The boiler could be composed of aluminum or stainless steel. Materials that are affected by heat are out of the question so fittings made of brass or stainless are the primary options. What becomes the next deciding factor is cost, availability and if you trust brass or not. Yet another factor is dissimilar metals interacting to produce corrosion but I haven't seen anything like that reported with this material.
Cost: There are at least 5 pieces of metal that go into creating a fitting for your vessel.
- Ball valve
- Threaded stem
- Locking nut
- Adapter inside
Availability: Brass you can find at most hardware stores. SS is usually only found online. http://www.bargainfittings.com is the best!!!! Excellent service and parts are sold as kits too.
Trusting Brass: I never really determined if there was a potential lead poisoning source to brass. None the less lead in brass is used to assist the machining of the material. Trace amounts of lead do exist on the surface of the material.
Cooler assemblies are different in that your dealing with plastic and thicker walls. When you apply a fitting to a cooler the walls of the cooler may change shape as your tighten the fitting. My next mash tun is going to be another converted keg with insulation.
Finally and the whole point to vessel fittings is the choice in hose adapters. You want a connection that is solid and won't pop off spraying you with hot wort. The cheapest method is to use the barb adapter. Though cheap, it doesn't allow you to change hose configurations easily. Next is the quick disconnect adapter which more complex and based on material will cost you more. Quick disconnects make the job so much easier.
Hints to assemble:
- Use gloves when handling stainless steel threads. Those ridges are sometimes very sharp.
- Teflon tape needs to be put on in the direction of threads being tightened. You will know you got it wrong when it bunches up.
- Have the proper equipment when tightening fittings. You will have to put some muscle into it and you don't want to slip.
- Making holes in SS vessel is takes time and care. Use the right cutting tool for the job and try not to cut yourself on the sharp burs produced. Use proper cutting oil for the drilling process
- Water test your fitting before firing up.