It reacts with a lot of metals like copper aluminium brass ect to form hydrogen gas and a #### lot of it too. If there was say a brass fitting or something that was flakeing or some kind of contaminate like say an aluminium tanker with the inner treatment coming off or metal shavings that would do it.
When i did oilfield they had a portion of the training where the safety dude dumped a teaspoon of powdered metal into some hydrochloric and it caused one HELL of a fireball when he took the lid off and poked a lighter on a stick into it. Apparently no one took him serious in most training so he started doing that. Made a very very clear point.