\"Inspection Modes for Centrifugal Compressors\"

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\"Inspection Modes for Centrifugal Compressors\" Centrifugal compressors are high-speed rotating turbine machines; some of their impellers rotate at speeds approaching or even exceeding the speed of sound. Therefore, in addition to requiring careful design and precise manufacturing, thorough inspection is also essential. At the same time, strict quality control must be applied throughout the entire production process for the important components of compressor products; relevant quality records must be kept, and complete product documentation must be maintained to ensure traceability of the products. I. Identifying the important components: Based on the quality grading standards for compressors and the specifications set by the design department regarding the key components of compressor products, inspection technicians identify the following as important components of the compressor (pressure vessels and certain auxiliary equipment are considered separately): Rotor assembly: rotor, impeller, main shaft, balance disk, thrust disk, shaft sleeve, spacer sleeve, disc, nuts, etc. Stator assembly: casing (volute, intake casing, cylinder, end cover), partition, seal. Transmission assembly: gears, housing. Coupling set: inner sleeve, outer sleeve, sleeve. Bearings, seals, bases, etc. Note: Seals, bearings, and floating ring seals are wear-prone and standard components; on-site inspections are conducted without keeping records. II. Inspection Items Throughout the Entire Process
Inspection Items | Part Name
Chemical Composition | Mechanical Properties | Ultrasonic & Radiographic Testing | Magnetic Particle Testing | Coloring Inspection | Dynamic Balance | High-Speed Dynamic Balance | Over-Speed Test | Hydrostatic Test | Airtightness Test | Dimension Inspection | Assembly Inspection | Runout Inspection | Operation Test | Disassembly Inspection | Disassembly Inspection

Machine Shell | √√√√ | √ | √√√√
Main Shaft | √√√ | √ | √ | √
Impeller | √√√ | √√√ | √ | √ | √
Rotor | √ | W | √√√ | √√
Diaphragm | √ | √
Gear | √√√ | √ | √ | √ | √√√
Machine Set | √√ | H | √H
Oil Station | √

