PIPE WITH INTERNAL PROTECTIVE COAT AND METHOD OF ITS MANUFACTURE Russian patent published in 1999 - IPC

FIELD: erection of pipe lines used for transportation of aggressive media; oil producing industry and petrochemical industry. SUBSTANCE: pipe with internal protective coat includes cylindrical insert made from corrosion-resistant metal strips at a thickness of wall from 0.1 to 2.0 mm; at the end surface pipe has bulge of no less than 1.0 mm over width of 2.0 mm. Other cylindrical insert also made from corrosion-resistant metal strips at a thickness of wall lesser than 1.0 mm and not more than 5.0 mm wide is mounted inside first cylindrical insert on side of end surface. blanks for cylindrical inserts have form of rectangle or parallelogram at base angle of 45 to 90 deg; length of base of blank for cylindrical insert is found from the following formula: L = π[D(100+m)-2S(100-n)]/100,, where L is length of base, mm; D is nominal diameter of pipe, mm; S is nominal thickness of pipe wall, mm; n is permissible negative deviation in pipe wall thickness, % and m is permissible positive deviation over external diameter of pipe, %. First cylindrical insert is made from corrosion-resistant metal strips inside end of pipe be welding with corrosion-resistant longitudinal seam at simultaneous securing of insert to inner surface of pipe by the same seam. Second cylindrical insert is made on inner surface of first insert from corrosion-resistant metal strips inside end of pipe by corrosion-resistant longitudinal weld whose direction and projection coincide with those of first cylindrical insert. EFFECT: simplified construction. 6 cl, 3 dwg