Abstract: A combined clamping and supporting ring for a reaction vessel having a radial flange at a junction between a vessel body and a vessel lid. The ring is capable of clamping around the flange to clamp the lid to the body and support the reaction vessel. The ring comprises a two-part collar comprising a U-shape main portion wide enough at one end to receive the flange of the reaction vessel in a direction parallel to the plane of the ring and a closure portion moveable with respect to the main portion to dose the collar. The collar has at least one support that fits under the flange of the reaction vessel to support the reaction vessel, and at least one clamping member that is arranged to engage above and below the flange to clamp the lid to the body when the collar is closed. At least two supports are provided in the main portion, one on each side of the U-shaped main portion.