I have been considering a few additions to my livietta (maximatic) but all of them include soldering fittings and I'm not 100% clear on what to use. Two different operations I'm looking at doing. First being the basic soldering of cap fittings to copper tubing. Are the soldering materials the same as basic copper plumbing in a house? Like can I just walk into home depot and say I need copper plumbing solder supplies and be set? Or are there different materials i.e. solder, flux, etc.? The second operation is adding fittings to the top of the boiler to attach a vacuum breaker (I know I can get a boiler cap to hold a vacuum breaker but I have other things I want to do as well) and the pressure relief valve (i want to put a gauge where the relief valve is currently like the current cremina). Is adding fittings to the boiler the same operation as cap fittings to tubing or is there more to it? Also I'll take warnings if there is some big safety issue with what I'm wanting to do. Thanks in advance!

WARNING: I have never done any soldering on a espresso machine!
However I have done lots of SILVER soldering on pressure vessels. The solder in your home plumbing melts somewhere in the neighborhood of 350-450 F. I would not ever use this on a pressure vessel that is subject to heat of the kind generated in an espresso machine.

Take a look at this site:
http://www.harrisproductsgroup.com/en/P...ilv-5.aspx

You would need to find a solder that is not toxic as well. I'm sure others here know the answer.
Also FYI silver soldering is a bit more complex than regular home plumbing soldering.

YMMV, but be safe!

Paul

As Paul said, "normal" plumbing solder would not be my choice either. These tend to be soft and flexible and so is not a good choice with pressurized vessels nor on tubing. Copper tubing will change in length as they heat and cool. The flexing may cause the joint to fail. Either brazing or silver soldering would be my choices. BUT, if you have no experience with these I would take it somewhere to have it done. Silver solder and brass for brazing requires high temperatures and without experience you can melt parts.

I agree 100% with what Paul and Randy said. In addition, making permanent or even semi-permanent mods to your machine that would NOT be easily reversible would likely cause the value to plummet.

Applying the newer style boiler cap w/ vacuum breaker is painless except for $. Measuring the boiler pressure via the steam wand for adjustment and/or troubleshooting purposes is also easy. HOWEVER, IF YOU INSISTED ON THIS JOB, you would need to visit a welding supply store (definitely NOT Home Depot) and buy some rods suitable for HVAC work. I assure you that the various terminologies associated with silver-soldering, silver-brazing, & sil-phos work vary with your GPS location . In addition, you would need a suitable torch and gas tank and maybe some fittings and tubing from Home Depot to practice with.

It would be nice to get some pics of the latest Maximatic to see their configuration for the boiler pressure gage.

Well shoot. Thanks for the info. Oh well it's not super important. I am good at soldering but have never brazed before. Would just adding fittings to copper tube still be out of my league? I wanted a brew gauge too but that would involve a pipe to tee into the line somewhere in the brew path. I was also wanting to try a different steam valve but I'd need to put together a new copper tube for that as well to feed it since the stock one is permanently attached to the valve but screws onto the boiler, so this would be reversible. Or is there a place I can order these tubes and fittings already cut and soldered together?

For those that are interested the only difference between soldering and brazing is process temperature. 800F is the line. Below you are soldering and above you are brazing. What is commonly referred to as "Silver soldered" is technically a brazed joint if the fill material melts over 800F. Increasing percentages of silver in an alloy raises the melting point. Pure silver melts at 1235F. Silver added solders normally max out at 5% silver and silver based braze starts at around 30% silver. Acetylene and Mapp gas torch work well when brazing unless you are willing to set up an oven or induction heating system. Big challenge is heat distribution (big parts take big heat and little parts not so much) and selection of braze alloy/flux. Lucas-Milhaupt / Handy and Harmon company has a wealth of information on brazing and how to select the proper braze alloy. Some of the newer silver added lead free solders work well and have pretty good strength numbers. Alloys are chosen based on materials to be joined, final use of product, ease of use, fit up gaps, and economy of fill material. Joint strength and fatigue resistance, electrical conductivity are other factors. Final part use for food and water handling, for human consumption, takes special consideration. Joint configuration is a factor for braze form (Fill rod, paste, or preformed shapes). Fortunately there are metallurgist and engineer types that have done most of the homework for us. Since we are talking about making copper tube assemblies, it is helpful to know that heating copper tube up until it is almost red will anneal it. Copper is one of the materials that can only be hardened by cold working the material. If you find you that your tube has gotten all mean and ready to crack, take the torch to it and after a quick quench (not necessary but gets you back to work faster and drops any scale off) you're ready to create that factory looking pipe. I sometimes anneal a pipe after forming but prior to brazing/soldering fittings to ease installation and to allow easy future adjustment. Nothing worse than working with a stiff old copper tube that could use just a bit of a tweak at the fitting to line up the threads. I also wouldn't worry too much about thermal expansion causing fatigue. Most of the components in an espresso machine heat up pretty even. Vibration and freezing full of water are the big killers of copper tubing. That's why no copper tubing in the engine compartment. Oh, I forgot tweakers. Causes complete disappearance of copper assemblies.
JPB

