A licensed contractor installed two newly manufactured vertical machine-mounted air receivers for instrument air processes at a wood treatment facility in November 2020.
During a scheduled maintenance service after eight months of operation, cracks were located on the top head of each vessel, specifically at the head-to-bracket weld fillet welds. The cracking was in similar areas on both vessel heads at the toe of the weld transverse to the weld start location. The facility Operations Dept. employees safely shut down the equipment and removed them from service.
The new air receivers were installed by a licensed contractor in site locations indicated by the owner. The flooring was concrete, and no vibration isolation pads were installed under the units as recommended by the manufacturer. The support legs were installed tightly to the concrete floor, not allowing room for movement.
The facility operates 24 hours hrs/day, seven days a week. The equipment has a duty cycle of 80%, and it was operating at the high end of its duty cycle limits resulting in many starts/stops on the equipment. Approximately 140-180 cycles per 24-hour period were reported.
Because the air receivers operate at a high-duty cycle, being installed without vibration isolation pads caused excessive stress at the toe of the fillet welds causing cracks to develop.