As a core piece of equipment involved in heat and mass transfer, the evaporator's operating status directly affects system energy efficiency and process safety. Establishing a standardized inspection process allows for the timely detection of defects and performance deviations throughout the equipment's lifecycle, providing a basis for maintenance, modification, or continued operation, thereby reducing the risk of failure and extending service life.
The inspection process typically consists of three stages: pre-commissioning inspection, periodic operational inspection, and overhaul-specific inspection. Pre-commissioning inspection aims to confirm that the equipment's manufacturing and installation quality meets design requirements. This stage includes visual inspection to confirm that the shell, heat exchange tubes, flanges, and supports are free from obvious deformation or damage; dimensional verification to confirm that key installation dimensions are consistent with design drawings; pressure and airtightness testing, applying pressure as specified and maintaining it for a certain period to observe whether the pressure drop is within the allowable range; non-destructive testing of welds and materials, such as radiographic or ultrasonic testing, to check for internal defects; and instrument integration testing to ensure that temperature, pressure, flow, and other sensor signals are accurate and matched with the control system. All inspection data should be compiled into a written report as the basis for equipment acceptance.
Regular operational inspections, aimed at monitoring status and preventing malfunctions, are typically performed monthly or quarterly. Inspection content includes: trend analysis of operating parameters, comparing actual and design values to identify gradual anomalies; visual or endoscopic inspection of heat exchange surfaces to determine for scaling, corrosion, or leaks; leak checks at seals, using visual inspection, test strips, or gas detection methods; functional verification of auxiliary equipment, such as circulating pump current, fan vibration, and bearing temperature; and calibration of safety accessories, such as safety valve opening pressure and pressure gauge accuracy. For minor anomalies, their impact should be assessed, and online intervention should be arranged or the next inspection interval shortened.
Specialized overhaul inspections are conducted after equipment disassembly or prolonged shutdown to comprehensively assess wear and remaining life. In addition to repeating the critical pre-commissioning inspections, this stage includes: ball-passing or endoscopic examination of the heat exchange tube inner walls to confirm for blockages, thinning, or cracks; corrosion depth measurement of the shell-tube sheet mating surface; inspection of the fatigue and deformation of the support structure; assessment of the material and workmanship compliance of replacement parts; and, based on the inspection results, proposing repair plans or replacement recommendations. Overhaul inspections often combine performance retesting, such as measuring heat transfer coefficients and pressure drops under full load, to verify the effectiveness of repairs or modifications.
The inspection process must strictly adhere to standards and operating instructions, using calibrated instruments and conducted by qualified personnel. Each step of the inspection should have clear judgment criteria, and results should be recorded as qualified, limited-use, or unqualified, with instructions for corrective action. Inspection records should be archived for traceability and comparative analysis, providing data support for optimizing subsequent maintenance strategies.
Inspections performed according to the established procedures can reduce the rate of sudden evaporator failures by 30% to 60%, identify repairable defects early, and prevent minor issues from escalating into equipment failure. Embedding the inspection process into the equipment management system, forming a closed loop of inspection, analysis, rectification, and verification, can significantly improve the operational reliability and economy of evaporators.