How long after pressure vessel repair should the initial inspection be conducted?

I. Is immediate inspection required after repair?

Yes, an inspection must be conducted immediately after all major repair work is completed; this is itself an "initial inspection." This inspection is not conducted after a certain period, but rather a comprehensive verification performed immediately after the repair is completed and the repaired parts have undergone non-destructive testing and pressure testing.

Inspection content includes:
Appearance and dimensional inspection;
Non-destructive testing (MT/PT/UT/RT);
Pressure testing and airtightness testing if necessary;
Safety accessory verification and material property review.

Only after passing the above inspections can the equipment be put back into service.

II. How is the next periodic inspection time determined after repair?

The next scheduled inspection cycle after repair is not recalculated from the repair date (3 years). Instead, it is determined by the inspection agency based on the safety status level assessed by the current inspection results:

Safety Status Level 1 or 2: Generally inspected every 6 years;

Safety Status Level 3: Generally inspected every 3-6 years;

Safety Status Level 4: Monitored use, inspection cycle determined by the inspection agency, cumulative monitored use time not exceeding 3 years;

Safety Status Level 5: Defects must be addressed, otherwise continued use is prohibited.

⚠️ Special Reminder: If the repair involves replacement of major pressure-bearing components, patching depth exceeding half the wall thickness, or multiple repairs, the inspection agency may downgrade its safety level, thereby shortening the next inspection cycle.

III. Initial Inspection Requirements for Special Types of Containers The initial inspection timeframes vary depending on the material and purpose of the pressure vessel:

Metal pressure vessels: Generally, the first periodic inspection should be conducted within 3 years of commissioning.

Non-metal pressure vessels: Generally, the first periodic inspection should be conducted within 1 year of commissioning.

Low-alloy steel spherical storage tanks with a standard tensile strength lower limit > 540 MPa: The first opening inspection should be conducted within 1 year of commissioning.

Medical oxygen chambers: After new construction or relocation, the first periodic inspection should be conducted within 1 year of commissioning.

Therefore, if the repaired container belongs to the above special categories, the subsequent inspection cycle should be adjusted accordingly.

IV. Other Factors Affecting the Inspection Cycle The following situations may lead to an appropriate shortening of the inspection cycle:

High corrosion rate of the medium on the material or unclear corrosion status; Harsh operating conditions or low management level; Poor weldability of the material or multiple repairs during manufacturing; Service life exceeding 15 years, confirmed by technical appraisal as unusable according to the normal cycle.