Helix Energy Solutions Group recently unveiled its Helix Fast Response System (HFRS), a unique Gulf of Mexico oil spill response and containment package consisting of two vessels, the Producer 1 and Q4000, and dedicated subsea components. The HFRS was critical to Noble Energy receiving the first deepwater Gulf of Mexico drilling permit on 28 February 2011. Critical to development of this capability was a cutting-edge, one-of-a-kind fatigue-enhancement process called UIT.
The Producer 1, a floating production unit (FPU) is itself a one-of-a-kind vessel. One of only two ship-shape FPUs operating in the Gulf of Mexico, it had its origins as a roll-on roll-off train ferry. In order to convert the ferry, Helix conducted major redesign and modification, including widening the hull, reinforcing the main deck, and installing the production topsides. During design, Helix engineers identified several fatigue critical areas associated with the moonpool: the hull interface structure, the lantern frame, and the outer support.
To strengthen the fatigue-sensitive weldments of these structures, Helix enlisted Applied Ultrasonics to employ its patented Ultrasonic Impact Technology (UIT). UIT delivers compressive residual stress, stress relief, grain modification, increased surface hardness, and weld toe geometry modification. These effects result in significant fatigue life enhancement and suppression of stress corrosion cracking. On the Producer 1, Applied Ultrasonics applied UIT to a variety of joint geometries and designs such as fillet welds of hull T-bars and side bracket plates; large diameter tubular T-, K-, and Y-joint weldments; and large diameter pipe splice welds.
In addition to providing significant fatigue enhancement, Applied Ultrasonics’ UIT is faster, better controlled and more reliable than other post-weld improvement processes such as toe grinding or hammer peening. The end result for Helix was much greater fatigue performance along with reduced time in the shipyard.