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Originally Posted by Kaleun494 Is your lab equipped with a oxy-acetylene or an air acetylene unit? We use MAPP gas for soldering and oxy/acetylene for brazing.
when Im doing demo. It always amazes me what lousy joints have held so well for 25-30-40 years. I guess lousy is as lousy does.
Originally Posted by Kaleun494 Thanks for the tip on staybright, I prefer soldering for the same reasons. Yep just keep in mind when it runs its done and you will have perfect joints, I usually use mapp gas when doing those as well. No need for the oxy/acct unless you want to melt the whole spool of solder lol
-usually I try to avoid brazing, silver soldering is more simple and faster plus I generally use staybright #8 which is good for up to 14,000 psig I believe which is plenty of strength for most systems. Thanks for the tip on staybright, I prefer soldering for the same reasons.
Originally Posted by htroberts Probably not the best forum for this post, but I'm not eligible for access to the 'pro' section yet... I'm about halfway through my local community college's first HVAC/R course, and we're practicing soldering. I've done plumbing work for years and thought I'd be pretty good, but I'm having a hard time (then again, I don't remember anyone ripping my solder joints apart before and critiquing them, so maybe I was never as good as I thought). I seem to have two major problems. The first is using just a little too much solder, especially on the 1/4" tube, but really all the way up to 1/2"--do any of you old hands have any guidelines on how to tell when it's enough without over-doing it? My second problem is with bare spots on the copper, where the solder doesn't stick. It's got to be hot enough--it's surrounded by good coverage, so I'm thinking that there's oil or something on the copper. We're cleaning the tube with emery cloth, but I wonder if I'm getting oil or some other contaminant from my skin onto the copper while I'm cutting and swaging it. They're short (2") pieces, so it's tough to completely avoid handling it. Any other advice here? Is there any flux/solder/refrigerant safe solvent that can be used to clean oil, etc., off the tube before sanding it? We're using Stay-Brite 8 and a paste flux from Harris. Thanks, Heath -First get the burs out of the end of the tube -use emry cloth on the point you will be soldering -flux the tubing very important to remember this step helps the solder stick, usually with silver solder I use a liquid flux and for brazing a paste but a paste can work with both -Important when heating the spot where the joint will be heat the point or connection that the tube will be sliding into the heat will cause the solder or braze to suck up into the joint sealing it -with silver solder remember this little saying when it runs its done(if you heated and fluxed properly) -Brazing requires the same principle for heating but you will have to make contact around the whole joint as the rod does not melt quite as fast as the silver solder -usually I try to avoid brazing, silver soldering is more simple and faster plus I generally use staybright #8 which is good for up to 14,000 psig I believe which is plenty of strength for most systems.
We just wrapped up our tubing unit and one thing to remember, when you start brazing don't use too much heat and don't heat the whole pipe (I've seen someone do this), that will cause corrosion scale buildup inside as well as outside in excessive amounts. Is you lab equipped with a oxy-acetylene or an air acetylene unit?
Originally Posted by rogerk http://www.youtube.com/watch?v=Rv-iv...ext=1&index=59 I like the transmission-fluid rag to keep the solder from sticking to the tube. I'm pretty sure my instructor would not approve of that particular technique... Thanks for the link, the video was otherwise helpful.
Originally Posted by beachtech bubbly solder sound like too much heat in my experience I meant to get back earlier & say thanks for the advice, but have been busy. I was indeed using too much heat, although I'd have sworn I wasn't. One of the guys in the class with more field experience showed me what he was doing, and he had the torch several inches further from the fittings than I did--I had the brightest blue inner flame cone right on my work. A little more practice and I passed my test. Now on to 15%, and then brazing.
you can not learn this in writing!!! there are some links on the net that have video.
don't or rather more to the point, do sweat it Match the heat to the materials-more heat on castings and valves-less on slim tubing. Heat the fitting circumferentially and it will heat the tubing enough scrub the tubing with either clean emory cloth or mesh; clean wire for female hubs. Periodically clean your brushes! They get loaded with pipe dope, grease, etc. Once the bristles load up with flux, they gunk up with dirt that will contaminate joints. Scrub the end of the female hub with emory so the solder sticks to the thin edge for a nicer joint transition. Deburr your tubing cuts for better flow; emory will deburr the OD so it fits fully into the hub. Watch those heat control pastes, sprays and wet rags. They can cool the pipe if too close. Try to use ceramic fiber blanket instead whenever possible. If you overheat a fitting, let it cool down, prep from scratch then be more careful. Don't try to slosh on more flux and pray it seals. You can wipe down hot solder with the flux brush or a clean cotton rag dipped in flux. Makes for a nice, professional looking joint without those solder-cicles and stalagtites. Make sure there is no tension on the joint just prior to soldering. A joint may seem snug only to loosen as the heat expands the female hub causing the tubing to slip out. Clean all flux off externally or it will corrode causing a leak. A mildly soapy rag will clean it and neutralize the acid flux. I've seen jobs where the tech polished the copper just before the unveiling to the homeowner--awesome! Bend a hook in the end of your solder to facilitate wiping it around the rear of the joint first. As you get around to the front, the hook will be gone leaving you with a straight stick to wipe across the joint and be done. If you see a solder-cicle/ stalagtite, flick it off with a backhand motion using your solder stick. You can cool a joint with a wet rag but blow on the joint to cool the solder and copper as much as possible with air/ breath first. The thermal shock of a wet rag on a blazing hot copper fitting weakens it. Make sure the type of copper is appropriate for the intended use. Size properly. Watch for dissemilar metal connections. Use dielectric unions as needed. Jet Sweats are your friend. HTH,
don't or rather more to the point, do sweat it
I almost always use soft solder (stay brite #8). (And I deal with systems with 1000's of refrigerant.) As everyone said here, heat evenly and let the heat draw the solder in. A bubbly solder is usually too much heat. For the small sizes you're praticing on, you do not need a flame thrower. Learn to use a smaller 'soft' flame and 'play' with the heat. Do not linger the flame on a particular area for long.
