Hydraulic Accumulators

June 10, 2017

Marine Riser and Tensioner System Hydraulics – Revisited.

Last year we discussed CPI sensor solutions for Oilfield hydraulic accumulators and cylinders, but in the fast-paced world of oilfield engineering, that was a long time ago.

For instance in 2016, CPI didn’t have a fully subsea capable (qualified to 5000ft), intrinsic safety rated (ATEX, IEC-EX) linear position sensor for hydraulic cylinders and accumulators.

But now we do. Meet the CPI SL2000

The CPI SL2000 was specifically designed to meet the needs of heavy duty hydraulic system manufacturers, who seek robust, accurate, and reliable solutions to position or charge sensing in long stroke cylinders or accumulators.

With a high-tech mechanical assembly and space-age material science, the CPI sensor surpasses the durability of all other sensor measurement technologies as well as other draw wire sensor technologies. For harsh duty internal or external cylinder applications, CPI’s technology may be the most hardened, reliable solution in the world.

Marine Riser And Tensioner System Hydraulics

Tensioner systems come in many designs but typically employ multiple hydraulic cylinders for stabilizers or the riser will buckle when the rig moves downward, and stretch when the rig rises. If you gather around the moon pool of any offshore rig or vessel during a storm you’ll see a riser/tensioner system hard at work. These systems use a bank of hydraulic accumulators to drive piston displacements in reaction to the heaving of a heavy sea. It is crucial that the tensioner can manage differential movements between the riser and the rig in real time to prevent shearing or undue stress on the wellhead. These huge and powerful accumulators are constructed using a gas and hydraulic fluid and can drive displacements from 10 to 15 meters.

Using the SL 2000 in Oil Platform Hydraulics

Because the core measurement technology of the sensor is mechanical draw wire, there are far less things to go wrong with a CPI sensor in a harsh environment. Furthermore the core sensing mechanics are incompressible allowing the sensor to operate inside the hydraulic cylinder, submersed in hydraulic fluid at full pressure. This kind of mounting flexibility makes for a clean integration into most cylinders and small external form factor for applications where a short magnetostrictive sensor is used as the transducer.

A few other notes about our linear position sensor technology.

  • Because of our innovative draw wire design, we can easily operate for the long stroke lengths in a marine riser tensioner system. CPI sensors have operated with high accuracy to 15 meters of stroke.
  • The CPI SL2000 can be mounted in any hydraulic cylinder or hydraulic accumulator that is at least 8″ ID.
  • Hardened operation is a standard feature of our design. Our sensors have no sealed cavities and are completely immune to pressure. As such, they can be mounted on the oil or gas side of the cylinder, or even outside the cylinder.
  • A patented LVDT based implementation means the core sensing technology is completely non-contacting and immune to local EMI distortions.
  • Our sensor is the only hardened sensor in the world that works with telescoping hydraulics.

Riser Disconnect Sensing and Control

CPI Sensors on the oil platform are also used provide critical feedback during a riser disconnect scenario. In this event, the riser must be disconnected before the rig is critically out of position with respect to the well head. Typically a tensioner ring employs six hydraulic accumulators with six valves controlled by the computer through signals from the valves and the CPI linear position sensor which is acting as the piston rod measuring system providing absolute (not relative) position measurement signals. Some systems are implemented with the cylinders mounted directly to the tensioner ring. In these systems, a riser disconnect detected by the CPI linear position sensor will cause the valve to limit the oil-flow and the riser will not gain momentum. The controlling system adjusts the position of the valves and the riser is brought up in a controlled way using input from CPI linear position sensors like the SL2000.

Contact CPI for Questions About ATEX Rated, Subsea Capable, Harsh Duty Hydraulic Cylinder Position Sensors

Our engineering team builds, installs, and qualifies these sensors uniquely into each application. Many options are available in the design of your sensor that can make it more robust, longer stroke, or even custom external mounting options for existing In-the-field cylinder applications.

Please call our engineering team today to discuss your hydraulic accumulator based application or see all our harsh duty linear position sensors.

Original content posted on https://www.cpi-nj.com/blog/marine-riser-and-tensioner-system-hydraulics-revisited/

October 17, 2016

Reinventing Draw-Wire Sensors – Introduction

Perhaps one of the most memorable moments of my career at CPI happened over a decade ago, when CPI was first asked to produce a robust hydraulic position sensor for a large well known maker of construction vehicles and equipment. In their larger machines, rod-type sensors were being used in the control system of long stroke hydraulics but their installation was problematic, and they often failed in rough conditions.

