Under the influence of whole industrial environment, Chinese welding standards started in early 1960s and were most affected by the former Soviet Union standards. With the development of china's reform and opening in the late 1970s, we started to adopt international standards and advanced foreign standards. During this period, Chinese government positively encourages to adopt the international standards and advanced foreign standards, by combining Chinese actual condition to prepare our national standards.

In 1988, the National Standardization Law was issued, in which the law provision clearly stipulates that "the state shall encourage the active adoption of international standards." At early 1990s, Chinese Government issued a series of new policies, which stress the "identical" or "equivalent" approach of adopting international standards and advanced foreign standards. Since 2000, in order to meet the needs of joining WTO, the adopting foreign standard police occurred some new changes, its most important feature is to emphasize the priority to adopt international standards, by the way for “identical” and “modify”.

The Chinese welding standards influenced by different policies mainly passed through the following stages:

1. 1960s-the late 1970s: basically adopting the former Soviet Union standards.

2. In 1980s: referencing to international standards and advanced foreign standards.

3. In 1990s: identical/equivalent adoption of international standards and advanced oversea standards.

4. Since 2000: identical/modification adoption of international standards.

Something may need to be clarified as following with regard to the difference between national standards and foreign standards：“identical” means that the technical content and text structure are same, only editorial differences exit；“equivalent” means that there are slight technical and editorial differences； “modification” means that there are significant differences in technical content, text structure, and all of those differences are clearly indicated.

1. 1 Conversion of Basic Standards

1.1.1 Standards for Terminology, Symbol, and Code

The main function for welding terminology and symbol is communication and information exchange, and the international standards usually play a key role with regard to professional communication among different regions, countries and industrial sections flue to difference in language, culture and customs.

The Chinese basic standards for welding mainly adopted the relevant international standards, but some of them may referenced with other foreign standards. For instance, the national standard, GB/T 3375 Welding terminology were prepared by referring to the ISO 857-1 and ANS/AWS A3. 0, and our new standards for Soldering and brazing terms mainly adopted ISO 857-2.

The welding symbol is usually considered as a special technical language during welding manufacture, and such kinds of languages are quite commonly used in technical drawings and documents. ISO 2553 specified the rule for the application of the technical language. There are different projection methods in technical drawings. The welding symbols may have different meanings in accordance with different standards. ISO 2553 provides a solution, and our national standard, CB/T 324 adopted the same way but specified more detailed regulations.

On the purpose of simplifying, one of the common practices is using numeral code to present different welding process. ISO 4063 systemically gives the numeral codes for varies process. Our national standard, GB/T 5185 is equivalent to ISO 4063 in order to ensure consistent.

The international standard ISO 6947 specified the definition for welding position. Our national standard GB/T 16672 equivalently adopted the ISO standard. Table 29-2 gives a comparison for ISO standards with Chinese standards.

1. 1.2 Standards for Joint Preparation and Dimensional Tolerance

The reasonable design can ensure the quality of welding joint, also can greatly improve the efficiency of welding production. The standards are quite important for choosing correct joint preparation and groove sizes.

ISO 9692 series standards specified varies grooves and joint preparations for different types of welding process, materials, thickness and structures. The first part (ISO 9692-1) applies to shield metal arc welding, gas welding, gas shield welding and high beam welding. The second part (ISO 9692-2) specifies the joint preparation for submerged arc welding. The third part (ISO 9692-3) is related to the inert gas arc welding for aluminum and aluminum alloy materials. The last part of series standard (ISO 9692-4) gives welding groove form and demotion requirements for composite steels. In the past, we only have two standards for welding groove (GB/T 985 and GB/1986), which subject to welding, manual welding and submerged arc welding process. In 2008, the ISO 6520 series standards are completely transformed as our national standards, and the welding joint design has realized equal with international practice.

The national standard GB/T 19804 specifies the general tolerances for size and form of welded structure, of which the requirements are equivalent to those of the international standard ISO 13920. The national standards for welding groove and dimensional tolerance corresponding lo ISO standards is shown in Table 29-3.

1. 1.3 Standards for Imperfection and Quality Classification

The existing welding technology is unable to fully avoid welding defect during the welding manufacture, therefore some procedure should be taken to control the welding defect to permitted range. The most effective moans is lo specify the limitations by standards.

GB/T 6417 series standards specified the welding imperfections categories and illustration. The fast part, GB/T 6417. 1 applies lo fusion welding, equal lo ISO 6520-1； and the second part, GB/T 6417.2 applies to pressure welding, equal to ISO 6520-2.

The national standards GB/T 19418 and GB/T 22087 specified the quality classifications for steels and aluminum alloys. The two standards are corresponding to the ISO 5817 and ISO 10042 respectively. GB/T 22085 series standards consist of two parts：GB/T 22085. 1 corresponding to ISO 13919-1 and GB/T 22085. 2 corresponding to ISO 13919-2. The series standards apply lo high beam on steels and aluminum alloys.

In addition, one standard subjecting to laser-arc hybrid welding on steels, nickel and nickel alloys

is under preparation on the basis of referring to ISO 12932.

The main purpose to specifying quality classification is to ensure manufacturer adopt an effective quality control means during welding production. The best economic benefit is to achieve acceptable quality with reasonable cost. Due to this reason, all of the standards applied three levels (B, C and D), as shown in Table 29-4.

1. 3. 2 Conversion of Management Standards

1. 3. 2.1 General Welding Management Standards

Our national welding quality requirement series standards consist of five parts corresponding to ISO 3834. 1 ~ ISO 3834. 5.

