<http://schema.org/articleBody>
" HOUSTON -- When Hurricane Katrina roared through the Gulf of Mexico three years ago, it ripped the drilling rig atop Royal Dutch Shell&amp;#039;s Mars platform from its clamps and slammed it back onto the top deck in a crumpled pile of steel. But the company&amp;#039;s Ursa platform, just 7 miles to the east, emerged unscathed as 80-foot waves and 175-mph winds hammered the region. A storm doesn&amp;#039;t necessarily wreak havoc on all installations it touches, said Peter Marshall, a retired Shell engineer and consultant, as operators continued preparations Thursday for Tropical Storm Gustav&amp;#039;s expected move into the energy-rich gulf. Some structures may get the brunt while others don&amp;#039;t, or a storm may expose an unanticipated weakness. In the case of the two Shell structures, the platforms themselves withstood the storm, Marshall said. The damage at Mars stemmed from clamps and bolts that failed to hold its drilling rig to beams. The repaired rig now has stronger clamps. &amp;quot;After an accident like that, people are a lot more cautious,&amp;quot; Marshall said. &amp;quot;That particular accident is very unlikely to happen again - either because of improvements or the fact that substandard platforms aren&amp;#039;t here anymore.&amp;quot; Hurricanes Katrina and Rita destroyed more than 100 platforms and shut in 92 percent of oil output and 83 percent of natural gas production. A shut-in involves closing safety valves below the water&amp;#039;s surface to prevent oil and gas releases. Gulf operators eyed Gustav closely Thursday as workers nonessential to production, such as cooks and cleaning crews, were evacuated. Production was largely unaffected, but some companies said they expect substantial shut-ins through the weekend in anticipation of the storm.   RELATED STORIES * PLUS: Onboard High-Tech Oil Rig, U.S. Answers to Gas Prices  * TECH WATCH: Tracking Saharan Storms to Predict U.S. `Canes  * FIRST LOOK: Extreme Simulator to Analyze Homes vs. Hurricanes  * SURVIVAL GUIDE: Gear, Prep and Evacuation Plans You Need  * SPECIAL REPORT: Lessons of Hurricane Katrina, 3 Years Later    Workers watch steel pipe descend through the drill floor of Shell&amp;#039;s Noble Clyde Boudreaux platform last year in the waters of the Gulf of Mexico. (Photograph by Ed Keating for Popular Mechanics) "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/science/a12217/4279511/>