Investigation of boiler tube failures in SWCC Jeddah power plant

Abstract EN

Leakages were observed from the roof tubes of the second pass of boilers #6, 7, and 8 of Jeddah Phase-3 power and desalination plant.

Saturated steam flows through the roofing tubes which were made of carbon steel, the temperature outside the tube is around 1280°C and the inside temperature is about 450 °C.

In one case (boiler #6), bifurcated roof tubes from the header showed cracks at the welding and pits around it.

In another case, (boiler #7), roof panel tubes under refractories were burst open and the adjacent tubes were also affected.

In boiler #8, the bifurcated roof tubes had developed linear and radial cracks.

Thinning down of the inner surface of the tube and bulging out of the outer surface of the tube were the familiar features of the failure.

Failure analysis was carried out using both non-destructive (ND) as well as destructive (D) techniques.

Methods of ultrasonic testing, optical and scanning electron microscopy, X-ray diffraction analysis and energy dispersive X-ray analysis were used during the investigation.

The macroscopic examination of the tubes showed the presence of cracks, pits, cavitation marks, and surface roughening.

The causes of failure have been determined and the mechanism of corrosion attack has been discussed.