The first four parts keep the same structure with those of ISO 3834. 1 - ISO 3834. 5, and the series standards are designed to consider different levels of quality assurance requirements and suit for practical demands. Those standards put forward different requirements on the basic principles of quality assurance. In addition, these requirements which have certain corresponding relationship with the ISO 9000 series standards, are materialized by combining the actual aspects of welding quality assurance. The fifth part gives the related standard document guideline.

As a complete set of management standards, the scope can be defined from three aspects: the manufacture using welding as a key process or it’s relative parties (such as user, third-party certification institutions or agencies) ; varies welding metal structures；the involved content including the factors influencing to welding quality.

The GB 9448 Welding and cutting safety is a unique mandatory standard in welding field. There is no unified ISO standard for welding and cutting safety issue. Therefore, our standard is mainly refer to the corresponding foreign advanced standards (ANSI/AWS Z 49. 1). Table 29-5 gives the detailed information with regard to general management standards.

1.3.2.2 Qualification Standards for Welding Personnel

One of the main characteristic of modern welding manufacturing is that more knowledge and technology are integrated into welding；personnel engaged in welding must have certain professional knowledge and skills lo ensure the effective implementation of the welding. Welding personnel qualification, therefore, has become one of the important links in quality assurance.

GB/T 19419 is equivalent to JSO 14731 in terms of technical content, the standard put forward the general requirements for welding personnel responsibilities and tasks. The basic starting point is to make clear personnel factors that may affect the quality of product, and give some corresponding requirements by llic principle of quality assurance.

In addition, one of effective control measures is to qualify the welder or welding operators’ skill in actual welding production. The main purpose of qualification standard is that welder or welding operator’s performance will be tested and qualified through a series of specially designed program to confirm his ability.

To cater to such a demand, ISO 9606 series standards are developed on the common basis of different structures, specifying general requirements for welder qualification. ISO 9606 consists of five parts for welding qualification test on different materials (steel, aluminums and aluminum alloy, copper and copper alloys, nickel and nickel alloys, titanium and titanium alloy, magnesium and magnesium alloy). At present, we have finished conversion in the first four parts, and ready to start the fifth part this year.

GB/T 19805 is prepared in accordance with ISO 14732. The standard specifies the welding operator examination requirements, applying to welding operator qualification.

The general standard requirements for welding personnel qualification in China are almost same with the international standards, as showing in Table 29-6.

1. 2. 3 Standards for Welding Procedure and Qualification

Choosing the correct welding parameters can ensure welding quality, and determine of welding procedure specification is based on welding procedure qualification. With regard to welding procedure qualification and specification standard system, our national standards mainly refer lo ISO system. Up to now, our welding procedure specification series standards consist of six parts corresponding to ISO 15609. 1 ~ ISO 15609. 6；and welding procedure qualification series standards. The situation is shown in Table 29-7.

1. 3. 3 Conversion of Production Standards

1. 3. 3. 1 Standards for Welding Materials

Welding materials have important influence on the final quality of joints due to its fusion into weld during welding. Therefore, the welding material standard has been one of key link in the quality control. In China, one special subcommittee for welding material (SAC/TC55 / SC1) is found and taken the responsibility of standardization work.

There are two kinds of classification designation of welding materials in the world for a long time. European countries generally adopt the yield strength and 47 joule impact value; While the Pacific rim countries use tensile strength and 27 joule impact value. ISO have made many efforts and investigation and finally combined the two systems into same ISO standards.

In the past, our national standards for welding material mainly referred to the AWS or JIS standards since we belongs lo Pacific rim country. But now we changed our track to ISO-B system. The standardization projects are still going on and Table 29-8 gives detailed information.

1. 3. 3. 2 Standards for Brazing and Soldering

The standardization for brazing and soldering is under the responsibility of one of our subcommittees (SAC/TC55/SC2)，the scope includes：filler metal, flux and relative test. One of significant differences in this field is that we prepared several standards for different filler metals while ISO，Europe or AWS formulate one unified standard. Table 29-9 shows the comparison.

1. 3. 3. 3 Cutting Standards

Cutting is one of allied process with welding, and the cutting standards are usually considered together with gas welding according to international practice. There are no national standards in cutting field because all of the former national cutting standards are adjusted as industrial standards during our national standard system modulation.

Due to the professional characteristics and industry technology development, our standards arc quite different from ISO standards, and we need to do some further improvement, as seen in fable 29-10.

1. 3. 4. 3 Standards for Welding Process

The standardization for welding process in ISO system is relatively weak, but the situation is improved in recent years. Our standards for common welding process basically refer to AWS and JIS standards, but for new welding technologies (especially laser, friction stir welding process), we mainly adopted ISO standards, as shown in Table 29-13.

1. 4 Concluding Remarks

By the efforts of several generations, the welding standardization in China has gone through different developing stages, started from scratch; from small to large； from close to open. With the continuous development of China’s industrialization process, the welding technology has become increasingly important in manufacturing industry and the corresponding standardization activities also received more attention. Chinese welding standard system are almost consistent with ISO and industrial developed countries, the main technical contents of welding standards generally keep synchronized with international standards, and also meet the actual demands to Chinese welding industry.

With the development and progress of welding technology, standardization in welding field is continually extended, especially in new welding technology area which may link and affect whole manufacturing industry, its standardization will become key emphasis in our work, and may also have influence on ISO standard.