A tamper resistant pipe coupling is formed of segments connected end to end using fasteners. The segments have bearing pads at each end, each bearing pad surrounded by a shield wall. The shield walls and the bearing pads form a well that receives the fasteners and provides defense against tampering. The well is filled with a potting material, such as refractory cement, to cover the fasteners and provide additional protection. Formations are provided on the bearing pad and shield wall to ensure positive mechanical engagement between the coupling and the potting layer. The shield wall and bearing pad may be integrally formed with the coupling segments or a separate component.