Compressor Repair

Spiderzmobile · Mar 6, 2019

PLEASE HELP!

I recently inherited a 20 Gallon Compressor, which does work (I tested it, before tearing into it); and it's something bigger than my 6 Gallon one

Unfortunately, this thing sat for quite a long time without being drained (i.e. it had a good amount of water inside and plenty of time to rust it up :wrong:

)

The drain cock was frozen shut so I drilled it out (along with the threads), I want to replace the "nut" that the drain valve screwed into but it doesn't want to come out!

I've been:
1. Spraying it down with penetrating oil
2. Using an impact driver and 1-1/8" Socket to no avail
3. Applied heat with a torch

Any thoughts... Prayers... Suggestions?

Sean the Dog · Mar 6, 2019

Stupid question, but is that a spot of weld just before 6 o'clock..?

Instead of removing the existing plug, what about tapping to a larger pipe size and then making/buying an adapter to fit the smaller drain plug?

dalmatiangirl61 · Mar 6, 2019

Those plugs are a pia to remove, if you can secure the tank so it will not move, a 6 sided socket and impact might work, or a few good whacks on a long cheater with a small sledge hammer, don't be shy about it. Otherwise drill and tap to next size then use a reducer.

rons · Mar 6, 2019

Use a 4-6 foot lever arm. The plug was tightened into the flange and then welded to the tank. Therefore it has been distorted and will be a tight fit.

There is no shame if you tap the hole up one size.

Leadfootin · Mar 6, 2019

Saw it almost thru to the threads and then try to remove. After cutting hammer inwards on both sides of the cut to help relieve the tension. Might have to saw a second cut in it to relieve enough. Then it should come out with reasonable amounts of brute force.

If not use a couple of cuts and strike towards centre with big chisel to loosen.

kustomizingkid · Mar 6, 2019

Straight in the scrap bin.

deltap · Mar 6, 2019

Bring to red heat with torch. Apply penetrating oil or old timers used bees wax. Use impact while still warm. If you get a little movement, more oil and drive back and forth with impact. The vibrations help to break rust. May have to repeat heat 2 or 3 times.

Froneck · Mar 7, 2019

I have run into that problem quite a few times. Of all the penetrating oils I have found Kroil the best. I would fill that groove around the plug with Kroil, let it sit keeping that thread groove filled with kroil. Might take a week! then put a good size pipe wrench on the hex. I keep a supply of knuckle busting wrenches around for that purpose. The plug is probably cast iron but 7018 welding rod will work to weld the knuckle buster to the hex and a few hits with a hammer will remove the plug if the pipe wrench don't.
If you want to use heat, the difference in the expansion rate between cast iron and steel is very small but steel is slightly larger. So with the impact wrench on the hex heat the steel around the plug fast using as much heat you have, Acetylene torch is best. Apply NO heat to the plug! The expansion of the steel with fast application of heat will make the threaded hole bigger. Slow application of heat will also expand the plug.

ratbldr427 · Mar 10, 2019

Tap it for the next size up.Looks like 3/8" go to 1/2".Reducing bushings are less than a $1.For that matter pipe taps are also cheap.

My concern would be a tank that was rusty inside and had sat for an unknown period of time could be a hazard.

You could hydro test your self,sending it out would probably cost as much as a new one(40-50$).Those small tanks have been known to fail and seriously hurt people.

metalmagpie · Mar 11, 2019

ratbldr427 said:
Tap it for the next size up.Looks like 3/8" go to 1/2".Reducing bushings are less than a $1.For that matter pipe taps are also cheap.

My concern would be a tank that was rusty inside and had sat for an unknown period of time could be a hazard.

You could hydro test your self,sending it out would probably cost as much as a new one(40-50$).Those small tanks have been known to fail and seriously hurt people.

Tap around on the bottom of the tank with a pointy hammer. See if it sounds solid everywhere. If it's about to rust through it usually will have delaminated some and you will hear a difference. If the tank is good, by all means either drill/tap to the next pipe size, or braze the nut closed and then drill and tap it again to the original pipe size.

I have to say, some of the answers on this thread were quite amazingly wrong. Saw off the nut indeed!

metalmagpie

Spiderzmobile · Mar 12, 2019

Sean the Dog said:
Stupid question, but is that a spot of weld just before 6 o'clock..?

Instead of removing the existing plug, what about tapping to a larger pipe size and then making/buying an adapter to fit the smaller drain plug?

No not a spot weld, I think it's a metal shaving from the "corners" of the nut, they've been abused from the socket and wrench

Spiderzmobile · Mar 12, 2019

I've used a "boxed end" wrench, but B/C of the 5° offset it's been tearing up the nut corners.
My Pneumatic Impact Wrench does a little better at gripping the nut; However, I didn't think about an "whacking" it with an Impact Driver (I'll have to buy one)

Spiderzmobile · Mar 12, 2019

I didn't think about welding and old wrench to the nut, sounds like a last resort.

Spiderzmobile · Mar 12, 2019

I drilled it out with a 1/2", so charts seems to say it would be a 9/16-18 tap, with a 9/16-18 to 1/4 NPT, with a new drain cock; that has its possibilities

Spiderzmobile · Mar 12, 2019

I thought about cutting it out, but I was afraid of jacking up the threads beyond repair

Spiderzmobile · Mar 12, 2019

Brazing it sounds good; now I need a set of oxy/acet tanks and torch!

Damn, hobbies are expensive; I just got my MIG/TIG/Stick machine (Plus, I also need the gas bottles)

"Honey, I need another tool!" LOL

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