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Is it safe to heat stuck IPS fitting in cast iron radiator? (And a mystery part question)

PGB1 Member Posts: 20
Hello All,
I hope this note finds everyone well & enjoying today!

I have a radiator that is (was) in a bathroom & connected to our hydronic system. I think it might have been a gravity or steam radiator earlier in life because the openings for pipes (both sides at bottom & one top) are 2" IPS. It has stacks of reducing bushings to get to 1/2".

Since I'm finally going to make that bathroom nice, I plan to do a prep & repaint on the radiator. (Methods & materials are to be determined. Lots of conflicting ideas on the paint topic.)

The fittings are stuck & all of my various penetrating oil tricks didn't work. I could not budge them with any of my pipe wrenches, all the way to 48" (getting older....).

Is it safe to heat the fittings and/or cast iron with a torch to hopefully break the seal? From experience welding & brazing cast iron, I know it can crack easily when cooling, but I expect my temperature to be much lower when heating for fitting freedom. I haven't any idea of how old the radiator is, so I can't verify the integrity of the iron. It was in the yard of our abandoned house when we bought it 35 or so years ago. It's the Plain Jane of the radiators in our house.

Another question I have is that the radiator has brass elbows that are two piece- one for the supply and one for the return pipes. The mating seal is similar to a ground joint union. I've tried to find some, but can't come up with a name for them. Do you folks know what they are called?

Thanks Very Much for helping! I sure appreciate the knowledge.
PS: I used the term IPS (Iron Pipe Size), as I've done since the 1970's. But I was recently scolded at a wholesaler. I was told to use NPT. Which is correct?


  • Jamie Hall
    Jamie Hall Member Posts: 16,601
    Tehcnically, IPS refers to the dimensions of the pipe itself, and NPT refers to the specific geometry of the threads... but when was the last time you saw a straight thread on an iron pipe?

    Yes you can heat it. Don't get carried away. It may not work... do you have to get the bushings out? Because you can cut them (try not to get into the threads) and collapse them sometimes.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 3,675
    edited July 17
    You can usually make 2 cuts to just before the threads and take a very small chisel and break out a pie shaped wedge then unscrew the busing. Unless it is too small for your current application I don't see why you need to get it out.

    There are reciprocating saw blades with a narrow profile that can be used to cut the slots in smaller sized bushings.

    The other half of those union elbows came with them and are not standardized, the fitting that mates with it came with the union. Unless you can find the other half in the house somewhere you will need to replace the union. CI radiators normally had large tappings that were bushed down to the size needed.
    EBEBRATT-Ed Member Posts: 9,685

    The fittings you want are "Union elbows" as @mattmia2 said. You can use heat. Cutting and collapsing a cast iron bushing can be done but it's not as easy as a steel fitting.

    I would lay the radiator on the floor and use a pipe wrench with a cheater pipe on it
  • psb75
    psb75 Member Posts: 435
    Be aware if you use a really big pipe wrench with a cheater bar on a hex head c.i. bushing the corners of the hex could crumble before the bushing threads break loose. Heating would would help. Laying the rad. flat on the floor is best position for using this much leverage. If the corners crumble then, you're obligated to cut and collapse the bushing. Good luck.
  • Big Ed_4
    Big Ed_4 Member Posts: 1,758
    I would just cut it out as mentioned by mat ..
    I have enough experience to know , that I dont know it all
  • mikeg2015
    mikeg2015 Member Posts: 1,183
    Just cut it out as mentioned. Make 2-4 cuts just short of the threads, then turn with a big pipe wrench and it should collapse slightly, which makes its diameter smaller and and breaks the rust free that holding it. Done this on a doze or so radiators and fittings now. Brass cuts like butter.

    As mentioned, cast iron radiator sections are made generic and use 1-1/2” or 2” tappings so they are universal with a 3 section radiator, or a 25 section radiator that needs 8x the flow rate.

    I have 3 radiators made with the same castings, but one is I think 8, another 16 and another 24 sections. The 24 and 16 heated like crap on steam being very short and connected at the top so I converted it to hot water and connected to to a salvaged combi boiler I got free from work.
  • PGB1
    PGB1 Member Posts: 20
    Thanks To All For Helping! I very much appreciate the sharing of knowledge.

