Analysis of the Current Situation and Countermeasures for the Standard System of Non-metallic Pressure Pipeline Components. Source: Guangzhou Institute for Testing Special Pressure Equipment...

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Analysis of the Current Situation and Countermeasures for the Standard System of Non-metallic Pressure Pipeline Components. Source: Guangzhou Institute for Testing of Special Pressure Equipment, November 29, 2018. Abstract: This article analyzes the current state of China’s standard system for non-metallic pipeline components, compares it with that of developed countries, and discusses the issues existing in China’s standard system at present, such as an imperfect standard framework, outdated standards, as well as the absence or ineffectiveness of key standards. Specific measures are proposed to improve China’s standard system for non-metallic pipeline components – namely, enhancing alignment with international standards, strengthening coordination among the organizations responsible for standard development, and accelerating the creation and updating of those standards that are in short supply or have become outdated. These measures provide practical solutions for the development of China’s standard system for non-metallic pipeline components. Keywords: Non-metallic pressure pipeline components; Standard system; Current situation analysis; Countermeasures CLC number: TQ320.72+4 Document code: B Article ID: 1001-9278(2018)10-0123-090 Introduction Pressure pipeline components refer to various parts that make up a pressure pipeline system, and the quality of these components is the foundation for the safe operation of pressure pipelines. According to the **Catalogue of Special Equipment**, non-metallic pressure pipeline components mainly include non-metallic pipes, non-metallic fittings and valves, non-metallic bellows expansion joints, non-metallic sealing elements, and non-metallic flanges. Common non-metallic pipeline components include polyethylene pipes (pipes, fittings, and valves), metal-reinforced polyethylene composite pipes, non-metallic/non-metallic composite pipes, non-metallic expansion joints, as well as non-metallic flanges and gaskets. At present, **a system combining type testing and manufacturing approval is implemented for most non-metallic pressure pipeline components. In recent years, with the advancement of technology and improvements in raw materials and manufacturing techniques, the performance of non-metallic pressure pipeline components in China has continued to improve. Thanks to their advantages such as long service life, corrosion resistance, and ease of processing and installation, they are being used more and more widely in fields such as petroleum, chemical industry, and urban gas transmission. Consequently, standard systems related to these components have also been gradually established and improved. Non-metallic pressure pipeline components are primarily used in environments where pressure is present and where flammable, explosive, or corrosive substances need to be transported. Their quality and safety are directly related to the safe operation of equipment or systems, as well as the safety of people’s lives and property. Standards are the technical backbone of economic activities and social development; standards determine quality. The level of industry standardization determines the technical security level of the entire industry and sector. Based on an analysis of the current status of the standard system for non-metallic pressure pipeline components in China as well as the differences in international industry standard systems, this paper examines the main problems existing in China’s standard system at present, and then proposes strategies and approaches for the development of such a standard system in the future. 1 Current status of the standard system for non-metallic pressure pipeline components in China: According to the **Special Equipment Safety Law**, non-metallic pressure pipeline components fall under the category of special equipment. Unlike other products, their standard system is composed of technical specifications and standards related to the safety of special equipment. China’s technical standards for non-metallic pressure pipeline components include general basic standards (including raw material standards), product standards, quality assessment standards, construction and welding procedure standards, as well as testing and conformity evaluation standards, covering essentially the entire life cycle of such components. 1.1 The safety technical specifications and the safety technical specifications for special equipment related to non-metallic pressure pipeline components are shown in Table 1. Safety technical specifications represent the basic safety and management requirements for the comprehensive and full-process supervision of special equipment in China. They are issued by the Special Equipment Safety Supervision Bureau under the General Administration of Quality Supervision, Inspection and Quarantine. This system constitutes a distinctive aspect of quality and safety management for special equipment in China, and it is mandatory as well as standardized. Compared to the technical standards discussed below, safety technical specifications do not cover technical details; they refer to certain technical standards. Although these standards are not at the standard level themselves, they are at a higher level than technical standards and represent mandatory requirements. Currently, the safety technical specifications for non-metallic pressure pipelines only cover aspects such as the design, manufacturing, type testing, periodic inspection, welding, operation management of commonly used polyethylene gas pipelines, as well as the qualification management of relevant organizations; they do not address other types of pipelines or safety accessories. With the increasing use of non-metallic pipes, the relevant standards are regularly revised and improved. However, there are still many shortcomings and issues related to their practical applicability. For example, TSG D7004—2010 only provides principle-based guidelines for non-metallic pipes, as domestic experience with regular inspections of polyethylene gas pipes is limited and there is a lack of technical expertise; as a result, its practicality is low. Several technical standards referenced in TSG D7002—2006 have been repealed or modified, making it difficult to guide practice. All these have had an adverse impact on the daily supervision and safety assessment of non-metallic pressure pipeline components. 