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Guy Wire Tension and Tower Vertical Alignment
 
GUY TENSIONING
 
There are two common methods of measuring guy tension on tall towers; Direct and Indirect.

The Direct Method uses mechanical or hydraulic equipment to actually pull the guy wire to measure the tension. Providing the gauge in use is accurate, this method is the most precise possible. The Indirect Method uses assumptions and calculations to predict the tension. The most common application of this method is the Sag Intercept method. This method is likely less accurate than the Direct Method due to the many variables in the calculations.

At Tower Network Services we perform guy tension measurements using a hydraulic system comprised of high-pressure pump, hydraulic jacks and pressure gauge. In fact, our guy pull kits actually contain two gauges; one a working gauge and the second a master gauge to verify the accuracy of the working gauge. All of our gauges are Certified for accuracy by an independent testing laboratory before we place them in service.

Ambient temperature affects tower guy tensions and must be considered when adjustments are made. To determine the temperature compensated required tension you must review the design drawings.

The usual practice is to interpolate or extrapolate using two design tensions to obtain the required tension at your given temperature. A thermometer for measuring ambient temperature at the anchor when the adjustment is taking place should be used.

Since guy tensions are such an important part of the tower design strength, we believe the effort and cost of accurate Direct Method tension work is easily justified.

 

 
TOWER ALIGNMENT
 
Two primary considerations apply when evaluating tower alignment;

FIRST, structure overall Plumb. This refers to the measurement of deviation from a perfectly vertical line from the tower base.

SECOND, linearity must be considered. This refers to the relationship between the Out of Plumb value and the vertical distance in which that deviation occurs. Deviations out of Plumb, if linear over the entire structure height, might not exceed the specifications. That same out of Plumb, if occurring in a confined section of the overall structure, could easily exceed the specifications. This is viewed as a "kink" in the tower.

The point to focus on here is that tower alignment is not simply, "How far out is my tower?". It matters where any deviation exists.

A proper Guy Tension-Tower Alignment report should include evaluation of any free-standing mast alignment. Samples of these pages from our Tower Inspection Report can be viewed by selecting  the "Tower Inspections" link button and choosing Page 5 and 6.


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