GB/T151 Heat Exchanger Standard Update Plan

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Purpose and Significance: Heat exchangers are unit process equipment used for heat exchange and transfer, and they are widely applied in industries such as petroleum, chemicals, metallurgy, power generation, pharmaceuticals, food processing, light industry, and machinery. According to statistics from the State Administration for Market Regulation, there are nearly 5 million pressure vessels and nearly 1 million heat exchangers registered in China, accounting for over 20% of the total. Heat exchangers belong to a specific type of pressure vessel, and ensuring safety is of paramount importance for them. Furthermore, as key energy-consuming devices in the process industry, their energy efficiency levels play a crucial role in ensuring the sustainable development of the energy sector. Since the 1990s, China has gradually pursued the idea of establishing a technical standard system for heat exchangers with Chinese characteristics based on research. By 2014, a system framework was developed, based on GB/T151, that covered standards for products, components, and performance; meanwhile, common requirements regarding safety and performance were specified for the first time in these standards. Over the past decade, driven by strategies such as achieving carbon peak and carbon neutrality, the energy industry has seen new developments. Demand in emerging fields continues to grow, new application scenarios are emerging, and there is a trend toward larger-scale operations. Heat exchanger products are evolving in terms of complexity and diversity, and the boundaries of existing standards have been surpassed. To this end, it is necessary to comprehensively examine and conduct adaptability research on the scope, methods, and indicators of standards. Efforts should be made to improve in the following four areas: 1) Application scenarios: The “energy-related” characteristics of petroleum are gradually diminishing, while its demand as a basic chemical material is on the rise; thus, there is a clear trend toward its “materialization” ； At the same time, demand in emerging fields such as clean energy, solar energy, and hydrogen energy is continuously growing. The original applicable fields and product scope of the standards no longer meet the needs of industry development. It is necessary to revise and improve the general technical standard system for heat exchangers, so as to summarize and enhance the common requirements for heat exchangers ； Expand the scope of the reference standards for heat exchanger products to include various types such as cartridge-type, fully welded plate-type, and plate-shell type heat exchangers ； Adopting and advancing standards for emerging heat exchanger products such as coil-type and vacuum diffusion welded plate types ； Considering standard sustainable development, provide guidance or solutions for incorporating subsequent products into the scope of GB/T 151. 2) Energy efficiency classification: Energy conservation and emission reduction have become one of the important means to achieve strategies such as carbon peak and carbon neutrality. For refining enterprises, which have high energy consumption and rely on energy recovery equipment, improving heat transfer in exchangers, as well as conducting energy efficiency calculations and evaluations, are key issues that need to be addressed urgently. Passive heat transfer enhancement techniques, represented by high-efficiency components and flow structures, have made significant progress, contributing to the advancement of heat exchanger heat transfer enhancement technologies; however, there is a lack of quantitative data to guide product selection and design ； Traditional flow path analysis methods have established the basic requirements for the structural design of the leakage areas in the shell side of shell-and-tube heat exchangers, but lack quantitative analysis or experimental data validation. To this end, it is necessary to quantify energy efficiency-related indicators and evaluation criteria, and gradually improve the methods for calculating and evaluating energy efficiency in various product standards. 3) Improvement of quality and efficiency: NB/T 47019 introduces a stricter TI grade of precision in addition to the existing Grade I and Grade II levels, thereby further enhancing the quality of heat exchanger components. Correspondingly, the standard needs to further refine the classification system for the quality of tube bundles. To this end, the standards need to establish a reasonable classification system based on usage characteristics, specifying the accuracy requirements for tube plate holes and the corresponding dimension series. It is also necessary to improve the design patterns, structural designs, and strength calculation methods for tube ends, and to set specific requirements regarding welding and expansion jointing processes as well as non-destructive testing methods, in order to enhance the inherent quality of heat exchangers. 4) Larger scale: The integration of refining and chemical processing, as well as the enlargement of industrial units, have become an inevitable trend in the development of the petrochemical industry. The dimensions of product structures are evolving towards more extreme values; the nominal diameter of many heat exchangers has significantly exceeded 4000 mm (e.g., EO reaction/heat exchangers, maleic anhydride reaction vessels, multi-stage coolers for styrene, etc.). The high-flow load conditions in heat exchangers make flow-induced vibrations in large tube bundles one of the factors that affect product reliability. The tube sheet design method has many limitations in terms of large-diameter pipes, non-standard piping arrangements, and accounting for the vertical self-weight load. To this end, the standards need to examine the technological advancements in product enlargement as well as relevant engineering experience, refine the applicable diameter ranges for different types of heat exchangers, improve design methods for fluid-induced vibrations, detail the accompanying engineering measures, promote the use of lightweight design methods for tube sheets, and optimize the calculation models, parameters, and evaluation criteria for tube sheets, thereby establishing engineering methods suitable for numerical analysis of tube sheets in large-scale heat exchangers. Scope and main technical contents: This standard specifies the general requirements, materials, design, manufacturing, inspection, acceptance, as well as installation and use requirements for metal heat exchangers. Design pressure applicable to this standard: The design pressure of shell-and-tube heat exchangers shall not exceed 35 MPa ； The design pressure of heat exchangers with other structural types is determined in accordance with the respective product standards. The design temperature applicable to this standard: The steel shall not exceed the allowable operating temperature range specified for that material in GB/T150.2-2011 ； The allowable operating temperatures for other metal materials are determined in accordance with the standards cited for those materials. In this standard, the nominal diameter applicable to shell and tube heat exchangers is not greater than 6000 mm, and the product of the design pressure (MPa) and the nominal diameter (mm) is not greater than 4.05×10^4. Main technical contents: a. Improve the general requirements: Enhance Clause 4.1.1 of the \"General Requirements\" in GB/T151; for heat exchangers of new types and structures that meet the general requirements of this standard, special technical specifications or corporate standards should be established based on the load conditions and structural characteristics, where no product standards currently exist. Improve Clause 4.1.2 of the \"General Requirements\" GB/T151, and supplement it with heat exchanger product standards such as SH/T3119-2016 (shell-and-tube type), NB/T47004.2 (fully welded plate type), and XXXX (plate-shell type). b. Formulate specific technical regulations for tube ends: Add Appendix N, which addresses the issue of the limited types of welding procedure qualification for tube end welding as specified in Appendix D of NB/T 47014, as well as its poor applicability; it outlines specific requirements for welding procedure qualification of tube ends with fillet welds, groove welds, and combined welds. To address issues such as the limited applicability of the non-destructive testing types and defect criteria for pipe ends specified in Appendix A of NB/T 47031.2, and in light of the industry’s demand for high reliability under high-parameter conditions, specific requirements for non-destructive testing of pipe ends are proposed, which define the grading of internal defects in pipe end test pieces as well as the appropriate non-destructive testing methods. Appendix P is added to specify the specific requirements for the qualification of the expansion fitting process using strength expansion heads. Appendix Q is added, outlining the evaluation methods and implementation details for the pull-out load of strength-welded, strength-expanded, and composite structure pipe fittings. Add clause 8.13 of \"Non-destructive testing\" in GB/T151 (the original 8.13 has been moved downward), providing principle-based provisions for radiographic testing of pipe ends (such as when specified in the design documents, or when the medium is extremely hazardous……), and specifying the minimum proportion for random inspections. c. Upgrade of specification parameters: The “range” specified in Clause 1.5 of GB/T151 has been improved; the diameter range for tubes that can be withdrawn has been increased to 6000 mm, while the range for tubes that can be pulled out is now 2600–3000 mm. The product of the design pressure and the nominal diameter has been increased to 4.05×10^4. d. Flow-induced vibration: Drawing on advancements in nuclear power technology and application cases in petrochemical engineering, refine the design methods for flow-induced vibration and further specify corresponding engineering measures ； Specifically, this includes improving Clause 6.8 of GB/T151 for the \"shell side,\" and adding new bypass design methods. Improve Appendix C of GB/T 151 on “fluid-induced vibration”, and specify the design principles for full support plates and anti-sound/vibration plates. e. Expansion of calculation methods for tube sheets: Explanation on the applicability of tube sheet loads (self-weight) and calculation methods (for large diameters). Method for calculating structural stress of large external flow guiding cylinder structures. Calculation criteria for the equivalent stiffness of kettle-shaped frustum structures. Requirements for a minimum distance are specified for the openings around the tube sheet. Stress analysis method for the equivalent solid plate structure of tube sheets. f. Supporting data upgrade: Additional large-diameter categories are added for the cylinder, with minimum thickness values specified. Provide the roundness tolerance for large-diameter cylinders. g. Refinement of heat exchanger energy efficiency indicators: Improve clause a) in section 4.3.2.1 of GB/T151 on “selection and calculation”, and add specific energy efficiency requirements ； Add clause d) in section 4.3.2.1 of GB/T151 under \"Selection and Calculation\" to supplement the methods for energy efficiency testing and evaluation. h. Concrete implementation of efficient heat transfer measures: Improve Section 4.3.2.2 of GB/T151 on \"selection and calculation\", and adopt efficient heat transfer elements or efficient shell-side structures as recommended methods to enhance heat transfer efficiency. Improve Section 5.4.2 of GB/T 151 regarding “heat exchange tubes” by adding high-efficiency heat transfer elements such as twisted tubes, and specifying the applicable scenarios and heat transfer efficiency indicators for each type of element. Improve Sections 6.8.2.1 and 6.8.2.3 of GB/T151 on \"baffle plates (elements)\", by adding typical diagrams, applicable scenarios, layout principles, and heat transfer efficiency indicators for high-efficiency shell-side structures such as spiral baffles and baffle rods. i. Quantification of shell-side flow path leakage indicators and energy efficiency grading: Quantitative data on leakage indicators for each shell-side flow path are provided, and a relationship is established between the tube bank level and energy efficiency indicators, thereby enabling data quantification and energy efficiency grading. j. Determination and optimization of shell-side flow path parameter indicators: Revise Section 6.8.2.2.3 of GB/T151 on \"Control of the clearance between heat exchange tubes and baffle plates\", break down and refine the clearance parameters to align them with energy efficiency grades. Revise Section 6.8.2.3 of GB/T151 regarding \"baffle spacing\", and verify the suitability of the minimum spacing requirement by incorporating flow field analysis. Revise Section 6.8.3.2 of GB/T151 on \"Bypass baffle settings\": by combining flow field analysis, determine the quantitative relationship between the bypass baffle structure and the bypass flow path, verify the setting principles, specify the required settings, and correlate them with energy efficiency grades. Revise Section 6.8.2.2.1 of GB/T151 regarding \"outer diameter of baffle plates and allowable tolerances\"; by incorporating flow field analysis, determine the quantitative relationship between the gap between the plate and the cylinder and leakage, improve the specifications for outer diameter tolerances and cylinder roundness; enhance these specifications while ensuring they meet the requirements of engineering construction, and align them with energy efficiency classifications. Revise Section 6.8.3.3 of GB/T151 on \"Pipe shielding\", determine the quantitative relationship between internal unpipeled channels and leakage by combining flow field analysis, verify the setting principles, specify the setting requirements, and correlate them with energy efficiency grades.