After many months of engineering and testing CPI produced the first version of our SL series sensors. Our new sensor was durable, accurate, and used a well accepted linear position measurement principle, the draw wire.  In our solution however, the draw wire mechanism was completely re-conceived and re-engineered for harsh duty and improved accuracy. The mechanical rotations of the draw wire were ingeniously coupled to an LVDT transducer system so the whole solution was non-contacting and virtually immune to all the environmental hazards, temperature and EMI your average 15 ton wheel loader runs into. The system was so unique and unlike anything that existed that we were able to receive several patents from it.

Proudly we demonstrated our achievement to our client, certain that we were onto something big here. Do you know what they said?   (wait for it….)

“Not high-tech enough”.

Maybe you’ve experienced this: one of those moments when words fail you and you’re quite sure your head will explode shortly.  You see, having witnessed the amount of research into material science, alloy’s, precision engineering, and component testing that went into our sensor, all I could think was “well define high-tech!”.

And so now a decade later, having seen our unique sensor gain wide acceptance in applications more diverse that we ever imagined (including construction vehicles), I’m calm enough to explain in this upcoming series, just exactly what constitutes “high-tech” in our hardened linear position sensor solution, and more importantly, why it outperforms every other sensor technology in the world for extreme duty, long stroke, or subsea applications.

 

Original content posted on https://www.cpi-nj.com/blog/reinventing-draw-wire-sensors/

 

August 2, 2016

CPI Announces Intrinsic Safety Rated Position Sensor

CPI Announces its newest member of the Subsea Linear Position Sensor family, the SL1490, CPI’s first fully ATEX & IEC-EX Intrinsic Safety rated sensor.

As the first sensor of its type in the world, CPI has again raised the bar for performance and reliability of hydraulic linear position sensors in the subsea environment. This sensor is specifically designed for the needs of the Oil and Gas exploration and refining industry satisfying needs on platform hydraulics and deep below the surface on hydraulic cylinders and accumulators used at the well head or in blowout preventers.

Combining Proven Technology Elements Into Something New And Unique

The design of the CPI SL 1490 actually combines two technologies that have been staples of piston position measurement in hydraulic cylinders and accumulators for decades: magnetostrictive position sensor electronics, and our patented linear-to-rotary-to-linear draw wire sensor as a piston displacment indicator.

Our sensor fits inside any cylinder housing of at least 8 inches in diameter. The sensor operates in any non-corrosive liquid or gas and sensor output is specified as either analog, digital, providing absolute position measurement signals.

Uses For the SL 1490 in Oil and Gas Exploration.

If you’re using any electronics on the surface of your rig, you know that explosion risk is always a concern. Our new sensor is fully ATEX and ICE-EX intrinsic safety rated making it the perfect choice for hydraulic accumulator array’s used in heave compensation systems around the moon pool, and any and all other large scale, surface based platform hydraulics.

Using our Linear Position Sensor Underwater

The SL 1490 is a fluid agnostic design. Unlike other sensor technologies we present no sealed cavities or electrical components that can be shorted out. The magnetostrictive sensor we use is an extremely short rod sensor, eliminating concerns of rod sag under vibration and the sensor is fully certified to operation in 5000 feet of seawater.

Call CPI Today to find out if this Game-Changing Sensor Technology could be right for your hydraulic cylinder or accumulator application.

This content was originally published on https://www.cpi-nj.com/blog/cpi-announces-intrinsic-safetry-rated-position-sensor.

 

March 30, 2016

Marine Riser and Tensioner System Hydraulics.

While CPI’s robust linear position sensor technology works great to report absolute cylinder position under the most demanding of conditions, it also has great application as a gauge of pre-charge pressure in a hydraulic accumulator. And perhaps nowhere is the operating environment of a hydraulic accumulator more challenging than in deep sea oilfield exploration riser tensioner systems.

Marine Riser And Tensioner Systems Explained

Crews of drilling rigs understand how critical this functionality is. Without a tensioner the riser will buckle when the rig moves downward, and stretch when the rig rises. If you gather around the moon pool of any offshore rig or vessel during a storm you’ll see a riser/tensioner system hard at work. These systems use a bank of hydraulic accumulators to drive piston displacements in reaction to the heaving of a heavy sea.   It is crucial that the tensioner can manage differential movements between the riser and the rig as the riser is connected to the wellhead on the seabed. The use of hydro-pneumatics in a system comprising a hydraulic cylinder, accumulator and typically wire sheaves, enables compensation for rig movements and maintains constant wire tension.  These accumulators are constructed using a gas (typically air or nitrogen) and hydraulic fluid to drive displacements up to 12 meters.

