Abstract: A dome clamp for retaining the dome lid of a tanker truck in a closed position. The dome clamp includes an upper tube, right and left clamp members, and a vertically adjustable locking means adapted to be movable from an unextended position out of contact with a dome lid to an extended position in contact with a dome lid. Each of the right and left clamp members have downwardly extending legs having claw members extending inwardly from a lower portion thereof, and arms extending inwardly from an upper portion thereof. The arms are positioned within the upper tube, and are attached to spring means for urging the right and left arms towards each other in an unloaded condition. The spring means allows the right and/or left arms to be moved away from each other in a loaded condition.