Strain distributions in five right angled multi-mitred composite pipe bends have been measured while subjected to in-plane flexure, out-of-plane flexure and internal pressure, each type of loading being applied separately. Strains were restricted to the linear regime and were less than 0.2%. Each bend and associated straight tangent pipes consisted of a PVC lining wrapped with E-glass chopped strand mat layers impregnated with polyester resin. Results were compared with theoretical estimates using existing conventional and finite element analyses. The pipes had a nominal inside diameter and an equivalent bend radius of 250 mmNOTATIONe n Maximum strain in thin straight pipe (radius r, thickness t) due to bending moment M assuming simple bending theory ( = Mπr 2 tE)e N Maximum strain in closed thin straight pipe due to internal pressure p [ =pr(2 - ν)2tE ]f Flexural stress concentration factor in pipe bend, equal to maximum stress σ n l length of tangent pipep internal pressurer mean pipe radius in straight pipe or pipe bendt pipe or pipe bend thicknesst 1 thickness of laminax, y, z global Cartesian co-ordinatesE modulus of elasticityG modulus of rigidityI second moment of area of pipe cross section about a diameterJ polar second moment of area of pipe cross-sectionK pipe bend flexibility factorM i in-plane bending momentM 0 out-of-plane bending momentR mean pipe bend radius (smooth bend), equivalent mean pipe bend radius (multi-mitred bend); see Fig. 1.α mitre angle2β bend angleλ pipe factor, equal to Rtr 2 ν Poisson's ratioρ radius ratio = rRφ circumferential angle coordinate2 i , 2 o relative rotation of centre line at opposite ends of pipe bend or specimen containing pipe bend-in plane flexure, out-of-plane flexure.σ n maximum stress in thin pipe bend section due to bending moment M, as calculated by simple bending theory ( = Mπr 2 t)