Before filling, the gas cylinders shall be inspected one by one by a full-time inspector before filling. The basic inspection items and safety precautions are described as follows.

1、 Whether the cylinder is manufactured at the manufacturing point with the manufacturing license issued by the labor department.

If cylinders manufactured by units without manufacturing license are found, they shall be marked and stored separately, the causes shall be found out and reported to the local labor bureau

2、 Whether the imported gas cylinders are inspected as qualified by the gas cylinder inspection unit with the inspection license issued by the labor department.

Imported gas cylinders found to be put into use without inspection shall be handled according to one of the above requirements.

3、 Whether the cylinders are out of service or need to be re inspected according to the documents of the superior or the manufacturer.

If the gas cylinders are found to be out of service or need to be re inspected, they shall be marked and transferred to the gas cylinder regular inspection station for disposal as required.

4、 Whether the cylinder material meets the requirements of the nature of the gas to be filled.

If the cylinder is found to be seriously rusted, or the internal corrosion products are not suitable for the nature of the gas to be filled, the requirements of the first item above shall be followed.

5、 Whether the gas cylinders containing permanent gas and high-pressure liquefied gas are of welded structure.

According to the provisions of the Regulations of 1989, the gas of high-pressure gas cylinders must be of seamless structure. High pressure gas cylinders with welded structures shall be treated according to the requirements of the first item above, and welded high pressure gas cylinders manufactured early shall be treated according to the requirements of the third item above.

6、 Whether the refitting of gas cylinders meets the requirements, and whether there are refitting by users themselves.

The "cylinder refitting" is a new addition of the 89 cylinder gauge, and the 79 cylinder gauge is only used for depressurization. There are two cases of depressurization. One is to reduce the operating pressure by one or more grades without changing the filling medium. For example, if the original design pressure of the oxygen cylinder is 15 MPa, it will be reduced to 12.5, 10 or 8 MPa and still be filled with oxygen. Another way is to change the filling medium for depressurization. For example, the original design pressure is 150 kgf/cm ² Oxygen cylinder, reduced to 30kgf/cm ² Modification of liquid ammonia or difluorochloromethane is now called modification. In the former case, because the color of the cylinder does not change, but the pressure relief steel seal is punched, the pressure relief cylinder is often thrown into the normal cylinder for filling, which is very dangerous. In order to avoid this situation, the 89 bottle regulation clearly stipulates that the first type of depressurization allowed in the 79 bottle regulation is no longer allowed, and only the modified depressurization is allowed. At the same time, it is stipulated that the refitting of gas cylinders can only be carried out by the regular inspection station of gas cylinders and should meet certain requirements.

There is another case of cylinder refitting, that is, changing the filling medium does not change the filling pressure. For example, for an oxygen cylinder with a nominal working pressure of 15MPa, nitrogen, hydrogen, air or carbon dioxide are refitted without changing the filling pressure. This case and the modification of the second case above involve the compatibility between gas and gas, gas and cylinder material, gas and residue in the cylinder, gas and cylinder valve or other accessories, which should be noted during inspection.

If it is found in the inspection that the refitted cylinders do not meet the requirements or the users refit the cylinders themselves, the cylinders should not be returned to the users lightly, but must be handled according to the first requirement above.