The most economical method of constructing cylindrical pressure vessels is to keep the length-to-diameter ratio between 2 and 5 while using a diameter that will provide the lowest number of courses. Occasionally a customer will order a vessel of a given capacity but allow the fabricator some leeway in its diameter and length. The fabricator may then select the size that will be easiest and least expensive to construct. If a 1000-gal tank has been ordered, for example, a course 8 ft long with two hemispherical heads 48 in in diameter might be used. The cylinder would then have a capacity of 752 gal and the two heads a capacity of 125 gal each, for a total of 1002 gal. By fabricating the vessel in one course rather than two, moreover, the manufacturer will save time in laying out the shell and in handling as well as the cost of joint preparation and welding on the girth seam. It is important to choose a length and diameter that will give the required capacity with as few seams as possible. The volume tables for cylinders and heads in this appendix, Tables A.1 and A.2, are based on the diameters and lengths most used in the pressure vessel industry. To use the cylinder tables, locate the inside diameter of the vessel in the first column on the left-hand side and move across horizontally to the column headed by the length of the cylinder. Read the capacity in gallons at this point. If...