Prevent Corrosion in Subsea Oil & Gas Exploration

Since 1969, FS Precision Tech (FSPT) has helped to prevent seawater corrosion for the global leaders in the subsea oil and gas industry.

Whether the focus is exploration, reservoir mapping, or long-term recovery; FSPT produces the highest quality titanium castings required to prevent subsea corrosion and ensure reliable field performance.

With FS Precision cost-effective titanium on board, subsea projects can perform brilliantly in the very worst subsea conditions. After years of supplying thousands of ocean bottom nodes and subsea connectors, we have had time and opportunity to fine-tune the solution that delivers what engineers’ require; and that solution is near-net titanium castings by FS Precision.

Learn more below…

In the article below, you’ll learn about titanium’s immunity to subsea corrosion in even the harshest of ocean conditions, and why our near-net casting process makes otherwise costly titanium an affordable solution for your business. You’ll also discover some of the deployed products already fitted with cast titanium components to prevent seawater corrosion. These products have accumulated thousands of operating hours with zero subsea corrosion in oil and gas exploration and recovery operations.

Dangers of Subsea Corrosion

What precisely is the process that converts critical subsea systems into malfunctioning rusty components? Nearly any metal that comes into contact with oxygen and hydrogen – which are found en masse in the subsea environment – will undergo the process of oxidation.

A charge imbalance exists between the electrons present within the metallic atoms and the hydrogen atoms contacting the metallic surface. Due to that imbalance, the metal is oxidized as electrons jump from their metallic hosts to find equilibrium with hydrogen atoms. After this electron exchange, the metal atoms react with the dissolved oxygen as stray ions migrate towards the surface of the metal. This chain of reactions results in the precipitation of an oxidized layer.

This complex atomic deterioration is actually a series of reactions involving both reduction and oxidation. Which, together, is commonly referred to as RedOx. This RedOx reaction is described in more detail in our article on how to prevent corrosion in chemical processing.

Steel – of which iron is a primary component – will precipitate into Iron Hydroxide, which is more commonly known as that eye-catching layer of rust. This layer of rust is exceptionally loose and readily comes free. On the other hand, aluminum will produce a more stable oxide layer simply known as aluminum oxide, or Al2O3. Nevertheless, in the turbulent subsea environment of the ocean, steel’s oxide layer will quickly deteriorate while aluminum’s will be picked apart by the abundance of chloride ions in a process called galvanic corrosion. This results in fresh layers of pure metallic surface for the corrosion process to perpetuate and wash your material away!

Seawater hastens the rate of corrosion due to its high electrolyte levels. The high salt content in this environment contributes additional ions to the water, which in turn increases the charge imbalance discussed above. Thanks to this increased charge imbalance, seawater functions as an accelerant for the deterioration of your metal components.

Titanium castings prevent seawater corrosion
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Prevent Seawater Corrosion with Titanium

How does titanium protect subsea systems from saltwater corrosion? Consider this: titanium generates its own protective shield against all forms of subsea corrosion, and will regenerate this shield the very moment it is damaged.

That statement alone cements titanium’s dominance over the alternative materials previously discussed. The following section will present the scientific explanation for titanium’s superior qualities and its ability to prevent to subsea corrosion.

Similar to other metal alloys, free titanium reacts when exposed to oxygen; but it is precisely here that all similarity between titanium and the also-rans vanishes. The nearly instantaneous reaction between elemental titanium and free oxygen produces a thin, but tenacious, film of effectively inert titanium dioxide (TiO2). This film, also known as titania, is unique in that it is impervious to damage from an extensive list of chemicals and molecules. Most relevant to this discussion is chloride ions. Unlike aluminum or steel, TiO2 is invulnerable to attack from the high chloride content in seawater, and therefore provides an armor shield that protects its underlying titanium host component against the effects of corrosion for the duration of its mission.

Perpetual attack by chloride ions is not the only threat to subsea equipment under seawater. Engineers must also be cognizant of scratches or other mechanical damage, as these are nearly a certainty when all deployment, recovery, and standard operations are considered. Mechanical impact in operation can damage coatings that are oftentimes applied to more conventional materials, such as steels and aluminum alloys. Damage to such coatings presents a localized point of corrosion, which can lead to ultimate failure.

