|Guy Wire Tension and Tower Vertical Alignment|
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.
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.