【Safety Management and Standardization of Special Equipment】- How to properly distinguish between internal and external pipes in boilers?

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Ensure proper safety management of special equipment; standardization ensures safety. [Special Equipment Safety Management and Standardization] – Comprehensive summary post! Constantly being updated – feel free to communicate! ! ! https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=5718553 (Source: Haichuan Chemical Industry Forum (Hua Haichuan Liu hcbbs)). Everyone is welcome to participate in the discussions. ---------------------------------------------------------The current boiler specifications state as follows: 1. 2.1 Boiler body: The boiler body is an integrated unit composed of the boiler drum (shell), start-up (steam-water) separator and water storage tank, heat exchange surfaces, header tanks and their connecting pipes, furnace, combustion equipment, air preheater, furnace walls, flue (air) ducts, framework (including platforms and ladders), etc. 1.2.2 Pipes within the boiler area: (1) Power station boilers, including main feedwater pipes, main steam pipes, reheat steam pipes, etc. (Note 1-2), as well as the branch pipes up to the first valve (valves not included; the same applies hereafter) ； (2) Boilers other than power station boilers that are equipped with steam (water, oil) cylinders (hereinafter collectively referred to as steam cylinders, Note 1-3), including the pressure-bearing pipes from the outlet of the feedwater (oil) pump to the first circumferential weld where it connects to the external pipes ； Those without separate steam cylinders include the pressure-bearing pipes from the outlet of the feedwater (oil) pump to the outlet valve of the main steam (water, oil). Note 1-2: The main feedwater pipeline refers to the pipeline from the check valve at the outlet of the feedwater pump to the inlet header of the economizer ； The main steam pipeline refers to the pipeline from the outlet header of the final superheater to the high-pressure main steam valve of the turbine (for boilers operating with a header system, to the first valve before the header) ； The reheat steam cold section pipes refer to the pipes from the turbine exhaust check valve to the inlet header of the reheater ； The reheated steam hot section pipes refer to the pipes from the outlet header of the final reheater to the intermediate-pressure main steam valve of the turbine. Note 1-3: Steam cylinders shall be designed and manufactured in accordance with the relevant regulations for boiler headers or pressure vessels. Notes 1-4: Power pipelines connected to the boiler but outside its scope of coverage can be subject to installation supervision, inspection, and periodic inspections in conjunction with the boiler, in accordance with the requirements for pipelines within the boiler’s scope. Regarding the scope of the boiler itself: 1. Compared with the original boiler specifications, the start-up (steam-water) separator and water storage tank are also included in the scope of the boiler itself, as they are the main pressure-bearing components of supercritical once-through boilers. 2. Slag removal equipment is no longer included in the scope of the boiler itself. Regarding the pipes within the boiler area: According to Appendix E of the original \"Rules for Supervision and Inspection of Boilers\", the scope of supervision and inspection for pipes within power station boilers includes the main feedwater pipe. The main feedwater pipe refers to the pipe that runs from the outlet isolation valve of the boiler feedwater pump (excluding the outlet isolation valve) to the inlet header of the economizer, as well as the branch pipes within the range up to the primary valves (excluding those valves). E2 Main steam manifold: The main steam pipeline refers to the main steam piping from the outlet header of the final-stage superheater of the boiler (or the steam collection header, if present) to the high-pressure main steam valve of the turbine (excluding the high-pressure main steam valve), as well as the high-pressure bypass piping and branch pipelines within the scope of the primary valves (excluding the primary valves themselves). E3 Reheated steam pipeline: The reheated steam pipeline includes the hot section pipeline of the reheated steam and the cold section pipeline of the reheated steam. The hot section pipes refer to the reheat steam pipes from the outlet of the boiler’s final stage reheat steam header to the medium-pressure main steam valve of the turbine (excluding the medium-pressure main steam valve), as well as the branch pipes located within the area before the primary valves (excluding those primary valves). The cold section pipelines refer to the reheat steam pipelines from the turbine exhaust check valve (excluding the exhaust check valve) to the reheater inlet header, as well as the branch pipelines within the primary valves (excluding the primary valves). Appendix C of the original \"Rules for Periodic Inspection of Boilers\": Scope of periodic inspection of pipes within power station boilers. Cl: Main feedwater pipes. The main feedwater pipes refer to those that run from the outlet isolation valve of the boiler feedwater pump (excluding the outlet isolation valve) to the inlet header of the economizer, as well as the branch pipes within the range of the primary valves (excluding the primary valves). C2 Main steam pipeline: The main steam pipeline refers to the pipeline that runs from the outlet of the boiler’s final superheater drum (or the steam collection drum, if one is present) to the high-pressure main steam valve of the turbine (excluding the high-pressure main steam valve itself), as well as the high-pressure bypass pipeline and the pipelines within the primary valves (excluding the branches connected to those primary valves). C3 Reheat steam pipeline: The reheat steam pipeline includes both the hot section pipelines for reheat steam and the cold section pipelines for reheat steam. The reheat steam hot-section piping refers to the reheat steam piping from the outlet header of the boiler’s final-stage reheat steam outlet to the intermediate-pressure main steam valve of the turbine (excluding the intermediate-pressure main steam valve), as well as any branch pipes within the primary valve (excluding the primary valve itself). The reheat steam cold section