ITS will participate in the soundproofing of industrial valves at a chemical site located in Western Europe, using skids, in order to prevent disturbances that would be linked to excessive noise emissions from such equipment, present in many installations, when it comes to controlling the flow of fluids, e.g. in pressurized piping systems:
- for employees responsible for process supervision and equipment maintenance, who must be able to perform their tasks under conditions that preserve their hearing and their ability to hear safety-related signals (vehicle movement, alarms - even more in case of risks associated with the presence of explosive products -). European Directive 2003/10/EC concerning the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (noise) is a reference document, fixing:
- limit exposure values for workers to noise: exposure level L EX,8h = 87 dB (A) and peak sound pressure pcrête = 200 Pa or 140 dB (C) ref. 20 μPa
- lower exposure values for workers to noise triggering action: exposure level L EX,8h = 80 dB (A) and peak sound pressure pcrête = 112 Pa or 135 dB (C) ref. 20 μPa
- higher exposure values for workers to noise triggering action: exposure level L EX,8h = 85 dB (A) and peak sound pressure pcrête = 140 Pa or 137 dB (C) ref. 20 μPa
- for local residents, who must be able to enjoy their peace and quiet, sheltered from intrusive noise emissions. French regulations, if applied, distinguish between the daytime period (7:00 a.m. to 10:00 p.m. except Sundays and public holidays) and the nighttime period (10:00 p.m. to 7:00 a.m. as well as Sundays and public holidays):
- in some cases, a prefectural decree (when it is not ministerial) sets the noise levels not to be exceeded at the property boundary: this is particularly the case for Facilities Classified for the Protection of the Environment (FCPE) e.g. 70 dB(A) during the day and 60 dB(A) at night
- emergence i.e. the difference between the equivalent continuous A-weighted pressure levels of ambient noise (considered industrial facility in operation) and residual noise (in the absence of the considered industrial facility, but measured over the period of operation of the considered industrial facility) is limited in the Regulated Emergence Zones (REZ), which generally include, near the considered industrial facility: homes, building zones and areas occupied by third parties e.g. Public Access Buildings (PAB), other industrial establishments. If the ambient noise level in the REZ (including the considered industrial facility noise) is between 35 dB(A) and 45 dB(A) then the admissible emergence is 6 dB(A) during the day and 4 dB(A) at night. If the ambient noise level in the REZ (including considered industrial facility) is greater than 45 dB(A) then the admissible emergence is 5 dB(A) during the day and 3 dB(A) during the night.
- in the case of a Facility Classified for the Protection of the Environment (FCPE), the marked tone, the presence of which is linked to the difference between the sound pressure level in a given 1/3 octave frequency band and the adjacent frequency bands, is considered undesirable if it exceeds 10 dB in the frequency range 50 Hz-315 Hz or 5 dB in the frequency range 400 Hz-8000 Hz
Besides limiting the noise they generate through the use of a diffuser or an in-line silencer (with equipment sizing and supply falling within ITS's scope of work), it is also possible - and this is the focus of the soundproofing project discussed here - to enclose industrial valves and piping sections within prefabricated modular chassis-mounted structures (the term "skid" is commonly used to describe these, even among French speakers, especially given the lack of a suitable alternative). In this instance, three such skids will be provided for the soundproofing of industrial valves and auxiliary equipment - often associated in this type of facility - with:
- for fixed or easily removable parts, by elements: industrial soundproofing panels with an absorbing face (modular)
- for acces: (rotating) acoustic doorsets with, for translucent parts (with glazing guaranteeing residual safety in the event of accidental breakage): acoustic window sets
Each skid will have a footprint of approximately 100 m² and a height exceeding 4 meters; the walls will be entirely (every single one !) easily removable - except where they consist of doors, which are also numerous - to allow easy access to all the enclosed equipment. To limit the weight of individual components - thereby facilitating handling by personnel who are not exactly Hercules, while complying with relevant safety regulations - the walls will be made up of a large number of juxtaposed panels, each fitted with two handles. Their design and manufacture shall be meticulous to ensure long-term airtightness (essential for effective noise control) and watertightness (necessary to protect weather-sensitive equipment, such as electrical components), despite the inherent durability challenges posed by the large number of interfaces involved in repeated disassembly and reassembly. The same applies to the numerous piping penetrations, which are quite large - and, as is often the case in such contexts - numerous and of varying sizes.
It is unthinkable to envisage the proper operation of enclosed equipment (within a skid) without an efficient air exchange system - to avoid highly undesirable overheating requiring inlets and outlets equipped with ventilation silencers; the resulting pressure loss shall be compensated for by the use of fans, which are inherently noisy, and which must be therefore also be fitted with noise attenuators in order to maintain overall performance regarding the limitation of sound transmission.
The tangible objective of the valve soundproofing being to reduce the sound pressure level at a distance of 1 meter from the walls of each skid to a maximum of 60 dB(A), based on the technical specifications provided by the Client - a world-renowned engineering firm rather than the site operator - mentioning noise levels exceeding 85 dB(A) near the main noise sources requiring an enclosure. To achieve this, it is essential to address acoustic wave reflections on the inner surfaces of the skids; this will be accomplished by using sound-absorbing materials within the panel construction - as previously described - featuring an absorption coefficient close to 1 (i.e. 100%) based on the weighted sound absorption coefficient alpha-w (αw).
Such a project to soundproof industrial valves using skid-mounted units will once again demonstrate the strengths of ITS and its commercial partners:
- optimized multidisciplinary design and site integration (including engineering work based on 3D modeling that accounts for every detail); given that nothing will exist at the time of this engineering work - neither regarding the valves requiring enclosures nor the on-site environment for the future skids - the quality of this capital project phase will hinge on an integral computer-aided design (CAD), for which experience of the assigned personnel will count as much as their imagination in addressing a wide range of technical challenges and delivering solutions that, in retrospect, will prove to be definitely the most appropriate
- high-quality manufacturing, ensuring seamless on-site installation and exceptional durability, even in harsh environments
- strict compliance to all technical specifications, projected costs, and contractual delivery deadlines
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3D modeling of the enclosed equipment and the skid within its environment is a key success factor for a soundproofing project entrusted to ITS, for what human resources play a decisive role for an optimized design. |
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