Performance Standards

PERFORMANCE STANDARDS
By: John W. Davis, PE

During the past several months, I have participated in a number of court cases which are worth reviewing for purposes of improved risk management. I assume it’s no revelation to you that each time you certify a crane, you assume a certain amount of risk. The trick is to minimize that risk. You may not be doing the things noted below, but you can use these comments to firm up your resolve to strengthen your risk management situation.

A recent case in California involved a commercial truck mounted crane that dropped a suspended load because the winch brake slipped and a worker was crushed. The crane had been inspected within the previous two months by a certifier and the brake problem had not been discovered. Other deficiencies had been discovered and listed and they were repaired by a service facility. Some of the repairs were structural and it was undetermined whether or not the crane had been load tested. In any event, the brake problem remained unidentified. The crane was returned to the owner and a couple of days later the injury occurred. The court found that the responsibility rested on the certifier because he failed to inspect or test the brake. His insurance settled for the limits of his policy. This case demonstrates the wisdom of testing at rated line pull and/or checking brake adjustment and wear. Failure of the certifier to determine that hoist brakes are within operational specifications is not defensible, even if a repair facility has worked on the crane in the repair-verification-certification process.

In another case an iron worker was killed when the power down brake failed to hold, dropped the load, and crushed him. The brake had not been inspected for several years nor had the function been tested at maximum line pull. The certifier and the owner were both held responsible because both had failed to heed the manufacturer’s instruction to inspect the brake at specific periods and the certifier had failed to test it. This case also demonstrates the wisdom of testing the hoist at rated line pull at minimum. Trial attorneys have the nasty habit of attacking if we inspect and don’t test or test and don’t inspect! The only sure way to minimize the risk is to do both. This issue is not limited to hoist brakes. The same concerns exist with boom elevation capacity and auxiliary hoists. Line pull capacities and boom elevation capability don’t require much weight to test and it seems foolish to leave it undone and risk a devastating law suit.

Another problem has surfaced regarding conventional crane booms. In this case, the 180-foot boom with a 60-foot jib failed and killed a laborer who was eating his lunch. It was determined that boom sections had been inspected prior to erection, but the specific section that failed was not specifically identified so the inspection was challenged and the owner’s insurance paid. I suggest that it is particularly important to identify the boom sections so that your inspection and load test can be substantiated.

Some manufacturers serialize the boom sections. If they don’t, the certifier should stamp an appropriate identification on each section and record the section identifications on the load test documents. I still notice that, from time to time, single pick quadrennial tests are being done. There’s no way this practice can be defended. Also, I notice frequent load tests that don’t even approach 50% of maximum capacity, which is hard to defend. Additionally, if the load tests are not designed to impose maximum line pull on multi-part reeving as well as on single line hoists, the load test is not really defensible. Take a look at CCAA Load Test Procedure for guidance on load testing.

Remember, by the time the attorneys look at an accident, the only thing left is the paper record and the fragile memories of percipient witnesses. Be sure that your certificates and check lists display sufficient information to demonstrate compliance with the regulations of appropriate jurisdiction. If they don’t look good to me, an attorney will attack them relentlessly; it only takes once!

Document is shared with the kind permission of John Davis, a colleague and fellow director at the Crane Certification Association of America (CCAA). The association promotes crane safety, improvement of the certification profession and addresses the subject of crane safety in governmental forums.

For more information visit the association page: http://ccaaweb.net/associations/1297/CCAANL0910.pdf

www.waterweightsinc.com

Structural Verification and Deck-Platform Testing

The Water Weights range of flexidams and mattress bags allows uniform surface loadings to be applied. Advantages over traditional solid weights include ease of handling and positioning on site, very low carriage costs and gradual application of load (often over a period of several days).

Loading is measured by means of a calibrated flowmeter to give accuracy of +1/-2%. By using our simple manifold arrangement several units can be filled simultaneously.

Water Weights provides specialist products, services and project management for structural testing. This includes verification of structural integrity of buildings, testing of bridges, elevators, loading ramps, gangways and decks.

Specific examples of applications include:

Roll on, roll off ferry ramps have been tested ranging from 70 to 600 tonnes

Ballasting arrangements for ship's conversion up to 300 tonnes

General floor testing applications to verify structural integrity on renovation; change of use or suspected structural damage. Examples include, 130 tonnes to an educational establishment and 40 tonnes to an historical monument.

