About Proportional Load Measurement Systems

The majority of load measurement systems are used on cranes having multiple rope falls where the load seen by the hook is shared proportionally between the numbers of ropes used in the rigging. On most of these applications, the load measurement transducer is positioned at some point in the rigging, (the rope tie-off point or the compensation sheave or the compensation lever) where only a proportion of the load is measured by the instrument (load pin, load link, wedge socket, clamp-on, etc.).

The dilemma faced with these type systems is the repeatability and accuracy of the load measured compared with that seen at the hook. When only a proportion of the load is measured by the transducer, any losses in the crane rigging systems due to friction in sheave bearings and friction in ropes traveling around the sheave radius is amplified through the load measurement system by the number of times the transducer load is multiplied to equal the crane capacity (parts of line).

Consider this example; An overhead bridge crane with a lifting capacity of 500 tons utilizing 20 ropes in rigging, with each rope (theoretically) taking 25 tons or 5% of the entire load. If a load transducer is placed in the compensation sheave
where the load from two ropes is supported, the output from the transducer is amplified by 10 times to enable the display to show 500 tons. Any losses in the rigging sheaves, both at the point of loading and during lifting and lowering of the load are also amplified 10 times. Therefore, a loss in sensing the load of 1%, between the hook and the point where the transducer is installed, is amplified to 10% on the display.

The error potential is even greater with clamp-on transducers and line riders in multiple rope cranes. These devices can only measure a percentage of the load seen through the deflection in the rope. Accuracy and repeatability is frequently quoted at plus or minus 5% to begin with, add on the issue of friction losses in the
rigging and you can see the limitations in accuracy and repeatability.

What can be done? Consider installing additional load measurement transducers in the rigging so that a higher percentage of the load is measured by the system, or ask us about our load measuring systems mounted on the hook block.

http://www.waterweightsinc.com/en/crane-load-measuring-monitoring.html

Testing Lifeboats Using Water Weights

Water Weights lifeboat proof load testing systems have been specifically designed to meet regulatory requirements for an evenly distributed load. Our remote system allows Proof Load Testing to be conducted safely, without the need for personnel to enter the craft during the proof loaded condition.

Water Weights lifeboat bags allow ease of handling and transportation compared with solid weights or traditional sand bags, especially in totally enclosed lifeboats.

Controlled loading, unloading and minimal handling of the test load to achieve a wide range of capacities, results in minimum downtime of equipment during test. Loading is measured by means of a calibrated flowmeter.

Remote System
A control manifold and pumping system are used to remotely fill the lifeboat bags negating the need for personnel to be in the craft during test. This system also remotely removes the test overload in instances where the winching system cannot recover the craft in its proof load condition. The bags are rated +/-1% of load when filled. Gradual application of load under test conditions is essential. This is more easily achieved using Water Weights than traditional solid weights.


Safety of Life at Sea (SOLAS)
SOLAS requirements Chapter III, for life saving appliances, details the testing procedures. Water Weights bags also comply fully with the Maritime and Coastguard Agency (MCA) regulations and US Coastguard requirements.

Load Measuring Systems Installed in the Crane Hook Block

For users with requirements to measure and display the load accurately at the hook, adopting the use of dynos (load links and shackles) which are suspended beneath the hook becomes the easiest standard. These devices provide significantly more accurate and repeatable load readings in comparison to the integrated proportional load measurement system. The load is transferred directly to them, via minimum rigging, ensuring minimal losses.

For clients that require a permanently installed solution, then a custom designed in hook load measurement device is the answer. By placing the transducer within the hook or close to it, we ensure that the load seen at the hook can be transferred almost directly to the transducer measuring the load. The displayed load is not an electronically amplified value and therefore losses are minimized.

A custom designed transducer involves replacing the hook trunnion with an instrumented strain gauged trunnion or installing a precision load measurement transducer within the hook or between the hook and the rope. The latter being suitable for crane of lighter duty with single rope connections, frequently termed “whip hooks”.

When these devices are connected to multi-linearization electronics, the accuracy and repeatability can be tuned to provide accuracies within the 0.1%, or better, of the cranes operating capacity.

For more information, visit:
http://www.waterweightsinc.com/en/load-measurement.html

Water Over the Turbine Generators. Oh My!

The mere thought of hundreds of tons of water hanging over electrical equipment is intimidating enough. But having it over machinery responsible for the power supply of thousands of households and businesses is almost unheard of during the infancy of Water Weights.

