Duncan Aviation Project: Phase II

April 14, 2019 at 1:13 p.m.

By GREENLINK Engineering.

This job was the second phase of an earlier project involving the roof of an airplane maintenance facility.

This phase II project required replacing aging wood sleepers supporting 400 feet of a roof-mounted gas line. The roof was built with an upper and lower section each about 200 square feet with a 2 ½ foot drop off. The gas line consisted of 21 sections with an expansion joint about halfway down the length.

The original system featured two parallel wood 4x4s positioned on the ridges with a cross beam for supporting the pipeline. The steel corrugated roof over the airplane hangar presented an unusual challenge because of the absence of a flat surface on which to position the support system. Some of the sleepers had begun to split and crack and others had slipped into the valleys of the corrugated roof, stressing the gas line and expansion joint and causing them to contort.

As in phase I, GREEN LINK custom-molded polyurethane saddles were placed over the corrugated ridges to provide a flat surface on which the KnuckleHead system would sit. The saddles were loose laid, but the KnuckleHead bases were bonded to the saddles using GREEN LINKAdhesive/Sealant to secure the installation.

Two installers worked in tandem moving down the pipeline, one removing the wood supports with the other following behind to install the GREEN LINK KnuckleHead system, straightening the pipe and expansion joint along the way. The GREEN LINK system consisted of parallel pairs of Strut KnuckleHeads into which steel channel was positioned to support the pipeline. The KnuckleHeads included extensions to ensure that the pipeline would consistently remain 7 ½ inches off the roof ridge. GREEN LINK Adhesive/Sealant was used to bond the channel into the strut head. The pipe was then clamped into position.

Replacing the sleepers with the lighter weight KnuckleHead system removed an estimated 539 lbs. of point loading from the roof. The two-person crew completed the job in less than 7 hours.