A clamping device suitable for securing a pair of flanges together is a unitary strip of a polymeric material that defines a multiplicity of clamping segments linked by flexible strip portions. The ends of the unitary strip define latching elements shaped to interconnect when the ends are brought together. Along one face of the unitary strip the clamping segments define teeth that project at opposite sides of the unitary strip, and these teeth define faces that are adapted in use to contact outer faces of the pair of flanges. Each clamping segments may define two opposing teeth. The clamping device can be operated with a single hand, being bent around the outside of the pair of flanges so that the clamping segments engage opposite faces of the pair of flanges and hold them together, and the latching elements are interconnected.