FIELD: machine building.
SUBSTANCE: in disclosed here set of heat-hydro-insulated pipes each heat-hydro-insulated pipe consists of one working pipe, for example steel one, one layer of hydro-insulation in form of casing out of polymer or polymer containing material and one layer of heat insulation out of foam polyurethane. Heat-hydro-insulating items are fabricated within working pipe diametre ranges from 25 to 230, preferably from 32 to 219 mm facilitating volume protection of a working pipe with heat-insulating material for each item. Volume protection is calculated from ratio of specific volume of hydro-insulation to a unit of payload volume of running metre of a protected pipe and is not less, than 0.15, also volume protection with heat insulation increases quantitatively with decrease of external diametre of a protected internal metal pipe within the range of the said values of the latter for assortment of heat-insulated internal metal pipes of diametres from 219/207 to 32/26. The method includes five main stages of pipe fabrication. At the first stage of fabricating the external pipe-casing polymer material is heated, extruded, formed, calibrated and the form of pipe-casing is stabilised at vacuum three-axes expanding and simultaneous cooling. At the third stage pipes are hydro-insulated ensuring volume protection of the working pipe with hydro-insulating material for each item. Volume protection is calculated from ratio of specific volume of hydro-insulation to a unit of payload volume of arbitrary running metre of the working pipe and is not less, than 0.15. Notably, volume protection with hydro-insulation quantitatively grows with decrease of external diametre of the protected internal metal working pipe.
EFFECT: increased process simplification and efficiency of production of preliminary heat-hydro-insulated pipe.
19 cl, 10 dwg