I always braze. Stay brite is for rotor lock valves which are alloy. They can't take the heat of brazing.
1) Clean the male portion with open weave cut cloth. I use Diversitech Grip Cut. 2) Female fittings should get a fitting brush cleaning. 3) Flux, beyond the area where you expect solder to end up. 4) Heat to melting point, heat draws solder into the fitting. 4a) Wipe the joint with a damp rag. 5) More practice.
soldering - heat the joint, not too much, use the flux brush, also I've been told the length of solder used equals the diameter. ie: 1/2 dia means use just a 1/2 length of solder. pre-bend the solder so you don't use so much. luck dan
When newbies are learning i have them lay the 15% silfloss against the joint till it starts to melt. Then once it does work your way around the joint, once that is done I put the heat around the back part of the fitting to move the silvfloss back into the joint. and capp of if a lot got into it. The key is this has go very quickly, forget the turbotorch of you be changing out a lot of txv's and schraders (pull them). The oxy/acty needs to be hot enough to make it happen....and use nitrogen. Keep a wet rag handy, and around what you do not want to get hot.
http://www.youtube.com/watch?v=Rv-iv...ext=1&index=59
I wish I could give you sage advice from years of soldering, but like most of the guys here I braze all the time. I certainly remember having to go through that soldering stage at the apprentice school (many moons ago) before getting to brazing, and I had those holidays (those spots without solder) too at first when the joints were busted apart. First off, make sure you're heating the fitting. Watch your flux; it reacts differently at different temperatures and gives you a visible sign of when to start feeding the solder. Watch what part of the torch flame you are hitting the joint with -- the tip of the inner cone is the hottest part of the flame, and it doesn't take much heat on such a small OD joint (i.e. try holding the torch farther from the joint than you would a 3/4" water pipe so that it doesn't heat up so quickly). Heat your joint evenly; don't loiter on one spot. Feed your solder in from the opposite side of the flame; if you've done everything right, then the capillary action will draw the molten solder around the joint toward the flame -- doubly so on such small tubing. All in all, the best advice from above was "practice makes perfect." You just have to practice. A lot. It might be easier for you if you practice on a larger OD tubing on your own. Since you've been doing plumbing work for a while, maybe practicing on some 3/4" and busting it apart can help. I'm going to say I think beachtech's correct -- I think you're putting too much heat on it. Work on making a good joint, then work on making it "pretty". You'll get through it, and you'll be on to brazing soon enough. Pay good attention when you get to that; brazing is a crucial skill in our field. You can just ask the three pipefitters that were fired this past week from my company. I get to go pull in some OT tomorrow repairing all the joints of theirs that failed on several new installs and cost them their jobs.
use your flux... After applying solder to the heated joint, use your flux brush with flux still on it & "wipe" around the soldered joint. You will end up with a solid connection that looks great. Another thing to look at is your solder itself, on more than one occassion I have had to use some sand cloth on the solder because where I had it stored, oil or other contaminants got on it.
use your flux...
Originally Posted by beachtech why not? start a new thread introducing yourself as the new guy on the block. you'll get to 15 in no time bubbly solder sound like too much heat in my experience i generally don't take my flame off the joint unless i am getting too hot. the technic for both is the same, except as i was saying, you don't have to spend as much time in prep for brazing. if the pipe is oily, you can burn it off with your torch followed by sanding and applying flux to it getting it ready to solder. Thanks. BTW, I like your signature quotes... and where'd you get the cutaway compressor illustration? I need a picture for the cover of my notebook. I was going to ask the girl () with the Canadian flags the same question, but I probably couldn't turn that one in.
Originally Posted by htroberts I'm working on it, but I don't want to make a bunch of nonsense posts just to get to fifteen. why not? start a new thread introducing yourself as the new guy on the block. you'll get to 15 in no time bubbly solder sound like too much heat in my experience i generally don't take my flame off the joint unless i am getting too hot. the technic for both is the same, except as i was saying, you don't have to spend as much time in prep for brazing. if the pipe is oily, you can burn it off with your torch followed by sanding and applying flux to it getting it ready to solder.
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