For pre-commissioning, a continuous low-pressure steam blow technique has become standard practice for cleaning most steam system circuits.
Pipe is fabricated under hot working conditions, which leads to a heavy oxide layer forming on its surfaces. This layer is known as mill scale and must be removed from critical systems before putting them into service.
Over time, enhancements have been made in plant start-up techniques to perform engineered steam blows, which remove mill scale. During a steam blow, the piping is blown with sufficient boiler pressure to ensure that enough dynamic pressure will be experienced in the pipe to provide adequate cleaning. Typically, boiler pressures used in steam blowing provide a dynamic pressure throughout the piping that is at least 20% higher than would be experienced in normal operating conditions (CFR ≥ 1.2).
Any potentially damaging particles will be blown out of the piping prior to plant operation ensuring a flawless start-up.
- Removal of residual post-construction debris
- Unseating mill-scale magnetite layer deposits and welding slag through thermal pipe shocking
- Purging high, medium, and low pressure steam lines leading to end users, such as well pad injection points, steam traps, etc.
- Commissioning of steam supply and distribution piping, including lines originating from traditional boiler and OTSG systems
- Cleaning of critical system piping leading to crucial components, such as steam turbine generators on cogeneration units
- Precautionary maintenance on older steam systems where contamination is suspected or major critical repairs have been conducted
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