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Improve Operational Efficiency in Upstream Facilities with Optimal Oil and Gas Fittings
Today’s offshore oil and gas operators face new and evolving challenges. Deeper wells cause the need for longer subsea tiebacks and are being used with innovative drilling/production techniques to maximize returns on investment. All onboard equipment must be carefully specified to contribute to safe and reliable operation in harsh offshore environments throughout the life of the asset. Even when working in highly corrosive environments and at increasingly high operating temperatures, owners and operators plan for a 20- to 30-year service life from their equipment.
Meanwhile, volatile market conditions and increasingly stringent environmental regulations have driven a greater need for operators to reduce their maintenance spend, increase speed to production of first oil, lessen their environmental impact, and enhance overall operational safety. Achieving such reliable asset performance is not always easy, but it is possible. And it often starts with making small, but impactful changes.
Pressurized small-bore fluid systems play critical roles on many offshore assets and onshore facilities. They’re depended upon to provide reliable, leak-tight service throughout many applications, including:
Hydraulic Power Units (HPUs)
HPUs provide power to topside, turret, and subsea production systems. HPU downtime can shut down these systems and cause significant financial losses each day. HPUs are complex pieces of equipment, and reliable oil and gas fittings play an essential role in helping the system work reliably. Learn more about considerations for HPU construction in this article.
Chemical Injection (CI) Systems
CI systems must maintain highly accurate and repeatable chemical dosage into the production well. Leak-tight performance is essential to protect personnel and the environment, and any form of downtime can result in significant production losses. A typical CI system may require hundreds of individual connections made with oil and gas fittings. Every one of them is a potential leak point.
Topside Umbilical Termination Units (TUTUs)
TUTUs, the associated umbilical connection, and isolation panels must provide a leak-tight connection as well as an isolation point between topside and subsea equipment while ensuring safe isolation for maintenance activities. These systems require high-quality and reliable fluid system components to perform their crucial functions. Failure can cause loss of containment or safety incidents, resulting in potential shutdowns and loss of production.
In each of these applications, Swagelok® FK series medium-pressure fittings represent an ideal solution to achieve reliable performance, minimal maintenance, and outstanding safety. Distinct from the standard Swagelok® tube fitting, the FK series fitting is designed to meet these needs and is an ideal oil and gas fitting for applications up to 22 500 psi (1551 bar).
Learn how we’re applying decades of experience supporting the oil and gas industry to benefit companies operating around the world.
What are FK Series Medium-Pressure Fittings?
Assembled correctly, FK series fittings deliver reliable, long-term performance in critical oil and gas applications via their unique design attributes. Their leak-tight performance can help both improve overall system efficiency and lessen your potential impact on the environment by reducing potential emissions.
This cutaway image shows how optimized seal contact can be achieved with two-ferrule fitting technology.
Anti-Vibration Fittings
The FK series’ hinging-colleting action allows for a slight amount of movement in the fitting (called “spring back”) while maintaining grip and force, creating outstanding vibration resistance. These anti-vibration fittings improve reliability in applications that regularly experience operational vibration. Spring back also helps fitting connections withstand thermal changes that can cause metallic alloys to expand and contract, which can compromise performance. The design can also be helpful in mitigating leaks related to pitching and rolling of vessels traveling to and from oilfields.
Leak-Tight Gas Seal
FK series fittings incorporate two contact zones across longer sealing surfaces—one along the tube and another along the fitting. These contact surfaces are angled slightly, providing optimized stress levels to maintain an uncompromising seal. The FK series fitting achieves such a seal with its two ferrules—the front ferrule creates a long plane of contact while the back ferrule effectively grips into the tubing itself and creates its own surface seal. Long, precisely machined surfaces on the front ferrule further contribute to a highly reliable gas-tight seal.
Ideal Grip Strength
FK series fittings feature a colleted mechanical grip using two ferrules—an ideal design for a fitting to create a robust grip. A hardened front ferrule enables the fitting to physically bite into the tubing, creating a very high pressure rating. These case-hardened ferrules deliver outstanding grip strength for uncompromising applications.
Optimized Sizing
FK series fittings are available in sizes up to 1 inch, ideal for the extreme depths of today’s drilling methods. Larger sizes allow platforms to achieve high flow rates at greater depths, creating efficiencies that other oil and gas fittings cannot.
Remakeability
The FK series differs by utilizing a female fitting body, a male nut, and pre-oriented ferrules. This design creates a unique dynamic wedge. The dynamic wedge allows for remakeable pullups by torque and provides gaugeability at initial assembly and remake of the tube fitting. The two-ferrule design creates a more robust bite into the tubing, creating a leak-tight gas seal upon initial installation and every remake.