1.2 Technical Standards In China, the standardization committees responsible for regulating standards related to non-metallic pressure pipeline components include the National Standardization Committee for Non-metallic Chemical Equipment (SAC/TC162), the National Standardization Committee for Plastic Products (SAC/TC48), the National Standardization Committee for Plastics (SAC/TC15), the National Standardization Technical Committee for Petroleum and Natural Gas (SAC/TC355), the National Standardization Technical Committee for Boilers and Pressure Vessels (SAC/TC262), the Special Standardization Technical Committee for Petroleum Pipes, the National Standardization Technical Committee for Pipeline Fittings, as well as the Standardization Technical Committee for Building Water Supply and Drainage and the Standardization Technical Committee for Gas under the Ministry of Housing and Urban-Rural Development. Although there are no specialized standardization committees for non-metallic pressure pipeline components abroad, the standards related to such pipelines are fairly comprehensive, distributed across various relevant standard systems. Some of the standards for non-metallic pressure pipeline components in our country are based on foreign standards, while other standards have been developed independently. The general basic standards for non-metallic pressure pipeline components are shown in Table 2. China’s standards include general standards covering pipeline terminology and definitions, dimensions and pressures, material grades and naming, strength design of pipeline systems, and the fabrication of pipes and fittings. Apart from the standards for specialized materials, all the general basic standards are **standards. With the exception of its standards for terms and definitions for which there are no corresponding international standards, all the other established standards draw on ISO international standards; the standards developed independently by China serve as a complement to the entire standard system. As shown in Table 3, the product standards for non-metallic pressure pipeline components in China cover, essentially, products that are currently widely used for gas transmission and the transportation of petrochemical fluids, such as polyethylene pipes, fittings, and valves, steel-plastic transition fittings, aluminum-plastic composite pressure pipes, steel-reinforced polyethylene plastic composite pipes and fittings, as well as expansion joints. These standards include industry standards for **, the petroleum industry, the chemical industry, and urban construction. Among these, GB/T 15558.1, GB/T 15558.2, GB/T 18997.1, etc., are all referenced in the safety technical specification \"Rules for Type Testing of Pressure Pipeline Components\" (TSG D7002—2006). As shown in Table 4, the performance evaluation standards for non-metallic pressure pipeline components in China cover aspects such as product dimension measurement, mechanical properties (including hydrostatic strength, tensile properties, and crack propagation resistance), physical properties (including melt mass flow rate, thermal stability, and longitudinal shrinkage), and welding properties (including tensile properties, peel strength, and hydrostatic strength). Technical standards serve as the technical backbone of regulatory and standardization systems, covering all aspects of products and technologies. Once these technical standards are referenced in the safety technical specifications, they acquire the same validity as those specifications and have a mandatory nature. The product standards and performance evaluation criteria for non-metallic pressure pipeline components in our country are relatively complex; there are numerous standard-setting committees responsible for them, and a wide range of standards are referenced. In addition to ISO standards, these include American ASTM and API standards as well as German DVS standards, although ISO standards remain the dominant ones overall. Among these standards, there are also some product and testing standards developed by our country itself, such as CJ/T 125, GB/T 15700, GB/T 29461, etc. There are a large variety of non-metallic pressure pipeline products in our country, and currently each product has corresponding product standards; some of these standards have been revised three or four times. However, some standards have not been revised since their issuance, such as GB/T 18997.1—2003, GB/T 18997.2—2003, and CJ/T 182—2003, which is related to the limited use of these standards. The standards for performance evaluation methods are almost based on the corresponding national standards; aside from some performance tests for specific products, they cover the testing methods for most of the performance aspects of common products, thereby meeting the needs for analyzing and assessing product performance. However, the updating and revision of method standards in our country are relatively slow; some of the corresponding international standards have been updated many years ago. For example, the latest version of ISO 9080:2003, to which GB/T 18252—2008 corresponds, is the 2012 edition, while the latest version of ISO 6259-3:1997, to which GB/T 8804.3—2003 corresponds, is the 2015 edition. To meet the construction requirements for non-metallic pressure pipeline components as well as the safety performance assessment of existing pipelines, China has also issued relevant construction and welding standards, along with non-destructive testing standards for existing pipelines, as shown in Table 5. With the exception of a few that adopt international standards, most of such standards are developed independently. This is particularly true in the areas of construction and non-destructive testing; they represent a summary of the experience gained in China’s polyethylene gas pipeline construction techniques over the past few years, as well as the application of advancements in non-destructive testing technologies. They also reflect an emphasis on ensuring the quality of pipeline construction and evaluating the safety performance of pipelines in service. 