Offshore Oil Platform Surface Preparation Using the Pliant Media Blasting Technology

Pliant abrasive media is transforming the way coating maintenance personnel approach offshore surface preparation. Pliant media users are often able to lower total job costs and provide higher quality surface preparation. 29(59,(:#2)#2))6+25(#0$,17(1$1&( Millions of dollars are being allocated toward the maintenance of offshore platforms with the goal to maximize oil production operations. A modern offshore platform extracting 40,000 barrels of crude oil per day at $18 per barrel could return nearly $720,000 a day. The opportunity costs during equipment failure or production shutdowns are large. Thus, platform owners expect innovative maintenance specialists to utilize maintenance solutions that minimize the adverse effects on production operations. Additionally, owners require performance within time, budgetary and space constraints common to offshore platform environments. As a result, maintenance professionals must carefully select appropriate products and technologies. Few new products have had the impact of pliant abrasive media. Pliant media has the significant ability to allow top quality surface preparation in close proximity to operating production equipment. An increasing emphasis on offshore preventative maintenance has led to scheduled coating maintenance long before total coating failure. Many offshore coating maintenance professionals start coating maintenance when only 3% to 6% of the coating is failing. This practice minimizes corrosion and minimizes the scale of operations required to restore the coating’s effectiveness – ultimately lowering the total life-cycle cost and the potential for future interruption to oil producing operations. Offshore Surface Preparation: Historically, painting contractors and offshore maintenance consultants have considered media cost and cut rates as key cost determinants. Conventional abrasives all offer similar cut rates and profiles with similar characteristics regarding freight, dust, rebound and waste. Except for price per pound and cut rate, no conventional abrasive material offered any exceptional benefit versus another that could be calculated into a given project. Therefore, cut rate and price per pound drove the choice to use one conventional abrasive over another, and project estimate calculations tended to overemphasize these elements. With the development of innovative abrasive blasting technologies, a variety of new, meaningful, valueoriented choices have become available. Considerations like media handling, freight costs, process cleanliness, personnel safety, containment costs, consumption rates and disposal costs are increasingly driving the decision to utilize one technology instead of another. Offshore coating professionals are beginning to consider the value of each benefit, even if they have an indirect effect on the total cost of the job. In many cases price per pound and cut rates have become secondary – especially when the benefits associated with new technologies offer higher overall cost savings. Abrasives like sodium bicarbonate (soda) have, for nearly a decade, enjoyed a leading role on offshore platforms among the new abrasive blasting technologies. In recent years, pliant media has been found to match soda as a useful tool as well. Pliant media can be defined as dual component granules containing a pliant, sponge-like material and an abrasive, cutting particle. As dual component granules, pliant media offer certain benefits commonly associated OFFSHORE OIL PLATFORM SURFACE PREPARATION USING THE PLIANT MEDIA BLASTING TECHNOLOGY David Miles, Offshore Coating Maintenance Consultant and President Progressive Technical Services, Inc Gretna, Louisiana, 70056 Tony Anni, Marketing Manager Sponge-Jet, Inc. Portsmouth, NH 03801 with conventional abrasives as well as those associated with high-tech, low dust abrasive technologies. It is one of the few technologies that combine the best attributes of each category. Pliant media technology is distinguished by its clean, dry, low dust, low rebound, reusable characteristics. It has been successfully used in offshore applications for the past three years. In addition to hands-on experience, both qualitative and quantitative data has been collected by operators, coating contractors and rig employees, revealing several important benefits. Overblast: One of the key surface preparation problems on offshore platforms is overblasting. Unintentional blasting of a nearby area is usually caused by excessive media rebound. With overblasting, damage occurs to surrounding areas and to what may have been a stable coating system. For example, blasting operations in tight crevasses around overhead pipe racks, especially below the main decking, are conducive to overblast problems since these areas are often hard to see during blasting and are hard to shield. If overblasting unintentionally removes existing coating systems, and these areas pass undetected, managers responsible for the coating project can be haunted with unscheduled and unbudgeted maintenance visits. Thus, the costs associated with the failure to control overblasting can extend well into the future long after the job has ended. As a result, offshore maintenance managers and supervisors are continuously searching for new technologies that limit overblasting. There are a number of alternative surface preparation technologies, but only a few are able to cut effectively and minimize media rebound associated with overblasting. Pliant media has been found to be effective at lowering overblast problems because of the energy absorbent physical and structural characteristics of its sponge-like component. It is also an efficient cutting technology partly because plaint media is manufactured to include such a wide range of traditional abrasive materials. One reason pliant media limits rebound is that it hits the substrate traveling at lower velocities than do other abrasive blasting technologies. Conventional abrasive technologies typically achieve strike velocities close to 660 miles per hour (at 100 psi), while pliant media products effectively hit the surface at 340 miles per hour (at 80 psi) both using a venturi blast nozzle1. Another reason why pliant media reduces rebound is because of its ability to absorb collision energy upon substrate impact. A discussion of elastic and inelastic forms of collision are useful to understand how pliant media lowers media rebound. Nearly all abrasive blasting technologies create tiny collisions, which form a series of either elastic or inelastic collisions. Inelastic collisions can be illustrated by throwing a beanbag against a wall and observing the result. Similar to what one would expect of the beanbag, at surface impact pliant media deforms, extending dwell time, dissipating potential rebound energy, flattening, exposing its abrasive components and contracting as it falls to the ground2. After leaving the substrate, theoretical calculations suggest pliant media velocities are reduced to 19 miles per hour, as compared to its initial strike velocity of 340 miles per hour3. Standard, crystalline-abrasive media, like silica sand or coal slag, form elastic collisions. Similar to a cue ball hitting another billiard ball, elastic collisions produce very little dwell time, dissipating little rebound energy on impact, and ricocheting in the manner one would expect a billiard ball to react when hit by the cue ball4. Observation, experience and theoretical calculations all suggest a significant reduction in over-blast with the use of pliant media. Pliant media’s post-impact velocity was reduced by over 94%, supporting hands-on evidence of minimal damage to surrounding offshore coating systems5. On the other hand, conventional abrasives Blasting near a “Pig Launcher” on this platform required little equipment wrapping and containment due to pliant media technology’s low rebound and low dust attributes. Figure 1 Media Consumption