black pipe assembly technique

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by rbptlp, May 23, 2007.

  1. rbptlp

    rbptlp New Member

    Messages:
    4
    I am helping my plumber do some of the work on my house, under his supervision
    and I'm good with PEX and copper, but can't seem to get the hang of black iron
    using Gasoila on first 3 threads, not too much, well-seated into threads, and tightening 'not too tight' (my plumber's instruction)
    but I think his idea of not too tight and mine are quite different
    redid some of the boiler trim and on pressurizing (only 15 psi) had drips at most of the unions
    so I am thinking I need to go WAY tighter
    maybe he means not gorilla tight
    the only tip I've found online is 'hand-tight and then 1.5 extra turns w/ a wrench'
    which is pretty close to what I was already doing
    (maybe not quite 1.5)
    but how do you go 'hand-tight' with a short nipple, for example? if one thread catches slightly, you're 'hand-tight' but not anywhere near 'sealed'
    I'd raher have torque recommendations for 1/2", 3/4", 1" etc
    or some other benchmark for how fully to apply the wrench

    and what is the danger of going 'too tight', anyway?

    anyone have any other rules of thumb?
    thanks very much
    Last edited: May 23, 2007
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Hand tight + one wrench turn is a rule for plastic pipe. It is not tight enough for black pipe. The link below shows the thread engagement , hand turns + wrench turns for various sizes of pipe. What size are you using? And you mentioned unions.....is it the union joint that is leaking, or the threaded pipe connection to the union fitting.?

    http://www.sizes.com/materls/pipeThrd.htm
  3. Gas is not water. Gas kills and having a gas leak on a gas line you just touched will scare the hell out of your customer whether it is a seepage leak or not. You'll lose that customer forever as well because they'll think you endangered thier life.

    I crank them till they stop. You can always tell if black iron was threaded by a new or old die. Old die usually means the pipe is going to travel all the way to the end. Newer will have that connection 3 to 4 threads deep.

    I take no chances on black iron because I know those systems over years start to leak from all the vibrations of the structure, causing the threads to allow leaks. I get calls from the utility company from customers stating the gas was just shut off and they found 13-20 leaks in the gas lines.

    Get there and the piping looks like the day it was installed.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,032
    Location:
    Cave Creek, Arizona
    pipe

    if you depend on hand tight with any specific number of turns with a wrench, you WILL have leaks. Properly adjusted sharp dies cut proper threads, but if they are not adjusted correctly they will either cut tight or loose theads and your "rule" will no longer work, even it it ever did. Old dies cut tighter threads because they are getting worn, so those will need more tightening that newer ones.
  5. rbptlp

    rbptlp New Member

    Messages:
    4
    update

    thanks for the tips
    according to the chart, 4.5 hand turns + 3 wrench turns is standard for both 1/2" and 3/4" black pipe
    that is probably more than I was doing, and may have been more than I am capable of doing
    I will count next time (I might have been doing more hand turns than I think)
    reassembled boiler trim yesterday going considerably tighter
    I also used a combination of teflon tape and Gasoila soft-set sealant (talked to Gasoila and that is what they recommended for problem joints)

    I think part of the problem is that my plumber put together the trim with a mix and match of what came with the boiler, his own odds and ends, and new stuff from the supply house
    so unlikely that any two pair of threads was matching up perfectly

    but it sounds like you are all pretty much saying go as tight as you can, that there is danger going too loose, but not a danger going too tight
    why did my guy say 'not too tight' ??

    again, thanks for the help
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,262
    Location:
    New England
    It's a tapered thread. In theory, if you tighten too much, it is like putting a splitting wedge into a log; you could split the fitting. Really hard to do, but possible.
  7. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I should have also mentioned to read the note that accompanies that thread chart I linked to. They ackowledged that field cut threads, and often even factory cut threads, do not have the full length of threads called out, and hence the variation in the turns required for "tight". I think we are all in agreement that you probably did not get it tight enough, because 3/4" pipe with for example a 12" wrench would take considerable effort to get tight. Unless you have arms like Mighty Joe Young an 18" wrench would not be too big!
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,032
    Location:
    Cave Creek, Arizona
    tight

    [​IMG]

    I use a 10" wrench on 3/4". An 18" wrench is WAY, WAY too big, unless you are a 98# weakling and need the Charles Atlas body building set. Do not spend any time following a chart as to "generic" threads. Just use some common sense. My wife's uncles put the waterers in for a dairy barn once. Since it was modular they precut the system, using the standard calculation for make up. Then they went in for dinner while the farmer's sons put the pipes together. Since the sons were built like 600# gorillas they tightened the pipes until there were no threads showing. By the time they reached the last waterer, the openings were 3" short from where they should be. The entire thing had to be taken apart and new fittings used because the old ones had been stretched by the tightening.
    Last edited by a moderator: Aug 1, 2007
  9. Clive

    Clive New Member

    Messages:
    5
    Location:
    Canada
    For a correct pipe thread you should be able to hand tight the fitting 3 turns, use a anaerobic pipe sealant on thread first then 4 turns with tefon tape, hand tight fitting on to pipe, wrench tight fitting 1.5 to 2 times with 14" wrench for pipe sizes 1/2" to 1" you will never get a leak, for union smear a coat of anaerobic sealent on union face, 2 to 3 turns of teflon tape on union thread tighten with 2 x 14" wrenches, 1 to tight 1 to hold against, make sure union faces butt up square, force tight but dont kill it.

