Some of the most powerful examples of motion, both controlled and uncontrolled, can be found where oil rigs live—way out at sea. It’s in these environments where gale-driven seawater can hinder the productivity of both the people driving pipe deeper and deeper into the sea and those responsible for ensuring this work is done safely and efficiently. Attendees of the recent Offshore Technology Conference (OTC) in Houston got the chance to learn why it’s so important to the people on these rigs that drilling pipes on their rigs remain secure.
Assemblies that vertically bundle and hold the pipes used in drilling are called fingerboards. As rig teams drill deeper and deeper, they continually add pipes that reach 90 ft in length. A typical rig can have hundreds of these pipes stored on deck before they are used. These heavy lengths of pipe must be secured in place at the top, and that’s the job of these pool-cue-rack-like fingerboards. Within this matrix-style racking system are pneumatically actuated latches to lock the pipes in place, controlled by an upstream pilot valve.
In a perfect environment, this can be a pretty simple automated application. However, the seas hate simplicity. That’s proven when sophisticated equipment is exposed to the corrosive effects of saltwater sprays. The automation used to ensure latching happens is often perched up in the air with those racks, so when they fail, changing a simple sensor or actuator can become hazardous duty.
“Companies in the drilling industry have told us that unlatched tubulars, such as drill pipes and casings, are an ongoing safety challenge,” says Craig Correia, director, Process Industries, North America, for Festo Corp., Islandia, N.Y. “When you try to solve this safety challenge by installing electronic sensors and associated wiring 75 ft or more above the deck, they must be robust enough to handle extreme temperature swings, impervious to corrosive environments, and explosion-proof.
“All are difficult requirements for a reliable and serviceable electronic-based system,” Correia adds. “Open loop systems with no feedback are common but they have challenged us to develop a closed loop solution.”
This artist rendition depicts a fingerboard assembly for managing drill pipes.
An Easier and Safer Way
In recent years, OEMs behind these automated rig-based systems have been looking for ways to limit their equipment’s direct exposure to such hostile elements. In response, Festo introduced OTC attendees to an Industry 4.0-based VTEM Motion Terminal system enabling the remote control, measurement, and observation of latch engagement. Electronics and sensors required for a closed loop control system are, thus, kept far away from those latches and the elements to which they’re exposed—yet crews are ensured of latch closure.
Any necessary changes to this system can be made in a decentralized environment. This reduces both the bandwidth required for communication and the complexity of controlling and programming tasks for the entire system.
“This means they don’t need to put an electrical sensor at the top of that rack,” Correia explains. “They only have to put a pneumatic actuator up there with a single tube. The VTEM Motion Terminal can accurately determine the state and position of the pneumatic actuator on the latch. So it’s only air, not electricity, being managed on the rack. This simplifies a pain point up high and brings intelligence down to the deck level, where it will be in a protected cabinet.”
In the fingerboard-latch app of the VTEM motion terminal, the position of each latch can be measured from closed to 100% open by analyzing actuator and supply line air pressure and flow. Additional scenarios such as blocked tube, air leaks, and physical impairment of the latch or actuator can be sensed and communicated. The system can display latch position graphically via human machine interface (HMI), communicate to a supervisory controller, and be available to be pushed to a cloud based solution via an IoT embedded gateway. A product key with digital map transmits information clearly and ensures traceability.
Advancements in Pneumatic Cylinders
A second advancement for this application is within the pneumatic cylinder itself. For safety reasons, a spring-return actuator is commonly used for fingerboard latches. The volume behind the spring typically intakes and exhausts to atmosphere—which leads to premature corrosion of standard cylinders. With Festo’s cylinders, a “rebreather” pneumatic function instead routes intake and exhaust air to the supply line. This ensures all compressed air entering both sides of the actuator is clean and dry. In addition, an enhanced wiper seal is used on the piston rod, and the spring has a corrosion-resistant coating.
This image depicts a latch with Festo’s pneumatic cylinder for opening and closing the latch. Used in conjunction with Festo’s VTEM motion terminal, proper opening and closing is confirmed with no need for electronic sensors to be used in the latches.
An App for Almost Everything
The VTEM Motion Terminal’s app-controlled platform is part of an industry-wide movement that carries another important acronym: cyber-physical systems (CPS). The National Science Foundation’s definition of CPS states these are engineered systems built from, and depending on, the seamless integration of computational algorithms and physical components. This is expected to change the way people interact with engineered systems—just as the internet has transformed the way people interact with information. CPS is expected to reduce system complexity and drive innovation and competition in both the process and manufacturing sectors.
Smart actuator technology in the motion terminal includes a bridge circuit with integrated sensors made up of four 2/2-way valves in the form of piezo pilot and diaphragm poppet valves. The valves’ ability to pressurize and exhaust independently of one another gives the user access to a wide range of conventional valve functions using a single valve. This valve technology can also be used to carry out proportional pressure regulation and complex control solutions. In addition to the oil-rig-based system just outlined, here are more examples of motion apps serving other industries:
The soft stop app helps machine builders and end users implement dynamic-yet-gentle positioning motion without wear-prone shock absorbers.
The ECO drive app operates as an actuator with the minimum pressure necessary for the load, allowing energy savings of up to 70%.
The leakage diagnostics app detects and localizes leaks thanks to separate diagnostic cycles and defined threshold values;
The directional control valve function app lets machine builders and end users modify a digital valve’s standard directional control functions, including replicating 4/2, 4/3, and 3/2 at any time and as often as necessary, even during operation. This lets organizations respond to many requirements at the touch of a button using a single valve platform.
The proportional pressure regulation app saves space and hardware costs by combining the functions of two individual and independent proportional pressure regulators in one valve (also handles vacuum).
The model-based proportional pressure regulation app stores fewer boundary parameters for the system (e.g., tube length, tube diameter, and cylinder size), ensuring maximum accuracy as the app compensates for decreases in pressure and volume.
The selectable pressure level app saves energy by setting several pressure levels; it can control speed by adjusting the flow control valve setting.
The supply and exhaust air flow control app replaces separate flow control valves on the actuator and allows designers to set tamper-proof travel speeds; an option enables dynamic flow control adjustment.
The presetting travel time app. The exhaust air flow control function adapts itself to the travel time and then maintains it; it automatically adjusts the values in case of influences such as increased friction due to wear.
The proportional directional control valve app. Two proportional flow control functions are integrated in one valve and on one platform.
In summary, the “appification” of pneumatic systems will result in less complexity, and therefore:
- Lower human error and fewer system failures;
- Less assembly work;
- Easier replication of systems;
- Fewer work stoppages and production errors;
- Faster diagnostics;
- Shorter machine setup and adjustment times.
In this new environment, a single motion terminal will replace up to 50 different hardware components based on app combinations. The Motion Terminal concept will open the door to standardized platform concepts for systems and system modules in a wide variety of environments. This will reduce hardware costs all along the supply chain as it lowers the number of different components to be defined and stocked as spare parts by the machine builder or end user. For example, valve variety is reduced to one and pressure sensor and flow control valves are integrated.
By focusing on a flexible CPS platform at the start of a project, even the planning stage, the search for suitable products and suppliers may even be shortened. And with fewer components, CPS could minimize the process steps required for logistics and warehousing and reduce the cost of data management and maintenance.