Cable trays offshore: A choice of materials

摘要

The choice of material for the cable trays systems on offshore platforms, since the total elimination of Hot Dip Galvanised (HDG) steel products because of their poor resistance in marine environment, oscillates between 2 metallic possibilities i.e. stainless steel 316L (NiCrMo) and " copperfree " aluminium alloys from the 5XXX (Mg) series like 5754 (former AG3, or AIMg3) and from the 6XXX series (Mg-Si) like 6063, and Glass Reinforced Polymer like the GRP (Polyester). The 3 possibilities: - Stainless steel 316L seems to be universal regarding the aspects of corrosion and fire resistance, but is an expansive, complicated and heavy solution - Glass Reinforced Polyester GRP is theoretically the best solution against corrosion, but all the material requirements regarding sun resistance, electrostatic accumulation, smokes limit the choice to wellknown and reputed manufacturers. Additionally, because of lack of electromagnetic protection, they are not recommended for telecommunications cables - Aluminium alloy 5754 has the best quality/price ratio, offering for the same loading function ca half the price and half the weight of the stainless steel and 30% less in price and weight than the GRP, but it can not be used for the stainless steel tubing trays because of the galvanic contact corrosion between both materials Finally, now that the historical suspicion about the use of aluminium alloys in offshore, especially in Europe, has been overcome with technical founded argumentation and precautions, it is the economic aspect of price and weight which should encourage engineerings to extend the use of cable trays systems in a material which is more and more mentioned as a possible solution in general specification of oil companies.