Passenger and freight elevator testing.

For further information visit:
http://www.waterweightsinc.com/en/deck-loading-testing.html

WATER WEIGHTS for testing Aircraft Elevators

Internal Study for US Navy Fleet Benefits

Aircraft Elevators are designed primarily to transport aircraft between the hangar deck and the flight deck. They are, however, also used to transport cargo and equipment. Aircraft Elevators are found on aircraft carriers and on some amphibious assault ships such as LHA’s, LPH’s and LHD’s. All aircraft elevators use hydraulic engines, sheaves, and wire ropes to lift and lower the Platform.

There are two major types of aircraft elevators, the deck edge and the inboard types. These names refer to the location of the elevator platform on the ship. The machinery for inboard and deck edge elevators operates under the same principles and is similar in arrangement. Deck edge elevators are cantilevered off the hull of the ship. Inboard elevators use the platform as a hatch at the flight deck.

Guide rails and rollers constrain the platform so it can only move in the vertical position. Mechanical Locks hold the platform in place at the flight deck level taking the load off the wire rope.

Elevator Testing

New and modified aircraft elevators are tested prior to regular operation to ensure proper performance of all elevator components. There are no periodically required tests of aircraft elevators. However, because load testing and operational testing are required whenever hoisting wire ropes are replaced, every aircraft elevator will be tested at least once every five (5) years.

Load testing proves the ability of an elevator to perform properly through the complete range of operating limits with the platform loaded. The aircraft elevator require load testing with the rated load only. The stress applied by ship motion on the load bearing components is less than the stress due to normal operation.

The operational characteristics of the aircraft elevator require that additional loading effects of ship motion on the platform and its rated load at the flight deck level will not stretch the wire ropes and cause the platform to drop below the deck level. The flight deck is held tight to the flight deck because the hydraulic engine applies a load to the wire ropes beyond that which would be added by ship motion. The loading is applied every time the platform reaches the flight deck, regardless of weight on the platform. Hence, A static and dynamic load test (typically 150-200%) over the rated load capacity would not provide any additional assurance of proper elevator operation.

According to the Naval Ships’ Technical Manual (Chapter 588) an aircraft elevator must be fully load tested after repair or replacement of any of the following components:

1.Wire ropes
2.Sheaves and cross head
3.Hydraulic Engine (ram or cylinder)
4.Guide rails
5.Platform structure
6.Guide or face rollers

Traditional Method.

Labor and support equipment using current methods with steel or concrete weights with an average test time of 5 days for all elevators. Assumption is that the testing is done as part of a shipyard contract.

1.Support crane on pier (for testing inboard elevators)
2.YTD crane (for testing outboard waterside elevators) or Support crane lifted onboard the flight deck in order to reach waterside elevators.
3.Tug for positioning YTD crane or rental of barge mounted crane
4.Crane Operator
5.Minimum of 5 Riggers for positioning weights
6.Test Director
7.Electrician

Water Weights Method

Using the Water Weights method, all testing would be completed in two days. No dockside crane support is required. Two technicians complete all labor requirements. All equipment is transported in a pick-up truck.

Equipment used was as follows: -

8 x 8 tonne (17632 lbs) WATERWEIGHTS test bags
4 x Certified Flow Meters
1 x Manifold Filling Assembly
3 x 50ft Fire Hoses
2 x Diaphragm Pumps (used for emptying the bags)
Fill time (assuming 240 gallons per minute) to achieve full load is 40 minutes. Emptying (using diaphragm pumps) is approximately 30 minutes.

Given the figures above the obvious cost savings is huge compared to traditional methods. Additionally, testing takes 48 hours as opposed to 5 days. This might allow a shortening of the time the ship spends in dock, and therefore increased availability. Finally, two other important issues may have significant effect.

A)The above estimates assume that all elevators will be tested one after the other on the same mobilization. This rarely happens. The additional costs of separate mobilizations of tugs, YTD and shore based cranes dramatically widens the cost differential between the WATER WEIGHTS method and traditional methods.

B)Inevitably there are failures and the need for re-test. The cost of mobilization for re-test using WATER WEIGHTS will be lower.

C)There is also the added benefit of scheduling flexibility to both the testing activity and the ship itself because of the elimination of trying to schedule a support crane, tug or crane barge on scheduled test days.