Steel Pipe & Tubing seem similar at first blush and in fact they share many characteristics but they also have some important differences
Steel Tubing is a hollow steel shape intended for structural purposes and made from carbon, stainless, or galvanized steel further divided as
Mechanical Tubing is used in low stress applications such as fences, kitchens, restaurants, hospitals, solar panels and made with wall thicknesses up to 10 gauge.
Structural Tubing is for high stress structural application like bridges, buildings, roll cages, and underwater platforms with wall thickness from 3/16” and up. It is often referred to as Hollow Structural Sections or just the acronym HSS