However, the very moment titanium alloys are exposed to the corrosive elements – by scratching, impact, or other mechanical damage – the process of oxidation described above will occur, and a new layer of tenacious titanium dioxide will appear to prevent corrosion at the site of damage.

Recall that scratching or damaging the preexisting titanium dioxide layer simply exposes a fresh layer of titanium alloy, where the entire electron exchange and titanium oxidation process occurs again in the blink of an eye. In short, titanium’s layer of corrosion resistance is entirely self-regenerating and impenetrable from seawater. All without the need for any additional steps of coatings or anodizing.

Titanium’s superior ability to prevent seawater corrosion is brought into sharp focus when directly compared to more conventional materials. The U.S. Naval Civil Engineering Laboratory submerged more than 1,000 metallic specimens in seawater at varying depths for 12 to 18 months. After this submersion, the samples were measured to determine precisely the amount of material loss due to subsea corrosion.

From that data, charted in the figure above, the obvious choice for mission critical subsea operations is titanium.  The chart illustrates the amount of material loss over a given period for a variety of metal alloys submerged in seawater. With absolutely zero Mils Per Year (MPY) of corrosion loss, titanium will stand its ground better than any other against all subsea corrosion.

Near-Net Casting

At FSPT, we do our part to prevent seawater corrosion by delivering titanium’s superior properties to the subsea industry through a process known as near-net casting. Seamlessly blending corrosion resistance with a cost-effective production process for creating components with complex geometry, we pride ourselves in minimizing material and machining waste while delivering the maximum return on your investment.

This cost-effective process begins with investment casting. We take your design in all its complexity and create an exact wax copy through injection molding. From there, we coat the wax in a ceramic shell, remove the wax, and fill the shell with molten titanium. Once cooled and removed from the ceramic – combined with additional post-cast processing – your cast titanium component is ready for its first quality inspection.

When designing components for deep subsea operations, two primary concerns that are likely in the forefront of your mind are 1) casting voids and 2) maintaining tight tolerances. At FSPT, we address and resolve both concerns. Trust us, titanium investment casting is the only thing we do, and we do it very well. We are ISO 9001 certified, NORSOK compliant, and adhere to strict ASTM and ASME manufacturing process and inspection standards.

After your titanium is separated from its ceramic shell, it is put under extreme temperature and pressure – up to 15,000 psi – in a process known as hot isostatic pressing (HIPing), to collapse any internal voids which may have formed during casting. Following HIP, we typically perform chemical milling of your component, where the hard alpha case layer generated by the high temperature of casting is chemically removed.  Our chemical milling is performed in-house, and is certified by Lockheed Martin.

Up to this point, our castings hold tolerances of approximately 0.010” – 0.015” tolerance; but remember our process is near-net casting. The cast titanium is just about what you need, but we offer you the option to take your product through a final machining process to achieve even greater precision if required. As you can see, throughout the entirety of your project, FSPT holds itself to extremely high quality standards.

Our process of near-net casting and machining ensures that no time or unnecessary expense is wasted machining a solid block of titanium down to the final product.  For many of our casting projects, a fully machined version may otherwise have begun as a 75-pound billet, and been machined down to a finished geometry of only three to five pounds or less. That’s money spent on wasted titanium and excessive machining operations! At FS Precision Tech, we like to say that “We put the air in your parts so that YOU don’t have to.

FS Precision titanium castings prevent seawater corrosion of seismic nodes

Titanium Castings in Oil & Gas Exploration

As clearly illustrated thus far, FSPT near-net cast titanium is ideally suited for the harsh environment of subsea oil and gas exploration. Seismic nodes, for example, are already equipped with FSPT titanium to ensure peak operating performance for the entirety of their mission.

These Ocean Bottom Nodes (OBNs) are deployed by the thousands to take up position on the ocean floor to survey, collect, store, and ultimately yield information to map subsea oil and gas deposits. That alone is a major technical challenge. Especially when it involves deployment in 3,000m of seawater for 30 days or longer, as projects with several major seismic survey companies require.

Naturally, there is no margin for error where any amount of subsea corrosion or water penetration can destroy sensitive electronics and important survey data. Every metallic fitting, valve, or connector will be faced with an onslaught of corroding seawater from the first moment chloride laden mist makes contact even before initial deployment.

