Radiator Air vent threads

branimal

I’ve got a few 1-way cast iron steam radiators that have air vent thread issues.
1. On one of them it looks like the 1/8 male nipple of an old air vent broke off in the radiator. How can I remove that male nipple? I have a Damaged Screw Extractor Kit. Not sure the extractor side is large enough to grab onto ID of the broken male nipple. Pic1
2. Another air vent threads seem full of crud. Pic2
3. Not sure how this last air vent was put on. How can i get it off without damaging it? Pic3

I’ve read I can use a pipe tap 1/8” 27 TPI to fix or refresh the threads on my radiators. Do I need a tapered or straight tap? Can it be carbon steel or do I need hardened steel?

I’d prefer to fix my current threads as opposed to drilling it out and re-tapping to a larger size thread if possible.

Thanks

JUGHNE

Picture 1; there is a pipe size extractor that should work on that. Plug the hole while applying some PB blaster or such. Keep the lock buster oils out of the radiator. The nipple is brass.

Picture 2; start with small round brush with water rinsing.
1/8 NPT will be tapered. You are just refreshing the threads so the cheaper tap should work.

Picture 3; I would just saw the cylinder of the vent off to get enough clearance to unscrew. The vent has probably done it duty and it's time is up.

#1 is the right location for steam.
#2 and #3 are not the right location. The top is for hot water venting use.

There should be a boss or plug in the lower 1/3 of the radiator for steam vents. (Opposite end of the inlet valve of course)

branimal

Thanks @JUGHNE

I found the HSS version of the NPT tap:

https://02b61d0.netsolstores.com/DWT64005taps_npt_hss_q.aspx

And a tap wrench:
https://02b61d0.netsolstores.com/DWTTW0tap_wrenches.aspx

Good tip on the incorrect location of the air vents for steam. I thought I saw a plug lower down on the rad. Gonna investigate.

branimal

Found the boss / plug on the lower 1/3 of the rad. I tried removing it with a regular screwdriver. Afraid of stripping it. I can hit with PB Blaster and a MAPP gas torch.

JUGHNE

That could be a tough removal. Possibly have to drill out so it leaves a ring resembling the broken off vent, then maybe the nipple extractor. Probably a steel plug.

Or if there is an undrilled boss at the same height, sometimes with an indentation, it may be easier to drill and tap in that spot.

branimal

How about an impact wrench? I've had luck removing a 3/4 black plug in the past with an impacter.

JUGHNE

Maybe, the main key is to have the screwdriver bit fit as well as possible. Even grinding the bit to match.

hot_rod

An 11/32 drill gives you the hole size to tap or re-tap 1/8 NPT

ChrisJ

hot_rod said:

An 11/32 drill gives you the hole size to tap or re-tap 1/8 NPT

I prefer a size Q (.3320") for 1/8" NPT.
11/32 being 0.3438, gives you a hair less bite.

JUGHNE

I have often wondered that if you drill out an already drilled and tapped opening, will you have any new meat left for new tapping?
Perhaps that is why some get drilled and tapped for 1/4"?

branimal

ChrisJ said:

hot_rod said:

An 11/32 drill gives you the hole size to tap or re-tap 1/8 NPT

I prefer a size Q (.3320") for 1/8" NPT.
11/32 being 0.3438, gives you a hair less bite.

Where can I get a size Q?

branimal

JUGHNE said:

Maybe, the main key is to have the screwdriver bit fit as well as possible. Even grinding the bit to match.

Yes... going to find the widest slot impact bit and grind it down to fit. Also will sand down the paint off the slot plug.

Big Ed_4

Drill and Tap , Break off vent and drill and tap ..

Neild5

You can get the letter Q drill from the same place you got the tap.

ChrisJ

I would probably use McMaster Carr but their prices are on the high side.

hot_rod

plenty of opinions on drill/ tap size. Looks like "R" is the most recommended size for 1/8" NPT.
I've used 11/32 for plenty of 1/8 NPT in all sorts of metals, without a problem. I wobble it a little to enlarge the top of the hole to ease the start off the tap.

Graingers is another source for single drills.

Hap_Hazzard

I'd recommend the Q drill. You're drilling out an existing fitting, so you want the clearance size, not the cutting size. I'd even recommend using a Q for a new fitting in cast iron so you end up with full-height peaks all the way through. You might have to back out and clean your tap a few times, but it's important to not end up with a big leak path.

Grallert

With a reverse twist drill you might be able to remove the nipple.

Big Ed_4

I never had luck with a easyout , Maybe if soft set pipedope or teflon tape was used . But they normally break off if they were installed dry and they get seized in the treads and break off spinning the vent out . The easyout tries to bite into bite into the nipple adds more outer pressure to the already seized nipple . If you drill into the nipple which will center the drill bit , what is left is the nipple threads coiled in the radiators threads . The 1/8" NPT tap will clean the threads out ..

SteamingatMohawk

Agreed regarding the easy out.

If the broken piece is actually brass its easier than steel/iron, using a jeweler's file (anything small enough to get inside the opening) you can make two grooves in the brass, then with a punch of screwdriver you can bend the broken piece enough to break free and remove it. Once the major pieces are out, you can manually clean out the threads before you retap the radiator. Just be patient.

