What is the minimum required sleeve size when installing a 50 mm (2 in) nominal pipe with 38 mm (1.5 in) insulation through a concrete block wall?

When determining the minimum required sleeve size for installing a 50 mm (2 in) nominal pipe with 38 mm (1.5 in) insulation through a concrete block wall, it's essential to account for the diameter of the insulated pipe and the necessary clearance for installation, thermal expansion, and future maintenance.

The outside diameter of the insulated pipe is the sum of the nominal pipe size and the insulation thickness. In this case, adding 50 mm (the pipe) to 76 mm (the insulation, which is twice the thickness of 38 mm) results in a total diameter of 126 mm.

To ensure the sleeve accommodates the pipe's diameter while allowing some clearance, a common approach is to provide an additional margin for safe installation—this is where the chosen sleeve size becomes important. The minimum sleeve size of 150 mm (6 in) offers adequate space for the insulated pipe to fit comfortably, helps with the ease of installation, and assists in preventing damage to the insulation during the pipe's thermal expansion and contractions over time.

Therefore, the choice of 150 mm as the minimum sleeve size addresses the practical aspects of installation and operation, ensuring the system functions effectively without undue stress on the insulation or the pipe itself.