Tapping 4-inch pipe

Rich L.

Thanks for clearification Tony, I meant a weld on thread-o-let.

Steve Garson_2

Tapping 4-inch pipe

I have working on my organization's heating system that has no air vents on the 200 feet of vents. Nada! Burns 385K BTU/hr of oil. Also, half the mains are uninsulated, but that will change this weekend!

Some mains have old nipples with caps from old radiators long removed that I can use to locate vents, but two mains will need to be tapped. I have tapped smaller pipe with no problem, but I have never tapped a 4-inch pipe. Obviously the wall thickness is greater. Will I need longer handles to screw the tap into the hole, or is it not much different from tapping a 2-inch pipe? I just don't want to find that I don't have the strength to turn the tap after I drill the hole.

Thanks,

Steve

Rich L.

tapping

Steve, we don't tap pipe. Because of the radius surface as well as the wall thickness it can be very difficult to get a good seal as well as dangerous. We use a device called a weld-o-let. It's essentially a half coupling, much beefier, that gets welded to the side of the pipe after the hole gets drilled. You can then screw anything you want in there.

Steve Garson_2

But with steam pressure of just 2 psi, is it really dangerous? There have been lots of postings on this site that you should tap the pipe and install some Gorton vents on a manifold. Unless I misunderstood.

Brad White_185

The term \"tap\"

is perhaps too general. As Rich said, the pipe wall is actually not tapped but a Weld-O-Let is applied.

The term "tapping" is understood to mean that it is done correctly, not a literal term, unless you are Eliot Spitzer.

To be fair, I have seen 1/8" and 1/4" instrumentation taps placed in 8 and 10 inch pipe, not saying it is correct to do so.

But you are talking about steam vents (air valves) which should be elevated off the main regardless, by at least six inches and on larger pipe than that.

Further, if in a manifold, that means you will probably be using some 1" pipe and fittings, just to allow any condensate to fall back, to keep venting velocities down and to afford you a base for fittings.

Once you install a Weld-O-Let, you are pretty much home free. Some Welding Required.

Bruce Stevens_2

Tap the side of the tee

to the last riser

Unknown

Tapping 4\",

as others have said a Weld-O-Let or welded "boss" is definitely the proper way, but I have drilled & tapped even smaller pipe sizes many times and I never had any problems.

Tony Conner_2

There Are Three...

... 'o-lets'. Weld-o-let for butt welds, sock-o-let for socket welds, and 'thread-o-lets' for threaded connections. You need a welder anyway, just make sure that if you ask for one of the welded variety, that you get him to weld a half-nipple onto the o-let if you chose one of the welded ones, before he wraps up his cables and drives away.

Brad White_185

You are right, Tony

I got lazy and in the office we call them Weld-O-Lets out of habit and because welding is required in each case. As you noted, each is specific to the connection and understood as such. Thanks for clearing that up.

Steve Garson_3

I realize price discussions are frowned upon here, but what range of prices would I expect to pay to have two holes and the appropriate device welded to the risers? It seems too small a job for anyone to want.

Rich L.

Welding

I would think you could find a shop willing to do this for a "fill in" job. Something to finish out a day. If you could have the boiler shut down and pressure off the pipe you should be looking at a couple of hours work plus materials. The rates differ across the country so just make a few phone calls. Where are you located? You can try smaller heating and cooling contractors but a mechanical contractor would be set up to handle it with a truck or trailer mounted welding rig. Since it sounds like you are going to do the work yourself once you get the holes in you could also look in the yellow pages under welding.

Good luck, Rich L

Steve Garson_2

Where to buy Theadolets?

When I call the welder, I want to make sure that the correct Threadolet is used. I'm having trouble locating a supply. I assume they are spec'd by pipe size and thread, for instance 1/2-inch NPV x 4-inch?

Any suggestions?

bob young

coupling

if the weld-o-let boss is not available a coupling [bl. steel ] can be substituted as long as you have a competent welder. only as a last resort.