free of charge. ] we will also bring a cooler full of beck's dark so the job goes extra smooth.

Unknown

Sorry I missed your post old friend,

not much of a beer drinker myself,,,white-rum & Pepsi is my preference. :-)

Dave