Corrosion Induced Explosion of a High-Pressure Fire-Extinguishing Gas Cylinder
- PDF / 1,891,475 Bytes
- 5 Pages / 595.276 x 790.866 pts Page_size
- 105 Downloads / 190 Views
CASE HISTORY—PEER-REVIEWED
Corrosion Induced Explosion of a High-Pressure Fire-Extinguishing Gas Cylinder Yong Jiang • Jian-ming Gong • Peng-jie Tang
Submitted: 7 March 2014 / in revised form: 25 June 2014 / Published online: 4 September 2014 Ó ASM International 2014
Abstract The failure of a high-pressure fire-extinguishing cylinder was investigated. Failure was induced by internal surface corrosion and stress corrosion cracking (SCC) due to condensation of carbonic acid. In internal surface, especially the area near the bottom of the exploded cylinder, severe corrosion was characterized by local pits. SCC initiated from these local corrosion pits was observed by metallurgical analysis. Microstructure of the failure cylinder near the internal surface consisted of multiplebanded structure and the banded structure could accelerate local corrosion initiation and propagation. The corrosion products built up on the fracture surface were primarily ferrous carbonate (FeCO3). The determination of moisture in fire-extinguishing gas was also examined.
for the explosion and evaluate the safety of unexploded eighty cylinders, an exploded cylinder was studied. The studied gas-cylinder was made of 37Mn alloy. The manufacturing procedure was successively as follows: seamless steel tube screwed-in flat ends, quenching, and tempering. After manufacturing, hydrostatical test (225 bar) and air-seal test (150 bar) were conducted to check the strength and airproof property. Table 1 shows the dimensions of the cylinder. Visual examination and scanning electron microscopy (SEM) observation on fracture surface, X-ray diffraction (XRD) examination of corrosion products, and metallographic examination were carried out in order to evaluate the causes of the failure.
Keywords Fire-extinguishing gas Cylinder Carbon dioxide Stress corrosion cracking (SCC)
Visual Examination
Introduction In 2007, from January to May, three similar cylinder explosion accidents occurred successively in different factories. These three cylinders were supplied by different cylinder manufacturers and after charging with fire-extinguishing gas (IG-541:50%N2 ? 42%Ar ? 8%CO2) in a same gas filling station, these cylinders were stored vertically in the workshop until the explosion happened. It was important that there were still about other eighty cylinders which were still in service. In order to determine the cause Y. Jiang (&) J. Gong P. Tang College of Mechanical and Power Engineering, Nanjing Tech University, Nanjing 211816, China e-mail: [email protected]
123
The cylinder was half-opening after explosion (see Fig. 1a). Local corrosion attacks characterized as ‘pits’ (see Fig. 1b) were obvious on the internal surface especially the zone near the cylinder bottom. Pit’s diameter and depth of about 1-3 and 0-1 mm respectively, were measured. Macro-characters of the fracture surface were different along the crack. Corrosion character was obvious in the part within 300 mm from bottom. In this zone, the color of the fracture surface was dark-white
Data Loading...
