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1. Skid-mounted: A method of equipment integration that involves fixing a set of devices to a support made of angle steel or I-beam. Skid-mounted equipment can include skid-mounted generator sets, skid-mounted air compressors, and heat exchange units. Skid-mounted systems generally encompass specialized elements such as process design, equipment, piping, structure, and electrical instrumentation. 2. Skid-mounted pressure equipment systems are formed by installing and connecting pressure pipeline components, pressure vessels, and a movable skid to create a system with specific functions. 3. The manufacturing and supervision inspection of skid-mounted pressure equipment systems are carried out by the inspection agency responsible for such supervision. Supervisory inspection cannot replace the self-inspection carried out by the inspected entity. Special equipment inspection agencies shall obtain the corresponding qualifications approved by **the relevant authorities. The manufacturer of skid-mounted pressure equipment systems must hold a pressure vessel design and manufacturing license corresponding to the appropriate class, a pressure pipeline design license corresponding to the appropriate class (or the design shall be carried out by the design unit of the pressure vessels in the system), as well as the necessary qualifications for pipeline installation. 4. Key design considerations 4.1 Due to the requirements associated with transport by skid-mounted units and space constraints, it is advisable to use highly efficient equipment and instruments, in order to reduce the need for longer straight sections resulting from the measurement accuracy of these instruments. 4.2 Traditional skid-mounted units generally adopt a single-base, single-layer structure; the equipment can be arranged compactly within the skid-mounted steel framework. For large skid-mounted units, it is necessary to consider a compact layout as well as ensuring the overall stability of the skid-mounted structure. The layout of equipment inside the skid should be designed properly to meet the requirements regarding structural deflection, and to prevent uneven load distribution, which could affect the overall stability of the skid as well as its handling and transportation. 4.3 For large-scale equipment, a horizontal layout is preferred, while the height and width of the equipment should be kept within reasonable limits. If the total height of the vehicle and its load, measured from the ground, exceeds 4 meters, the total width exceeds 2.55 meters, and the total length exceeds 18.1 meters, then it constitutes an over-dimensional shipment. From Article 3 of the Regulations on the Traffic of Vehicles Engaged in Overdimensional Transport on Highways (Order No. 62 of 2016 issued by the Ministry of Transport of the People’s Republic of China). 4.4 Electrical and instrumentation design for the process pipelines of skid-mounted equipment (1) The electrical and instrumentation components should be installed as much as possible inside the skid; it is not advisable to separate them ； (2) The piping and valve assemblies of a single unit should be arranged within one skid as much as possible; connections between skids are generally made using flanges ； (3) The piping layout within the split jack should be as short and straight as possible, while still meeting the requirements related to thermal expansion and thermal stress, in order to save space ； (4) For the programmable valve skids of PSA units, a single-layer or two-layer arrangement can be used (a two-layer arrangement saves space, but maintenance is more difficult). (5) Pipe supports should be installed within the individual skids ； (6) Ladders or straight stairs should both be considered within the pry bar. The following is from the WeChat official account on chemical process equipment: The interpretation of TSG D7006-2020, the Rules for Supervision and Inspection of Pressure Pipelines, published in June 2021, specifies the relevant requirements for skid-mounted pressure equipment systems or mechanical equipment systems. A skid-mounted pressure equipment system or mechanical equipment system that includes pressure vessels is considered a skid-mounted unit, while one that does not include pressure vessels is regarded as a combination of pressure pipeline components. Pressure pipeline components, movable skids are installed and connected to equipment and structures such as pressure vessels or mechanical machinery, thereby forming a system with certain functions; this constitutes a skid-mounted pressure-bearing equipment system or a mechanical machinery system (hereinafter referred to as the equipment system). The regulatory requirements regarding design/manufacturing are as follows: Pressure vessels and pressure pipeline components installed in equipment systems shall be designed and manufactured by units with the appropriate qualifications, and shall undergo manufacturing inspection in accordance with the relevant safety technical specifications. 【Note: Requirements for design/manufacturing qualifications】 For equipment systems that include pressure vessel and pressure pipeline components: they can be assembled by manufacturing units holding a manufacturing license for pressure vessels of the corresponding grade within such systems, with the system’s production being supervised and inspected in accordance with the requirements regarding component assembly sets specified in these rules ； 【Note: Installation in the workshop of the pressure vessel manufacturer is required, and supervision of the component assembly unit is necessary】 Alternatively, it may be assembled by a manufacturer holding a license for manufacturing component assembly units, with the system being subject to manufacturing supervision in accordance with the requirements outlined in these rules for component assembly units ； 【Note: The component assembly unit is installed in the respective workshop, and supervision of the installation of this unit is required.】 Alternatively, it can be assembled at the installation site of that equipment system by a contractor holding a pressure pipeline installation license corresponding to the relevant level for such systems, with the installation being supervised in accordance with the relevant requirements of these rules. 【Note: Pressure pipeline units are installed on-site, with on-site supervision and inspection】 If the administrative approval required for component assembly units is abolished in future reforms of administrative regulations, the equipment system shall be assembled by manufacturers holding a pressure vessel manufacturing license of the appropriate level for such systems ； Or it may be installed on the construction site of that equipment system by an installation unit holding a pressure pipeline installation license corresponding to the appropriate category for that system. 【Note: Requirements for manufacturing supervision and inspection】 The pressure pipelines in the equipment system can be treated as auxiliary devices of pressure vessels and registered for use in accordance with the regulations applicable to pressure vessels ； For those that are only pressure pipelines, registration for use shall be carried out in accordance with the regulations for pressure pipelines. The equipment system is subject to direct application by the user unit for registration; there is no need to submit notifications for the installation of pressure vessels or pressure pipelines, nor is any installation inspection required. 【Note: Requirements for qualification levels】 Pressure vessels and pressure pipelines in equipment systems shall be subject to regular inspections by institutions that possess the appropriate qualifications for conducting such inspections on pressure vessels or pressure pipelines. 【Note: Requirements for periodic inspection】