Steam system is an important auxiliary system used for different purposes onboard ship. While working on ship or in steam system, one must have heard an abnormal banging and rattling sound from the steam pipe. This is known as Steam hammering.
Let’s understand the cause and remedies of the same.
Steam Hammering in Steam System
In a steam piping, when steam flow is suddenly stopped or condensed, then it results in gaseous shock wave, which are thermal shock wave resulting in to steam hammering.
- Normally, if the steam piping system is not properly drained then the steam travelling in the pipe will come in contact with cold water and implode causing shock wave, developing thermal stress.
The term “implode” is similar to “explode” in meaning but opposite in functionality. When due to sudden drop in pressure vacuum is created and if this negative pressure or vacuum is not released, then it causes shock wave leading to implosion.
- Hammering can occur when there is sudden change in the load or sudden increase in the steam pressure by ship’s boiler.
- If the piping system has sharp bends then this will cause condensation of steam and thus hammering.
- If the steam is used for heating purpose in a heater and if there is a leak then this will cause fluid to come in contact with high pressure steam causing hammering.
Effects of Hammering
- As discussed, steam hammering will produce thermal shock and hence thermal stress on the piping system. This are already under high temperature stress and additional stress can reduce the working life.
- If there is hammering due to sudden rise in the steam pressure, it may lead to cracking of steam pipes.
- Due to the implosion effect, there can be cavity formation and erosion of the piping leading to thinning of the pipes.
- Drain the steam system at initial stage so that all the condensed water is removed.
- Avoid sudden increase of the steam pressure.
- Piping system and pipe design to be such that they are smooth and with minimum number of bends.
- Sharp bending of pipes to be avoided.
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