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.

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!

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.

MTNW employees calibrate two Foss tugs in Puget Sound by having them pull against each other

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.

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.

An HH-65C flight crew hoists an injured hiker to safety from a mountain peak in WA at an altitude of 6,300 feet.

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.

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.

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.

Because the LCI-90 payout measurement is so accurate, the construction team was able to go directly to the location of the stuck pig, dig down to the pipe, remove the obstacle, repair the pipe and keep pigging…all within a couple of days. This is exactly what Measurement Technology cable tension monitoring systems are designed to do! Provide fast, accurate information that prevents problems and saves you time and money.

In the picture below you can see the “pig” device that the CD Lyon team is pulling through the pipe to look for obstacles.

CD Lyon planned to use a 5/8” wire rope to pull the pipe pig and new pipe slipline. They needed to measure up to 14,000lbs of tension, which is load at which the pipe lining may be damaged.

This wire rope size and tension range was a perfect fit for our compact HRT-3MM tensiometer (dynamometer). We paired this tensiometer with our LCI-90 display, which was housed in a portable and rugged Pelican case.

In the photo below you can see that Coordinated Wire Rope and NTT Fabrication built a custom winch skid, on which they mounted the Pelican case and LCI-90 display. You can see the LCI-90 and case immediately to the left of the controls for the winch.

The photo below shows how the HRT-3MM tensiometer rides the cable it is monitoring. NTT Fabrication built an articulated arm which allows for lateral movement of the tensiometer (tracking line as the winch spools) and also supports the device in the case of a slack line situation.

MTNW’s solution provided an inexpensive and portable line monitoring system without the need for winch modifications. We pre-calibrated the system before it was sent it out, and Coordinated Wire Rope found that their new LCI-90 + HRT-3MM cable monitoring system was not only easy and intuitive to work with, it worked from the moment they pulled it out of the box.

Running line tensiometer measuring tension on mooring lines for the Frontier Duchess.

On short notice, Matthew flew for over 20 hours from Seattle, through France, down to Port Harcourt Nigeria. Once in country, he was met by a friendly security team that helped him travel safely to the local heliport. From there it was a short but scenic 30 minute helicopter trip across the Bay of Biafra to the Duchess.

MTNW was called in to help install, calibrate, and commission the ship’s 8 mooring line tensiometers and LCI-90 winch displays. Mooring monitoring is crucial to FPSO and drill-ship work because ship managers need to reliably place and tension their anchors in order to limit ship movement. During drilling, the operators aim to keep the ship within a 12 inch circle. For a 75 foot wide and 475 foot long vessel like the Duchess, 12 inches is 1.3% of the ship’s width and .2% of its length… imagine attempting this feat while bouncing around on high sea states.

LCI’s WinchDAC software showing line tension for 8 mooring lines on the bridge of the Frontier Duchess.

In a traditional mooring setup, the vessel operator will notice a sudden change in position and will attempt to rectify the situation before the ship drifts too far and breaks the drill column. Essentially, the operators can only respond to problems after they have occurred, they have no foolproof means of predicting them. With MTNW’s mooring line monitoring system, the user can ensure that the tension on the mooring lines is low enough that the anchors are not at risk of shifting while also being high enough to keep the vessel in place; thus minimizing the chances of an anchor slip. In addition to this functionality, MTNW’s system can also monitor the payout of the line which enables the operators to accurately place buoys (with accuracy better than 30cm) to lift the mooring lines over subsea cables and pipelines.

The bottom line is that when you combine the action of dynamic sea states with the grid of subsea cables and pipelines crisscrossing the bottom of the ocean, mooring line monitoring becomes critical for personnel and property safety.

On the Duchess, Matthew worked closely with the ship’s electronic technicians and quickly brought the system online. All eight units were commissioned and calibrated (through a great deal of teamwork involving anchors, cranes, winches, and a tropical storm) and are now providing accurate and useful feedback for the ship’s operators. All on board were eagerly awaiting the opportunity to see the system in action during their next drill operation.

One of the key considerations any rig manager needs to think about when completing a mooring monitoring installation or retrofitting a legacy mooring/winch system is to think about where the tension, speed, and payout data needs to be seen. MTNW’s LCI system is designed to provide local visibility at the winch controls, but it also integrates to a PC based software interface that aggregates all mooring line parameters into one view at the bridge or control room (see image). This functionality was very popular with the crew of the Duchess, particularly the Captain, as it allows them to operate the entire system from the comfort of the bridge.

Another LCI system benefit is in the ease of hardware installation and maintenance. The LCI tensiometers are built with a removable center sheave which makes installation…even with deployed anchor lines…a breeze. Because we pre-calibrate our tensiometers before they are deployed, installation and commissioning often takes less than a week on site.

With installations all over the world, MTNW’s LCI team is rapidly becoming one of the leading experts in providing retrofit solutions for legacy mooring systems.