Delmar RLT

Measurement Technology NW (MTNW) implemented its running line tensiometer (RLT) technology with a Samson synthetic rope in an offshore mooring monitoring project engineered by Delmar Systems.  This implementation is MTNW’s first use of tension measurement technology with 2”+ synthetic ropes.

Recently, Delmar Systems was contracted to moor an offshore supply vessel (OSV) to a major offshore platform in the Gulf of Mexico. The OSV is being used as a support vessel while dive operations are conducted. The OSV is using a three-point mooring system consisting of two stern hawser lines attached to the platform and a bow mooring line attached to a preset suction pile foundation in 2,900 feet of water. The mooring system had to be as robust as possible while still maintaining ease of handling and rigging by the vessel crew.

To achieve a higher Maximum Breaking Load on the OSV bow mooring line while maintaining deck maneuverability, Delmar chose Samson’s AmSteel-Blue HMPE rope made of high modulus polypropylene (HMPE) as the bow winch line. An MTNW RL-20175K running line tensiometer provided tension measurement for the bow line.  During the design phase of the project, MTNW thoroughly tested and calibrated the RLT using the specified 2¼” AmSteel-Blue rope. 

 “This is MTNWs first use of an RLT to measure tension in a major synthetic mooring line of this large diameter,” said Tom Rezanka, managing director of MTNW.  “Our RLTs are more commonly used to measure the tension of wire rope, but synthetic lines have different mechanical characteristics under load.  We were able to collaborate closely with the R&D engineers at Samson.  The monitoring system was fully tested, calibrated and witnessed on an ABS-certified test bed with the resulting accuracy identical to wire rope applications. The trend in mooring is lighter and stronger, which will require increased use of synthetic ropes and new, modern technologies to monitor them. Our sensors and systems are proven to work with any lines.”

“Both the AmSteel-Blue winch line and MTNW’s RLT have been working flawlessly together and have played a vital role in the success of the project,” said Dillon Shuler, engineer at Delmar Systems. Rezanka explains, “MTNW RLTs are being used more frequently for mooring monitoring because our modern design provides a rapidly deployable solution for retrofitting existing winches.  We can deploy on virtually any winch, with an installation time measured in hours, not weeks or months.”

“Since the Macondo oil spill, we have seen a significant increase in interest from risk managers and lifting/rigging engineers for determining line and cable tensions in all environments,” said Rezanka.  “If it can be monitored, alerted on, and data-logged to a computer it needs to be.  Our solutions support the increasing safety requirements for offshore operations and allow project managers to sleep better at night.”

Original article can be found at: http://www.marinelink.com/news/approaches-offshore340216.aspx

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.

Petroleum coke is a hard, porous, charcoal-like substance that is used in many commercial applications, but getting it out of the drum is difficult. For over 100 years Flowserve has specialized in high-pressure coke cutting tools designed to remove finished coke and prepare the drum for its next processing cycle. Flowserve’s most recent cutting head and pump produces 4,500 psi with 1,200 gpm throughput that can cleanly empty a coking drum with only 2-4 hours of automated cutting. Imagine cleaning your sport court or house deck with that!

However, during this process cut coke chunks will often fall down on the waterjet head and trap it in the drum. To alert operators of this condition, Flowserve chose MTNW’s 3-sheave 20KIP tensiometers (dynamometers) to understand where the jet is in the drum (line payout), how fast the jet is being lowered (line speed) and how much weight is on the jet (line tension). We worked closely with our load pin manufacturers to ensure that these tensiometers were intrinsically safe for this refinery application. This kind of accurate line control data allows operators to increase both personnel and property safety factors.