Procedures for regular inspection of pressure vessels

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Procedures for Regular Inspection of Pressure Vessels

I. Inspection Procedures
1. Inspection procedures for small boilers and pressure vessels: The user applies for an inspection → pays the inspection fee and signs an inspection contract → the vessel to be inspected prepares for the inspection / the inspection agency makes necessary preparations → technical documentation is reviewed → inspection of the vessel itself, auxiliary equipment, safety accessories, and other components → an inspection report is issued → the responsible engineer reviews the report → the technical supervisor approves it → the inspection report is sent to the user.
2. Inspection procedures for large boilers and pressure vessels: The user applies for an inspection → an inspection agreement is signed → a site inspection is conducted → the vessel to be inspected provides technical documentation → an inspection plan is developed → a budget for the entire project is prepared → the vessel to be inspected prepares for the inspection / the inspection agency makes necessary preparations → internal and external inspections are carried out → thickness/ hardness measurements are taken → surface flaw detection is performed → a hydrostatic test or pressure resistance test is conducted (if necessary) → a leak test is carried out (if needed) → an inspection report is issued → the responsible engineer reviews the report → the technical supervisor approves it → the inspection report is sent to the user.

II. Requirements for Inspection Work
1. Requirements for regular inspection of pressure vessels. (1) Prepare the technical documents related to the equipment to be inspected (original technical documents, operation records, inspection data, past inspection reports, documents related to repairs and modifications, certificates of use, etc.). (2) Attachments or other objects that affect the inspection of inner and outer surfaces shall be cleaned and removed in accordance with the inspection requirements. (3) Scaffolds and portable ladders erected for inspection must be safe and sturdy, to facilitate inspection and testing work. (4) Before inspection, the power supply related to the pressure vessel must be cut off, the fuse must be removed, and clear safety signs must be installed. (5) The internal medium must be completely removed; all sources of liquid, gas, or steam should be isolated using blind flanges, and clear isolation markers should be installed. (6) In the case of media that are flammable, toxic, or asphyxiating, conversion, neutralization, disinfection, and cleaning must be carried out, along with sample analysis; the results of this analysis must meet the requirements specified in relevant regulations and standards. The interval for sampling and analysis should be specified in detail in the relevant regulations of the using unit. (7) After the manholes and access holes are opened, all flammable, toxic, or harmful gases that may be trapped must be removed. The oxygen content in the gas inside the pressure vessel should be between 18% and 23% (by volume), and it should also be equipped with ventilation, safety rescue, and other facilities. For those containing flammable media, it is strictly prohibited to use air for displacement. (8) The switches of pressure vessels that can rotate or have moving parts must be locked and secured firmly. (9) The surfaces that require inspection, especially the corroded areas and those prone to crack defects, should be thoroughly cleaned. (10) The supply voltage of the lighting fixtures and tools used for testing shall comply with the provisions of GB 3805 \"Safe Voltage\". (11) During internal inspections, there should be a dedicated person to supervise, along with reliable communication measures. (12) When on-site flaw detection is required, the radiography area should be isolated and safety signs should be installed. 2. Requirements for regular inspection of boilers: (1) The equipment to be inspected must be shut down 3 to 5 days in advance, so that the necessary preparations for the inspection can be made. (2) Open all door and access devices such as manholes, phone ports, inspection holes, furnace doors, ash doors, etc., to allow thorough cooling and ventilation inside. (3) Remove dust, scale, and dirt from the equipment being inspected. (4) Isolate the steam, water, sewage, air and flue ducts connected to the equipment under inspection using blind plates. (5) Remove the internal components and insulation that obstruct inspection. Elevators and scaffolds that require inspection at height. (6) Check whether all relevant technical documents for the boiler (manufacturing, installation, operation, repair, modification, inspection reports) and various related records are complete. (7) The boiler room supervisors should be on site to ensure safety supervision and assist with the inspection work. (8) For fuel and gas boilers, it is also necessary to reliably cut off the source of oil and gas and carry out ventilation and replacement. (9) Power station boilers shall be prepared in accordance with the requirements for the inspection of power station boilers.