SHARPLY BENT BRANCH PIPE MADE FROM COMPOSITE MATERIAL AND METHOD OF MANUFACTURE OF SUCH BRANCH PIPES Russian patent published in 2003 - IPC

FIELD: manufacture of pipe line parts from composite materials, mainly sharply bent branch pipes at passage area of 50 to 400 mm. SUBSTANCE: proposed branch pipe is intended for transportation of acid brines, pulps, sand and gravel mixtures stratum water at considerable content of abrasive particles, sludge and soot at pressure of up to 4.0 Mpa. Proposed branch pipe includes internal envelope made integral with centering surfaces in form of taper bell mouth; it is provided with lining layer formed to half length of taper bell mouth by circular winding of 2 to 6 layers of lining material laid on 2-3 layers of fabric prepreg forming inner surface of taper bell mouth and part of torus surface and internal envelope; structural layer is formed by stack of structural layers impregnated by binder including two circular adhesive layers of non-woven cloth, 2-3 circular layers of fabric and one circular layer of dry molding glass tape. Connecting members are provided with taper tail-pieces with at least one circular projection engageable with respective groove found in load-bearing jacket and made in form of triangle whose larger side adjoins taper surface of tail-piece and vertex is directed towards load-bearing jacket in such way that angle of inclination of side directed towards outer end faces of connecting members exceeds angle of inclination of side directed towards their tail-pieces. Load- bearing jacket is made by stage-by-stage forming of stacks of reinforcing material including one longitudinal and two circular layers of fabric or roving impregnated with binder; layer of dry molding glass tape is laid on first stack and then on every second or third stack and on last stack. Forming internal envelope is started with circular winding of 2-3 layers of prepreg tape which are laid at outer end faces of mandrel on its taper and partially torus surfaces, after which layer of lining material is formed so that it overlaps layers of prepreg tape wound previously by half length of taper surface of mandrel; then, circular anti-adhesive layer of tape, for example fluoroplastic tape and preliminary molding of lining layer is performed by braiding with dry molding glass tape followed by partial hardening; then, braiding made from dry glass tape and layer of anti- adhesive tape are removed and stack of structural layers is formed by circular winding of two adhesive layers of tape made from non-woven material followed by manual impregnation with binder; after final hardening of internal envelope, mandrel is disassembled and its components are withdrawn from hardened inner envelope and internal envelope is bonded with connecting members over engageable taper surfaces for forming outer load-bearing jacket. Required thickness of load-bearing jacket is built up by stage-by-stage forming of stacks of reinforcing material including one longitudinal and two circular layers of fabric or roving impregnated preliminarily with binder; molding of stacks by braiding from dry glass tape is performed after forming 1st stack and then every 2nd and 3rd stacks, as well as after forming last stack of load- bearing jacket. EFFECT: enhanced strength and reliability. 3 cl, 5 dwg