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Using a union at a sillcock connection

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Using a union at a sillcock connection runderwo@mail.win.org 06-27-2007
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Posted by runderwo@mail.win.org on June 27, 2007, 8:41 pm
Hi,
I've been having a lot of problems getting my new sillcock to thread
into the corresponding copper fitting (Sweated onto the supply pipe).
I have had to re-do the supply several times because the chrome
sillcock (1/2 mip) wants to eat the copper threads instead of going in
peacefully.

Here is my idea for repair and rationale:

12" Sillcock 1/2 MIP, screwed to 1/2 FIP copper fitting, sweated to
short copper pipe, sweated to male side of brass union
Female side of brass union sweated to copper pipe sweated to supply
tee

The sillcock is then joined to the supply at the union instead of at
the copper fitting.

Rationale:
- The male brass union will not eat the threads of the female brass
union.
- The brass union will not seize. Copper and chrome may seize, and in
this design that is actually a benefit. The next guy can just turn
the sillcock out, and with it comes the male half of the union (the
part that is harder to damage).
- The "Wiggle" from using the sillcock will be on the male side of the
union, which is held rigid by the threads, so it shouldn't be possible
to break the union seal by using the sillcock roughly.

Problems:
- The sillcock is screwed in and the downspout must be vertically
aligned for the freezey-proof to work. Conceivably, I can see a
scenario where when on one turn when the downspout is aligned, the
union has not yet sealed, but then the union becomes tightened before
the sillcock is vertically aligned on the next turn.
- Is a union going to be reusable in this situation? If the next
guy's going to have to dig into the wall in any case, I'll just sweat
the whole thing and be done with it.


Another idea was to sweat a 1/2 male fitting onto the supply pipe, and
then attach a threaded copper coupler to the sillcock and use the
copper coupler to connect to the male supply fitting. Copper on
copper, so no seize and no eaten threads, but I don't even know if a
threaded copper coupler exists, much less if it would be possible to
seal the threads.

Ideas? Flames?


Posted by on June 27, 2007, 9:17 pm
wrote:
> Hi,
> I've been having a lot of problems getting my new sillcock to thread
> into the corresponding copper fitting (Sweated onto the supply pipe).
> I have had to re-do the supply several times because the chrome
> sillcock (1/2 mip) wants to eat the copper threads instead of going in
> peacefully.
>
> Here is my idea for repair and rationale:
>
> 12" Sillcock 1/2 MIP, screwed to 1/2 FIP copper fitting, sweated to
> short copper pipe, sweated to male side of brass union
> Female side of brass union sweated to copper pipe sweated to supply
> tee
>
> The sillcock is then joined to the supply at the union instead of at
> the copper fitting.
>
> Rationale:
> - The male brass union will not eat the threads of the female brass
> union.
> - The brass union will not seize. Copper and chrome may seize, and in
> this design that is actually a benefit. The next guy can just turn
> the sillcock out, and with it comes the male half of the union (the
> part that is harder to damage).
> - The "Wiggle" from using the sillcock will be on the male side of the
> union, which is held rigid by the threads, so it shouldn't be possible
> to break the union seal by using the sillcock roughly.
>
> Problems:
> - The sillcock is screwed in and the downspout must be vertically
> aligned for the freezey-proof to work. Conceivably, I can see a
> scenario where when on one turn when the downspout is aligned, the
> union has not yet sealed, but then the union becomes tightened before
> the sillcock is vertically aligned on the next turn.
> - Is a union going to be reusable in this situation? If the next
> guy's going to have to dig into the wall in any case, I'll just sweat
> the whole thing and be done with it.
>
> Another idea was to sweat a 1/2 male fitting onto the supply pipe, and
> then attach a threaded copper coupler to the sillcock and use the
> copper coupler to connect to the male supply fitting. Copper on
> copper, so no seize and no eaten threads, but I don't even know if a
> threaded copper coupler exists, much less if it would be possible to
> seal the threads.
>
> Ideas? Flames?

