Is the inspection cycle for the wall thickness data of the external pipe gallery once a year or once a quarter?

There is no nationwide uniform mandatory regulation regarding the inspection frequency for the wall thickness of pipes in external pipe galleries. It mainly depends on the following key factors; therefore, a cycle of once a year, once a quarter, or even more frequent or less frequent intervals is possible. The key determining factors include: 1. Pipeline medium and risk level: ◦ High-risk media: Pipelines transporting corrosive, toxic, flammable, or explosive media require shorter inspection intervals (for example, once every quarter or half a year). ◦ General media: Pipes used to transport non-corrosive or low-risk media (such as circulating water, air), with inspection intervals that may be long (once a year or more frequently). 2. Design specifications and standards: ◦ Specific industry standards to be followed (such as SH/T 3533 and SY/T 6553 in the petrochemical industry), or corporate standards, which specify inspection requirements for different types of pipelines. 3. Historical data and corrosion rate: ◦ If historical inspection data show that the corrosion or thinning rate of the pipes is high, the inspection interval must be shortened to enable close monitoring. ◦ If the corrosion rate is slow and stable, the cycle may be maintained or extended. 4. Laws, regulations, and compliance requirements: ◦ It is necessary to comply with the provisions regarding regular inspections set out in regulations such as the \"Regulations on the Safety Supervision of Special Equipment\" and the \"Technical Regulations for the Safety Supervision of Pressure Pipelines\". These regulations typically specify comprehensive inspection intervals (such as 3 or 6 years), but wall thickness monitoring, as a means of routine surveillance, is carried out at frequencies determined by the company based on risk assessment. 5. Corporate management system: ◦ Each factory or management unit formulates detailed \"Equipment Inspection and Testing Procedures\" in accordance with its own safety management system, which specify the frequency at which the wall thickness of various pipes in the external pipe galleries is to be checked. Summary and recommendations: • The most common practice is to conduct regular measurements of the wall thickness of critical, high-risk pipelines on a quarterly or semi-annual basis ； A annual inspection is conducted on ordinary pipelines. During major equipment overhauls, more comprehensive shutdown inspections are carried out. • To obtain an accurate answer, you must consult: 1. The design documents and safety assessment reports for that external pipe gallery. 2. The “Pressure Pipeline Management System” or “Equipment Inspection Procedures” of your organization. 3. Records of wall thickness inspections and analysis reports for the pipelines over the years. Safety tip: The ultimate purpose of the inspection cycle is to ensure safety. When corrosion is suspected to be worsening or when the pipeline is approaching the end of its service life, the inspection frequency should be increased immediately; it is absolutely not acceptable to stick mechanically to the original schedule. It is recommended to consult your company’s equipment engineer or safety management department.

Usually once per major overhaul cycle.