Problems during commissioning of new centrifugal compressor units in the chemical industry after installation
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As the title suggests, let’s discuss the commissioning issues related to newly installed centrifugal compressors (motor + gearbox + compressor) in the chemical industry. What exactly does individual unit commissioning entail? Is it necessary to carry out it in the following 4 steps: 1. No-load operation of the motor； 2. No-load test run of motor + gearbox ； 3. Perform a no-load (or light-load: inlet valve opened at 10%-15% to prevent surging) trial run of the motor + gearbox + compressor ； 4. Rated load trial run of motor + gearbox + compressor ； Are all 4 steps mentioned above necessary to be carried out? If so, should they be done by the owner or by the construction contractor? We welcome all experts to share their insights. The following are the requirements regarding commissioning or individual unit testing as specified in several standard codes: 1. Article 3.8.1 of GB50275 \"Code for Construction and Acceptance of Fan, Compressor, and Pump Installation Projects\": The installation and commissioning of centrifugal compressors shall comply with the requirements of Sections 2.1 and 2.5 of this code (Article 2.5.17 requires that, after successful operation at low load, a load test shall be carried out in accordance with the provisions in the accompanying technical documents) ； At the beginning of the load test run, the exhaust pressure of the main engine should be increased gradually, reaching the operating conditions step by step; once the temperature of the bearing lubricant and the vibration levels of the bearings stabilize, the engine should be operated continuously for 2 hours). 3.8.2 Article 5: At the beginning of the load test run, the exhaust pressure of the main engine should be increased gradually; the increase in pressure should not exceed 0.1 MPa every 5 minutes, and the engine should be brought to its operating conditions step by step. Once the temperature of the bearing lubricant and the vibration levels of the bearings stabilize, the engine should operate continuously for 4 to 8 hours. Is the load test operation specified in GB50275 to be carried out by the construction unit? 2. Article 7.8 of GB50231 \"General Specifications for Construction and Acceptance of Mechanical Equipment Installation Projects\": No-load test run of the complete machine. Article 1.0.3: The installation work for mechanical equipment shall cover the construction and acceptance processes from the time the equipment is unpacked until it undergoes no-load testing; for mechanical equipment that requires operation under load to carry out testing, the process may extend up to the load testing stage. There is no requirement for a load test run. 3. Article 7.4.2 of HG20203 “General Specifications for the Construction and Acceptance of Chemical Machinery Installation Projects”: The single-unit trial run is generally carried out in two phases: no-load and load-bearing. The duration of the trial run can be referred to in Table 7.4.2 (8 hours for no-load trial run of centrifugal compressors, and ≥24 hours for load-bearing trial run); the steps for increasing or decreasing the load shall be carried out in accordance with the machine’s technical documents and the relevant current “special specifications”. 7.4.5 Article 3: Commissioning procedure: Start of gear rotation → No-load operation → Load operation → Voltage/rate increase → Operation at rated load → Voltage/rate decrease → Shutdown → Shutdown of utility systems → Drainage → Disconnection of power supply and other power sources. Does the load test need to be carried out by the construction unit? 4. Article 9.4.2 of SH/T3538 \"General Specifications for the Construction and Acceptance of Petrochemical Machinery and Equipment Installation Projects\": The duration of the individual trial operation of each machine shall comply with the provisions in the product’s technical documents or the requirements specified in the design documents. The single-unit trial operation time for machinery and equipment should be 2 hours. If the machine equipment tested in single-unit operation is equipped with a gearbox or hydraulic coupler, it shall be tested and evaluated separately in accordance with the steps and requirements specified in the product’s technical documentation. 9.4.3 The medium to be used for the individual trial operation of the machine shall be determined based on the design documents and actual conditions. Unless otherwise specified, water, air, or nitrogen should be used as the medium. When selecting the medium for trial operation, the following requirements must be met: b) When using air or nitrogen as the medium for trial operation, the power required and the temperature rise after compression shall not exceed the rated values; if these values are exceeded, the trial operation parameters should be adjusted or a specified medium should be used for the trial operation. How to understand the commissioning work carried out using air or nitrogen as a medium – does it refer to low-load testing or load testing? 5. Article 12.3 of SH/T3539 \"Construction and Acceptance Standards for Petrochemical Centrifugal Compressor Units\": The motor shall be tested under single-unit operation for 2 hours ； Article 12.4: Transmission test run, with the coupling between the transmission and the compressor disconnected ； Article 12.6: During the mechanical trial run of a motor-driven centrifugal compressor, the inlet valve or control damper of the compressor should be set to its minimum operating position, while the outlet valve should be in the fully open position. There is no explicit requirement for a load test run.
