Steam Safety - How exposed are you at work?

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Steam has many applications. It can heat, do work, sterilize and move over long distances. Industrial applications where steam is often used include power generation, heating, tires manufacture, paper, food and beverage, wood products, pharmaceutical, refining and chemical.

So what is Steam?

Steam is water that has been boiled into a vapor. Generally, when water is boiled into vapor, the volume increases by 1,600 times. Condensate is the steam cooled back into the liquid state. Condensate in steam systems can result in component collapse, cracks, ruptures, overstressed gauges, valve failure, heat exchanger tube failure and failure of pipe supports. Most steam system failures are caused by water hammer where condensate exists with steam.

What is a Water Hammer?

Have you ever heard a loud 'BANG' or hammer-like sound after quickly turning on or off a water faucet? This is the sound of water hammer in the water piping system. In a factory, a pump starting up operation or shutting down, or an air vent suddenly closing are examples of when this might occur. In addition to water transport piping systems, water hammer also occurs in steam and condensate recovery (i.e. water circulation) systems.  Note that as steam is involved, this type of water hammer is also sometimes referred to as 'steam hammer'. When water hammer occurs, a momentary abrupt pressure change of over 10 MPa may occur inside the piping. This impact can severely damage piping, equipment or machinery housing, possibly resulting in damage not only to gaskets in junctions, but also to valve flanges or the valves themselves. Some other terms you may hear include;

  • Hydraulic shock (Water Hammer) – Often occurs because of sudden stopping of flow.
  • Thermal shock – As steam collapses, condensate rapidly rushing in to fill the void.
  • Flow shock – A consequence of steam rushing down a cold pipe and producing a large quantify of condensate at a high velocity.
  • Differential shock – Occurs whenever steam and condensate flow in the same line, but at different velocities ultimately resulting in a slug of condensate impacting components which changes direction (tees, elbows, valves, etc.).

So how can you keep yourself safe?

  • Check and repair piping insulation. The insulation not only helps to save energy, it helps to reduce accumulation of condensation in the piping system.
  • Properly label steam and condensate lines
  • Utilize energy control procedures (lockout/tagout) prior to performing work.
  • Identify and utilize appropriate PPE. Consider body parts which could be exposed and ensure proper protection. Consider openings where steam could become trapped, increase exposure duration and result in a more severe burn (e.g. through an open sleeve cuff). Consider applications where the PPE could become wet and lose insulating properties. Heat resistant PPE must be appropriately rated
  • Prior to performing work, consider waiting for systems to cool to minimize risk of a third degree burn. Exposure to 60°C water for only five seconds may result in a third degree burn.