Abstract: A unitary removable and reuseable jacket for the thermal insulation of pipe accounterments. The fully-formed generally-rectangular jacket is composed of three layers: a heat and water resistant outer fabric layer, a hardened rigid-cell polyurethane middle layer, and a thin flexible heat-shrinkable plastic inner layer. The inner and outer layers are joined together by perimeter seams and a transverse center seam which form two pockets adapted to contain the polyurethane foam middle layer. The inner and outer layers are formed at time of manufacture while the middle layer is formed during the application process. During the application process, an exothermic chemical reaction is generated by the combination of the chemicals polyol and isocyanate which are inserted between the inner and outer layers through holes contained in the outer layer, to form a rapidly expanding and hardening rigid cell polyurethane foam middle layer.