System for forming lined passages through concrete walls

A system of modular spools to be joined together in a unitary stack and mounted in a concrete wall form to create a lined passage of uniform diameter D through a concrete wall molded in the concrete wall form, the concrete wall form including first and second form plates mounted in fixed spaced relation to each other and separated by a wall width W, the system including a multiplicity of modular spools, with each spool comprising:

• an annular shell having an inside diameter D, an axial length less than W, a front rim, and a rear rim;
• flat front and rear flanges extending radially outwardly of the front and rear rims, respectively, of the shell, and the flanges each having an inner diameter D, so that a series of the spools can be assembled, end-to-end and flange-to-flange, without change of the internal diameter D through the entire assembly;
• a first plurality of the spools each having an axial length L1;
• and a further plurality of the spools each having an axial length L2, with L2>L1;
• the difference between L1 and L2 being one inch (2.5 cm) and L2 being no larger than six inches (15 cm).