The air conditioning packs are in the unpressurised area, under the centre fuel tank ona B733. There are two of them. At the exit of each pack is a big Non return valve just before the conditioned air is ducted into the pressurised fuselage at the back of the fwd freight bay. There is a duct clamp here at the entry point. This is the only clamp failure that can cause depressurisation, but I would have thought that had both packs been operating then the decompression would have been a bit slower. Any clamp failure in the system before, or after this would not cause this.
There are hundreds of clamps between the engines and the freight bay. They rarely fail and it is only with the help of our friend Murphey that this incident happened.