Offshore units are often exposed to severe weather events such as hurricanes and loop currents. ABS, based on experience with classing and certifying a large number of these units, has verified that some of the events may cause failures that compromise the structural integrity of the units.
After 2004-2008 with hurricanes such as Rita, Ike and Ivan, the Gulf of Mexico (GoM) has since maintained a relatively quiet decade without severe weather-induced disasters to offshore structures. Fast forward to 2017, and offshore structures in the GoM have experienced a formidable hurricane season highlighted by menacing Hurricane Harvey.
When facing incoming severe tropical storms and hurricanes, it is common for offshore production facilities to activate their operational shut-down and crew evacuation procedures to protect their crew. Facilities are exposed to treacherous conditions due to surging waves, whipping winds and torrential rains, especially in the direct path of the storm. Once crews return to offshore units, operators and lessees can identify major damages and structural failures. Historically, we have seen cranes and drilling derricks with compromised structural integrity and major visible failures.
In 2005, this wave of severe storms provided a call-to-action to revisit design requirements. As a result, the offshore industry came together to discuss ways to improve structural integrity and equipment reliability. The American Petroleum Institute (API) collaborated in updating environmental requirements related to higher waves and stronger winds. This resulted in more robust API environmental requirements incorporating the recent weather events, which were adopted by the offshore industry and regulatory agencies.
ABS in-service survey regime includes structural inspection of the unit. During these regular, periodic activities, our surveyors have encountered failure cases due to structures experiencing local overstressing and fatigue that is not easily detected. Preventing these failures requires close-up inspections of critical areas and is vital to preserving structural integrity.
With over 2,000 fixed platforms and floating platforms operating in the GoM, major and minor failures are likely after hurricane exposure. The Bureau of Safety and Environmental Enforcement (BSEE) has outlined regulatory requirements for operators and lessees in the GoM to detail their inspections, plans and reports due to known and potential damages to facilities after severe weather events (NTL No. 2009-G30). These inspection plans and reports are specific to platforms subjected to hurricane force winds as defined by the National Hurricane Center.
Luiz Feijo is the Director of Projects, Offshore, and Corporate Offshore Account Managers at ABS.