A tensioning system that can be used with a heater blanket and a vacuum bag for heating a workpiece can include a tensioner including at least one flexible rod. The tensioner can further include an end cap positioned on one or both ends of the flexible rod. The tensioner can be inserted through one or more sleeves attached to the vacuum bag, and each end of the flexible rod can be positioned within a pocket and thereby attached to the vacuum bag. In one implementation, the flexible rod can be rotated relative to the one or more end caps to decrease or increase a length of the tensioner, and the length of the tensioner is thereby adjustable. The tension applied to the vacuum bag can mitigate sealing of a seal of the vacuum bag with a layup mandrel.