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Introduction
Published in Srinivasan Chandrasekaran, Offshore Semi-Submersible Platform Engineering, 2020
Based on the purpose and application, risers are classified as drilling riser, production riser, injection riser, workover riser, and export/import risers. Drilling risers are the primary conduits, deployed for drilling the oil wells. Marine drilling risers are conduits of a large diameter, consisting of the main tube and external auxiliary lines. Pressure in the main pipe is kept low so that the pipe can receive input from the auxiliary lines, which are maintained at a higher pressure. Drilling risers are connected to the subsea blowout preventer securely. As marine risers are suspended during installation, they float at greater water depths. Hence, they are controlled using top-tensioners to ensure the stability of the platform during drilling. Alternatively, they are also attached to buoyant tubes to reduce the top tension.
Diffusers
Published in Lorin R. Davis, Fundamentals of ENVIRONMENTAL DISCHARGE MODELING, 2018
Diffusers consist of a manifold pipe, closed at the end, with discharge ports spaced along its length. The ports can be simply holes in the side of the manifold as shown on Figure 2.3 or fitted with risers as shown on Figure 2.4. The risers may have one or more discharge ports. Risers are used to raise the discharge point above the manifold, to allow the manifold to be buried or to allow check valves to be used to prevent back flow. One of the check valves that is becoming more popular with diffuser nozzles is the rubber “duck bill” type check valve made by the Red Valve Company,* since they do not stick or foul like mechanical swing check valves do.
Constructions and related matters relevant to environmental health
Published in Stephen Battersby, Clay's Handbook of Environmental Health, 2023
John Bryson, Stephen Battersby
Wet risers are used to supply water within buildings for firefighting purposes and should be in fire-resistant shafts. The provision of a built-in water distribution system means that firefighters do not need to create their own distribution system with which to fight the fire and avoids the breaching of fire compartmentation by running hose lines between them. Although it should be noted that the risers themselves (as for any other services) should be properly fire stopped as they pass through the building; otherwise they could compromise the compartmentation. Wet risers should be inspected and tested regularly to ensure the equipment is functioning correctly and ready for use.
Static analysis and verification of flexible riser for underwater compressed air energy storage system with different boundary conditions
Published in Ships and Offshore Structures, 2021
This problem can be further studied from the following aspects: The static model could be modified to account for the material torsion, which is the cross-sectional rotation along the centreline.The vortex-induced vibrations in the dynamics, which are also an important factor in the fatigue fracture of flexible risers, could be studied.The effect of the flow rate, velocity, and pressure of the air pressure inside the riser should be considered.