High-strength, fatigue-resistant pipe connectors suitable for use in offshore risers, tendons and pipelines, such as may be connected to floating production systems (FPSs) principally used in the production of oil and gas. The present connectors include tubular pin and box components with mating frusto-conical, concentrically-grooved mating surfaces which threadingly interlock, and non-threaded (e.g., flat) mating surfaces that seal and preload (e.g., preload at least a portion of each component in compression), via axial advancement of the pin component into the box component. In such connectors, axial movement of the pin into the mating box results the in radial expansion of the box and radial contraction of the pin until the concentric thread patterns match and interlockingly snap into the connected position.