2 Analysis of the current status of standard systems for non-metallic pressure pipeline components abroad. Internationally, the standard systems for non-metallic pressure pipelines mainly include those established by the International Organization for Standardization (ISO), the American Society for Testing and Materials (ASTM), the American Society of Mechanical Engineers (ASME), European standards (EN), the American Petroleum Institute (API), as well as British standards that are based on European standards (BS EN) and German standards that are based on European standards (DIN EN). These represent the most advanced technical standards worldwide. The standard system consists of basic standards, product standards, test method standards, etc. ISO/TC138 is the Technical Committee on Plastic Pipes, Fittings, and Valves for Fluid Conveyance, and it is a specialized technical committee of the International Organization for Standardization. ISO/TC138 currently has 31 full members including China and 30 observers, with its secretariat located in Japan. ISO/TC138 has 7 sub-technical committees, among which those related to non-metallic pressure pipeline components are SC3, the Committee on Industrial Plastic Pipes and Fittings; SC4, the Committee on Plastic Pipes and Fittings for Gaseous Fuel Supply; SC5, the Committee on General Performance Testing Methods for Plastic Pipes, Fittings, and Valves; SC6, the Committee on Reinforced Plastic Pipes and Fittings for Various Applications; and SC7, the Committee on Thermoplastic Valves and Accessories. The standard system for ISO non-metallic pressure pipeline components has essentially adopted a relatively fixed \"seven-part standard\" structure, namely general provisions, pipes, fittings, valves and auxiliary equipment, suitability of the system, construction and installation specifications, and guidelines for quality assessment. This essentially covers all aspects of pipeline components, including the performance requirements for products made from various materials (such as pipes, fittings, and valves), the specific requirements that must be met to construct a pipeline system, the installation guidelines to be followed during on-site installation, and the methods for quality assessment. Such a standard framework is based on the principle of material classification, taking full account of the respective properties of each material; at the same time, the product standard systems for different materials can be compared with one another, thereby creating a standard system with a clear structure and well-defined content. The European EN standards, as well as the standard systems of the UK and Germany, follow a pattern similar to that of ISO standards, with only differences in certain performance indicators and methods. The United States, on the other hand, adopts a regulatory standard system that combines mandatory regulations with voluntary industry standards. As can be seen from Tables 4 and 5, most of the method standards for non-metallic pressure pipeline components in China adopt ISO standards. As shown in Table 6, some foreign standards related to non-ISO non-metallic pressure pipelines are listed. Compared with our country, the standard systems for non-metallic pressure pipelines in foreign developed countries have two main features: one is comprehensiveness and systematicness. In addition to focusing on the entire life cycle of pipelines from design to disposal, it also includes standards related to pipeline integrity management, risk analysis and assessment, design based on safety and reliability, inspection based on risk, and failure modes, thus forming a comprehensive system that is more operational. Second is to keep up with the times. The formulation and revision of standards are closely aligned with current technical levels, the latest research findings, and practical realities; they emphasize safety principles, feature simple procedures and short cycles, and can provide timely guidance for practice. Establish a supervision mechanism for the standard development process, ensure transparency in the standard formulation and revision process, and improve the standard service system. 3 Problems in the standard system for non-metallic pressure pipeline components in China: The degree of refinement of a standard system reflects the depth of research on products and the level of applied technology. The standards for general fundamentals are product classification and the basis of design ； The standards for raw materials are a prerequisite for ensuring product performance ； The standards regarding product performance serve as a basis for defining the product’s capabilities and ensuring they meet the requirements for engineering use ； Construction, welding, and inspection evaluation standards are the guiding specifications for pipeline engineering applications ； Standards in testing and qualification assessment are effective means to evaluate whether all aspects meet the expected requirements. At present, many of the standards for non-metallic pressure pipeline components in China are formulated with reference to ISO international standards, thus possessing a certain degree of international applicability. However, due to issues in China’s product manufacturing technology and standard management systems, the classification of product standards is not uniform enough, and their formulation and revision are not timely enough. Compared with the international standard system, the prominent problems in China’s standard system include three aspects: first, there is no unified and comprehensive national standard system. At present, China has not established a complete and systematic standard framework for non-metallic pressure pipeline components, which results in a lack of planning and scientific approach in the development of these standards. There is no proper arrangement of standards formulation and revision plans based on market conditions and industry needs; as a consequence, some standards are revised passively in response to changes in international standards, which also contributes to the overall low quality of these standards. There are numerous organizations responsible for standard setting, and the standards managed by different standardization committees remain relatively independent of one another; the mechanisms for coordinating their efforts are inadequate. As a result, the current standard system for non-metallic pipes suffers from conflicts and overlaps, which poses difficulties in the implementation and enforcement of these standards. This situation is particularly inconsistent with the **“Belt and Road” strategy that is being vigorously promoted at present. For example, the specifications for the properties of polyethylene pipes used in gas transmission, as set out in \"Buried Polyethylene (PE) Pipeline Systems for Gas Use – Part 1: Pipes\" (GB/T 15558.1—2015), which falls under the jurisdiction of the National Plastic Products Standardization Committee (SAC/TC48), differ significantly from those specified in \"Special Polyethylene (PE) Materials for Gas Pipeline Systems\" (SH/T 1768—2009) by the Sub-Technical Committee on Petrochemical Plastic Resins Products of the National Plastic Standardization Committee (SAC/TC15/SC1). In the national standard, the long-term hydrostatic strength curve of the blended materials at 80 °C does not allow a value of 5,000 hours to be reached before…