Remember, a properly set pressuretrol will have less than 2 psig at the boiler, teflon tape or sparingly using pipe dope will prevent leaks. Just try not to get any inside the radiator.

branimal

I got a HD brand nipple extractor set and used the 1/8" nipple extractor and a wrench. I turned and heard a crack. Upon closer inspection I cracked the radiator on both sides of the air vent threads. Hairline cracks. I did hit it with PB blaster 24 hours prior. Maybe heating it up with a Mapp gas torch would have helped? As @Big Ed_4 said the brass vent was probably put on dry and seized to the cast iron.

The nipple extractor can no longer can bite into the brass vent's inside diameter because the opening is too large.

Not sure what to do at this point. I am chalking this up as a loss and maybe I can experiment with this one. Would the drill out method work to remove the broken brass nipple? I've read on other threads here that JB-Weld can repair cracks in raidators.

If JB weld does work, how could I secure an air vent to that hole?

The easy out turned out to be the hard way out. I did have a bit of get-it-done-ittis. I am now appreciating how brittle CI radiators are.

Grallert

You should be able to find a radiator like that one. That one is done. Salvage yards, habitat for humanity Restore outlets often have radiators. craigs list etc.
You can get a set of left hand twist or reverse twist drill bits that make short work of broken off nipples. They will either drill it out and then you can run a tap through the hole or they will free the nip and spin it out the way it went in. Worth every penny

branimal

Grallert said:

You should be able to find a radiator like that one. That one is done. Salvage yards, habitat for humanity Restore outlets often have radiators. craigs list etc.
You can get a set of left hand twist or reverse twist drill bits that make short work of broken off nipples. They will either drill it out and then you can run a tap through the hole or they will free the nip and spin it out the way it went in. Worth every penny

I do see rads on CL for fairly cheap.

The reverse twist drill bit works similarly to a nipple extractor?

Big Ed_4

Normaly I would recommend cleaning and fully epoxy up that port and drill and tap another . With that style radiator where they casted in a boss I am assuming there in not ..The crack seems to work it's way to the inside . To make sure the crack does not entend you can drill a stress release hole at the end of the crack . Which I don't think you can get to . A Dremel may come in handy to clean and grind out the crack . The hole looks expanded , a fix would be drilling it out slightly bigger then a 1/8"NPT nipple and use a stripped out repair kit that uses epoxy and a release agent and you can mold in a new set of threads . You may want to drill out the port first to release the pressure before you start ... If you have the patience epoxy can work . The easier way is throw money at it and replace it .

P.S. A good steamer would always have a good tap to clean out the threads first with changing vents . Buy it with the drill bit and you will have the complete repair kit.. They sell a cheap all in one cleaning tool ( with an easy out on one end ) but I find a good tap works best ..

Grallert

branimal said:

Grallert said:

You should be able to find a radiator like that one. That one is done. Salvage yards, habitat for humanity Restore outlets often have radiators. craigs list etc.
You can get a set of left hand twist or reverse twist drill bits that make short work of broken off nipples. They will either drill it out and then you can run a tap through the hole or they will free the nip and spin it out the way it went in. Worth every penny

I do see rads on CL for fairly cheap.

The reverse twist drill bit works similarly to a nipple extractor?

Well in a way. They are regular drill bits but meant to be used in reverse. So sometime they simply drill out a offending fastener or fitting etc. in that case no foul simply tap the radiator, but sometimes the cutting face of the drill "bites" the nipple and reverses it out. What they don't do is expand in the nipple or what ever it is you're trying to remove. Super handy. Don't waste any time on that radiator. It is possible to salvage it but not likely and not worth it. If it were an unusual or ornate rad, sure.

branimal

Update on removing old air vent plug.

@JUGHNE pointed out that the air vents located near the top of two of my radiators were for venting hot water radiators NOT steam radiators. I was able to remove a slot driven steel plug with 1/2" slot bit attached to my impact wrench. I had to grind the slot bit down. And then increase the slot depth on the plug with a grinder and cut-off wheel. Going slow and letting the impact wrench shake the bit around helped.

I plugged the hot water air outlet with a brass plug. Covered it with pipe dope.

Out of interest why are vents on steam and water radiators located in different spots?

And I suppose they made this radiator compatible with both steam and hot water.

Can anyone tell me approximately how old this radiator is? It was a bear to move around. 31"x21"x11".

Big Ed_4

Air is lighter then water and steam is lighter then air .. The taps are used to remove the air from the radiator ... When water enters the radiator it fills from the bottom and air is trapped near the top .When steam enters a radiator it fills to the top and air is trapped on the bottom .

mattmia2

Looks like it is too late for you now, but the manual type of impact driver where you hit it with a hammer works well for slotted or phillips fasteners that really should have been allen or torx or square or hex to allow the necessary force for removal to be applied. Hitting it with a hammer tends to push the bit in to keep it from caming out. You would have to be careful with that thin boss. When dealing with things in a boss like that I have sometimes clamped a small hose clamp around the outside of it to give it a little extra support.