FK series end connections provide benefits in oil and gas applications not only in fitting form, but when integrated into medium-pressure trunnion-style ball valves (Swagelok FKB series). These valves provide positive shutoff in applications up to 20 000 psig (1378 bar) and feature an advanced design that reduces seal wear, delivering the reliability operators need in challenging offshore environments.
Hear how an oil and gas equipment manufacturer is finding value by using FKB series valves featuring FK series end connections in HPUs.
A Comparison: FK Series Fittings vs. Cone and Thread
Cone and thread fittings have traditionally been chosen in critical oil and gas applications for their high pressure ratings. However, cone and thread technology has a few drawbacks when compared to FK series fittings that may contribute to inefficiency and additional maintenance needs.
Assembly
Cone and thread assembly requires specific knowledge and experience, and the assembly process can be labor-intensive and time consuming. Cone and thread fittings also require specialized tools and materials to successfully complete an installation, including coning and threading tools, along with cutting lubricant to reduce friction during the cutting process. By contrast, an FK series fitting can be successfully installed with an everyday wrench and vise. FK series fittings allow assemblers to complete installations approximately five times faster than comparable cone and thread fittings, providing a first-time, leak-tight seal.
Maintenance
By achieving a leak-tight seal upon proper initial installation, FK series fittings minimize the need for rework after asset delivery and significantly reduce the overall cost of maintenance. Over time, cone and thread fittings will eventually and naturally back off, requiring additional attention. It is estimated that a typical topside installation will require about 20% of cone and thread connections needing rework during the initial assembly and pressure test. By contrast, a properly installed FK series fitting should require almost no rework due to its simple installation procedure and the ability to verify installation using a gap gauge tool.
Complexity
Cone and thread fittings require additional antivibration components within systems that experience regular shock or vibration. If installed without antivibration glands or by a technician who is not intimately familiar with the preparation and assembly process, the cone and thread fitting can leak far earlier than anticipated by the operator. FK series fittings are designed to resist vibration and help prevent this issue without additional components.
Use Case Example: Time Savings That Add Up
Choosing FK series oil and gas fittings over cone and thread fittings can yield considerable time savings, which is especially important when fabrication time is compressed to meet constantly moving deadlines for packages and projects. Consider fabricating a medium-pressure skid package for an offshore topside application. Say the skid will use 316 stainless steel tubing and fittings, and a single trained installer will make up each of the skid’s 500 connections.
The time to complete installation of either oil and gas fitting type will depend on the tubing diameter, material type, and skill level of the installer.
It is reasonable to assume the FK series fitting takes approximately one minute to install from start to finish. A typical cone and thread fitting can take 5 minutes (or five times longer).
The total time to complete the skid’s 500 fitting connections with FK series fittings is approximately 2000 minutes (33.3 hours) compared to 10 000 minutes (166.7 hours) for cone and thread fittings.
Watch a side-by-side installation demonstration to see the time savings for yourself.
Read more about the differences between cone and thread fittings and FK series oil and gas fittings in this article.
Material Selection Considerations
Because oil and gas platforms operate in harsh environments where corrosion is a constant concern, material selection when specifying all manner of critical components is important (which you can read more about in this article). To best protect your assets from corrosion-related issues, FK series fittings are available in several material options, including alloy 2507, alloy 625, and 316 stainless steel.
Alloy 2507 specifically provides our highest levels of corrosion resistance in high-chloride applications, helping to prevent issues on offshore platforms. Composition includes nickel, molybdenum, chromium, nitrogen, and manganese, offering excellent resistance to general corrosion, pitting corrosion, crevice corrosion, and stress corrosion cracking (SCC), while maintaining weldability. Additionally, 2507 provides higher yield and tensile strength for increased pressure ratings, allowing FK fittings to achieve high-pressure capabilities with lower wall thickness, allowing for increased flow of fluids.
Swagelok material science specialists are available to help you select an optimized combination of materials to best suit your needs in the most cost-effective manner based on deep understanding of factors that contribute to corrosion, as well as the properties of materials that help fight it.
Learn more about different corrosion types typically seen in oil and gas operations, including how to identify and counteract them, in our Materials Selection Guide.
A Strong Choice for Today’s Oil and Gas Applications
The challenges faced by today’s upstream oil and gas operators point to the need for high-quality, reliable components that can deliver high levels of performance in unforgiving applications. This includes oil and gas fittings optimized for effective operation in demanding environments.
Swagelok FK series fittings offer a way to reduce maintenance costs, increase speed of production, mitigate environmental impact via leak reduction, and enhance overall operational safety. Their robust design, simplified assembly process, and availability in high-performing alloys make FK series fittings an optimal choice for the demanding nature of today’s upstream oil and gas industry. Plus, FK series fittings are backed by our full suite of service offerings, including specialized training, on-site evaluations, design and assembly services, and much more.
Get in touch with oil and gas fluid system specialists to start a conversation about how you can achieve more efficient installations and greater application reliability with advanced fittings technology.
