Literature review: Investigation into the degradation of Ex ‘e’ enclosures manufactured from glass reinforced polyester/polymer (GRP)

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  • Published: February 2022
  • REF/ISBN: 9781787253018
  • Edition: 1st
  • Status: Current

The research is concerned with two main aspects of an increased safety enclosure: ingress protection and impact resistance. Minimum levels of these parameters that should be maintained are discussed. While material degradation will not necessarily lead to immediate and catastrophic failure of the enclosure, it will slowly reduce the capacity of the enclosure, to fulfil its increased safety function.


The focus of the study is on glass reinforced polymers, and glass reinforced polyester (GRP) in particular, as used for Ex 'e' enclosures. Research is intended to provide a broad investigation of degradation/ageing processes, particularly those relevant to the petrochemical/energy industry, and a range of environmental conditions, including those in the Middle East. It includes consideration of:
− saline atmospheres (chlorides);
− UV radiation;
− solar heating (infrared radiation), and
− sand abrasion.


The following areas are considered to be out of the scope of this investigation:
− The investigation of likely degradation products including micro fibres and microplastics.
− Enclosures made from non-glass reinforced polyester materials (e.g. carbon reinforced plastics, metals) even if these are available for the purpose.
− Investigation of surface treatments (such as adhesion promoters, dispersion additives) used on glass fibre or other ingredients. However, polyester gel-coat is not considered a surface treatment (because it is applied first to the mould) and, therefore, is in scope of the research if relevant to Ex 'e' enclosures.
− Synergistic effects of e.g. sealants, or atmospheric chemistry on the GRP material, except in general terms where relevant.
− Attack by biological micro-organisms can occur (HSE), but is outside the scope of this study.

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