pipelines refer to the reheat steam pipes from the turbine exhaust check valve (excluding the exhaust check valve) to the reheater inlet header, as well as the branch pipes within the primary valves (excluding the primary valves). The definition of pipes within the scope of power station boilers is provided in the \"Notice from the General Office of the State Administration for Market Regulation on Carrying Out Special Inspections and Rectifications of Potential Hazards Related to Pipes within Power Station Boilers\", Municipal Market Regulation Special Letter (2018) No. 515. Pipes within the scope of power station boilers include the boiler’s main feedwater pipes, main steam pipes, reheat steam pipes, etc. The main feedwater pipeline refers to the main feedwater pipeline from the shut-off valve at the outlet of the boiler feed pump (excluding the valve; the same applies hereinafter) to the inlet header of the economizer, as well as any branch pipelines within the primary valve. The main steam pipeline refers to the main steam pipeline from the outlet of the final superheater in the boiler (or from the steam collection box, if one is present) to the high-pressure main steam valve of the turbine, as well as the branch pipelines within the primary valves. For power station boilers operating with a main steam header, this refers to the branch pipes up to the main steam header and the primary valves. The reheat steam pipeline includes the reheat steam cold section pipeline and the reheat steam hot section pipeline. The cold-section piping refers to the reheat steam piping from the turbine exhaust check valve to the reheater inlet header, as well as the branch piping within the primary valves. The hot-section piping refers to the reheat steam piping from the outlet header of the boiler’s final-stage reheater to the intermediate-pressure main steam valve of the turbine, as well as the branch piping up to the primary valves. Description of the latest boiler regulations: The new rules differentiate between the pipes within the scope of power station boilers and those within the scope of boilers other than power station boilers, and specify requirements for each category. By incorporating the relevant provisions of the original \"Rules for Boiler Supervision and Inspection\", the original \"Rules for Periodic Inspection of Boilers\", and Document No. 515, the definition of pipes within the scope of power station boilers has been further refined. A. Pipes within the power station boiler area: The pipes within the power station boiler area include the main feedwater pipes, main steam pipes, reheat steam pipes, etc., as well as the branch pipes up to the first valve (excluding the valve itself, the same applies hereafter). The main feedwater pipeline refers to the pipeline from the check valve at the outlet of the feedwater pump to the inlet header of the economizer, as well as the branch pipelines up to the first valve. The main feedwater pipeline does not include the check valve at the outlet of the feedwater pump, but includes the welds downstream of the valve. For branch pipes, the first valve is not included, but the welds prior to the first valve are included. The main steam pipe refers to the pipes from the outlet header of the final superheater to the high-pressure main steam valve of the turbine (for boilers operating with a header system, up to the first valve before the header), as well as the branch pipes within the range of the first valve. The main steam pipe does not include the high-pressure main stop valve of the turbine, but does include the welds upstream of the valve. For boilers operating with a header system, the main steam pipe does not include the first valve before the header, but it includes the welds prior to that valve. The branch pipes are the same as above. The reheat steam cold section pipes refer to the pipes from the turbine exhaust check valve to the reheater inlet header, as well as the branch pipes up to the first valve ； The hot-section pipes of the reheat steam refer to the pipes from the outlet header of the final reheater to the intermediate-pressure main steam valve of the turbine, as well as the branch pipes up to the first valve. The cold section pipes of the reheat steam system do not include the turbine exhaust check valve, but do include the welds located behind it. The hot section pipes of the reheat steam system do not include the turbine medium-pressure main steam valve, but do include the welds located in front of it. The branch pipes are the same as above. The main steam pipeline refers to the pipes from the outlet header of the final superheater to the high-pressure main steam valve of the turbine (for boilers operating with a header system, it goes up to the first valve before the header). This means that the scope of pipes covered by these regulations for boilers does not include the headers ； Regarding steam (water, oil) cylinders, and the issues related to their management, looking at the history of boiler supervision in our country, there have been some changes. According to current regulatory requirements, enterprises that hold the appropriate manufacturing licenses for boilers and pressure vessels are allowed to produce such steam (water, oil) cylinders. The original boiler regulations specified that steam distributors had to meet the technical requirements of the boiler header, while the new regulations provide two options: they can also be designed and manufactured in accordance with the relevant regulations for pressure vessels. The steam (water, oil) distribution cylinders designed and manufactured according to the boiler header are regarded as boiler components, and are inspected and registered for use together with the boiler. Regarding pipes outside the boiler range: The power pipes connected to the boiler but located outside its range are sometimes inspected along with the boiler. To facilitate businesses, by comparing the technical requirements for inspection of pipes within pressure pipelines and boilers, it is found that the differences are not significant; therefore, these pipes can be subject to installation supervision inspections and regular inspections in accordance with the requirements applicable to pressure pipelines. Alternatively, they can also follow the requirements for pipes within boilers and undergo installation supervision inspections and regular inspections together with boilers.