i go with regular lead free plumbing solder. that absolutely works. hell, your copper plumbing in your building is done that way. and it adheres to health department rules (here in sf very strict). and what's the pressure in an espresso machine? less than 1.5 bar. line pressure in your water supply is often higher otherwise you couldn't fill your boiler without a pump. have you seen soldered copper plumbing bursting under normal conditions? i haven't...
jonny, i would just go ahead with regular lead free plumbing solder. easy to work with and safe.

Just two points to think about...
1. Most solder, including the common 95/5 lead-free plumbing solder, has decent strength (many thousands of psi) at room temperature. What is very hard to find is the strength at elevated temperature, like around 250F. Indium Corp. merely says "good high-temperature strength".
2. The load on a plumbing solder joint, in simple terms, is a function of geometry and pressure. In common plumbing joints, the cross-sectional area of the pipe/tube is less than the area of solder in the solder joint. Household plumbing from city water runs at up to 80 psi in areas where I've lived. Plumbing in an espresso machine in the path of the brew cycle might be at 130 psi (your 8 or 9 bars). Not a huge difference. But if you're on the boiler, the ratio of pressurized area to solder area could conceivably be much larger than for normal pipe/tube joints, so even though the boiler pressure is lower, analogies to household plumbing may not be relevant here in terms of estimating strength and safety. Most people can look at the joint in question and determine if it's similar to a household plumbing joint, or more like a boiler/pressure-vessel joint. The latter would beg for some calculations to assess the safety.
-Ed

As mentioned, what you want is silver solder. Technically, it's considered silver brazing. Be careful, because hardware stores do sell a "silver solder", which is used for plumbing, etc. However, this is different than true silver solder, such as the type used in jewelry work and/or the brazing of metals.

Also, as mentioned, the plumbing type solder has a lower melting point (not to mention, typically a lead content), which may not make it the best choice for use in your espresso machine (although it probably would work - just not as nice as silver soldering/brazing would).

Silver solder comes in different alloy percentages. The lower the silver percent, the higher the melting point (if I recall correctly). It's also sometimes referred to has hard/medium/soft silver solder in the jewelry world. Due to the different melting points, you can use it to braze joints (such as on rings, etc.) next to one another. For example, if you have to solder two areas, you would do the first using hard solder, which has a higher melting point. Once you effect that connection, then you would step down and solder the joint next to it, using a lower temperature silver solder. This allows you to solder the 2nd connection, without as much risk of melting the previous joint next to where you are working.

If you have a welding supply place in town, check them out. They should have what you need. As mentioned, it will probably take a gas torch. You might be able to use propane also. Normally the silver alloy content is around 45% or 56% or so. Either of those will produce a very good brazed connection. Be sure the surfaces are perfectly clean (even free from the oils of your fingers) and use flux. The silver will seek the heat, so torch placement is important. Check YouTube for videos on how to silver solder.

Good luck!

Ray

I can't speak to the advice given the OP so far regarding work on high temp and pressure systems; my experience is in household plumbing, which, as was said, can reach T and P that are kinda high, only not as much. In a home, unregulated (main) pressure is often 90-100 psi. Pressure spikes due to thermal expansion caused by a water heater can be even worse, if not remediated. You should know that since the late 1980s solder and flux sold for use in potable water systems are lead-free by law. There are "easy" plumbing solders with a few % silver that melt more gradually and in the low 400s, and more regular ones that replace the silver with antimony and melt around 450F-460F. If you have the option of using a water-soluble flux, do so. Petrolatum-based fluxes also exist, and many plumbers use them all the time, but they leave a foul-tasting residue (think smoldering candle wick) that can take a long time to dissipate. For MSDS on a typical range of plumbing fluxes and solders, there's this:
http://www.oatey.com/Channel/Shared/Pro...heets.html
If you really are working in the soldering temperature range, MAPP gas gives a hotter flame than propane, works with the same torch, and costs but a little more.