Over the years , circumstances surrounding oil & gas operations have changed significantly , and keeping fluid systems and their basic components in peak working order has become increasingly important . As operational costs continue to rise and labor is in short supply , more platform operators are focused on the goal of finding well-built components that last longer and perform at a high level over their lifetimes .

Additionally , platforms are becoming less accessible as they move farther offshore , and therefore , changeouts of equipment are getting more costly . Finally , drilling operations are going deeper than at any time in history , so components must be rated to accommodate the increased pressures that occur at those depths .

Offshore Drilling

Offshore drilling platforms are complex operations . Between the instrumentation lines , hydraulic power , chemical injection ,

deluge systems , and numerous other components , platforms often consist of nearly 50,000 feet of tubing , more than 20,000 fluid system components , no less than 10,000 fittings , and up to 8,000 mechanical connections . Maintaining such a system safely and reliably can be challenging . Choosing the proper components and materials is crucial to keeping drilling platforms operating and avoiding pitting , see Figure 1 , and crevice corrosion , see Figure 2 , which are more likely to occur on drilling platforms than in other applications .

To understand how these components will perform , oil & gas instrumentation engineers should equip themselves with the knowledge and training necessary in metallurgy and materials science . Working with reliable suppliers who can help train engineers on these important elements of component selection is vital . The best training programs focus on materials science to aid professionals in understanding how to obtain the best field service results .

Figure 1 : Though 316 / 316L stainless steel has been the standard for oil and gas operations for years , it is particularly susceptible to pitting corrosion .

Alloy Evolution and Why Training Matters

Harsh oceanic conditions often lead to corrosion , see Figure 3 , which will negatively affect a platform long before it ceases operations , but replacing components on an ongoing basis is costly and risky . Therefore , the goal is to extend component lives as long as possible . Yet , deciding which materials to select and specify is not an easy task , see Figure 4 . The answer depends on what the individual is trying to accomplish and what the specific application is .

Figure 2 : Crevice corrosion ( top ) often occurs between tubing and tubing supports ( bottom ). It is often caused in deepwater oil and gas applications by exposure to sunlight and saltwater .

In the past , 316 stainless steel tubing – which forms a passive , chromium-rich oxide layer on its surface to inhibit corrosion

– was the primary choice for oil & gas applications . Its time-tested performance met the needs of most applications , and under the right conditions , can still do so , Figure 5 . With the evolution of the oil & gas industry and the increasing complexity of operations , higher-performing tubes and fittings are now required – and 316 stainless steel is not always up to the task .

Fortunately , other alloys are available that resist corrosion , including super duplex stainless steel and 6-moly stainless steel . Although these alloys often perform better than traditional 316 stainless steel , they may not be the answer for every application on an offshore drilling platform .