plumbing qn: putting flux on copper fittings makes them not fit?

John Ketterman

Good point. I did think of that after a while, but wiping did not seem to help. Maybe I did not clean it enough. I'll try again.

On the other hand, maybe I've ended up with copper dust in the flux...

John Ketterman

I'm an amateur homeowner who is learning to solder 3/4" copper pipe.

I find that I can take (say) a 90o elbow and slide it onto a piece of copper pipe just fine, and then easily turn it to the direction needed. Then I take it off, polish inside of elbow and outside of pipe, flux both sides...now the elbow won't go on, it just jams. If I do manage somehow to push it all the way, it won't turn. If I wrestle it off and wipe off the flux, then it again goes on and rotates just fine.

What am I doing wrong? Surely flux is soft and can't prevent copper fittings from sliding?

Tony_23

Hint

When you're done sanding, before you flux it, wipe or blow off the copper "dust" from the sanding.

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Brad White_68

Solder Fittings

Sometimes the pipe and fitting tolerances are just too close in the same direction. Unusual but it happens.

3/4" copper tubing per ASTM B-88 is 0.875" OD with a tolerance of (IIRC) plus or minus 0.001 on diameter and 0.004 on wall thickness.

(OD is the same, wall thickness changes for types M, L and K.)

Fittings are manufactured per ASTM B16.22 and I cannot find the tolerances for those off-hand. Suffice it to say that they are in ID consistently larger than the tubing OD by about (IIRC) 0.0015 inches depending on size. This holds regardless if brazing type or refrigerant long sweep els or off the shelf short radius tees, although the brazing socket is not as deep as a solder joint socket.

Point here being that the tubing has to have tolerances to account for swage and die wear; a little slop so that things fit in the real world. See # 4 below.

It would seem that the dry fit and turning eases thoughts of "out of round" issues such as a dropped tube end.

Could be that:

1) You are using too much flux and creating a suction vacuum when you try to fit them. (A thin film on each surface is all you need.)

2) You are using older or contaminated tinning flux and the tin chunks or dirt are jamming the fitting.
EDIT- copper chunks as mentioned moments ago..

3) In polishing did you use too coarse a means? (Wire Tube brush or emery cloth on the coarse side or steel wool on the fine side?) Thinking the ridges compounded by too much flux here.

4) You have a batch of pipe that is at the larger end of the tolerance scale and fittings at the smaller end of the tolerance scale. Dies and swages were worn in opposite directions to the tolerances were beginning to coincide.

Things you might try:

A. Use Less Flux. A schmear, neatly applied. Tinning type I like, it can cover a lot of sins.

B. Use the least coarse means to polish. '000' steel wool maybe?

C. Pre-tin your fittings; heat the elbow and place the tubing in the socket while hot. Use thermal expansion to your advantage.

What you are seeing happens rarely in my experience (as a homeowner, handy man, landlord (ret.) and engineer. Generally a tight fit is also solved by a fresh cut and a different fitting, one the other or both.

Jerry_15

Change to a good water base flux, and keep your day gig.

hr

Are you using a pliers to hold

the fitting or tube. It's pretty east to egg shape either with not much force.

I use a solder flux that actually has ground up solder in it and have not had this problem, if the fittings fit dry.

Is it good quality pipe and fittings? Not soft, roll copper by chance, is it?

hot rod

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bob_50

If you

are useing a solder bearing flux sometimes the heat generated by the friction of twisting the fitting can change the mechanical energy to heat and melt the solder before the fitting is all the way home.

John Ketterman

No, I'm not using pliers and I'm bending it. It's Home Depot stuff, hard, not bendable tubing. I am not using solder-bearing flux.

Techman

Tough Fittings

Hello All.I have had the same "hard to turn" fitting to tubing connection for YEARS. I atribuited it to the heat generated[heat of expansion?] by hard working hands and the friction of copper cleaning,sometimes I use Visegrips ,twist and go!I do a lot of refrigeration and very am stingy on use of flux.Good day to all!

Unknown

Good thinking

I never even thought about the friction when cleaning the pipe . Sometimes it does get hot when I use grit cloth .

What brand pipe are they selling at HD ? We've been having alot of problems with oversized Mueller type M - mainly 1 inch and 3/4 inch . It's so bad that I've been having pains in my wrists and fingers from trying to slip the fittings on . This is pain that I never had until recently....... ( coincidence ? ) .

Jerry_15

Since I went to pro-press this is all a mercifully dim memory, but I do recall that if I reamed the pipe after I cleaned the end, this might occur. If you are using a tapered reamer after the cut it's a given. On those rare occasions when I have to sweat, I peel it out with a swiss army knife, (doesn't expand the end). I use Everflux water base now and it acts as a lubricant, also doesn't make me sick, or stink the house up. If you let it sit for awhile, maybe, but I don't think the flux is your problem. It's the process. Keep your day gig.

Ted_9

I unfortunatly had to buy some 3/4 type m and fittings. We had a treible day with the fittings. I wasnt the pipe,because we used different pipe. I use Nokerode and mesh, emory cloth type.

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JK_4

soldering copper every day

I work with copper almost every day and the follwing are just my experiences or things that I was taught but that dosen't mean they are right. The two most common causes for this problem are 1) the pipe from home depot is sometimes the manufacture seconds meaning that the tolerances were not close enough to sell to supply houses in that tradesmen using large amounts would be complaining as opposed to homeowners that will deal with it because for the few peices it's easier that doing a return and 2)after cutting the peice you have slightly out of rounded it or lefta very small ridge due to either cutting to fast or a dull cutting wheel. occasionaly I have seen old flux cause problems with fitting as well as soldering and tinning flux begin to solder it self (ie: tinning). I also advise against wiping or blowing as the purpose of cleaning is to eliminate forign impurities and wiping or blowing introduces impurities to the cleaned copper(oils from skin and who knows what in breath) although this may cause problems with proper soldering but not fitting. Idon't know if any of this helps. the best suggestion is always find a professional.

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bob young

gel flux

if you are using GEL type flux that could be your problem.

ajc

plumbing qn: putting flux on copper fittings makes them not fit?

I've been having this problem on and off for 27 years. It seems to have gotten worse recently with the proliferation of foreign fittings (from Korea and Canada) I doubt that its the flux. When the tube is cut with a tubing cutter (Ridgid makes the best by far), a ridge is left on the pipe. I've had fittings that would not turn. The solution is to buy a Ridgid #227 inner-outer reamer. First ream the inside of the tube and then do the outside. This procedure works every time. Ridgid makes a cheaper version (model 127), but its not as easy to do the outside of the tube with this model. The 227 is far superior.

Brad White_9

Some validity to your points

but the questioner mentioned that a dry fit worked fine, no out of round or ridge issues. The flux made the difference.

Not that I have absolute faith in the ASTM standards, but all things being equal, the tubing does have to mic within those tolerances to have the label put on it. This is not to state nor deny that unscrupulous marketeers might label things erroneously; sometimes I have to check my cynicism at the door.

And Rigid Rules I will have to check out the 227. Will it correct for out of round?

Brad