Abstract: A lock for a device having as a component thereof critical for use and/or operation thereof a tubular member, includes a tubular insert for disposition in a gap provided in the tubular member such that the insert becomes a portion of the tubular member, a lock member for encircling an anchoring structure and for making a locking connection to the insert. The insert is provided with a frangible portion which renders the insert more susceptible to breaking than the lock member. Upon breaking of the insert, the tubular member portion is broken to provide the device with a broken component critical to the operation thereof.