The main distinction is between connection styles. Threaded fittings suit smaller lines and maintenance-friendly assemblies, while welded fittings suit more permanent piping systems where joint strength and leak control are priorities. Flanged fittings make sense when equipment, valves, or pipe sections may need removal later.
Material grade also changes the decision. Common stainless grades may be suitable for general water, air, and mildly corrosive service, while more demanding fluids or outdoor exposure may require a grade with better corrosion resistance. Buyers should match the fitting material to the pipe, gasket, fasteners, and operating environment rather than choosing stainless steel as a single category.
Start with the piping layout and the job of the fitting. An elbow changes direction, a tee creates a branch, a reducer changes pipe size, and a coupling or union joins straight runs. Mistakes often happen when a buyer sends only a pipe diameter without saying whether the connection is threaded, welded, socket weld, butt weld, or flanged.
Check compatibility before price. The fitting should match the pipe standard, wall thickness or schedule, thread form where applicable, and face type for flanges. A stainless fitting that is close but not matched can create sealing problems, installation delays, or unnecessary rework.
Consider the service conditions. Fluid type, pressure, temperature, cleaning chemicals, outdoor exposure, and contact with other metals all affect material choice. For example, a fitting used in a clean water line has different priorities from one used near salt air, chemicals, or food-process washdown.
A useful next step is to send a simple specification: fitting type, nominal pipe size, connection type, stainless grade if known, quantity, and application. If the grade or standard is not fixed, ask which options can be supplied and what documents can be provided with the order.
