Methods for assembling rotor blades are provided. A method includes receiving a first portion of a rotor blade at an erection site. The method further includes receiving a second portion of the rotor blade at the erection site. The method further includes aligning the first portion and the second portion at the erection site, the first portion and the second portion supported on a fixture system when aligned. The method further includes connecting a blade component of the first portion and a blade component of the second portion together at the erection site.

A preform made from two different materials that do not bond together by a bi-injection process, using the same mold, is presented. An outer layer of the preform can be first made, then an inner layer molded through a center hole in a bottom of the outer layer, and the two layers connected. Inner/outer preform materials can be different, such as PET/polyolefin or polyamide, or the same, such as PET/PET. To prevent mutual bonding during molding of the second layer, a non-stick coating may be sprayed onto a surface portion of the first layer prior to molding the second. In embodiments, manufacturing order can be either outer/inner, or inner/outer, and the non-stick coating sprayed on the inside/outside of the layer first molded.

A method of joining polymer-lined pipe sections end-to-end comprises friction welding a polymer liner bridge fitting to parent liners of the pipe sections and welding metallic outer pipes of the pipe sections to each other before, during or after the friction welding operation. The fitting may be engaged telescopically with the pipe sections in socket formations formed by the parent liners. Friction welding is effected by relative rotational movement between the fitting and the pipe sections about a common longitudinal axis. A spinning tool is advanced longitudinally within at least one of the pipe sections, inserted into the fitting, anchored within at least one of the pipe sections, engaged with the fitting and rotated to effect the relative rotational movement. This friction-welds the fitting to the parent liners simultaneously at interfaces located at respective ends of the fitting.