The perils of mixing
15 Jan 2000
A mystery leak at a refinery has highlighted corrosion problems that can occurring at mixing sites, according to researchers at The Welding Institute (TWI).
The leak came from an injection point where liquefied petroleum gas (LPG) and naphtha mixed. These should not form a corrosive mixture, but a team from TWI found that the LPG line contained low levels of hydrogen chloride, while the naphtha line contained water. The two combined downstream from the T-joint where the injection took place to form corrosive hydrochloric acid.
The problem could have been avoided by using a corrosion-resistant alloy, according to TWI. A design where the fluid injection had took place into the centre of the main stream, rather than from the side, would also have avoided the problem.
