It is not unusual for a contractor or building owner to climb up on a commercial roof and encounter sagging pipes and ducts. The causes vary. In some cases, the supports have deteriorated due to weather. Wood sleepers are probably the most common type of support failure. Over time, weather cycles will eventually cause the wood to submit to biological attack and soften. In other cases, the weight of HVAC equipment such as chillers or air conditioning units exceeds the strength of the support material.
KnuckleHead Supports eliminate both of these problems. KnuckleHeads are molded from glass-reinforced nylon, a particularly tough material that is resistant to all types of weathering including freeze-thaw cycles, moisture, UV exposure and stress. Further, each KnuckleHead can support up to 600 lbs. of weight, sufficient to handle the most demanding of loads.
However, it is not unusual to encounter sagging pipes and ducts even when supports are fully intact. In this case, the culprit is likely incorrect spacing, meaning that the supports are too far apart for optimal weight distribution. The placement of pipe and strut supports should be calculated in advance to eliminate the possibility of sag.
Support interval tables are available from Green Link to ensure the correct spacing of KnuckleHeads to eliminate pipe and duct sag. These tables present the maximum suggested spans for Schedule 40 Steel Pipe, Schedule 80 Steel Pipe, and PVC Pipe per ASTM A53-86.
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The KnuckleHead Support System is engineered to safely support pipes and equipment without compromising the integrity of the roofing system. KnuckleHeads are tough, durable and strong. Proper spacing will ensure a successful, long term installation.