How do CPI Linear Position Sensors Fit In?

Critical to operation of the tensioner system are accurate measurements of the air/oil compression ratio. Control systems must monitor and replace lost air dynamically and the position of the piston for a given hydraulic oil pressure is a direct indication of the need for increases to gas volume which can then be injected by an automatically controlled compressor.

CPI Linear Position Sensors like the SL-1500 and others are designed for these kinds of applications:

Hydraulic accumulator piston position sensing

CPI SL1290 Series For Hydraulic Accumulators

  • Because of our innovative draw wire design, we can easily operate for the long stroke lengths in a marine riser tensioner system. CPI sensors have operated with high accuracy to 15 meters of stroke.
  • Hardened operation is a standard feature of our design. Our sensors have no sealed cavities and are completely immune to pressure. As such, they can be mounted on the oil or gas side of the cylinder, or even outside the cylinder.
  • A patented LVDT based implementation means the core sensing technology is completely non-contacting and immune to local EMI distortions.
  • Our sensor is the only hardened sensor in the world that works with telescoping hydraulics.

Riser Disconnect Sensing and Control

Another key function provided by CPI Sensors is to provide critical feedback during a disconnect scenario. In this scenario the riser must be disconnected before the rig is critically out of position with respect to the well head.  Typically a tensioner ring employs six hydraulic accumulators with six valves controlled by the computer through signals from the valves and the CPI linear position sensor which is acting as the piston rod measuring system.  Some systems are implemented with the cylinders mounted directly to the tensioner ring as opposed to using a wireline implementation. In these systems, a riser disconnect scenario detected by the CPI linear position sensor will cause the valve to limit the oil-flow and the riser will not gain momentum as it often does in a wireline system. During disconnect the control system controls the position of the valves and the riser is brought up in a controlled way again using input from our sensors.

Contact CPI – Lets Talk Accumulators

CPI sensors are no stranger to oil field operations, and are one of the most unique offerings in the world for long stroke, piston accumulator position sensing in extreme environments.

Please call our engineering team today to discuss your hydraulic accumulator based application or visit us at http://www.cpi-nj.com.

 

This content was originally posted at https://www.cpi-nj.com/blog/marine-riser-and-tensioner-system-hydraulics/

 

August 14, 2015

The Challenge of Subsea Position Sensing

One of the more challenging Hydraulic applications in the world exists far below the ocean, on the sea bed to be exact. A place where mother nature and the laws of entropy conspire to make all man made contraptions suffer, and challenge the ingenuity of engineers and scientists on a daily basis.

One such contraption is the large piston based hydraulic accumulators used in undersea mining and drilling operations as part of critical blowout preventer systems. In principle the operation of these systems is rather simple: The large hydraulic accumulator stands by full charged, ready to deliver massive force to the blowout preventer when a failure in the integrity of the pipeline is detected. The proper operation of the preventer, will prevent millions of gallons of crude oil from spilling into otherwise pristine waters.  The failure of the blowout preventer on the other hand, can cause spectacular failures and environmental disaster as is all too well remembered from the Deepwater Horizon debacle that cost 11 lives and untold damage to wildlife and local ecology.

Deploying Hydraulic Accumulators in a Sub-Sea Application

Because all hydraulic Accumulators leak over time, they must be periodically replaced to insure that charge pressure has not dropped as to make the cylinder ineffective in an emergency.  Imagine the cost involved of going down to the sea bed every 6 months to pull up and replace these accumulators, “just to be sure” they are in working condition.

A better solution uses a CPI SL-1500 sensor on the sea bed to detect the position of the piston in the accumulator. As the pre-charge pressure of the accumulator leaks, the CPI sensor sends back extremely accurate position signals which tell technicians when they “really” have to replace an accumulator.  By having real data on accumulator pressure, CPI sensors can save drilling operators hundreds of thousands of dollars by allowing them to intelligently delay the replacement of these Hydraulic cylinders until it is really needed. Alternately they can prevent a safety disaster by allowing operators to detect early failures of these accumulators.

For more information on our Subsea sensors like the SL – 1500, visit our hydraulic accumulator applications page or www.cpi-nj.com.

This content was originally posted at https://www.cpi-nj.com/blog/the-challenge-of-subsea-position-sensing/