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Coating Protection
Published in Karan Sotoodeh, Coating Application for Piping, Valves and Actuators in Offshore Oil and Gas Industry, 2023
Coating system 7 is divided into three categories: 7A, 7B and 7C. System 7A is used for carbon steel and stainless-steel coating in the splash zone. The splash zone is an area in the sea or ocean located immediately under and above the mean seawater level. This area is at major risk of corrosion in the offshore environment, as discussed in more detail in Chapter 1. System 7A is not typically applicable for valves and actuators, since they are not installed in the splash zone. The cleanliness level of the substrate before applying coating should be ISO 8501-1 Sa 2½. The roughness of the surface should be based on ISO 8503 standard achieved by medium-size abrasive grit (G), equal to 50–85 μm. Coating 7A could be either two-component epoxy or polyester-based coating with a minimum number of two coating layers. The complete coating system should have a minimum 600 μm DFT. Polyester-based epoxy and silicate have a chemical curing mechanism. The main reason why polyester coating is proposed for the splash zone is that splash areas are exposed to a high degree of erosion and wearing. Polyester coating is a thick coating type with excellent wearing and abrasion resistance. In addition, the curing time of polyester is fast (a few hours), and it has very good corrosion and chemical resistance.
Codes and Specification Guides
Published in Mohamed Abdallah El-Reedy, Steel-Reinforced Concrete Structures, 2017
Most specifications take into consideration the method of construction—for example, whether the concrete is cast in situ, is precast, or is prestressed—as well as the weather conditions that might affect the structure. Structures that are exposed to severe corrosion include marine structures that are directly exposed to seawater, such as ports, offshore platforms used in the oil industry, and bridge supports. The parts exposed periodically to dry cycles and cycles of seawater are especially exposed to corrosion. These parts make up the “splash zone” and are considered one of the most vulnerable elements of the structures, where the possibility of steel corrosion is very high.
Tidal and Wave Power
Published in Bella H. Chudnovsky, Transmission, Distribution, and Renewable Energy Generation Power Equipment, 2017
The splash zone will often be protected by epoxy or polyester coatings—in a thickness that takes into account the special stresses—normally more than 600 µm DFT in total. For optimum protection against impact damages in such areas, zinc-rich primers are normally avoided while fiber reinforced coatings are recommended as a means of increasing the impact resistance.
Risk assessment in the maintenance of offshore caisson operations
Published in Structure and Infrastructure Engineering, 2019
Olubukola Tokede, Adam Ayinla, Peter E. D. Love, Dominic Ahiaga-Dagbui
Caissons are tubular members suspended from dead weight supports (DWSs) from the topside of an offshore platform and can weigh as much as 50,000 kg (Lee & Burch, 2014). Caissons serve either as a conduit for controlled discharge into the sea or for housing firewater/seawater lift pump. Offshore caissons are usually made of welded ferritic carbon steel that is covered by a coating to assuage the effects of corrosion and mechanical damage (Lee & Burch, 2014). They are often situated in the splash zone (i.e. the area immediately above and below the mean water level), subsea and above sea level. Access to the splash zone can be difficult due to weather conditions and often associated with enhanced corrosion and fatigue due to changing tidal conditions (i.e. wetting and drying of exposed metal surfaces) (Nash, 2011).
Time-dependent seismic fragility curves for aging jacket-type offshore platforms subjected to earthquake ground motions
Published in Structure and Infrastructure Engineering, 2018
Ali Akbar Jahanitabar, Khosro Bargi
The location of steel jacket platforms several miles offshore is not a new situation. Oil and/or gas production platforms have performed in such harsh environmental conditions for decades. By considering the severe environment of offshore platforms, these infrastructures are constantly exposed to corrosion of members, especially in splash zone, thus there is a decrease in thickness of members in time, which may affect the expected performance of structure in earthquake ground motions. Splash zone is part of the structure that is periodically in and out of the water due to influence of waves, tidal actions and settlements, therefore, the maximum corrosion rates of steel occurs in this zone of offshore structures. ‘A structure should be designed to minimize the surface area of steel in the splash zone’ (NACE Standard RP0176, 2003). Based on information obtained from Pars Oil and Gas Company, in the area where the case study platform is located, corrosion rate (Rcorr) of steel in splash zone is .3 mm/year.