Abstract: At approximately 2:00 p.m. on January 19, 2009, Employee #1 was conducting a 3,000-pound-per-square-inch test of an oil field recovery heater. He connected the test plumbing tree to the heater and increased the pressure to the test goal. A o.75-in. diameter schedule 40 threaded pipe nipple connecting the tree to the 3-in. diameter water tubes of the heater developed a leak. While under the test pressure Employee #1 began to tighten the nipple. The test tree broke away from the water tubes, striking and throwing him approximately 25 ft away and to the concrete floor. Employee #1 was hospitalized with a fractured back.