Galvanized and Stainles Fitting Pressure

[kjjohn]

Sorry, it's 304 alloy.

[inonickname]

I am going to be buying stainless pipes and fittings. For the larger ones I will use screws and o-rings, but on the smaller ones I will be using taps and dies to create threads. Can this stainless threaded part be welded to increase strength?

Depends on the alloy involved. Some stainless steels are quite weldable. Others are not (or at least, not unless you're a very good welder...but if you were you wouldn't be asking us these questions).

Assuming the threads involved are formed well (no breakages, material and hole correct size) there should be no issue in using the threads alone. Welding them will only reduce serviceability.

Properties of 304 stainless.

It has excellent forming and welding characteristics.

It is weldable, though assuming you have a good tap and die set the threads will hold easily. (and the correct technique is used).

Unless you use specialized wires/rods the weld will NOT have similar properties. Consider this if you are choosing the stainless steel for properties such as corrosion resistance.