CoatingsPro Magazine

MAY 2017

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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Page 34 of 84

34 MAY 2017 COATINGSPROMAG.COM than reducing the other. Load can be decreased to the cables simply by reducing the cable spacing, but that squared term applied to the span means that inch for inch, reducing the hanger spacing will give you the greater change in result as compared to tightening the cable spacing. Take our overzealous worker example with a 6-inch (15.2 cm) deflection now governed by clearance requirements. Note first that the required deflection is now not only a maximum deflection requirement but also a minimum deflection require- ment. To keep cable forces in check, deflections are minimum, meaning larger deflections are welcome and will create smaller tensile forces in the cables. However, to abide by clear- ance restrictions, deflections must also have a maximum value. It is best, therefore, to design for as great a gap in design tensions to allowable tensions as possible due to almost certain field adjustments that will add tension to the cables. In our earlier example, our cable tension with a 6-inch (15.2 cm) deflec- tion was calculated at 12.6 kips — well above the 6.87 kip allowable force. If cable spacing is halved from 5 feet (1.5 m) to 2.5 feet (0.8 m), leaving the hanger spacing as is, the cable tension drops from 12.6 kips to 6.3 kips, an acceptable value, but not the desired outcome. A lternately, however, if the hanger spacing can be halved from 20 feet (6.1 m) to 10 feet (3.1 m), leaving the cable spacing as is at the 5-feet (1.5 m) centers, the cable tension drops from 12.6 kips to 3.2 kips — a huge difference that creates that desired gap in design tensions versus allowable tensions that allows for field adjust- ments of the cable. Way Ahead Now, all is not doom and gloom with cables. Given proper protocol in maintenance and rigging, it is very safe. Consider the following key factors with cable use: • Maintain a proper cable inspection plan; it is paramount to safety and needs to be on every contractor's to-do list. Immediately retire any cables from use that do not meet industry standards. • Know your maximum cable allowable forces and minimum deflection crite- ria for each application, and strive to remain within the limits. Utilize several stress gages placed on cables in key locations throughout the platform area (e.g., fascia cables vs. Safety Watch CALL 407-298-7050 DYNAMIC DIAMOND TOOLING "BEAST" Finally an EDGE Grinder that WORKS ! ALL-IN-ONE MACHINE • Grind Right UP and INTO The EDGE • Use the same diamonds on the edges as you do on the main floor • Machine converts from 12" Head to a 20" Head in minutes •Available in 3-Phase or Dual Phase Power • Variable Speed Search: DDT The Beast Overview GRINDER H H ZERO-TOLERENCE EDGER H POLISHER SLICER H H BURNISHER H SCRUBBER Zero - Tolerence Edging Wr i te in Re ad e r In q u ir y #387

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