Fast forward to the present, the method is now the norm in testing both conventional and nuclear powerhouse cranes across the country. This is a tribute to the safety, design & engineering of equipment, and dedication of all at Water Weights and the crane testing industry.

Besides the obvious advantages of cost effectiveness, time efficiency during mobilization, and handling of the test weights, the important issue of minimal floor loading is a tremendous advantage. Testing with traditional methods in the past (especially in the heavy ranges above 200 tons), required reinforcing turbine deck structures to handle the fully laden solid weights. Gradual application of load under test conditions has also proven essential in avoiding accidents and damage during testing.

Proof load testing is an essential part of any inspection, repair, and maintenance program for lifting equipment. In situations where live load testing is not specifically mandated, it is still an essential element of safe maintenance and protection from liability.

Our proof load testing bags have evolved a long way since the standard bags originally designed for testing in the offshore oil industry. The current systems not only work in the harshest of environments but also are the safest, accurate and most efficient in testing cranes inside plants and onshore sites.

The use of water filled bags for load testing all kinds of lifting equipment is now recognized worldwide as a safe, efficient and cost effective system. With Water Weights you pay for the actual crane test, not the transportation.

For more information please visit:
http://www.waterweightsinc.com/en/utilities.html

On Proof Load Testing and WaterWeights

1. In majority of countries, load testing of lifting equipment is a mandatory requirement. Such requirements are legal minimums and many companies or industries choose to set more rigorous standards internally.

2. Proof load testing is an essential part of any inspection, repair and maintenance program for lifting equipment. In situations where live load testing is not specifically mandated, it is still an important element of safe maintenance and advisable for liability purposes.

3. A successful proof load test instills confidence in customer, operator and owner of lifting equipment.

4. Use of Water Weights bags for load testing all manner of lifting equipment is recognized world-wide as a safe, efficient and cost effective method.

5. Water Weights bags have been specifically designed and physically proof load tested to verify that their operational integrity exceeds safety standards for lifting equipment.

6. All equipment has a proven and certified factor of safety in excess of 6:1.

7. Gradual application of the load under test conditions is key in achieving a safe and controlled environment during testing. This method identifies any fault or defects in the equipment under test, before catastrophic failure occurs. This is only possible by using Water Weights.

8. In the event of failure of equipment being tested, consequential loss or damage is limited and often prevented using Water Weights.

9. There have been several serious accidents during proof load testing involving substandard water containers which were simply not designed for the physical demands of proof load testing. We strongly advice users to request evidence of "physical proof load test", from a recognized government body or testing authority proving that equipment meets with the minimum factor of safety legally required.

10. All Water Weights bags come fully certified with evidence of physical proof load test, and type test from the American Bureau of Shipping (ABS), and Water Weights is certified to ISO 9001-2008.

For more information, please visit www.waterweightsinc.com

Crane Load Testing and the Environment

At Water Weights we are committed to environmental awareness and preservation. We conduct our activities in a manner that manages environmental issues responsibly.

We fulfill this commitment by:

Lowering the carbon footprint when crane testing compared to traditional methods
Invasive species mitigation and prevention through equipment inspection procedures
Conducting operations in an environmentally sound manner without disturbing local ecosystems during testing
Promoting environmental responsibility among our employees
Pursuing continuous improvement in our environmental performance

Carbon Footprint

Transporting Water Weights water bags to a test site causes considerably less CO2 emissions than using traditional solid weights. The following numbers are based on travel of 100 miles for a 100 ton load test:

Transporting solid weights by road:
Number Semi-tractor trailers needed: 6
Estimated CO2 emissions: 0.9 tons

Transporting solid weights by rail:
Number rail cars needed: 2
Estimated CO2 emissions: 0.3 tons

Transporting Water Weights bags by road:
Number of Water Weights pickup trucks and trailers: 1
Estimated CO2 emissions: 0.08 tons

Aquatic Nuisance Species

Aquatic nuisance species (ANS) (sometimes called exotic, invasive, non-indigenous or non-native) are organisms that invade ecosystems beyond their natural, historic range. Their intentional or unintentional release may harm native ecosystems or commercial, agricultural, or recreational activities dependent on these ecosystems.

Water Weights’ inspection procedures address the challenge of unintentional introduction of ANS into our waterways through crane testing. These procedures are part of internal processes certified to ISO 9001:2008.

Enhancing Crane Load Testing

Traditional crane management in the US is based upon periodic inspection, routine maintenance and (depending on regulation) load testing up to 125% of safe working load.

