Water Well Journal
Issue link: http://read.dmtmag.com/i/515025
It's okay to use unmarked tiedowns, but welded steel chain should be considered to be equal to the working load limit of grade 30 proof coil. Other unmarked tiedowns are equal to the lowest rating of its type in the FMCSA's table of working load limits. "Bungee cords don't count," Renner says. "It has to be a rated strap, and the load has to be able to withstand the strapping." Acceptable tiedowns include chains, synthetic rope, manila rope, wire rope, and steel strapping. Andrews & Foster prefers "ratchet" boomers with chains or ratchets with straps instead of "breakover" boomers because Kinder feels they are easier and safer to use when transporting a load. In addition to the working load limits, how you're securing the cargo matters. If you are directly securing the cargo—which means you attach the tiedown from an anchor point on the vehicle to a point directly on the cargo—you can use the 50% of the work- ing load limit of each tiedown. If you are indirectly securing the cargo—which means you attach the tiedown from an anchor point on the vehicle over, through, or around the cargo to another anchor point on the vehicle— you can use the entire working load of each tiedown. Renner gives the following example to illustrate how working load limits affect the number of tiedowns you need: You're securing a load that's 18 feet long and 40,200 pounds on a flatbed with 4-inch wide-load straps using an indirect tiedown method, and it's not against a bulkhead. The straps are rated at 5000 pounds each. Under the length requirements, you would need three tiedowns—two for the first 10 feet and an additional tiedown for the remaining 8 feet. But, the weight of your cargo requires you to have more. Under the aggregate weight limit requirement, your secure- ment system must be able to withstand 20,100 pounds (half of the total weight of the cargo). Because you're indirectly tying down the cargo, you can use 100% of the 5000-pound weight limit of each tiedown. In this case, you would need five tiedowns because 20,100 pounds divided by 5000 pounds is only 4.02. Twitter @WaterWellJournl WWJ June 2015 29 TIEDOWNS continues on page 30