Piping related accident

Rust-jacking
To avoid welding in a plant that handled flammable liquids, an extension was bolted on a pipebridge. The old and new parts were painted, but water penetrated the gap between the bolted surfaces and rusting occured. Since rust has seven times the volume of the iron from whcih it was formed, it forced the two surfaces apart. Some bolts failed, and a steam main fractured.

Screwed plugs are weak point.
Many plugs have been blown out of operating pressure. In one incident, a half inch plug blew out of a bellows soon after it was installed and was followed by a stream of hot oil. Another incident occured when a heat exchanger was being pressure tested. The test was taken above the test pressures when the plug blew out, injuring 2 men. In a different incident, a plug blew out of a swing valve, followed by a leak of 2 tons/hr of gas. Plug was part of the design. Probably never inspected, a common failing with a check valve.

The above incident was taken from an article written by Trevor Kletz titled "Unexpected equipment involved in process plant accidents". The point that Trevor was making is that often times design engineers fail to pay attention to peripherals such as a screwed in plugs (didn't get an engineering degree to worry about it). It is not glamorous and it is much more interesting to focus on stress analysis, pipe dynamics, fluid flow than to worry about rust, plugs, drains and so on.. Received on Fri Jul 27 01:11:00 2001