how tight is tight enough?

OK, it's going to be difficult to answer this in a forum, but I'll pose it anyway. I'm installing a new shower valve (Hansgrohe) and the connections to the valve are 1/2" NPT. The valve body is brass and I'm plumbing with copper. So I have 1/2" threaded copper adapters screwing into the brass body. I'm using 3-4 wraps of tape, then a little white teflon paste (Oatey).

With all the warnings about not getting carried away with my big wrench and risking a cracked body, how does a DIYer know when enough is 'nuff? Fixing a leak after everything is plumbed would make for a very, very bad hair day. (I told you it wouldn't be easy)

-art-

I would use two channel locks that are 12-14 in long. Channel Lock number 420, I think and tighten until it is difficult to make it screw in. I would pre solder the adaptor before applying any pipe tape as the tape has a tendency to vaporize leaving you with leaks. I only use teflon pipedope which can be soldered and still have no leaks. There is a time and place for teflon tape but I use it very rarely.

ANSI provides specifications for tapered pipe thread engagement.

For 1/2" IPS, the specified makeup is 4 ½ turns by hand ( .320" thread engagement) plus 3 turns by wrench for a total thread engagement of .534"

They go on to note, however, that there would be plus or minus one turn tolerance on this, and they also note that in field and even factory practice, the total threaded length of fittings ( total # of threads ) is often less than the spec. If your fitting doesn't go 4 turns by hand, it probably wont need three wrench turns.

So, what is the answer: hand tight and then wrench tight. How tight? You do develop a "feel". I would say that steel fittings have more ability to absorb the "tolerance" mentioned. Softer metals like copper, and then especially plastic, there is the ability to overtighten and distort the fitting.

I have a slightly different feeling about teflon tape than you will hear from most plumbers here; and they are all successful pros so I never argue with them. But I stick to the manufacturers recommendation of one and one half to two turns of tape. I like the pink or yellow. The thin white tape, 3 turns is probably OK. But too much tape can interfere with the threads. Just my opinion.

interesting - never thought about the possibility of an ANSI spec. I use the white tape and tend to stretch it a little so the 3-4 wraps sounds OK.

Yes, I always solder first, then screw in the adapter. Didn't realize the dope could take the heat, though - good to know if I'm forced to solder after.

and yes, I know well that this sort of thing is as much an art as it is science. However, I think I see that - generally speaking - 6-7 turns ought to do the trick, but don't try to forct it past 6 if it doesn't want to go. I'll experiment a little and see what this 'feels' like!

thanks!

-art-

tight

ANSI standards are for perfect threads in a laboratory, just like the EPA mileage figures for a car. "Your actual experience will be different, and will probably be less." It is a matter of feel and experience, and not being able to tighten it any further.

hj, I did try to make that point. Right in the ANSI standard they acknowledge that in the "real world" threads are often not to the letter of the spec. This is where the " feel " comes only with experience.

update

thanks, guys - as a enjuneer in my other life, I'm well aware of the differences between the textbook and real world. until you guys gave me the "textbook" on this - plus a little real world insight - I was flying blind. And with a leak being extremely difficult to fix without a big tearout once it's in, I was more than a little nervous. Now I've got something to work with, and that's a lot more than I had yesterday!

tanx!
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update: removed all the adapters and cleaned the threads. 3+ wraps of white tape and a little dope on all, and the best I could convince myself to do was 5+ turns with my 10" crescent at the end (total turns from initial thread engagement). It seemed to be pretty consistent on all 5 ports. Leaktest on the supply ports should come tomorrow - the others by end of week. Here's hoping!!
-art-

watertest.....

well, finally got all the supply plumbed and connected to the shower control. Closed the stops at the control and opened supply valves. No leaks! and since there's far more pressure on the supply connections than the outputs to the fixtures I feel pretty confident I got it right.

Like I said earlier - about 5 to 5-1/2 total turns was all a could convince myself to give it and it appears to be enough. I'm sure the tape and paste contributed, but when I tried a fitting clean I didn't get much further. Maybe the fact that it's made in Europe makes it different from US fittings?

Whatever - I'll finish the fitting connections tonight and cap for a total test.

thanks much!