Underwater steel structures

This specification covers a cold-applied coal tar painting system for undergroxmd and underwater steel structures, consisting of two cold-applied coats. This system is suitable for use on parts or structures exposed in Environmental Zones 2C (fresh water... 

Buoyancy in some form is employed in nearly all categories of underwater and surface systems to support them above the ocean bottom or to minimize their submerged weight. The buoyant material can assume many different structural forms utilizing a wide variety of densities. The choice of materials is severely restricted by operational requirements, since different environmental conditions exist. For example, lighter, buoyant liquids can be more volatile than heavier liquids. This factor can have a deleterious effect on a steel structure by accelerating stress corrosion or increasing permeability in reinforced plastics. 

Zinc dust coatings are utilized in large quantities for the protection of structural steel, also including underwater steel construction and ship building [5.56]. Zinc dust is used in organic and inorganic binder systems (alkali silicates, ethyl silicates) [5.56, 5.105]. 

Seica, M.V., Packer, J.A., 2007. FRP materials for the rehabilitation of tubular steel structures, for underwater apphcations. Composite Structures 80, 440—450. 

Shamsuddoha, M., Islam, M.M., Aravinthan, T., Manalo, A., Lau, K.T., 2013a. Effectiveness of using fibre-reinforced polymer composites for underwater steel pipeline repairs. Composite Structures 100, 40—54. 

Another loading condition in underwater applications is the application of external hydrostatic stress to plastic structures (also steel, etc.). Internal pressure applications such as those encountered in pipe and... 

In the oil and gas industry, the term abandonment generally refers to the activities undertaken to remove the structures used to sustain oil and gas production after the production is ceased. The structures range from a few tonnes of steel on the seabed to a complete platform constructed from around 30000 tonnes of steel framework. The task of removal requires extremely detailed and careful planning as well as substantial resources. Explosives are very efficient tools for cutting steel underwater and have been the preferred choice of many offshore operators for over 40 years. Also explosives offer the flexibility of a single controlled cut or multiple simultaneous cuts for remote and safe toppling of very large structures [129]. 

Forgeson, B., Southwell, C. Alexander, A., Corrosion of metals in tropical environments, part 3-underwater corrosion of ten structural steels, Corrosion, 16, pp 105-114, 1960. 

Du Font s thermoplastic polyester elastomer (TPE) Hytrel has been used in an underwater fiber optic cable produced by Shiplex Wire and Cable Corporation. The elastomer is used to position the fiber optics and is chosen because of its modulus properties that help prevent microbends in the fiber optics. The thermoplastic polyester elastomer is extruded over a central steel wire that imparts strength to the cable. Six fiber optic strands with a diameter of 5 mils each are then positioned and covered by a second Hytrel layer, which is added as part of a coextrusion with nylon to obtain greater abrasion resistance. Additional steel layers and a longitudinally formed copper tape are added, and the whole structure is then enclosed in a polyethylene jacket. 

The fuel building Is a rectangular, reinforced concrete structure containing a reinforced concrete, stainless steel lined fuel storage pond for underwater storage of new and Irradiated fuel. Separate stainless steel lined compartments are provided for underwater transfer of new and Irradiated fuel and to allow loading of Irradiated fuel Into the transport flasks. The... 

Finally, to expose the lower plenum, the core support floor had to be raised and removed. During construction of the plant the core support floor (CSF) as installed weighed 270-ton. The CSF is a five-foot-thick, 31-foot-diameter, concrete structure encased in a carbon steel liner. Since the CSF was radioactive, steel shielding plates were positioned on top of the floor prior to its removal with a hydraulic jacking system (Fig. 7). Shield water in the PCRV protected underwater divers who entered into the steam generator ducts that went through the core support floor. Once inside these ducts the divers had to cut their way out to access the underside of the CSF. Once under the CSF the divers were used to sever all connections so it could be raised and removed. The CSF, due to the added weight of the shield plates, the attachments on the underside that had been cut and any entrained water... 

Another rapid loading condition in underwater applications is the application of external hydrostatic stress to plastic structures (also steel, etc.). Internal pressure applications such as those encountered in pipe and tubing or in pressure vessels such as aerosol containers are easily treated using tensile stress and creep properties of the plastic with the appropriate relationships for hoop and membrane stresses. The application of external pressure, especially high static pressure, has a rather unique effect on plastics. The stress analysis for thick walled spherical and tubular structures under external pressure is available. 

Electrochemical protection is divided into cathodic and anodic protection. Cathodic protection based on the change of potential of a metal in the negative direction is realized in electrolytic environments, in most cases neutral, mainly of steel and reinforced concrete structures. A well-designed and correctly realized CP reduces the corrosion rate to almost zero. In practice it is realized with the use of an impressed current or protectors (galvanic anodes). The scope of application is enormous and continuously increases. With the use of this technology it is possible to protect vessels and ships, docks, berths, pipelines, deep wells, tanks, chemical apparatus, underground and underwater municipal and industrial infrastructure, reinforced concrete... 

The shielding and containment for a modern BWR typically comprises a steel or concrete inner containment (the drywell) connected by underwater ducts to a suppression pool full of water, the purpose of which is to condense the escaping steam in the event of a circuit breach. Two layouts which have been adopted are the bulb-and-torus design (Fig. 9.2) and the more recent weir wall construction described in detail later for the Grand Gulf BWR. The standard PWR containment consists of a concrete structure with either a... 

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