Steam Power Plant which uses environmentally friendly types of boilers such as CFB (Circulating Fluidized Bed) type boilers. Failure of the boiler pipe has a big impact on the process or the losses it causes. This study will analyze the failures that occur in the boiler tube waterwall of PT. DSSP Power South Sumatra which suffered damage by testing chemical content, hardness test, tensile test, metallographic testing, and Scanning Electron Microscopy (SEM) testing. The test results show that the composition contained in the boiler tube waterwall is not in accordance with the standards, there are some elements that are lower than the specifications. The mechanical properties of watertube boilers are still in accordance with the standards. Leaks that occur in pipes are caused by creeping cracks and causing fatigue so that the damage begins with 'thermal fatigue' which causes cracks in certain weld seams. These open cracks produce leaks which cause the discharge of high velocity fluids which hit adjacent surfaces creating an 'erosion' failure which then results in thinning of the walls of the tube. The thinning of the walls then causes another leak. Therefore, a series of erosions occurred which resulted in several leaks. The fact is that the failure is preferably located in the area of the weld seam which makes it the root cause of the failur
