An anchor apparatus for anchoring a sealing member to an internal surface of a curved section of pipe, the apparatus comprising:- a body; a plurality of anchor members adapted to be moved relative to at least part of the body into engagement with an internal surface of a curved section of pipe; seal engaging means (18, 20) for urging at least one sealing member into engagement with said internal surface; characterised in that it further comprises: at least one convex surface, provided on at least a first of said anchor members, and adapted to be urged into engagement with the radially outer part of said internal surface of the curved section of pipe by movement of the corresponding said first anchor member into engagement with said internal surface; at least one concave surface, provided on at least a second of said anchor members, and adapted to be urged into engagement with the radially inner part of said internal surface of the curved section of pipe by movement of the corresponding said second anchor member into engagement with said internal surface, wherein said apparatus is adapted to be retained in position in engagement with said internal surface by means of engagement of at least one said convex surface and at least one said concave surface with said internal surface. a body; a plurality of anchor members adapted to be moved relative to at least part of the body into engagement with an internal surface of a curved section of pipe; seal engaging means (18, 20) for urging at least one sealing member into engagement with said internal surface; characterised in that it further comprises: at least one convex surface, provided on at least a first of said anchor members, and adapted to be urged into engagement with the radially outer part of said internal surface of the curved section of pipe by movement of the corresponding said first anchor member into engagement with said internal surface; at least one concave surface, provided on at least a second of said anchor members, and adapted to be urged into engagement with the radially inner part of said internal surface of the curved section of pipe by movement of the corresponding said second anchor member into engagement with said internal surface, wherein said apparatus is adapted to be retained in position in engagement with said internal surface by means of engagement of at least one said convex surface and at least one said concave surface with said internal surface. at least one convex surface, provided on at least a first of said anchor members, and adapted to be urged into engagement with the radially outer part of said internal surface of the curved section of pipe by movement of the corresponding said first anchor member into engagement with said internal surface; at least one concave surface, provided on at least a second of said anchor members, and adapted to be urged into engagement with the radially inner part of said internal surface of the curved section of pipe by movement of the corresponding said second anchor member into engagement with said internal surface, wherein said apparatus is adapted to be retained in position in engagement with said internal surface by means of engagement of at least one said convex surface and at least one said concave surface with said internal surface.