For example, for an impeller, the inspection throughout its production process is carried out as follows: 1. As soon as the forging material used to manufacture the impeller arrives, external inspectors first mark the material code on the piece (e.g., 06-1065); this is a permanent marker that ensures traceability of the product. During processing, inspectors supervise the operators to accurately and correctly transfer this mark ； At the same time, assist the external personnel from the procurement department in collecting samples from the forgings and delivering them to the laboratory of the Metrology and Physics Department. Once the test results are available, compare them with the standard values; if they meet the standards, a \"Material Inspection Report\" will be issued. 2. After stress relief, the forged billet undergoes rough machining, followed by ultrasonic testing. For those that pass the test, an ‘Ultrasonic Testing Report’ is issued; for those that fail, the inspection staff are notified to take appropriate action. 3. After the processing required for developing the manufacturing process is completed, magnetic particle testing is conducted on the surfaces of the components that make up the impeller before welding; only those that pass this test proceed further. 4. After the impeller is welded, after heat treatment, after sandblasting, and after the overspeed test, multiple coloring inspections are carried out. If any issues are detected, the inspector promptly notifies the relevant personnel to carry out repairs in accordance with the procedures specified in the process documents. After the overspeed test, those that pass the coloring inspection receive a “Coloring Inspection Report,” while those that fail are notified so that appropriate actions can be taken. 5. After the impeller welding is completed and rough machining is done, heat treatment is carried out (with a test ring in the same furnace) to conduct mechanical property tests. The heat treatment inspector verifies whether the results meet the design requirements; if they do, the inspector stamps the \"Mechanical Property Test Report\" with the annotation \"Performance satisfactory\". 6. Thereafter, the impeller is precision turned to meet the requirements specified in the drawings, and then sent to the inspection station for a comprehensive check. Once it is confirmed that all the aforementioned inspections have been carried out and passed, all requirements regarding dimensions, surface roughness, and geometric tolerances are checked and recorded (some non-critical areas for which no tolerances are specified may not require recording). If any non-conformities are found during the inspection, a \"Non-Conforming Product Review Form\" must be issued immediately and delivered to the construction team in the relevant workshop. The construction supervisor shall organize the designers, process engineers, and inspection personnel to conduct an on-site review. Meanwhile, appropriate status markings should be applied to the workpiece; after the review is completed, the corresponding status markings shall be used instead. 7. After a single impeller has been properly dynamically balanced, an overspeed test of the impeller is carried out in accordance with API617 requirements. Upon completion of the test, an inspector checks for any deformation of the impeller as well as conducts a coloring inspection. If it passes these checks, a \"Impeller Overspeed Test Report\" and a \"Coloring Inspection Report\" are issued; if it fails, the relevant procedural guidelines must be followed until the impeller meets the required standards. III. Information dissemination 1) When inspectors conduct inspections in accordance with the \"three principles,\" and identify non-conformities, in addition to issuing procedures such as \"review\" or \"scraping,\" they must also prepare a \"Quality Daily Report\" and submit it to the chief engineer. 2) Upon receiving the \"Quality Daily Report\", the chief engineer conducts a thorough investigation, assessment, and analysis; thereafter, the information is compiled via computer and sent to the quality control officer, who then distributes it to the respective designated departments. 3) At the end of each month, each inspection team fills in the quality issues that occurred in the workshop in the \"Parts Quality Issue Statistics Table\" and submits it to the quality control officer. The quality control officer then aggregates these reports and sends them to the relevant supervisors, so that they can stay informed about the quality situation in a timely manner. IV. Product Documentation Product documentation serves as proof of product quality and is an important basis for ensuring traceability of products; it must receive sufficient attention throughout the entire inspection process. 1. For all important components, various relevant inspection records must be collected simultaneously during the comprehensive inspection, ensuring that they are complete, thorough, accurate, and error-free. 2. After the product has passed the testing phase and has been packaged and shipped, the inspection team in the final assembly workshop prepares an \"Archiving Catalog\" for that product. This catalog includes details such as the product’s model number, code, serial number, as well as the names and material codes of its main components (permanent identifiers recorded during the inspection process). It is submitted to the data clerk on the specified date each month; the data clerk then makes copies in the required number and distributes them to the relevant inspection teams. 3. The heads of each inspection team organize various inspection reports and records related to the important components produced in their respective work areas, based on the material numbers listed in the archive catalog. After being reviewed by the chief engineer, these documents are submitted to the archives manager by the specified date. 4. Once all the inspection documents related to the important components in each work area have been collected, the file manager must carry out tasks such as classification, organization, statistics, and binding to ensure that the product files are complete and thorough. Product files are properly stored for the required period. V. Work of inspection technicians 1. Inspection technicians carry out quality inspection tasks under the direct supervision of the head of the Quality Inspection Department, and provide guidance to the inspectors’ work. 2. Inspection technicians should have a certain understanding of the design theories behind products, but they need to be thoroughly familiar with the structure of those products as well as the manufacturing processes used to produce them. 3. From the arrival of raw materials at the factory to the final inspection of the products to ensure they meet quality standards and then their packaging and shipment, each inspection stage is supervised by inspection technicians. The technician in charge of inspecting a particular section is referred to as the chief engineer for that section. 4. The contract products are assigned to inspection technicians according to a certain pattern; these technicians are responsible for gaining an overall understanding of the products involved in the project, for receiving visitors who come to supervise the production of these products, and, when necessary, for collecting inspection data and submitting it to the customers after organizing it. The technical personnel responsible for inspecting the contracted products are known as project engineers. 5. The inspection technicians are responsible for preparing the \"Contract Breakdown Sheet\" for the project products, which details the main technical specifications of these products as well as the materials used for their key components. It also outlines the inspection items that need to be carried out, and this sheet is sent to various inspection teams to remind inspectors to conduct their inspections in strict accordance with the requirements outlined in the contract and technical agreements. 6. The inspection technicians are responsible for preparing the \"Product Guide Cards\" and \"Typical Product Inspection Management Standards\" for various product series, providing guidance for inspectors in conducting product quality inspections and ensuring quality control. 7. The inspection technicians are responsible for preparing the \"Inspection Plans\" for each series of products. These plans specify at which stage the inspection of key components is to take place, what tests need to be conducted, what standards shall be applied, and what types of verification methods will be used. Such plans can be provided to users or third-party inspectors for use during on-site inspections. The «Inspection Plan» was developed by drawing inspiration from advanced manufacturing enterprises in the international industry, thereby enabling the inspection of compressor products to be largely in line with international standards. 8. In their daily work, inspection technicians should frequently go to the workshops and proactively provide support for production there ； Once the inspector issues a \"Non-Conforming Product Review Form,\" the technical personnel of the relevant workshop’s construction team should be convened to attend the review of the non-conforming products at the site as soon as possible. With a strong sense of responsibility toward product quality, strict controls and thorough evaluations must be carried out ； It is necessary to pay timely attention to the design, process-related documents, and work requests from other departments issued online; any content related to one’s own work should be issued promptly and printed out for delivery to the relevant inspection teams for execution. 9. Inspection technicians should actively participate in various technical research activities organized by departments such as the Chief Engineer’s Office and the Science and Technology Association, in line with their job responsibilities, in order to improve product quality and work standards. 10. While continuously improving their own professional skills, inspection technicians should also regularly provide targeted technical training for inspectors, explaining product knowledge, process knowledge, relevant standards, and process specifications in order to enhance the inspectors’ theoretical knowledge and working capabilities. VI. Inspector’s Responsibilities 1. The inspector carries out product quality inspection work under the leadership of the head of the Quality Inspection Department and with the guidance of the technical staff in the inspection technology team. 2. The responsibilities of the inspector are “identification, verification, reporting, and supervision.” That is, based on the “three principles (drawings, processes, standards)”, it is necessary to “verify” whether the individual components and the entire product throughout the production process meet the requirements ； This is followed by the responsibility of quality control, which involves approving qualified products and rejecting unqualified ones, while issuing the corresponding documents ； The responsibility of reporting entails fulfilling the above two duties; at the same time, it is necessary to promptly provide written feedback to the chief engineer on the characteristics and causes of defective products, as well as the specific actions taken by the relevant workshop to deal with them. If necessary, this information can be reported directly to the head of the quality inspection department ； During the product manufacturing process, in addition to carrying out inspections, it is also necessary to ensure that the operators’ procedures comply with the requirements of design specifications, manufacturing processes, and relevant standards, so as to produce qualified components – this is the responsibility of supervision. 3. During the inspection process, if any discrepancies are found with the requirements outlined in the “Three Checks”, a \"Report on Quality Issues\" should be prepared promptly, along with a \"Non-Conforming Product Review Form\“. This form must specify the characteristics of the non-conforming product, the reasons for its occurrence, as well as the department and individual responsible. At the same time, corresponding status labels are attached to the components being inspected. Once the review results are available, the results of the re-inspection are checked in accordance with the recommendations given, and the re-inspection opinions are recorded on the review form. 4. In accordance with departmental requirements, collect complete and thorough inspection records for the product’s key components, organize them in a proper and accurate manner, and submit them to the chief engineer for review and archiving on schedule. 5. Inspectors must continuously improve their own capabilities, focus on learning product-related knowledge, enhance their work skills, receive training in quality awareness, and boost their professional ethics in order to carry out their inspection tasks effectively.