The example of application of fiberglass pipes on epoxy binding at replacement of steel pipes in heat supply system is considered. Fiberglass pipes in the deals with the influence of the degree of polymerization of the binder in the composite material of pipes that does not comply with the normative values on the work of the elements of the heat supply system when the coolant passes through it. When installing pipelines made of composite materials based on thermosetting polymers operating at elevated temperatures, it is necessary to control the supplied products for compliance with its regulatory requirements with mandatory control of the degree of polymerization of binders.

Keywords: fiberglass pipes, degree of polymerization, linear thermal expansion, shrinkage stresses, quality indicators, operation