The previous section described several steps before filling the cylinder. Now let's go on to the following parts

7、 Whether the original marks of gas cylinders conform to the standards and regulations, and whether the steel seal is clear and legible.

Check the original signs of gas cylinders. In some gas cylinder reload stations, little attention is paid, which is very unfavorable to ensure the safe filling and use of gas cylinders. Some illegally manufactured gas cylinders, stopped gas cylinders, gas cylinders requiring re inspection, welded high pressure gas cylinders, and high pressure gas cylinders "restructured" from waste seamless gas cylinders can not be cleaned if they are mixed with normal gas cylinders for a long time. If such gas cylinders are not removed through inspection and continue to be used, they will inevitably lead to explosion accidents and cause heavy losses to national property and personal safety. Therefore, attention should be paid to this inspection. If the original marks are found not in conformity with the regulations and the cylinders need to be removed during the inspection, they shall be handled according to the requirements of Item 1 and Item 3 above respectively. Gas cylinders with illegible steel seal shall be handled according to the requirements of Item 3 above

8、 Whether the gas cylinder is within the valid probation period of regular inspection, and whether its inspection color code meets the requirements.

Gas cylinders used beyond the inspection period can be found at any time in some areas, especially in villages and towns and individual gas plants, which is very dangerous. On July 9, 1988, an oxygen cylinder explosion occurred in a township shipbreaking factory in Dalian City. The exploded oxygen cylinder was manufactured in April 1985, and was put into use after it passed the re inspection by the Municipal Boiler and Pressure Vessel Inspection Institute in June 1986. On June 31, 1988, it was sent to a township oxygen plant for air inflation. On July 3, when checking the cylinder, it was found that the cylinder had exceeded the valid inspection period. However, considering that the number of cylinders requiring regular inspection was very small, the cylinder would be inspected again when it returned next time, so the cylinder was charged with oxygen at a pressure of about 13 MPa. At 11:00 a.m. on July 9, the bottle was transported back to the ship dismantling plant along with 30 other gas cylinders and stacked in the sunny place at the foot of the mountain. At about 12:30, the bottle suddenly exploded and flew towards the back slope 146m away from the cylinder stacking place, then bounced off again and fell 17.8m away, and the bottle body almost spread into a flat plate. Several other gas cylinders stacked together with the bottle were also shaken away, and one of them flew 149 meters away from a house. A total of 10 cylinders were damaged. When the gas cylinder exploded, the employees in the factory ate lunch in the canteen far away from the gas cylinder stacking place, so no casualties were caused. It is not difficult to imagine that if this explosion accident did not occur in the ship breaking plant but in the filling room or full cylinder storage room of the oxygen plant, the consequences would be unimaginable.

The reason why the static pressure explosion accident of the above cylinder can occur at 13 MPa lower than its design pressure is that the employees of the shipbreaking plant lack the knowledge of the safe use of the cylinder, do not close the cylinder valve after the gas in the cylinder is exhausted, and the sea water is poured into the cylinder. Under the action of chloride ions, the inner wall of the cylinder suffers serious corrosion, and the wall thickness is significantly reduced (the measured minimum wall thickness is 1,45 mm), so that it explodes under the sunlight at noon.

From the above accident cases, it is not difficult to see the danger of using cylinders beyond the inspection period and the necessity of inspection signs. Therefore, it is required that gas cylinders beyond the inspection period shall not be inflated. Gas cylinders found to exceed the inspection period during the inspection shall be handled according to the requirements of the third item above.

The color code for spray inspection of gas cylinders is a new regulation of the Regulations of 1989, which aims to make the inspection status clear at a glance and to find the inspection mark easily. There are five colors and two shapes of the color code to be checked, with a cycle every 10 years. If the color and shape of the inspection color code do not meet the requirements during the inspection, the gas cylinders shall be handled according to the third item above.

9、 Whether the nominal working pressure marked on the original mark or inspection mark of the cylinder meets the specified filling pressure of the gas to be filled.

Before the promulgation of the Regulations of 1989, there were a large number of high-pressure gas cylinders that did not change the filling medium but only reduced the service pressure by one or more grades. The most common are oxygen cylinders and carbon dioxide cylinders. If oxygen cylinders with pressures of 12.5, 10 and 8 MPa are used, carbon dioxide cylinders with pressures of 12.5 MPa are used. As the color mark on the outer surface of such gas cylinders has not changed, they are often mixed with normal gas cylinders for filling, which is very dangerous. In order to avoid this situation, Regulations 89 clearly stipulates that such depressurized cylinders are no longer allowed to be used.

79 The reason why the bottle regulations allow the use of the above depressurized gas cylinders is that the supply of gas cylinders was in short supply at that time, and a temporary measure was taken to meet the needs of the society for gas. At present, the supply of gas cylinders is abundant. In order to ensure the safe filling and use of gas cylinders, this measure should be canceled.

In addition to the above depressurized cylinders, low-pressure cylinders made in the Soviet Union and Italy with a working pressure of 3 MPa and a depressurized pressure of 30 kgf/cm were also found in Jiangsu, Henan, Liaoning and other provinces ² Gas cylinders are mixed with high-pressure oxygen cylinders to fill with oxygen, which is more dangerous. Pay more attention when checking.

If the nominal working pressure of the gas cylinder is not in conformity with the specified filling pressure of the gas to be filled, it shall be handled according to the third item above.