Method of thermally insulating stop valves, and thermal-insulation device

A heat-insulated box for providing heat insulation of a parallel-slide valve installed perpendicularly to a pipeline, the heat-insulated box comprising:

• a plurality of sections of glass foam heat insulation comprising at least four combination pieces configured for covering a portion of the valve perpendicular to the pipeline and a semi-cylindrical portion of the pipeline adjacent to the valve, each of the at least four combination pieces comprising two rigidly interconnected quarter-cylindrical segments that are oriented perpendicular relative to each other such that one of the rigidly interconnected quarter-cylindrical segments is configured to be installed on the parallel-slide valve and the other of the rigidly interconnected quarter-cylindrical segments is configured to be installed on the pipeline;
• sealing gaskets of a cellular rubber substance positioned at edges of each of the plurality of sections to provide a seal between each of the plurality of sections;
• a plurality of metallic outer protective envelopes each having an inner surface adhered to a corresponding one of the plurality of sections;
• and
• latches coupled to at least some of the plurality of outer protective envelopes and configured to couple adjacent ones of the plurality of sections together.