    Thanks Jamie Hall for explaining the difference. It's coincidental that you asked when was the last time I saw straight threads on an iron pipe. By trade, I'm an industrial electrician. Our schedule 40 & 80 threads are the same as plumbing, except ours aren't tapered. Our fittings are looser, so starting the pipe into the fitting's easy.

    I'll never forget, on one job once, I had my threader set up. A young, smart mouthed plumber on the project was too lazy to get his threader out and used mine. The only reason I noticed was that I heard the unmistakable screech of dry thread cutting. I climbed down & told the guy he was welcome to use my threader, but to use the oil pump. Purposely, I never mentioned the straight thread dies. He carried several of his custom threaded lengths of black pipe up the scaffold to his boss. It wasn't long before I heard the boss screaming at the guy about the straight threads not starting in the fittings. Boss man knew exactly what the little brat did.

    Thanks To Everyone for advice on how to remove the fittings & the name of the union elbows. I probably should have known the fitting name. Amazing how much I forget things lately.

    The Probably Boring Back Story...
    I was very lucky to have had the opportunity to lean some plumbing, heating & cooling. While working as an electrician, since plumbing, heating, cooling, ventilation & electrical all coincide, a master plumber, 30 years to my senior, was assigned to work with me for 3 years. He was also a certified welder. We worked with mostly boiler systems (hydronic & steam), chillers (Generally R-22, 502, CO-2 or Ammonia) & some ventilation and related work. Once in a great while we would work on DWV as side jobs. That man could wipe bell & spigot joints like Da Vinci could paint. His horizontal runs looked better than any vertical I could have wiped. He was great at lead service pipe wiping, too. (I cheat & use compression or flare fittings.)

    That master plumber was the crabbiest man on planet Earth, so no one would work with him. (I'd be crabby too if I spent my career carrying around C.I. pipe, cast iron radiators & tubs and the like.) I had a reputation of being tolerant and peaceful, so I got him. He taught me more than I could have imagined & I'm thankful for the education. I completed this plumbing apprenticeship in the 1980's & got my journeyman's card, thanks to that plumber's teachings. (He didn't want any part of an apprenticeship to me for electrical, as he was well into his 60's.)

    The advice you all gave for removing the fittings is great & very well appreciated.
    I have more confidence now that I won't damage the radiator. Actually, the fittings could probably stay. The only reason I want to remove them is that there are several reducing bushings stacked to get from 2" FIPS to 1/2". (Picky, huh?) I'd like to use a 2 x 1/2 brass bushing, but not rough cast brass. Or, make one on the lathe.

    I used the suggestion that you all made about making cuts in the fitting and collapsing it on a junk picked bicycle with a stuck seat post. (Aluminum to steel welded itself.) Your ideas worked like magic!

    As soon as I get some time to myself, I'll work on the radiator fittings. Challenges are fun.

    The radiator's outside now, so there's easy working room. For a 5 foot 9 inch, 145 pound second-half-of-60-something year old guy, getting the radiator outside was not as difficult as I thought it would be. I chained it to my hand truck, looping through the sections, not the push nipple area. I made two 8-foot 2x6 ramps with 5/16" tall speed bumps every 16" for the 4-step stairway. The ramps also got guard rails on the outside edges. They werre screwed into place on the stairway & off I went. It was amazingly easy to control the load on the way down. I was amazed how far the 2 x 6 planks bowed under the weight.

    I have no idea how I thought of the speed bumps and of using the longest ramps possible for minimal angle. There's no way I'm that smart on my own.

    Getting it up the stairs when done? To Be Determined...

    Thanks Again Everyone!
    JUGHNE Member Posts: 8,684
    The RGC I have in stock has somewhat tapered threads.
    The couplings are straight threads.
    If running RGC UG, I would use heavy WP tape on the couplings.
    There is only about 1/2 turn to tighten then threads are all buried.

    I have used the same pipe threader for electric RGC, black gas pipe and black boiler pipe for 40 years.
  • PGB1
    PGB1 Member Posts: 20
    Thanks for taking time to comment, Jughne.

    I apologize that this is way off topic, but it may be of interest to some. And it certainly will serve as a sleep aid to others...

    You mentioned tapered threads & thread sealants on conduit. It's a can-o-worms that's resulted in many lunch break discussions over the years. There's enough controversy & drama over the subject that it could have its own reality show on TV: "Conduit Wars". Here's my take:

    I'm of the old guy generation, with over 47 years as a master electrician. Most of my work was with RMC (rigid metal conduit) or IMC (intermediate metal conduit).

