Techniques for implementing a pipeline system including a pipe fitting, which includes a fitting shell that define a fitting bore and a tubing cavity around the fitting bore. The tubing cavity interfaces with pipe segment tubing to facilitate fluidly coupling the fitting bore to a pipe bore. The fitting shell includes a seal groove that is recessed into a fitting shell surface that facilitates defining the tubing cavity. The pipe fitting includes a belt seal having a multisided axial cross-section profile, in which the belt seal is to be disposed in the seal groove to implement a fitting seal in the pipe fitting that includes a protruding portion having a wedge-shaped axial cross-section profile that protrudes beyond the fitting shell surface into the tubing cavity to facilitate sealing a fluid conduit implemented in an annulus of the pipe segment tubing in the tubing cavity of the pipe fitting.