    Clive
  10. grease it up and crank it down

    I have run into many gas lines that were
    literally only hand tight with the "tefflon slick tight"
    on the threads.....

    it works , but its not right and is sort of scarey to me..

    I ran into a drip leg on a water heater last year that
    literally fell out in my hand when I began to loosen it.
    the fellow must have jsut put it in there one or two turns
    and it vibrated itself outover the years.....


    Put tefflon tape on the pipe if you so wish...then
    Put pipe dope LIBERALLY on the male threads. just
    slop it on heavy , the dope is cheap and is less expensive than a leak......

    then tighten down the pipe till it feels "taught"


    not breaking the pipe off in the fitting , so the next poor bastard
    that comes along cant ever get the pipe apart again... and not "sissy" hand tight either ..


    "taught" is a point of tightness
    you learn from simply from doing it.
    Last edited: May 27, 2007
  11. Anyone know where you can find that coated underground pipe? Black iron that is that has the protective coating.
  12. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,032
    Location:
    Cave Creek, Arizona
    pipe

    If you really want it, I personally will only use it for very short underground runs, most plumbing supply stores will have it. The only way I will use it is if I wrap the ENTIRE pipe and fittings with the protective tape, not just the fittings and damaged areas. It is about the worst material you can use, other than unprotected pipe. It would be better if it were at least galvanized pipe with the coating.
  13. Clive

    Clive New Member

    Messages:
    5
    Location:
    Canada
    I agree, I would not use it as a lead in water supply, either type k copper or cpvc pipe, cost wise cpvc is the best for your buck, I just installed a 80ft lead in 2" glued fittings, piping will run 160 psi in service we tested to 200 psi for 2 hrs no problems, has some issues with back fill and compacting but is clean, approved for potable water, and has a great C-factor.

    Clive
  14. rbptlp

    rbptlp New Member

    Messages:
    4
    thanks all

    I have re-done both the boiler trim and the gas line and both are now 'taught' (I like that term, and I feel it now) and completely leak-free
    thanks again for all the feedback

    (my rule of thumb now is 2 turns Teflon + Gasoila first 3-4 threads, roughly 7 turns total - usually about 4 turns hand tight and 3 more with a 14" wrench - I adjust as needed - some threads want another full turn, or even 2; some need a little less
    but now I know what tight feels like)
  15. gtmtnbiker

    gtmtnbiker New Member

    Messages:
    30
    Location:
    Massachusetts
    I have some questions on black pipe assembly.

    What do you do if you're trying to put a T on the pipe and it needs to be aligned in a certain direction?

    So if I put the fitting on hand-tite and then use a pair of wrenches (one to hold mating pipe) to tighten it, I want to ensure that it's tight but I don't want to over-tighten. Also, it has to line up in some direction.

    There were several posts that reference the word "taught". I think they meant to say "taut", right?
  16. statjunk

    statjunk DIY Senior Member

    Messages:
    542
    I've always tightened the living you know what out of the black pipe I've installed. Never had one leak and never had one break.

    Tom
  17. frenchie

    frenchie Jack of all trades

    Ditto.

    Get it as tight as you possibly can - then tighten it some more to align it.

    An "extension" on your wrench (piece of black pipe slipped over the handle for extra leverage), helps a lot.

    Mind you, I weight about 140.
    Last edited: Aug 1, 2007
  18. gtmtnbiker

    gtmtnbiker New Member

    Messages:
    30
    Location:
    Massachusetts
    Thanks for the tips. I was afraid of overtightening it but I think I understand now.
  19. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    Overtorquing a connection isn't a concern if you select the correct size wrench. For 1" down to about 1/2" use a 12" or 14" pipe wrench. The connection will be tight when you can't go any further and a significant number of threads are engaged. If you use an 18" or 24" pipe wrench it is possible to break 1" connections even if you aren't a real "husky" unit. Of course if you are making up bigger connections then it's time to pull out the big iron. I never want to see another 48" wrench.:D

    For alignment, consider how much further it needs to be turned. If it's more than about 1/2 turn then maybe it's time to back it off and use more or less tape on the threads. Once you've done it a few times you'll get a feel for what is tight enough.

    Always keep in mind the number of threads engaged. Disassemble and inspect any connections that don't engage enough threads. The joint might not leak with enough pipe dope and 2 or 3 threads engaged but the joint does not have near enough strength to be safe.

    A final note on over-torquing. Listen to the joint and pay attention to the feel as you make it up. Connections may be cracked by the tapered thread and you can hear the metal break. You can also feel a change in torque (either constant or decreasing torque) as pipe begins to fail in shear.
  20. markts30

    markts30 Commercial Plumber

    Messages:
    630
    Location:
    Phoenix, AZ
    But the 48" steel wrench almost tightens the fittings itself..
    Of course, it does weigh about 50 or so lbs...LOL
    Not bad if you can tighten by pulling/pushing down, but a real bear if you have to tighten by pushing UP!!
Similar Threads: black pipe
Forum Title Date
Plumbing Forum, Professional & DIY Advice Natural Gas leak in black pipe in attic Oct 6, 2014
Plumbing Forum, Professional & DIY Advice Measure black iron pipe Sep 3, 2014
Plumbing Forum, Professional & DIY Advice Identifying 2.5" black pipe May 11, 2014
Plumbing Forum, Professional & DIY Advice Question about black plastic pipe between meter and house. Jan 3, 2014
Plumbing Forum, Professional & DIY Advice How to Hang Black Pipe or Lay on Ceiling Joists Nov 29, 2012

Share This Page