Insulation of pipework using hard cladding or soft lagging is widely used and has been carried out to reduce noise emissions, and more rarely to provide thermal insulation (e.g. compressor fuel gas lines). Although proven and effective for noise control, it can lead to issues with maintenance and corrosion further down the lifecycle of the pipework.
Issues with using cladding / lagging for pipework noise abatement include:
The ingress of water beneath the cladding / lagging - this has led to some cases of significant hidden corrosion of the pipework which also has a cost and time impact for National Grid. The ingress of water can be caused by poor workmanship or the cladding / lagging being unsuitable for the application.
The need to remove cladding/lagging in order to inspect the pipework beneath - there is an ever present risk of corrosion of pipework beneath lagging. When removed as part of routine maintenance, the cladding / lagging must be scrapped and replaced with a brand new equivalent; currently cladding that has been removed from pipework cannot be reused due to its design and the installation and removal methods employed. This has high cost implications for National Grid.
There is no robust way to compare the performance and cost of existing noise abatement methods or to evaluate novel technologies in the marketplace – The default solution applied for noise abatement is currently lagging / cladding without a proper consideration of the wider issues e.g. whole life cost, maintenance, corrosion protection, etc. Novel technologies may offer the same or better noise abatement performance, and offer the opportunity to alleviate the associated corrosion and inspection issues.
Issues with existing methods of machine train noise abatement are:
Standard OEM machine train packages default to noise mitigation at sound levels significantly higher than permitted on National Grid installations. This gives rise to requirement for bespoke noise enclosures by third parties at greater expense and with OEM package integration issues.
These issues have had cost, time and safety implications across all National Grid Gas Transmission sites. Due to the ageing asset base these issues are likely to worsen in the future. National Grid requires a comprehensive and evidence-based approach for evaluating the different noise abatement techniques available, so that the Best Available Technique (BAT) solution for a given project can be identified.
These issues are widespread across the network of compressor installations and other above ground assets and will increase in frequency and severity as the asset base ages, bringing potential for significant future cost exposure.