    The very first electrical conduits were rigid and tapered threaded. This is when the gas street & building lamps were converted to DC. I still see it when working side jobs in old office buildings, theaters & such.

    I use straight thread dies meeting ANSI NPSM standards. Now it is against code for field threading.
    In the way old days, we were not allowed to taper in the field in jurisdictions that stood to NFPA-70. Exactly the opposite.

    NFPA-70 334.28 requires tapered threads in the field. Many jurisdictions that have their own codes still do not allow tapered threads. Once, out of state where I suddenly can't remember (dementia?), the local code was tapered threads only in most locations and straight threads in hazardous sections of those locations. So, the surgical prep room got tapered threads and the operating theater got straight threads. The compressed gas areas & petroleum pumping station likewise. We had to stop each conduit at the fire wall, put an explosion proof enclosure, do the conductor vapor proofing, then continue with straight threads.

    And it gets more confusing:
    Our electrical termination points have zero taper- couplings, conduit bodies, cast hubs, etc. 100% straight threads with no shoulders on couplings. (Hubs- yes)

    Personally, I don't use tapered. It makes for easier pulls. I've had many, many occasions where the petroleum resistant jacket on THHN tore on the edges of the tapered threaded conduit, no matter how well reamed. Why? Because our fittings are straight through. The endof the pipe is quite prominent in the flow path.

    I've never had an inspector knock me down for using straight dies & have seen inspectors give grief for people using tapered dies, despite 344.28. Reasoning? Ground integrity. (More threads in contact) Their Solution? Install bonding jumpers across each joint. ($$$)

    When I was an inspector, I did not care either way as long as the ground path was compliant, would be permanent and the insulation or jacket on the wires were not damaged during the pull.

    Also of note is that quite often, depending on the thickness of the enclosure's wall, there sometimes are not enough straight threads on a tapered end to grab the required bushing. Straight threads also butt very nicely to tapped holes in cast enclosures. This helps keep moisture that condenses on the outside of the box out of the box, especially if a metal sealing ring is sent in first.

    If the budget is unlimited and time is limited, there are always compression fittings. No threading involved. To me, using those where not necessary is "New School", as is throwing MC all over the place instead of installing EMT (thinwall conduit) indoors. I recently had some journeymen assigned to me at an auto company that did not know how to bend pipe. No idea. One asked me to show her how the Chicago bender worked. I'm glad someone showed interest.

    Another glitch with tapered threads is that, in hazardous locations, five threads must be firmly engaged with the fitting. Depending on the fitting & thread length, with tapered threads this often isn't possible (I've seen inspectors who have knocked down tapered threads in such installations.)

    As far as keeping water out of the pipe underground- It's Not Possible. Ever.
    Our straight thread fittings do no seal. (Ask any plumber who has swiped a coupling from the electrical crib.)

    Even with RTRC or HDPE conduit having fused joints I've encountered water within a year. Reason? Condensation sneaks in from what ever is above ground, no matter how hard one tries to seal the fitting at the boxes, such as is done in explosion proof locations.

    Advice- Skip the RMC & IMC underground if possible. In a few years, you will not be able to remove the conductors. They will fuse themselves to the rust & magnetite that forms on the conduit's inner walls. Thin wall (EMT) never goes underground. Ever. Not even an inch of it.

    There are very few situations, other than stub-ups, where RMC (rigid metal conduit) or IMC (intermediate metal conduit) goes underground these days. It's only used where certain, required burial depth exceptions are invoked. (And the stuff is expensive!)

    Thread sealants, such as teflon tape, are absolutely out of the question due to the requirement for a low impedance grounding path. I've seen people tape around the outside of joints, but wonder how long that lasts, especially in shallow burial depths where UV penetrates.

    I suppose one could use anti-oxidant paste, such as NoAlox or Penetrox, on the joints. I always use that for conduit bodies, enclosures & such that will be eventually damaged and in need of replacement. Our straight thread fittings don't seal watertight, so the anti-ox won't keep water out, just prevent seizure from galvanic induced corrosion.

    Personally, I believe the old adage "Water Always Wins" applies here.

    Assuming anyone is still awake after reading this, I apologize for going way off topic. Hopefully today I can work on extracting the radiator fittings. It will be a fun project.
    Thanks again to everyone for giving many good ideas & thoughts!

    Please Enjoy This Day!

    Larry WeingartenJUGHNE