As I prepare to build my first steam (donkey) project, I'm confused by the choice of materials, valves, etc. available. I notice my engine (Graham) is fitted with brass tube intake and exhaust tubes-like the K & S tube from the LHS. I see, for example, PM Research has elbows, unions, bushings and what looks like heavier-or thicker-walled tubing, or 'pipe'. So the question is: do you guys use threaded unions, silver soldered joints, thin walled tubing, 'pipe', check valves........and whatever? I'm building a 30psi engine. What do I need to 'pipe' it? Of course, I would like to have some scale looking elbows, etc. I see, too, the threading is new to me also, so its buying taps/dies apparently. Bill