A closing element on a blowout preventer that forces together two steel blocks with rubber surfaces to form a seal with each other (blind or shear ram) or around a string of pipe (pipe ram). Variable-bore pipe rams can close around a range of pipe diameters.
During normal drilling operations, the drillstring fits through the rams in the blowout preventers. The rams are equipped with large rubber packers designed to close around tubing, drillpipe, casing or close off the open hole.