Construction of process systems can lead to various kinds of debris and unwanted material getting inside the pipework – particularly in harsh environments like the Sahara Desert. Additionally, mild steel pipe often has a coating of mill-scale left over from the manufacturing process and grease and oil can also be present. The welding process generally leaves debris behind too. All of this can mean that a newly-constructed process systems can be very dirty and contain significant debris that needs to be removed prior to system start-up.
In hydrocarbon processing plants, having dirt in the systems can cause operational problems, including malfunctioning valves and instruments and, ultimately, off-specification product.
Willda Group provides a complete range of flushing and cleaning services for process system pipework, including air flushing, explosive venting and water flushing (high-velocity/flow water creating turbulent flow).
High-velocity water flushing
High-velocity flushing techniques are typically utilised for small-bore pipework systems with diameters of 6” and below. The high flow rate of the water creates a high velocity through the pipework which induces a turbulent flow.
In turn, this stirs up the debris and carries it out of the system. External filtration systems then remove the debris so that the water can be re-used.
The flushing is carried out by pumping water, from a bulk storage tank, to create velocities of at least 5 metres per second from the system's highest point down to the lowest point, at which stage it is filtered and returned to a bulk tank for recycling.
High-velocity air flushing and explosive venting
For situations where it is not desirable to expose process systems to water, or where environmental conditions make flushing with vast quantities of water undesirable or uneconomical, two methods of water-free debris removal are available:
High-velocity air flushing involves the use of air compressors to create turbulent flow within the process pipework. This then stirs-up the debris and carries it out of the system.
Explosive venting involves the pressurisation of an enclosed system, usually to around 4 or 5 bar. The system extremities will be flanged with bursting discs, designed to rupture at a pre-defined pressure. Upon rupture of the discs, debris contained within the pipework will be carried from the system.