A scaffold company with a plank testing program can virtually eliminate plank accidents.
The center piece of the program is the Indian Mill SPT6 Scaffold Plank Tester. Scaffold planks get beat, banged, ran over, sawn, drilled, welded on; water soaked, dried out, and in Industrial plants gets exposed to chemicals and acids. There are many things on a scaffold job that can damage scaffold plank. Visual inspection and machine testing is the only way to know if the planks can safely support the worker and equipment.
Used planks need to be visually checked for rot, acids, alkali, burns, cuts and any other physical damage that obviously require throwing it out but after the visual inspection has been done the plank can be verified as meeting all OSHA and ANSI standards of strength and deflection using the Scaffold Plank Tester from Indian Mill. (SPT6)
The testing of the plank will in no way damage the wood fibers in a qualified scaffold plank. In house testing has run 1,000 iterations on the same test piece without any damage. The measured deflection stayed with in 1/100 of an inch for the complete test. Non-Destructive testing is no more damaging than a worker walking across a plank.
The calibration of applied weight is to the one tenth of a pound. Calibration of length of deflection is to the one tenth of an inch. Recalibration of tester electronics is to be done annually.
The answer is: No one knows with out periodic inspection and testing. When manufacturing a new scaffold plank the process of qualifying a piece of wood to be a scaffold plank is extensive but with time and use that same plank can be physically damaged to where it no longer can safely support a worker. Also at some point in time every plank will have to be removed from service and only by testing can you know when that time is.
All planks up to 12 inches wide and 20 feet in length can be tested.
The test data is stored in the onboard computer and can be down loaded to a central system as the test are being run or in daily reports. Testing information is very important for inventory control and plank tracking.
A customer can mark his own planks with testing stamps or paint the end of the plank with the color of the month to signify testing. As a feature Indian Mill also provides a hot branding device to automatically burn in the date that the plank passed the test. Most customers prefer the automatic hot branding.
|Light||Medium||Heavey||US Allowable Deflections||Canada Allowable Deflection|
|Length||Span||25 lbs ft2||50 lbs ft2||75 lbs ft2|
|6 ft||5 ft||250 lbs||250 lbs||312 lbs||1.0"||.75"|
|8 ft||7 ft||250 lbs||292 lbs||437 lbs||1.4"||1.05"|
|10 ft||8 ft||250 lbs||333 lbs||*500 lbs||1.6"||2.2"|
|12 ft||10 ft||250 lbs||*416 lbs||N/A||2.0"||1.5"|
|*Not for nominal DI65|
Center point load testing is placing the load exactly in the middle if the span. Distributed load is weight spread the length of the plank. The center point load is 5/8 (.625) of the distributed load. For testing purposes it is much simpler to use center point which yields the same results. The distributed load numbers are the criteria for the span charts showing 1 man, 2 men, or 3men working on a plank.
|Center Point||Distributed Load|
|250 lbs||=||400 lbs|
|292 lbs||=||467 lbs|
|312 lbs||=||500 lbs|
|333 lbs||=||533 lbs|
|468 lbs||=||750 lbs|
The testing process has been simplified by the following procedure: Set the barriers to the desired span, place a calibrated load on the center of the plank and measure the distance of plank bending. This procedure will develop the properties of a scaffold plank.
|* ANSI A10.8 .18.104.22.168. Length of span / 60||L/60||L/80|
|* OSHA Standards Subpart L 1926.451 (a) (1)||4 to 1 safety||--|
|* OSHA Standards Subpart L 1926.454
General guide lines and tables
|(a) 8 ft plank|
|(b) 7 ft span|
|(c) Load 50 pounds per ft2 (292 lbs)
Load placed in center of the plank
| Calculation for the center point loads.
84"L x 10"W = 840"2 ÷ 144"2(1 ft2) =
5.83 ft2 X 50 lb ft2 = 292 lbs
|(d) Deflection is less than 1.4"|| Calculation for the amount of deflection.
Length of plank in inches Divided by 60
OSHA’s US L/60 Canada L/80