A Comparison of Fatigue Life Improvement Methods for an Existing Offshore Jacket Platform Structure

Abstract

Most offshore Jacket platforms are installed in shallow water, less than 300 meters for drilling and production of oil or gas. They are normally fixed to seabed and constructed as three dimensional frameworks with tubular members as structural elements. The surrounding environment around offshore platform is affected by various environmental loads that comprise of wind, waves, currents and earthquake. The major load in such structures is wave loading, repetitive in nature which causes time varying stresses that results global and or local fatigue damage on the offshore steel structure. This study includes fatigue assessment of a selected jacket structure using ANSYS software. This study concentrates mainly on the stress reduction at joints by various methods under the applied cyclic loading. The various methods considered in this study are providing: joint cans with branch stubs, grouted connections, FRP wrappings, stiffeners at the joint section. A comparison of various methods for reducing the hotspot stresses which increases fatigue life are studied and the most effective one is recommended.

Numerical hydrodynamics-based design of an offshore platform to support a desalination plant and a wind turbine in Egypt

“…In regards to wave condition, Ras Ghareb area faces rough marine conditions. The significant wave height and wave period were determined for a 1-year return period in the Red Sea zone as 2.15 m wave height and 5.08 sec wave period [23]. Moreover, maximum wave height and the highest time period occurred for a 1-year return period are 5.18 m and 6.5 sec and for 100-year return period are 7.92 m and 8 sec [24 and 25].…”

Conceptual Design and Numerical Analysis of a Novel Floating Desalination Plant Powered by Marine Renewable Energy for Egypt

“…The average draft is 50 m in the selected area [26] Distance from the shore: Maintaining a buffer zone of a 2 km distance from the coastline has been considered far from any anchoring area or oil industry installation, and other activities. Environmental loads: Based on the database and historical weather information, significant wave height and wave period were determined for a 1-year return period in this area, producing values of 2.15 m for the wave height and 5.08 s for the wave period [27]. Moreover, the maximum wave height and time period for one year are 5.18 m and 6.5 s and for a 100-year return period, are 7.92 m and 8 s, respectively.…”

“…Environmental loads: Based on the database and historical weather information, significant wave height and wave period were determined for a 1-year return period in this area, producing values of 2.15 m for the wave height and 5.08 s for the wave period [27]. Moreover, the maximum wave height and time period for one year are 5.18 m and 6.5 s and for a 100-year return period, are 7.92 m and 8 s, respectively.…”