I don't understand why a sillcock will not screw into a copper pipe
fitting. I've done many of them and they went on no problem. Have
you replaced the fitting on the pipe which may have bad threads?
It's also possible you have a sillcock with bad threads. Also, many
sillcocks are made so they can either be screwed on or soldered on.
So, you could solder one on. No reason you should have to use a union
in this application, which is just asking for more potential problems.


Posted by runderwo@mail.win.org on June 27, 2007, 10:39 pm
On Jun 27, 8:17 pm, trad...@optonline.net wrote:
>
> I don't understand why a sillcock will not screw into a copper pipe
> fitting. I've done many of them and they went on no problem. Have
> you replaced the fitting on the pipe which may have bad threads?
> It's also possible you have a sillcock with bad threads. Also, many
> sillcocks are made so they can either be screwed on or soldered on.
> So, you could solder one on. No reason you should have to use a union
> in this application, which is just asking for more potential problems.

I guess I don't understand that either. It's in the same hole the old
one came out of so I would assume the hole is lined up. I can feel it
catching but it cross-threads every time. I guess it could be bad
threads, but I checked that the copper fitting will screw onto the
sillcock by hand before installing it. After slightly cross-threading
one and removing it, I was able to "fix" the copper threads by hand by
screwing it onto the sillcock. It just won't go on that way when it's
in the wall for some reason.

The sillcocks I got are from home improvement megastores. Two have
flare ends and one has a MIP End. It seems like the one with the MIP
end should be able to be soldered, but I was unable to get a 1/2
copper pipe into it.

The idea behind the union was to avoid the chrome seizing the copper,
but from the sound of it that's not much of a problem? The one that
came out had a copper supply fitting on a galvanic nipple that the
sillcock was soldered to. The copper-galvanic joint was a molten mess.


Posted by on June 28, 2007, 8:55 am
wrote:
> On Jun 27, 8:17 pm, trad...@optonline.net wrote:
>
>
>
> > I don't understand why a sillcock will not screw into a copper pipe
> > fitting. I've done many of them and they went on no problem. Have
> > you replaced the fitting on the pipe which may have bad threads?
> > It's also possible you have a sillcock with bad threads. Also, many
> > sillcocks are made so they can either be screwed on or soldered on.
> > So, you could solder one on. No reason you should have to use a union
> > in this application, which is just asking for more potential problems.
>
> I guess I don't understand that either. It's in the same hole the old
> one came out of so I would assume the hole is lined up. I can feel it
> catching but it cross-threads every time. I guess it could be bad
> threads, but I checked that the copper fitting will screw onto the
> sillcock by hand before installing it. After slightly cross-threading
> one and removing it, I was able to "fix" the copper threads by hand by
> screwing it onto the sillcock. It just won't go on that way when it's
> in the wall for some reason.
>
> The sillcocks I got are from home improvement megastores. Two have
> flare ends and one has a MIP End. It seems like the one with the MIP
> end should be able to be soldered, but I was unable to get a 1/2
> copper pipe into it.

The ones intended to be soldered or scerwed on that I have seen have
male threads on the outside. Inside where the threads are, it's made
to accept 1/2" copper pipe if you want to solder it in instead.

The advice to buy taps/dies is interesting, but I would think the
tools would cost more than just buying a new sillcock and soldering on
a new threaded adaptor.



>
> The idea behind the union was to avoid the chrome seizing the copper,
> but from the sound of it that's not much of a problem? The one that
> came out had a copper supply fitting on a galvanic nipple that the
> sillcock was soldered to. The copper-galvanic joint was a molten mess.



Posted by Joe on June 28, 2007, 12:48 am
wrote:
> Hi,
> I've been having a lot of problems getting my new sillcock to thread
> into the corresponding copper fitting

<snip>

> Ideas? Flames?

Find a real honest-to-gosh hardware store and buy a 1/2" NPT pipe tap
and a 1/2" NPT pipe die. Clean the threads up with each of these tools
and they will work perfectly. If you have trouble assembling at the
installation site, then you have an alignment problem that you didn't
notice at first. Correct that and you're good to go. HTH

joe


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