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Sch40 black pipe too fat????

SteamFTW Member Posts: 44
I'm going to have to go old-school (manual threading with "reversible dies") on a project soon, and I remember it being a PITA to get the dies to bite squarely when "reversed", because one isn't using the "workholder" side of the die head. So I found a 3-foot black threaded steel nipple (1" NPT, A53.Gr.B) to practice on. I cut it into a two pieces with a Ridgid 2-A (and fresh cutting wheel), and after 10 minutes of getting nowhere and feeling like an idiot, I turned the die head around. SURPRISE: the pipe won't even fit in the "workholder" end! Wouldn't fit in a 1" Ridgid 00-R or 12-R die head! Probably never would have noticed if I'd threaded it on a machine or with a 65-R.

Has this ever happened to anyone? Seems pretty fishy to me if a 1" pipe won't fit in a 1" die head. And I don't mean "won't fit" as in: put enough oil on it, and expect the black paint will get rubbed off by the inside of the "workholder". I mean "will not fit" as in: grind down a bevel to get the die started, use a ridiculous amount of cutting oil, and still feel the teeth bind up before you finish one full rotation.

It might have nothing to do with the country of origin, but I've never experienced this before with North American pipe. I even checked with two other 1" pieces I had on hand (USA and Mexico): they fit even without removing the swell left from the cutter. The troublesome piece was stamped with the Roman typeface you see everywhere on Asian engineering documentation, so I'm assuming that's where it was made. Perhaps that's not a valid assumption.

Thanks for your insight.


  • leonz
    leonz Member Posts: 682

    The wall thickness of schedule 40 steel pipe can vary from 0.109" to 0.375" according to "DESK REFERENCE" if that is any help.
    EBEBRATT-Ed Member Posts: 13,127
    Whatever pipe you have doesn't sound like real schedule 40 or 80 or anything else. The OD sounds to large.

    @leonz. The OD of schedule 10, 20,40,80 and 160doesn't change. only the wall thickness changes
  • SteamFTW
    SteamFTW Member Posts: 44
    My working hypothesis is that the machine that cut the threads may have made the OD of the pipe behind the threads bulge enough to exceed the margin of error on 1” pipe.

    This was originally a factory-threaded nipple. My first cuts were as close to the threads as possible. I cut another couple inches off the pipe, and the OD at that cut (with only light deburring) will _just_ fit.

    Verrry interrresting—(but schtoopid?)
  • pedmec
    pedmec Member Posts: 713
    What did you use to cut the pipe. If you use the rolling pipe cutter you probably beveled the pipe a little. just grind the edge off if that's the issue. If your cutting schedule 80 it will bevel even more
  • ScottSecor
    ScottSecor Member Posts: 642
    edited October 2022
    Been in the heating business for thirty five years and do not recall having this issue with steel schedule 40 pipe.

    I can tell you that when I first started in the business, I decided to crank the handle on the cutter about as tight as I could, not knowing any better. I wrongly assumed that by tightening the handle more I could cut the pipe faster. Eventually I was able to get through the pipe, but I "flared" the end of the pipe slightly as a result.

    I would suggest you take your time and possibly oil the cutter wheel and try again. It's been a long time since I used a 2A cutter but I would think about six to eight revolutions. If you have the same issue, you may find the cutter wheel is incorrect for the material you are cutting. If you have a band saw, Sawzall or cutoff wheel on a grinder you may can compare.

    EBEBRATT-Ed Member Posts: 13,127
    That's why I prefer my DeWalt band saw to a cutter. No burr to remove inside or outside.

    In fact, I have done tons of Victaulic cutting everything with a band saw. Draw a line around the pipe and with a little practice yo can cut as straight as a cutter and a lot easier.
  • hot_rod
    hot_rod Member Posts: 18,209
    Does the tube have any listings stamped on it? If so it should be in tolerance. Or the listings are fake 🤓
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • SteamFTW
    SteamFTW Member Posts: 44
    @hot_rod The stamp is the most distorted I've ever seen. What's legible is "...Steel....ASTM A53Gr.B..." The illegible part probably included "QC FAIL". (This is the last time I buy a pipe nipple from a guy in a trench coat full of wristwatches.)
    JUGHNE Member Posts: 10,297
    Did you try the nipple threads in your threader die?

    They should have screwed in easily.

    The only time I have problems with the threader starting is with 3/4" ips.
    This was on black pipe and also galvanized rigid conduit.
    Two different threader heads, one with new jaws.
    New pipe cutter wheels.

    I always plan on beveling the edge for that size.
  • SteamFTW
    SteamFTW Member Posts: 44
    @JUGHNE Thanks for sharing your experience. I did try the factory-threads, but not with the die head. I test fit a new Ward elbow. Tight but no worse than usual for overseas threads. I used the factory-threads on a domestic nipple to set the dies in my die head. If there's ever a "next time"...