Roughneck Mag

Protecting Instrumentation in Extreme Climates

Many locations for field-based process instrumentation equipment in Eurasia, especially Siberia, can present the most extreme climatic conditions. Providing high quality environmental protection for such applications benefits greatly from experience.

Intertec specializes in field protection enclosures to protect equipment and over its 40 plus year history, it has developed probably the most complete portfolio of instrument protection components and equipment available worldwide. Every common environmental protection can be configured using the range, from simple frost/condensation protection, to the most demanding requirements – such as extreme winterization.

One of the key technologies underpinning the range is the material used for the main enclosure structure. Intertec enclosures, cabinets and shelters are all fabricated using a special high-performance grade of glass fibre reinforced polyester (GRP). This fire-resistant material is very stable, almost immune to damage from chemical and petrochemical media, and has a strength that almost matches stainless steel – for just a quarter of the weight.

Environmental protection components are available for users to build their own protection enclosures. Alternatively, Intertec offers a turnkey service that will provide complete, prefabricated hook-ups for field instrumentation: the service covers the complete process from engineering design, to assembly and on-site delivery.

Turnkey Solutions

If turnkey protection solutions are requested, this route allows Intertec designers to incorporate field-proven techniques into the enclosure. The field experience behind these expert techniques means that they will sometimes safeguard end users against costly field failures or even plant shut-downs that might occur due to conditions or circumstances that might not be foreseen during the design cycle by the average engineer.

Intertec has a very large database of designs covering all common field instrumentation applications, from instrument connection to sampling points (see Figure 1). Its designs are optimized for reliability and use know-how derived from thousands of applications around the globe (the company has shipped well over half a million field protection enclosures).

This approach does not restrict users from customizing the solutions: many users have preferred suppliers of process transmitters for example – and sometimes supporting components such as manifolds and tube fittings – such preferences can easily be accommodated in a design. Users can also choose from traditional connection or ‘hook up’ configurations or more innovative close-coupled solutions (which are increasingly being favoured today to enhance measurement accuracy).

Turnkey systems are also fabricated using common layout principles that reduce the variability of instrument installation and provide a site standard – simplifying ongoing maintenance.

Figure 1: Assembled and ready-to-connect field instrumentation protection systems are available from Intertec. Enclosure opening styles and many other features can be specified to suit the need.

Extreme Protection

The construction principles employed for the main enclosure elements means that designs can be adapted easily for the most demanding environments such as extreme winterization.

Achieving a stable thermal environment inside such structures depends on good insulation. Most rigid cabinet designs usually feature a layered construction, with outer and inner skins sandwiching some internal layer of insulation such as mineral wool. The usual way of achieving good insulation properties is by increasing the thickness of insulating materials. When designing environmental protection enclosures, the construction materials and processes become very important. Galvanized or stainless-steel enclosures are made of materials with high thermal conductivity (λ ≈ 15 – 50 W/m K). Any metal connections between outer and inner shells provide a thermal shortcut. And with metal constructions, it is almost impossible to avoid metal parts in some design elements because the stability of this type of housing is based on bent sheet metal, and insulation materials are typically soft.

An alternative technical solution to manufacturing enclosures without thermal shortcuts is a sandwich-construction housing based on glass-reinforced polyester (GRP) skins. This is the approach favoured by Intertec. The thermal conductivity of GRP can be two orders of magnitude less than metal (λ ≈ 0.2 W/m K).
A sandwich construction means that enclosure parts can be joined using bonding techniques, avoiding thermal short cuts between the inner and outer shells. The overall thermal insulation of a GRP sandwich shelter is typically more than twice as good as a steel shelter with the same insulation thickness – reducing and simplifying the demands of the internal protection components required such as heating or cooling elements.

Varying the thickness of the intermediate insulating material provides the means to improve the thermal stability of the enclosure for different winterization requirements. The basic construction approach is equally suitable for fire protection needs. Enclosures or cabinets with GRP skins sandwiching around an 80-mm thickness of mineral wool are adequate to maintain fire protection for 30 minutes for example. Thicker insulation layers can extend the fire protection interval all the way to 120 minutes. Shelters built to meet this demanding specification can be created using an insulation thickness of the order of 160 mm.
Intertec offers a typical cabinet designed for fire protection of valve actuators at the Kirishi refinery. In this instance the independent Russian institution, Pozhaudit, tested the design to verify the performance level (the test demonstrated that the internal temperature did not rise above 60 Celsius for at least 30 minutes when subjected to an oil based fire with a temperature of around 1000 C).

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