The National Weather Service (NWS), a part of the US Government, is tasked with providing weather forecasts and warnings to organizations and the public for purposes of protection, safety and general information. A critical resource to enable NWS to accomplish its task is its network of NEXRAD Doppler radar systems in 154 locations across the United States, as well as six locations overseas.
Data gathered from NEXRAD (Next Generation Weather Radar) is used to display precipitation location, intensity and type. Local TV news viewers are familiar with Doppler weather radar because its colorful images bring the weather forecast to life, enabling viewers to easily understand location and movement of precipitation in their area. In addition, NEXRAD imagery is relied upon by many government, military and aviation organizations enabling them to conduct their operations safely.
From a distance, a NEXRAD weather radar installation looks like a giant golf ball sitting on a tee. The “tee” is a sturdy structure that supports the radar antenna and raises it above local obstacles such as buildings and trees. The “golf ball” is the radome, which houses the rotating radar antenna dish. The dish inside the radome is 28 feet in diameter, operates 24-hours per day, and rotates 360° at varying speeds depending on atmospheric conditions. It continuously emits calibrated radar pulses that reflect precipitation data back to the antenna from over 100 miles away.
Here is how NWS meteorologist Greg Schoor describes it: “This big, massive dish sits on a pedestal, spins around, and a big antenna that hangs on the front side of the dish shoots out an electromagnetic pulse.”
The rotating dish is attached to the pedestal, which in turn is attached to the floor of tower structure using an array of twelve very important bolts. Years ago, NWS engineers determined that these bolts were critical to overall system integrity, and therefore must be properly maintained at an appropriate tension. To meet this requirement NWS chose to use visual tension indicating DTI SmartBolts from Stress Indicators, Inc.
SmartBolts® technology contributes to reliable and accurate NEXRAD operation by ensuring that each radar antenna remains properly aligned, thus supporting the integrity of the entire system. All NEXRAD sites must collect accurate data because information from many sites is combined and used to analyze weather phenomena of immense scale. One could say that DTI SmartBolts safeguard the most important bolted joints in the NEXRAD system.
Dan Hoffman, a Logistics Management Specialist at National Weather Service, informs us that “the radar is calibrated to a certain azimuth. If the pedestal bolts are loose and it turns even a small amount, we cannot be sure of the results we get because we calculate meteorological target position and measure Doppler shift. The benefit of using SmartBolts to secure the pedestal is that we know the pedestal is secure, we know the pedestal is level and we know the pedestal is in the place it needs to be”.
NWS must be certain that these critical bolts are properly tightened in each of the 160 NEXRAD sites. By using SmartBolts ® Visual Indication System™, they have removed all doubt. DTI SmartBolts display tension in real-time with a color indicator. When the bolt is properly tensioned, the indicator is black. If the DTI SmartBolt loses tension for any reason, the indicator changes color from black to bright red, signaling an inspector that the bolt needs to be re-tightened. If so, he need not use an expensive and cumbersome torque wrench, a regular wrench will do the job. Just tighten until the indicator in the bolt head returns to black, and one can be sure that the bolt is properly tensioned and the system is secure.
The SmartBolts® Visual Indication System is an intuitive system to visually verify bolt tension and does not require additional training or special tools. Employees of the NWS have been installing DTI SmartBolts at a dozen or more sites each year since 2007, and require only an ordinary wrench to achieve proper bolt tension in this critical application. According to Hoffman, the NWS has “had good success with SmartBolts for years”. All 160 NEXRAD sites are expected to be outfitted with DTI SmartBolts® by 2018.
The sites are operated by several U.S. Government entities, including the United States Department of Commerce, the Department of Defense, and the Department of Transportation. DTI SmartBolts are a preferred source at NEXRAD sites operated by these agencies, a testament to the unique bolting solutions that can only be provided by Stress Indicators, Inc.