Tolerances. The tube holes must be drilled in the baffles with a certain tolerance over the tube outside diameter. When the maximum unsupported length is 914 mm or less, this tolerance is 1/32 in (0.8 mm) in diameter. For larger unsupported lengths, it must be 1/64 in (0.4 mm).
The maximum diametral clearance between the baffle and the interior shell diameter is defined by TEMA as follows: