Cable Lay or Pipe Lay Barge Monitoring

Thursday, January 20th, 2011

In late 2010 we supported a Trinity Offshore project in Vancouver, BC by instrumenting a custom cable-laying barge for tension, speed and payout monitoring of the cable.

Trinity built this specialized barge to deploy cable for the telecommunications and electrical industry.  One of the primary challenges with laying sub-sea cable is that the cable has to be laid in one continuous line without connectors.  This means that if you lay your cable too slowly, the cable could bend and kink under its own weight, but if you lay too quickly you can pull the cable apart.  Once bent or stretched, the entire span (which in Trinity’s case this last summer was several miles long) has to be rebuilt.

Here is a picture of the continuous cable coiled ready for deployment.

The Trinity Offshore team requested that we provide a solution that allows their line engineer to monitor the cable deployment for both tension and speed. Their cable runs from a forward rotating drum to the stern chute. The cable is fed through an LCM and over a chute into the water. Here is an image of the chute.

Here’s how they instrumented the chute with one of four load pins.

The speed and payout was measured by installing two proximity sensors on a wheel assembly.  Due to gravity, the wheel maintains contact with the cable and turns as the cable spools out.  The spokes provide the targets for the proximity sensors.  The proximity sensors are slightly staggered to provide the proper waveform to determine payout and direction.

Monitoring tension was a more involved calculation because it wasn’t feasible to measure the cable tension directly. To measure the cable tension we looked at the force on the chute.  However, the chute was resting on four points instead of two.  We initially developed a custom firmware application to handle this specific application with a dual-axis load cell, but the output was too noisy and of insufficient amplitude.   On the fly, our onsite engineer developed a solution with Trinity in which two of the horizontal load cells were rotated 90 degrees. The result was that we used all four load cells to measure load in the vertical direction, and an inclinometer on the chute to measure the angle of the cable as it came of the chute relative to gravity. Our LCI-90i unit summed the four load cells and used the inclinometer input to calculate the tension and compensate for any inaccuracies due to cable angle variations.  This project demonstrates our flexibility when reacting to the difference between what is calculated on paper and what a real-world situation throws at us.

MTNW’s combination of engineering, hardware, and software skills allowed us to build and deploy a solution that fit Trinity Offshore’s application exactly.

Tags: barge monitoring, cable lay, cable measurement solutions, cable payout measurement, cable speed measurement, cable tension measurement, cables, continuous coil, custom system, deployment, electrical and telephone, instrumented chute, island to island, load pins, payout, payout measurement, pipe lay, speed, tension, trinity offshore project
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Load Cells, Load Pins, Tension Links, Instrumented Shackles & More

Friday, October 15th, 2010

While force transducers are not listed on our product sheets as standalone products, they have always been an integral part of our line monitoring systems and we understand for many customers this is the point where you start your problem-solving discussions. That’s also a perfect time to contact us. Our load measurement/sensor design expertise is deep and varied, which means we can provide you with a total package solution that represents the best overall value in design, features, performance, and support.

Here are some examples of our recent design work with sensors:

• A 2,100,000lb pound pin for a large winch manufacturer.
• 2 pancake compression load cells for an unique custom level winch application.
• A 60,000 pound load pin for instrumenting the brake band on a tug towing winch, one of many.
• 4 – 100,000 pound tension links for a Potash mine rail car monitoring application.
• Class 1 Div 1, clamp-on, double-ended shear beam load cell rated for 400,000 pounds
• 35,000 pound load pin for a blimp/aerostat deployment sheave assembly
• 180,000 pound dual axis load pin for a ROV launch and recovery system
• 6 – 3,800 pound instrumented shackles for two research vessels
• 2 – 4,000 pound dual axis load pins for a research vessel
• Many 7,000 pound tension links for a ferry terminal fleet with factors of safety greater than 8 times
• 4 – 23,000 pound weigh modules for a pipe lay barge application

While our reputation for sensor quality and reliability was first achieved in the oceanographic industry, Measurement Technology NW has recently seen significant growth within the Oil & Gas industry and many of the force transducers we design now have intrinsically safe ratings (Class 1, DIV 1, Div 2, ATEX Zone 2, etc.) as required for sensitive installations.

If your measurement or monitoring application needs sensors, and you’d like to discuss how these sensors will interact with your particular environment and application, please give us a call.

Tags: high accuracy, instrumented shackles, load cells, load links, load measurement system, load measurement systems, load pins, measure load, measure tension, measure weight, measurement sensors, measurement systems, Measurement Technology, MTNW, reliability, safety, shackle monitor, tension links, transducer, transducers
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Launch And Recovery System (LARS) Winch Monitoring with OceanWorks & Dynacon

Friday, September 10th, 2010

When you are 1,200 feet down in the ocean working on delicate operations, where ocean pressures are equal to 74,900lbs per square foot, you don’t want to be in anything but an OceanWorks Hardsuit™.  OceanWorks has been an MTNW customer for many years and we thought it would be interesting to show off some of their latest LCI-90i supported systems.

In the images below you can see the OceanWorks Hardsuit™ 1200 (www.oceanworks.com) owned by the Italian and French Navies.  This Hardsuit™ can go 1,200 feet deep and typical dives are 6-8 hours in duration but there are emergency reserves for up to 24 hours.  Life support is maintained via a set of oxygen bottles contained on the suit. Only power, communication and telemetry are provided through an umbilical from the surface.  The Hardsuit™ 1200 weighs approximately 750 lbs in air but is only about 5 lbs in water.

These OceanWorks Hardsuits™ are supported by Dynacon launch and recovery systems (LARS) (www.dynacon.com).  Dynacon is a premier partner of MTNW.  The Dynacon LARS (Launch and Recovery System) system for this Hardsuit™ is also rated to 1200’ and made to meet Det Norske Veritas (DNV) requirements.  The LARS is equipped with a TMS (Tether Management System) which enables the Hardsuit™ to fly in and out at various depths and not worry about managing a long umbilical cord from the surface.  The Dynacon LARS is capable of folding up for transport to an alternate vessel.

You can see the LCI-90i display panel-mounted into the enclosure on the side of the LARS.  The LCI-90i display provides decimal point accuracy in reading winch tension, speed, and payout for lowering the Hardsuit™ into the deep and an electroluminescent screen for direct sun-light view-ability.  Dynacon has trusted MTNW’s LCI-90 displays as their primary winch monitoring interface for over 12 years.

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Aerostat Winch Monitoring With Allied Power

Thursday, July 22nd, 2010

There is growing demand for lighter than air, near space systems that can carry aloft wide-area communications, broadband, and sensing devices to meet the requirements of military and commercial customers for network connectivity and ready access to mission critical information. Aerostats, which are commonly referred to as blimps, play an important role in our nation’s rapid response communications infrastructure – from supporting climate research and natural disaster response to combating terrorism and providing deploy-able “eyes in the sky” for our military personnel in the field.

MTNW provides aerostat monitoring hardware and data-logging software to several manufacturers involved with aerostat ground systems here in the United States.

One of our long-time partners, Allied Power out of Beaverton, OR (www.alliedpower.com), is using our LCI-90i smart display to view tension, speed, and payout data from the winches that power their aerostat ground station controls.

For this application, Allied Powers’ winch (EHS-5-43D hoist system) can store up to 4,400 feet of 1/2 ” diameter fiber optic cable and control the ascent and descent of the aerostat balloon at speeds up to 115 feet per minute while providing up to 5,500 lbs. of single line pull capacity.

You can see our LCI-90i display in the image above just to the left of the control joystick. Our display provides Applied Power and their customers with unmatched durability, reliability, and accuracy, thanks to features that include fast line tension sampling rates (up to 200Hz), a rugged and high-temp range capability (-45ºC to 75ºC), and direct sunlight viewability with our industry-leading electroluminescent screen.

Allied Power’s system includes variable speed payout and recovery via proportional joystick controls, and to support these functions the LCI-90i provides programmable alarms (high and low limits to tension and speed/payout settings) to allow for ease of use and additional operator safety.

MNTW is excited about our partnership with APPI and their 25 year history of providing winches, hoists, and positioning systems to industrial, commercial, and military customers. We are proud to be part of a rapidly growing solution for our nations critical communications infrastructure.

Tags: Allied Power, APPI, Communication Infrastructure, Hoists, LCI-90i, Positioning Systems, winch payout, winch tension, Winches
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Slickline Monitoring With DynaWinch

Thursday, July 15th, 2010

One of our leading partners, DynaWinch, out of Calgary, Alberta, has been working with the MTNW LCI-90i display for years to bring decimal point accuracy to their arsenal of down-hole tools and applications.

Recently, DynaWinch has incorporated our displays (both the LCI-90i and the LCI-80) into their new product line of slickline skid units. They now manufacture electrically, hydraulically, and diesel driven skid based units for all types of environments and needs.

Their product line includes aluminum wireline van bodies for slickline, case hole, and open hole logging, mast units, swabbing rigs, and wireline skids for on-shore and off-shore applications. And, their wireline accessories include hydraulic drawworks packages, customized control panels, measuring systems, spoolers, and down hole tools.

The picture below shows Tom Rezanka, Managing Director of MTNW’s LCI product line, sitting at the controls of a DynaWinch wireline van built for one of their customers. Notice the beautiful display immediately in front of Tom. If Tom were an operator, that display would provide him with line tension, speed, and payout information through its electroluminescent (day-light readable screen) at line data sampling rates of over 200Hz! The display will also provide the operator with the ability to store up to 14 different tension and payout calibrations with automatic recall.

Michael Fernquist, Technical Project Manager for DynaWinch, explains to Tom how the operators use the controls and display information in their job.

Here is a picture of the MTNW 90i display incorporated into a an electrically driven wireline skid unit. You can see that our displays are built for rugged, all-weather conditions. If you thought our electroluminescent displays look good in the sun, you should see them in the rain!

Tags: LCI-80, LCI-90i, Line Tension, Slick line monitoring, Slickline Monitoring, Well Servicing Monitoring, winch payout, winch tension
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Tension Calibration for a Winch Monitoring System

Wednesday, April 7th, 2010

In a previous posting we discussed the technique of calibrating the payout line parameter for winch applications.

It is also important to understand the technical challenges of calibrating the tension line parameter of your winch monitoring system.

The calibration of a tension measurement system can be achieved through several methods.

It’s always best to conduct a live calibration of the winch monitoring system once the sensors, displays and line have been installed and the wrap angles determined and identified to be fixed (more on the wrap angle in another blog).

Since tension sensors behave in a very linear fashion, meaning that their electrical output has a linear relationship with the load applied to the sensor itself, a single, two-point calibration (a low tension and high tension reading) is often sufficient to calibrate a tension monitoring system.

We typically can calibrate a system to better than ±0.5% without too much trouble.

Calibrating a winch monitoring system requires the use of an additional (previously) calibrated tension sensor, typically a tension link. Make sure that the tension link has a valid certificate, that it is not expired. You can often rent these for days or weeks at a time.

Calibrations are typically good for a year for these types of devices.

Winch tension calibration often requires additional support from your marine operations group because they will need to provide the winch operator, a previously calibrated tension sensor, deck hands to rig the tension link to the winch line and winch time to complete the calibration procedure.

There have been many times we have been scurrying around the deck to get this done before the vessel leaves the port or the fuel truck shows up (all deck work ceases when the vessel is fueling).

One side of the tension link should be secured to the winch line and the other should be secured to either a rigid solid structure like the deck or weights of known values.
The winch operator can now carefully haul in the line slowly till the desired tension is reached or the weights have been lifted off the ground.

We prefer to use weights as they provide a more stable measurement platform. Because the winch line is basically a big spring, if you are securing your winch line to the deck the system can relax causing the tension link reading to change before the data is applied to the display.

Our method is to collect the tension sensor analog output (mA, volts, mV, etc) at two known line tensions, one high and one low. The low value can be either zero or near zero, depending on the application. The high point can be either the breaking strength of the line or the maximum tension the deployment can expect. It should be noted that the breaking strength of the line is a much higher value than the working tension range of the winch operations. Setting the high calibration point to the breaking strength will reduce the accuracy of the system at lower tension ranges.

We hardly ever calibrate to the maximum breaking strength of the wire rope as the forces required make the rigging difficult and increases the likely hood of something breaking and creating a safety hazard.

Always remember to stand way from the direction of the winch.

I was fortunate once to be able to walk away from an installation in Chile were I was not positioned properly and a snatch block gave way shooting across the deck and denting the bulkhead between myself and the Chief Engineer.

In terms of calibration, note the sensor output at the low and the high points and enter the data into your display. The LCI-90i display will automatically calculate the slope and offset of sensor output verses applied load and apply this over the complete working range of the sensor.

The LCI-90i makes calibration easier than most other systems because the input fields and buttons are right on the main face of the display. Inputs can be changed and updated on the fly without the use of an additional computer. Analog sensor values are displayed during the calibration making the calibration quick and easy.

If higher levels of accuracy are required, you can input more calibration points to develop a “look up table”. This can also be used if the sensor is exhibiting non linear characteristics. Synthetic ropes often will deform under tension and will perform non-linearly. The LCI-90i display allows the end user to develop and reference a “look-up” table without additional programming or a PLC interface.

Other calibration techniques can be used such as shunt calibration, voltage substitution, etc. These techniques, however, are hardly ever used and not worth learning about.

Good luck in your calibration. If you have questions, please don’t hesitate to give us a call.

Tags: barge mooring, cable tension, cable tension monitoring, Line Tension, mooring line tensiometer, Puget Sound, tugboat
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Winch Instrumentation, Cable Tension Measurement and Line Control Overview Brochure

Friday, March 12th, 2010

We have just updated our division brochure with our new products and services. The images on the brochure come from our customers, vendors and partners!

We’re excited about 2010 and the many oceanographic, offshore, and construction projects we’re working on. Give us a call. We enjoy talking through questions about running line tensiometers, winch and cable spooling instrumentation or any kind of line tension/control project.

You can download the new division brochure by clicking here.

Tags: Line, Line Control, Line Systems, Line Tension
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US Coast Guard Uses an MTNW Running Line Tensiometer for R&D

Wednesday, February 17th, 2010

Through one of our partners, Dillon Quality Plus, the Coast Guard purchased and used our HRT-3mm Running Line Tensiometer (or line rider) to measure the cable tension loads during some qualification testing on an improved rescue hoist for the Coast Guard H-65 Dolphin Helicopter.

The hoist was improved by adding a clutch designed to release if the cable forces exceed a known value.  The Coast Guard tested the release force pulling on the cable at various speeds from 1 in/s to 30 in/s.  After the hoist passed this testing, the Coast Guard then conducted a number of drop tests that consisted of a 600 pound mass attached to the end of the cable and various amounts of slack in the cable from 1 to 5ft.

During all testing, the tensiometer (or dynamometer) was attached to the cable and the load output was recorded.  The HRT-3mm system worked perfectly.

The HRT-3mm is designed to measure running line cable tension loads from 0-13,000 lbs.  It only weighs 30lbs and is compact but reliable.

Tags: cable tension monitoring, calibration, Coast Guard, HH-65C, HH-65C Dolphin Helicopter, Injured Hiker, Line Rider, Line Tension, Running Line Tensiometer, Search and Rescue, tensiometers, tension meter, winch payout, winch tension
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Cable Tension Meters (or is it Tensiometers or Dynamometers?) for Barges, Rigs, Construction, and Pipeline Inspection.

Tuesday, January 12th, 2010

We often get asked questions about the difference between tension meters, tensiometers, and dynamometers. There is good reason for the confusion because many different industries use the same words for different applications. For example, the word tensiometer, which we use to describe our primary cable tension/payout monitoring equipment, is also used to describe a soil moisture monitor, and dynamometer is a word that was widely used within North America for a device for measuring automotive horsepower.

At Measurement Technology NW we focus on measuring cable tension in many different applications (from 1,000 lbs-1,000,000 lbs) and we use the words tensiometer (dynamometer) and tension meter interchangeably. Even though the words mean much the same thing, our tensiometers can be provided with an extra sensor to measure payout and speed – two line control parameters that are not always considered when referencing a standard “tension meter”.

Tensiometers can be of two main styles; running line tensiometers (RLT’s) are designed to ride the line and provide measurements of tension, speed and/or payout as the line moves through the unit. Static tensiometers are devices that clamp onto to non-moving lines and only need to provide a measurement of line tension.

Our customers use MTNW tension monitoring devices in applications such as: offshore mooring, barge mooring, oceanographic payload monitoring, ROV launch and recovery system monitoring, tethered pipeline inspection (or pigging) monitoring, etc. Usually it is a safety requirement that drives the procurement of these tensiometers.

Here is a picture of a barge mooring monitoring project for which Ombak Marine Group in Kuala Lumpur has installed a group of MTNW’s tensiometers. These units are defined as tensiometers (or dynamometers) because we are helping them measure all three line parameters.

Our running line tensiometers are 3 sheave devices that detect tension by the deflection of the strain gauge transducer installed in the load pin that is in the center of the top sheave.

Here is another picture from an NPCC barge mooring monitoring project. NPCC, based in Dubai, ordered 8 running line tensiometers (or dynamometers) from us. You can see how we have installed this device in a compact area under a platform. It is tethered from above to avoid damage in a slack line event and tethered fore and aft to prevent rocking.

Whether you call it a tensiometer, a tension meter, or a dynamometer (and hopefully we’ve cleared away some of the confusion), we build the most rugged, accurate, and easily installed cable tension monitoring device in the industry.

Tags: cable tension, cable tension monitoring, tensiometers, tension measurement, tension meter
Posted in Line Control Systems | 2 Comments »

Dillon Tensiometer (Dynamometer) Upgrade for NDT Pipeline Pigging & Inspection Services

Friday, January 8th, 2010

We recently completed a refurbishment and upgrade to an older Dillon Tensiometer model owned by NDT Services. Frank Vignall, from NDT, has been using a 40KIP Dillion Tensiometer for many years to support his pipeline inspection services. In his work he mounts the tensiometer on a cable used to pull a package through a test pipeline to determine how much pressure it will require to push a similarly-sized scientific package through a fluid or gas pipeline for customers. NDT Services sends their scientific packages through pipes to find defects and identify pipe locations where repairs need to be made. Their old Dillon tensiometer had parts that were worn out and no longer serviceable. You can see in the pictures below that in our upgrade we installed modern wiring, a strain gauge module and a Hall Effect sensor to measure cable payout.

The load cell on the Dillon unit was still functional but the rotational sensor had failed. MTNW designed a special gear tooth sensor and mounted it to the spur gear on one of the outer sheaves. In this manner we were able to obtain a digital quadrature pulse train that MTNW’s LCI-90 processed into a real-time display of speed, payout and cable direction. In the course of this retrofit MTNW worked with engineers from Dillon, the spur gear manufacturers, and our rotational sensor manufacturer. In the end we were able to measure 72 pulses per sheave rotation with a highly accurate payout resolution. The existing load cell was found to be functional and when connected to our LCI-90 display found to be very accurate in calibration. We also installed new bulkhead connectors on both the tensiometer and display units.

This Dillon Tensiometer is over 10 years old and came from the original Dillon series. It weighs about 350 lbs. As you can see in the picture below, we now make comparable tensiometers (dynamometers) which weigh less than 1/3 of the original Dillon model but which can support a similar tension range. Our RL-60 frame size (shown below) can accommodate a tension range from 0-60KIPS. For greater accuracy, we have used custom load pins in this frame size for lower (0-20 & 0-40 KIPS) maximum loads.

We also paired this older Dillon unit with our WinchDAC software for PC logging and remote viewing of operational data. Now NDT can build and send data directly out of WinchDAC into Excel for further report building. See our WinchDAC Software for Single Winch images below.

Given that Dillon was one of the first tensiometer manufacturers in North America it has been gratifying to see how well suited our modern technology was to the functional upgrade of this older system.

Tags: cable tension, cable tension monitoring, Line Tension, winch tension
Posted in Line Control Systems | No Comments »

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