Regarding the commissioning of the DCS chain

Each company in CNPC and Sinopec has very strict regulations regarding the management of interlock protection systems. The process unit that utilizes the interlock protection system is the primary responsible party, while the relevant functional departments are responsible for approving it and overseeing its implementation. The instrument is responsible only for the actual implementation of the interlock modifications (interlock values and schemes) that have been proposed by the process unit and approved. It is also a primary responsibility of the instruments to ensure that the interlock protection system functions properly. Whether to activate each component of the interlock protection system depends on the actual production conditions and requires approval at various levels; the process department does not have the authority to deactivate or activate such components on its own, except in emergency situations (for which there are corresponding emergency response procedures).

Management of the instrument interlock protection system: Interlocks are divided into process interlocks and equipment interlocks, and are classified into Category A and Category B based on their importance. Among them, the critical and important process system interlocks, as well as those that may lead to personal injury, equipment damage, or serious quality defects in the products, are classified as Class A interlocks. The Operations Department classifies the interlocks within the devices under its responsibility based on the above definitions, compiles them into a list of interlock classifications, and submits it to the company’s Maintenance Department. After being reviewed by the Mobility Department in conjunction with the Production Department, it is submitted to the company’s office ； It shall be issued for implementation upon approval by the company’s deputy chief engineer in charge. When it is necessary to make changes to interlocks (including changes to set values, interlock procedures, principles, etc.), to deactivate or reactivate them, or to cancel them, an application must be submitted in advance. The applicant shall prepare the approval form and submit it to the Mechanical Department or the Production Department for review. The Mechanical Department is responsible for equipment interlocks, while the Production Department is responsible for process interlocks. The reason, implementation plan, and preventive measures taken should be specified on the approval form. The release and restoration of interlocks are requested by the operation department or the instrumentation unit, while changes or cancellation of interlocks are requested by the operation department. The cancellation of Class B interlocking must be proposed by personnel at the level of technical assistant or above, approved with a signature by personnel at the level of chief engineer in charge of the system, and authorized by personnel at the level of deputy department head or above. The disactivation of the Class A interlock protection system is proposed by the chief engineer in charge of the equipment, approved with signatures from personnel at or above the deputy department head level, and authorized by the head of the company’s Production Department or Machinery Department. For the deactivation of important interlocks related to the safe operation of installations and large-scale equipment, the Mechanical Department shall submit a request for approval to the company’s deputy chief engineer, based on the actual circumstances. Changes or cancellations to interlocks are proposed by the chief engineer in charge of the equipment, approved by personnel at the department head level or above, and after the application is submitted to the Mechanical Department for approval by the technical supervisor in charge at the company’s general management office, they are put into effect. The restoration of interlocking is proposed by personnel at the level of technical assistant or above, approved with a signature by personnel at the level of chief engineer in charge of the equipment, and authorized by personnel at the level of deputy chief engineer or above. After obtaining approval to make changes, disable, restore, or cancel the interlock protection system, it is necessary to obtain an interlock work order from the Mechanical Department prior to implementation; the order must specify in detail the basis for the work, the person responsible for carrying out the work and the supervisor, the contents of the work, and the time schedule. To prevent mistakes, a two-person operation system must be employed, with one person operating and another providing on-site supervision. Before operation, the interlock status should be carefully checked and verified, and close communication should be maintained with the process operators during the operation. After the task is completed, the person who carried out the task and the supervisor must record the details of the task on the interlock work order and sign to confirm it. The maximum period for lifting the interlock is 6 months. Interlocks that cannot be put into use after more than 6 months must have their approval forms processed again. Interlocks that are ready for operation should have the procedures for resuming use carried out promptly, so as to be put back into service as soon as possible. Before starting up the new unit for trial operation, or before putting the equipment back into service after maintenance, all interlock circuits must be thoroughly inspected and verified, and the interlock protection system must be calibrated. The interlock inspection test for the new device is led by the Engineering Department, which organizes the relevant units to complete it prior to the handover ceremony. Based on the test results, an interlock test form is filled out and signed by the personnel who participated in the inspection; this form is then submitted as part of the handover documents to the Machinery Department for storage. After the device is repaired, the interlock test is requested by the device technicians to the Mechanical Department, which then organizes professionals in mechanics, electricity, and instrumentation to carry out the test together with process engineers. The test results are recorded on a test form, and all personnel who participated in the interlock test must sign this form. Three copies of the interlock test report are prepared, with one copy kept by the Mechanical Department, one by the Instrumentation Unit, and one by the Operations Department. Important interlock protection systems must have clear markings. The newly added interlocking protection system must come with complete drawings and documentation. The emergency stop buttons of the interlock protection system shall be equipped with reliable guards. The switches and buttons on the panel of the interlocking system are operated by the operators, while the switches and buttons behind the panel are operated by the instrument technicians. When instrument operators are working on the interlock system and need to operate switches, buttons, etc. on the control panel, they must first contact the process supervisor and obtain permission before proceeding with the operations. After the task is completed, the operator must be notified promptly so that they can check the status of the process and reset switches, buttons, etc. The components used in the interlock protection system (including primary sensing elements and actuating elements), as well as the computing units, should be calibrated according to their respective specified calibration cycles; typically, these can be overhauled, inspected, and calibrated during major shutdowns of the equipment. Newly replaced components, instruments, and equipment must pass inspection and calibration before they can be installed in the system. The maintenance and repair of instruments in the interlock protection system are carried out in accordance with the requirements of the \"Procedures for Maintenance and Repair of Petrochemical Equipment\" (SHS 07007-2004). The interlock protection system should have sufficient spare parts, the types and quantities of which are stocked in accordance with the stockholding standards and the regulations for spare parts management.

Now, the number of interlocks that need to be disabled is determined by process requirements