Apparatus comprising a support member having a flat surface adapted to receive and support a seam region of a flexible belt comprising thermoplastic polymer material having a predetermined glass transition temperature, a heatable member having a smooth heatable flat surface for compressing at least a portion of the seam region of a flexible belt placed on the smooth flat surface of the support member to heat the portion to at least the glass transition temperature of the thermoplastic polymer material, the smooth surface of the heatable member having a profile which is parallel to the smooth flat surface of the support member, and wherein the heatable flat surface comprises a low surface energy or abhesive material.