Jan 2016

Keeping Water Away From Where It Shouldn’t Be

Though water is a fundamental material for fire protection, processes and domestic usage, there are times where water shouldn’t be in some places.

How Water Can Be a Problem

Water can be a reactive chemical, generating heat and pressure. The products of the reaction can be toxic and corrosive. The most famous case is the Bhopal incident: water entered a tank containing methyl isocyanate. The reaction generated heat and pressure, causing the tank to fail and releasing material into the neighboring communities.

Water can also be a catalyst to chemical reactions. For example, a distillation residue was contaminated with water (in that case, only 1%). But a small amount lowered the decomposition temperature of the residue by over 200° F. The pipe carrying the residue was provided with a steam jacket, with the temperature of the steam above the reduced decomposition temperature of the residue. The residue decomposed, causing the pipe to rupture.

Water itself can create a physical explosion. When boiled, water vapor will increase in volume by 1,600 to 1,700 times its liquid volume. If water is allowed to enter a confined space, it will increase in pressure if not allowed to vent. The most common instances are water-tube boilers where the tubes fail or smelt-water reactions in chemical recovery boilers.

What Can You Do to Prevent Water From Becoming a Problem

  • Ensure that your Standard Operating Procedures (SOPs) recognize processes and storage where water can:
  • React with the materials stored or in the process.
  • Act as a catalyst to a process.
  • Undergo a change from liquid to vapor.
  • Have your SOP describe ways to prevent water from getting into places where the above examples could take place. Conversely, if there are occasions where water must be in the area, the SOP should cover this special event, which would include a permit process.

Risk Logic can provide guidance where water can be a hazard to your processes.