Advanced flanged thru-the-wall fittings, enabling only single-hole penetrations for piping, have been introduced by ModuTank Inc., Long Island City, New York, US. Wall-piercing bolts are eliminated by this design. Wide, thick, gaskets tightly seal the fittings under externally adjustable force against tank walls. Bolt-related leakage is eliminated, and no wall sealants are required. The new fittings are available in PVC, stainless steel and Hastelloy in standard sizes for 2in to 12in piping. Larger dimensions are available on a custom basis. They are equally suitable for new and existing steel, and for concrete tanks with or without epoxy or glass coatings, or with membrane liners. The fittings accommodate any wall thickness and are removable for repeated installation in other tanks. These fittings normally include an expansion joint and internal elbow.