When commissioning newly installed centrifugal compressor units in the chemical industry, it is usually necessary to follow certain procedures and standards. These steps include: 1. **Motor no-load test run**: First, the motor is tested under no-load conditions to check whether its operation is normal, with no abnormal noises or vibrations. 2. **No-load test run of motor + gearbox**: Next, the motor and gearbox are connected together to carry out a no-load test run, in order to check whether their operation is coordinated and whether there are any abnormal noises or overheating issues in the gearbox. 3. **No-load (or light-load) test run of motor + gearbox + compressor**: Next, the compressor is added for a test run; at the beginning, a lower operating capacity can be used to prevent compressor surge. Gradually check the coordination and stability of the entire system. 4. **Rated load test run of motor + gearbox + compressor**: Finally, the system is gradually brought to operate at its rated load to verify its performance and reliability under long-term operation. Whether all of these steps need to be carried out usually depends on the project requirements and relevant standards and specifications. For example, both GB50275 and HG20203 explicitly stipulate the requirement for load testing. Since testing is not only an important step in checking the operation of equipment but also relates to the safety of subsequent operation and maintenance, these steps are usually carried out. As for the entity responsible for the trial run, it is usually the construction unit that carries out this task under the supervision of the owner or the supervising engineer. The construction unit must carry out detailed and systematic commissioning work in accordance with the technical documents of the equipment manufacturer and relevant specification requirements. During testing, an appropriate medium (such as water, air, or nitrogen) should also be selected, and the parameters during the trial operation must be strictly controlled to ensure the scientific validity of the testing. .
Hello, Mr. Liu. I found your previous posts very helpful; I was involved in a project abroad that involved the installation and commissioning of Ingersoll Rand centrifugal compressors. I’d like to discuss the practices used abroad, as they may differ from those in China. 1. No-load test run of the motor ； ---------- This step must be completed; for any motor, it is necessary to disconnect the coupling in order to enable single-unit operation, and the commissioning record form provided by the owner must also be filled out. This is a requirement of the owner’s company. Additionally, single-unit testing of the motor is also required by the manufacturer, who provides corresponding commissioning forms. 2. No-load test run of motor + gearbox ； --------- Our engine unit doesn’t have a gearbox, so this issue does not apply to us. My personal understanding is that it should follow the manufacturer’s technical requirements. 3. Perform a no-load (or light-load: inlet valve opened at 10%-15% to prevent surging) trial run of the motor + gearbox + compressor ； ------------- This part needs to be completed: we need to open the anti-surge valve and run the machine for 2–4 hours with no load applied, as required by the manufacturer; during this time, relevant data must be recorded. 4. Rated load trial run of motor + gearbox + compressor ； ----------- This part needs to be completed as it is a requirement from the manufacturer; it must operate under rated load for 72 hours, during which time performance tests need to be carried out. The anti-surge line may also be tested during this period. Are all 4 steps mentioned above necessary to be carried out? If so, should they be done by the owner or by the construction contractor? -------------------We are led by the owner, who has a commissioning department that takes charge of the process, with the construction contractor providing support.
Thank you for sharing this, buddy. Is your Ingersoll Rand centrifugal compressor a large-scale air separation compressor? Generally, for such large units, an anti-surge operation test needs to be carried out after installation. My unit is relatively small; smaller units usually have an anti-surge simulation system built in during manufacturing. However, a joint commissioning test to evaluate the performance of the unit is still necessary after installation. The joint commissioning test is definitely carried out by the owner. In previous installations, I never conducted load tests either – the construction company would carry out low-load tests and then hand over the unit to me for the joint commissioning test. For this new project, I went through all the relevant specifications again; some require load tests while others don’t, so I’m a bit confused. I’d like to know how other professionals in this field handle this
The Ingersoll Rand centrifugal compressors in our project are large-scale natural gas compressors. Once the mechanical construction is completed, the responsibility for the interface is transferred from the construction party to the owner’s commissioning department. Therefore, the mechanical operation (commonly referred to as no-load operation) is carried out under the supervision of the owner and the manufacturer, with the cooperation of the construction party; subsequent operations such as load operation, surge protection testing, and performance testing follow the same pattern. I am not very familiar with the situation in China, so I hope everyone can share their insights
There are 4 steps in total. According to Ingersoll Rand, the motor testing should last around 4 hours; it is necessary to check that the magnetic field lines are aligned properly. The testing plan is usually prepared by the construction party【but actually the client is also involved and must approve it】. During the testing process, the client is generally responsible for starting and stopping the machine, while both parties are involved in the disassembly and inspection of the machinery. There are so many standards that it can be a bit confusing. You seem to work in the coal chemical industry; in that case, you can refer to the petrochemical industry standards. It is essential to conduct tests under rated load. The old version of the SHT standard required 72 hours for such tests, but the new version does not have this requirement. You can also refer to two other standards: HGT 20205-2017, Standards for Construction and Acceptance of Chemical Machinery Projects【Centrifugal Compressors】, SHT 3519-2013, Standards for Construction and Acceptance of Centrifugal Compressor Units in Ethylene Plants, SHS 01041-2019, Maintenance and Repair Procedures for Gear-Type Centrifugal Compressors, and SHS 01019-2019, Maintenance and Repair Procedures for Horizontal Split-Type Centrifugal Compressors – all of which require 72 hours of testing under rated load