As stated previously, OBNs are deployed and recovered as a group. Thousands of units must be placed on the ocean floor, often by way of a violent high speed “node-on-a-rope” deployment system, and then subsequently retrieved via a similarly violent recovery process. Naturally, a prompt deployment and recovery decreases the customer’s turnaround time and increases the amount of data collected.

These mass deployments are a less than graceful procedure; and as the nodes are violently manipulated during deployment and recovery, mechanical damage can be expected. This creates yet another opportunity for corrosion to fester and hinder OBN operations.

It takes just one of those components, perhaps worn down as little as a few thousandths of an inch, to begin to leak, and the entire OBN could be facing tens of thousands of dollars in internal water damage, as well as loss of data.

With this knowledge, managing a precise tolerance stack-up is an absolute necessity, especially when operating at 4,000 psi on the seafloor.

It was for precisely this challenge that FSPT stepped up for the Manta project. Eliminating subsea corrosion was critical, and the need for exceptionally tight tolerances was absolute. FSPT delivered on both with the cost-effective titanium near-net castings described above. Using this method, we’ve produced thousands of near-net cast titanium housings that are an integral facet to Manta’s reliability and exceptional performance.

FSPT’s unwavering quality delivers cost-effective corrosion resistance that eradicates any amount of subsea degradation on your exploration craft. From long term exposure to the ocean, or freshly exposed metal due to hard contact, our titanium will not yield. This resolute stance keeps Manta at the very front of OBN technology, and we would be happy to extend this technology to your oceangoing project.

Titanium Wave Glider

FSPT’s expertise extends far beyond OBNs used for localized exploration. The need to prevent subsea corrosion accompanies every ocean project, as a major ocean exploration company discovered while developing an environmentally friendly method to chart the world’s oceans. Relying solely on solar and wave power, theLiquid Robotics Wave Glider was conceived as a completely autonomous ocean-going vehicle to gather sensor data for months at a time.

Titanium castings prevent seawater corrosion of wave glider components
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As stressed up to this point, all modern technology has its enemies, and the Wave Glider was no exception. Carrying such advanced equipment as energy gathering wings, sensitive sensor packages, and data storage units; this craft was faced with an assault from subsea corrosion and infinite opportunities for damage during its mission.

Included in the list of Wave Glider’s enemies are hurricanes, cyclones, and even shark attacks. Naturally, opportunity abounds for a scratch or chipped component to spiral into corrosion, or for a year’s worth of subsea exposure to take its toll on the craft’s seals.

These seals, in conjunction with precisely crafted housings, are responsible for shielding the glider’s batteries, data sensors, data storage chips, and numerous other critical systems from the harmful effects of the ocean. As with an OBN, any small amount of material degradation can lead to a substantial repair cost, the loss of the Wave Glider itself, and/or the total loss of months’ worth of critical data.

Originally fitted with costly machined components, the Wave Glider performed admirably and clinched the Guinness World Record for the longest single mission by an unmanned autonomous surface vehicle. However, fully machined titanium components are an expensive endeavor. Inordinate amounts of time and machining costs were spent simply removing material from a solid block and replacing it with empty space. This is a wasteful and inefficient use of resources given the alternative cost-efficiency available with FS Precision Tech’s near-net casting.

Faced with such immense adversaries to success, this exploration company partnered with FSPT to craft a product that checks off every technological marvel on its list, while operating with impunity against the ocean’s corrosive might, and improving cost-effectiveness at the same time. This was an ambitious goal, but that’s why our customers come to us; as this is precisely the challenge we perfected our titanium near-net casting process to conquer.

FSPT brings the largest return through minimizing material waste and maximizing the amount of titanium that goes into the final product. FSPT is currently working to apply cost-effective casting to keep the Wave Glider performing admirably and corrosion free. The Wave Glider will soon be showcasing FSPT’s commitment to maintaining a cost-effective path to titanium’s ability to eliminate subsea corrosion while contributing to technologies for a healthier planet.

Titanium castings prevent subsea corrosion of oil recovery connectors

Prevent Seawater Corrosion in Oil & Gas Recovery

Once a deposit of salvageable resources has been discovered and effectively mapped, the next phase is to shift from an exploration to a recovery operation.

This phase in the subsea oil and gas industry will once again expose critical components to the unrelenting pressure of subsea corrosion. FSPT’s experience and expertise are again available to ensure a successful recovery through cost-effective precision wrapped in corrosion resistance.

