GRP Enclosures at a Glance

What are GRP Enclosures used for?

GRP enclosures are often used for protecting various instruments (particularly those with electrical components) from the elements and from human interference and degradation (e.g. vandalism). As such, these enclosures must be extremely sturdy, and resistant to great extremes of temperature. Examples of the applications GRP enclosures are used in include housing differential pressure flowmetres and process transmitters in oil refineries, as well as petrochemical and chemical processing plants. They may also be used to contain elements, such as noise and fire, creating safer working environments within certain industries.

These enclosures are often made on a bespoke basis to suit uniquely challenging environments; in very cold climates, for instance, they may be made larger to allow workers to use them with gloves on, in addition to being built to withstand the surrounding temperatures.

What are the Benefits of GRP Enclosures?

This type of enclosure is much loved by industry as it is very durable and can last almost indefinitely, making it extremely cost-effective. Most industries also find them more practical than traditional metal enclosures as they do not require the same level of maintenance and upkeep.

What are GRP Enclosures Made of?

GRP enclosures are made from a substance known as “glass reinforced plastic”. This material is a composite material which, outside of industry, is often referred to as “fibreglass”. It is typically composed of tough and resilient plastic resin (usually an unsaturated polyester dissolved in styrene) that has strong glass fibres blended throughout.

GRP enclosures

The polyesters used in these resins are created through the reaction of various organic acids (often phthalic or maleic anhydrides) with an alcohol, such as propylene glycol or ethylene glycol. The use of different alcohols and acids produces resins with different qualities, allowing the manufacture of bespoke materials for a range of different environments and applications.

The polyester and styrene solution is “cured” until hard; during curing, molecules are cross-linked in a process known as polymerisation. The hardening process is generally instigated by a catalyst, usually and organic peroxide (e.g. methyl ethyl ketone peroxide) and an accelerator (most commonly cobalt naphanate). This is a very delicate process as if it is not done in the correct order, the mixture is likely to explode—the accelerator must be added first, and stirred in completely, before the catalyst is applied. To prevent accidents and speed up the whole process, many resins are supplied in a “pre-activated” state, so that only the catalyst needs to be added to initiate curing.

Another advantage of the resins used in making glass reinforced plastic is that they can be cured at room temperature, rather than requiring high heat or intense pressure. Ergo, this exceptionally durable material can be produced economically, without the need for expensive, complex machinery. This also factors into the availability of bespoke enclosures, as this low cost allows for the creation of small runs of an item or even one-offs, without breaking a company’s bank.




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