SpudFiles

Well I have been wondering what you all think is the best way to sonnect up two metal pipes for spudding the list is fairly long but there are a few common ways in which one could do so which can eb found below. Please share you opinion with me and give a reasoning.

1. Soldering
2. Brazing
3. Threading
4. Welding(what kind?)
5. Compression fittings
6. Epoxy or another glue

So what are your opinions, what is the best connection in terms of price, equiptment, knowlage, simplicity and of coarse strength.
I thank you all ahead of time for your opinions, comments and ideas.
John Bunsen

Threading by far....
you can buy pipes threaded.. often easier than nonthreaded ones.. you don't need a welder.. epoxy can be a little inconsistent...soldering and brazing- the same as welding.

Threaded fittings are just the easiest to work with, no hassle really in my opinion

Threaded coupler, or if you cant get that try a normal coupler wth metal epoxy

Let me make things a bit more specific, the connection has the be good to atleast 900psi and all things(but epoxy, solder ect.) will be self made that means it would include threading my pipes on a lathe, not too hard but still a thing to consider.

Well threading is a bit of work, but doable, though then you need to get them to seal, with tape and all, which some times can take a few tires. Also, if I remember correctly, you need something special if you are going above 2".
Sweating (not soldering) is imho the easiest to get sealed up well, though if you have temperature sensitive pieces, tricky at the least. It is also fairly easy to undo, though not as easy as threaded.
Compression fittings are the ultimate when it comes to ease of changing the setup, but be prepared to pay an arm and a leg for fittings that work past 900psi...
Assuming you are a certified to weld pressure vessels, then welding is the most permanent.
Epoxy I would use as a last resort, because it is pretty much the same as sweating, but with more tolerance, and no heat, but it is not undoable.

Ok, thanks for that response, one question: What is the difference between soldering and sweating?

I may be getting far too picky about words, but if I am not mistaken, soldering is done with a soldering iron, usually for attaching electronics, though I guess occasionally it can be used, with very high power irons, for bigger stuff. Sweating, is when you use a blowtorch, to heat up your pipes, or what ever.

So really there is no forking difference....

So what do you say is better: the plain old teflon tape used to seal the threaded ends of pipes or those spray, dif or what ever on things? Latter i ahev never tried.

Also anyone diagree to the statement made that threaded connections are the best?

john bunsenburner wrote:Also anyone diagree to the statement made that threaded connections are the best?

Only the nit-ick that the pipe must be designed to be threaded in the first place. Thin wall pipe will loose a heck of a lot of strength if it is threaded.

Definitely threaded. But I will often use a thread goop instead of teflon. It seals better and its easier on larger diam threads. don't forget that it looks better. I always seem to get teflon tails on my threads

Brazing. It's easy enough if you use the right materials, flux, and fuel.

Well of coarse all the pipes would have to be suited for the chosen meathod.
Seeing as how my main work material is alluminium, do your opinions change?

Not really. You can get different fluxes and solders for different materials. Aluminum is pretty easy to braze.

If you have acces to a lathe and you can thread the pipes yourself I'd go for threaded , with an O-ring...

Running through the list;

Although there does exist a type of solder that claims it will bond to aluminum, I have never used it, and would not trust it for that reason.

Brazing seems to be a viable, although slightly costly option.

http://www.aluminumrepair.com/more_info.asp

Threading requires some skill, knowledge, and additional tooling to cut inside threads. These tools are however, inexpensive. Boring bar and screw cutting gauge.

http://busybeetools.ca/cgi-bin/picture10?NTITEM=B1989

If you place your seal inboard of the threads, the thread depth is of no concern as far as working pressure goes. There does however need to be enough material remaining to carry the tension loads placed on the tube by the pressure acting on the "end piece". This can be calculated.

The threads are handling their load in shear, which will have to be calculated as well.

Welding requires equipment and practice. At least an oxy/acetylene torch, proper flux, and rods.

Compression fittings? Possible, but I'm not sure I would trust them with aluminum tube. The expansion rate due to temperature changes may cause problems with leaks, and fatigue failures.

Epoxy is not something I would trust at 900psi. Sorry Jack.

John, do you have any experience working with machine tools? A class at school perhaps??

While it's not the most "elegant" looking solution, cross bolting as I used on the co-ax might prove easier.

At the time I lacked the proper tooling to cut inside threads, and cross bolting, though crude in appearance, was a workable solution.

But don't let me dissuade you from taking a stab at cutting threads. It will most certainly be something that you will use frequently once learned.

Just my .02