That experience stems from thousands of successful titanium connectors that FSPT has produced for the global leader in subsea oil and gas recovery system connectors. The Wet Mate Connector serves as a glowing example of our near-net castings at work to eliminate subsea corrosion and ensure the reliability required for recovery operations.

When connecting to critical systems within the ocean bottom christmas tree or manifold, it is imperative that components are impervious to the effects of seawater corrosion. Any amount of degradation over time can lead to a costly system failure and production down time. As with our OBN customers, this Wet Mate Connector customer was faced with stringent operational and NORSOK requirements for precise and complex geometry as well as immunity from subsea corrosion for as long as the component is in operation.

Using our near-net casting technology, FSPT has produced tens of thousands of connectors that continue to perform flawlessly in the field without the slightest indication of corrosive damage. Additionally, these connectors are designed to remain in pristine operating condition for at least 25 years underwater. Our customer’s statement highlights the confidence and reliability that FSPT strives to maintain;

Field-proven design providing a reliable sealing and mating mechanism throughout the life of the connector

The customer’s confidence stems from FSPT’s precise, cost-effective titanium connectors, which  continue to be produced on an ongoing basis. Operating at thousands of feet of depth – at more than 4,000 psi – and all the while resisting corrosion on all fronts.

ALL BUSINESS AS USUAL FOR FSPT

Titanium’s application in the oil and gas recovery field is nearly endless. Imagine your most mission critical systems and components on a subsea christmas tree improved top to bottom from weight reduction to immunity from corrosion using titanium.

The most geometrically challenging designs that would send machining costs skyward can be produced by our certified near-net investment casting process. And while we’re at it, we’ll improve the strength to weight ratio, provide regenerative corrosion resistance, and ensure you pay for the titanium you get, not the titanium that would otherwise be wastefully converted into dirty chips on a factory floor.

What we have is the perfect process for christmas tree components where corrosion resistance is an indisputable necessity, and reduced weight is a major operational bonus. Subsea christmas trees are exposed to endless opportunities for damage and corrosion, and the thought of your system protected by FS Precision Tech titanium should be all you need to submit an inquiry.

In addition to Christmas tree components, cast titanium’s use extends to subsea manifolds during recovery operations. Virtually every intricacy, channel, and obscure feature that might otherwise require two or more machined parts welded together could potentially be cast as one solid, robust, piece of hardware. That’s our cost-effective process at work.

In fact, the word is already out for cast titanium’s use for subsea christmas trees and manifolds. A current industry leader in subsea oil recovery systems is hard at work to deliver the latest and greatest to almost every corner of the subsea industry.  From recovery operations to ROV services, they will have a solution; and we’re delighted that their solution will include our near-net titanium castings.

FSPT is Certified Quality and Proven Reliability

FS Precision Tech is an expert in titanium castings for the subsea oil & gas industry. In fact, many of the biggest names in the business have recognized the unique potential of titanium’s technological benefit delivered via FSPT’s cost-effective investment casting technology.

NORSOK Certified Titanium Investment Castings
TS 16949 Certified Titanium Castings for Automotive Applications

While not required in the subsea oil & gas industry, FS Precision Tech has been ISO TS16949 certified for the automotive industry for nearly a decade. The practices and disciplines required for this certification are extensive, and illustrate the technical sophistication of our processes and procedures.

These TS16949 practices ensure repeatable, predictable quality; and ensure that our processes are as efficient as possible and our PPM levels as low as can be practically achieved.

Our AS9100 and Nadcap certifications for aerospace applications – while also not directly required in the oil & gas applications – further establish FS Precision Tech as the foremost advanced titanium investment castings supplier in the industry.

Conclusion

The subsea oil and gas industry operates in a harsh environment. Corrosion is incessantly probing for weaknesses to exploit while mechanical damage attempts to create new sites for corrosion in a never-ending cycle of potential deterioration. To keep your components operating at peak efficiency they must stand fast in the face of every threat the ocean holds.

FS Precision Tech has fine-tuned a very complex manufacturing process in order to create the components you need to survive the harsh environments of subsea exploration and recovery. We reliably produce cost-effective corrosion resistant components that are capable of achieving the exact precision you require. Our near-net cast titanium and years of experience in the subsea industry are at your disposal. Simply submit an inquiry here, and we will gladly discuss what we can offer you to safeguard the indomitable position of your oceangoing operations through all that subsea corrosion can throw your way.