Such challenges have been behind the recent significant rise in preference for outdoor enclosures made from GRP (glass reinforced polyester) – compared with traditional metal constructions.
This article looks at GRP and its relevance to some of the most pronounced challenges in today’s instrumentation projects:
Semi-passive cooling technology designed to protect sample conditioning and analyzer instrumentation. In this application, onboard an LNG vessel, heat exchangers – boosted by ‘cold’ water from deep beneath the vessel – cool instrumentation power dissipations up to 900W.
Many of the most significant projects of current times involve installing plants in extreme locations. Take the LNG plant currently being constructed in the Siberian Yamal peninsula for example, or the amazing Prelude floating LNG vessel which will be located some 200 km offshore from Western Australia.
Dealing with the intense cold of an Arctic environment demands very high performance insulation. The basic GRP sheet material used in INTERTEC’s enclosures has a very high thermal resistance compared to metal, with an efficiency that is over 1,000 times superior. GRP sheets are also fabricated easily in composite ‘sandwich’ forms, enclosing high performance insulation. As such insulation is added as an integral part of the structural material, it gives uniform protection over the whole enclosure. By being bonded or injected into place, no interior-exterior fixings or components are needed – which themselves can create ‘thermal short cuts’.
This holistic approach to enclosure design has particular benefits in avoiding the cold-spots (or hot-spots) that can lead to problems. It delivers extremely stable operating environments for instrumentation, which can be crucial in many applications – such as process analyzers.
Naturally, this construction also greatly reduces the energy required to heat or cool electronics equipment.
Another key demand today is for greater reliability and lifecycles. Again, this is being driven hugely by the demands of challenging upstream projects – such as platforms in the North Sea – where the risk and cost of equipment failures and downtime can be huge. Even 316 stainless steel can corrode quickly in some of these extremely harsh environments.
The outer GRP sheets of the composite construction material used in advanced GRP field enclosures provide the required environmental protection. GRP is an inherently inert material that is virtually immune to corrosion and atmospheric pollutants. It is also resistant to a wide range of petrochemical media.
GRP does not rust or degrade in any meaningful way. High levels of UV can induce some surface brittling, leading to marginal damage over long periods of time. However, in practice, such degradation is prevented by a UV-resistant gel-coat applied to the panel surfaces. INTERTEC employs a specially developed gel-coat of unsaturated polyester resin that matches the properties of GRP, which is applied as a spray before the panel is fully cured. The polyester resins of the gel-coat and panel form a chemical bond; after curing the coating provides an extremely durable, but flexible, surface finish with a high resistance to weathering and hydrolysis loads. It is also much more resistant to UV than plastic materials, such as the acrylic paints used by many metal cabinet manufacturers. The gel-coat is typically applied as a 500 micrometre-thick layer. In contrast, the acrylic finishes of steel cabinets, and of cars and trucks, are often only around 70-80 micrometres.
The only degradation that occurs with such a gel-coat surface layer is very slight thinning over time due to UV radiation – which has been measured at about 100 micrometres over periods of 30 years – and which has no overall effect on the housing’s structural integrity, stability or function. Extremely hostile conditions combining high UV with abrasive sand or dust storms can slightly increase gel-coat loss rate, but again there is no fundamental change in the performance of the underlying enclosure. The combined contributions of resistance to UV, corrosion and chemicals means that GRP field enclosures offer ultra-long and maintenance free lifecycles.
A passively cooled shelter for a difficult desert location. A coastal location means the atmosphere contains corrosive salt and chlorine, as well as sulphur from the natural gas media. Daytime temperatures can reach 55°C in the shade. Even though the shelter has a volume of 142m3, cooling is entirely passive. 85mm-thick composite-GRP walls are used.
The problems of producing solutions for remote locations are often exacerbated by the lack of a reliable electricity supply. In the case of SCADA instrumentation for a desert pipeline for instance, which requires cooling, the threat of dust and sand storms can create reliability problems for conventional active HVAC employing fans. Power consumption will also typically need to be minimised to reduce the scale (and cost) of local power generation from solar cells, wind, generators etc. Employing passive cooling technology has been an answer for many of these systems, but this tends to work well only in arid climates with large daily temperature swings.
There are now novel additions to passive cooling systems which allow passive cooling to be used in many different climate conditions – even equatorial regions. INTERTEC employs two main techniques for example. One is the use of micro pumps – which can be powered by small solar panels – to improve the circulation of the cooling media. The second is the augmentation of the performance of the cooling media – which is typically water – by means of cooler or chilled water. Again, at the heart of such solutions are enclosures with advanced insulation efficiency.
Finally, one of the most intractable problems facing many plants and processing organisations is not related to protection performance, but the scarcity of skilled engineers. In INTERTEC’s case, the response to this general problem has been to offer factory-based system building services.
This portion of our overall business has more than doubled in size recently and well over half the enclosures shipped are now in the form of turnkey instrumentation systems.
The major reason behind this trend is very interesting. Processing companies have outsourced a lot of their engineering needs to project companies. In addition to improving the ‘bottom line’ an underlying reason – at least in the western world – is the ageing population of engineering talent. Many western engineers have reached retirement age and it’s been difficult to find suitable replacements – reinforcing decisions to outsource.
If you look at the emerging economies – particularly BRIC countries – their engineers tend to be very young and have relatively short experience. There are so many opportunities that they frequently ‘job hop’ as well. On an increasing number of requests for quotation that INTERTEC sees, it’s clear that many engineers have only a limited understanding of the standards involved, and the bigger picture. This problem is amplified in many cases as it is coinciding with a growing need for more complex protection.
One of the key responses that INTERTEC has made has been an evolution of the turnkey instrumentation design and building services to encompass the most large scale instrumentation projects. Examples include shipping complete and tested skid-mounted systems, fully-equipped analyzer shelters, and perhaps some of the most complex projects of all – sophisticated ‘remote instrumentation enclosures’ (RIEs) which are being used to decentralise control and instrumentation equipment into the field, close to the process. www.INTERTEC.info
Turnkey design and building services are helping plant and processing operators to overcome the challenges of limited engineering resources. The most complex of requirements can be handled offsite.