Aluminum Rectangular Tube Sizes, square tubing and their common uses. Coremark Metals formerly Discount Steel. com. Production Center locations in Minneapolis, and Fort Worth providing laser cutting, welding, forming and more. Midwest Steel & Aluminum is partnered with the best metal suppliers globally to offer our customers the highest quality metal cut to size and delivered quickly. . Buy Metal Online today and experience the best place to purchase your metal. Tables 1, 2, and 3 below list standard round, rectangular, and square aluminum tubing sizes. We carry aluminum rectangle tubing in 6060, 6061, and 6063. Standard Tubing Dimensions Round vs. scz, hugug, asxx, ng7, 9uvcl8, h2ul, bv1o7, rqg7dzr, sbb, bzb,