Periodic inspection tends to limit itself to the externally visible structure and the mechanical components. Proof load testing of cranes gives a snapshot of the asset’s capability at the time of testing and an overview of the general mechanical condition of the asset. It does not give any information with regard to the internal structural integrity of the asset or indeed any future structural verification. Risk based NDE will be used on a very limited basis. Many facility cranes were installed in the 1960’s and are now reaching the end of their design life. This leaves the alternatives of replacement or life extension to support the extended life of the facilities they serve.

Water Weights Inc. works with Imes who approaches the management of cranes in a different way. This approach requires a full understanding of the structural integrity of the asset, the effect of corrosion on the rated capacity, an assessment of fatigue cycle history and a thorough understanding of the remaining life of the asset.

The Imes technology has the capability to establish these parameters for existing cranes and is able to develop a long term management plan to achieve the maximum life from these assets. The capability of the asset is determined by inspection using visual, acoustic and other non-destructive techniques (depending on the particular asset). This is coupled with a corrosion study and the degraded material properties are modeled in a Finite Element package. This model is used to determine the capacity and capability of the asset as it currently is, compare it to its original design code and establish its performance against current design codes. Predictions of performance against the load test can be made and verified by instrumentation mounted on the crane during test. Areas of weakness can be identified and an engineering plan put in place to re-establish the asset integrity before a load test is failed. The ability to predict failure modes with this methodology also enhances the safety argument for maintaining ageing assets in operation

The difference between periodic inspection and testing and condition / reliability based approaches is that, in the latter, the condition of the asset is constantly understood, monitored and managed. Instrumentation is provided on the crane to record load history and other appropriate parameters to the asset. Predictive techniques are employed to support maintenance/replacement on condition instead of period, and life expectancy of the asset can be accurately forecast for budget and capital finance planning.

Water Weights working with Imes are able to offer this service as an enhancement to load testing. In the event where a full load test is not possible for any reason, using this technology without a full proof load or where critical lifts are being made enables the management and mitigation of risk.

About US

Water Weights provides specialist proof load testing products and services.

Water Weights' water filled proof load bags were originally designed in 1979, as a safer and more cost effective alternative to solid weights, for testing the safe working load of cranes on North Sea oil & gas installations. This simple idea quickly became a revolutionary alternative to traditional methods of testing lifting equipment.

Since those early days, continued product development of what has become a highly engineered and certified system, greatly increased the practicality, economy and safety of providing proof load testing in various industrial applications. In addition, certain proof load testing situations have only become feasible because of Water Weights. Applications have expanded to include all types of cranes, lifting equipment, lifeboats, davits, elevators, platforms and bridges.

The company's continuing evolution enabled expansion of expertise to encompass a wide variety of associated services and engineering project management. Water Weights now provide load measurement systems and services including crane systems, tension load links and shackles, batching systems, bare load cells, installation, calibration, and other specialist load monitoring packages.

Water Weights' customer base now includes oil & gas, defense, construction, process, power & utilities, and marine & shipping industries offering global services in 15 countries in four continents.

Water Weights' core commitment is the provision of products and services to the highest standards. The company is registered to ISO 9001:2008.

Water Weights in Power Generation Plants

Water Weights are extensively used in the testing of cranes in power generation facilities. Water Weights load test bags are light and easy to transport, weighing less than 1.5% of rated load when empty and rolled. The water bags also come ready rigged and ready for placement onto crane hook, which saves on set up, and labor costs.

Controlled loading and minimal handling to achieve a wide variety of loads (% of SWL) equate to minimum downtime for equipment under test. The bags are rigged empty and filled while suspended which eliminates having to reinforce the deck structure when testing with solid weights, especially in the higher ranges.

All Water Weights bags have a designed factor of safety in excess of 6:1 and each bag is physically proof load tested to minimum of twice it's rated capacity. All bags are fully certified and come with documentation of inspection and testing from birth. We fully recommend you ask your supplier for documentation of certification when using any test equipment on critical equipment and facilities.

Water Weights is fully committed to environmental awareness and preservation. We conduct our activities in a manner that manages environmental issues responsibly. Water Weights fully manage environmental impact by:

•Lowering the carbon footprint when crane testing compared to traditional methods
•Internal invasive species mitigation and prevention program
•Conducting operations in an environmentally sound manner without disturbing local ecosystems and bottom sediments by managing turbidity and flow rates during filling and discharge.
•Promoting environmental responsibility among our employees
•Pursuing continuous improvement in our environmental performance

http://www.waterweightsinc.com/en/utilities.html