CLADDING TECHNOLOGY SHANXI CO., LTDTSG Z6002 Chinese Welder Qualification Rules for Special Equipment
Overview and Regulatory Context
TSG Z6002 is the Chinese regulation governing the qualification of welding operators for special equipment, issued by the State Administration for Market Regulation (SAMR). This regulation is the primary reference for welder qualification in China and is mandatory for TS-licensed fabrication of pressure vessels, pressure piping, and other special equipment. Understanding TSG Z6002 is essential for managing welder certification in Chinese fabrication environments and for ensuring compliance with Chinese regulatory requirements.
Qualification Requirements and Categories
TSG Z6002 defines welder qualification requirements based on welding process, material, position, and thickness. The following table summarizes the key qualification categories:
| Qualification Category | TSG Z6002 Requirement | Notes |
|---|---|---|
| Welding process | Same process (SMAW, SAW, GTAW, GMAW, FCAW, ESW, PTA, laser) | Each process requires separate qualification |
| Material | Same steel type or same material group | Based on Chinese steel classification |
| Position | Same position (flat, horizontal, vertical, overhead) | Separate qualification for each position |
| Thickness | 0.5 to 3× qualified thickness | For plate and pipe |
| Joint type | Same joint type (butt, fillet, lap) | Butt weld qualification does not cover fillet welds |
| Test method | Destructive testing (bend, tensile) and NDT | Visual inspection is mandatory |
Overlay Welder Qualification Requirements
TSG Z6002 includes specific requirements for overlay welder qualification. The following table summarizes these requirements:
| Requirement | TSG Z6002 Specification | Typical Application |
|---|---|---|
| Overlay process | Same process (SMAW, SAW, PTA, laser, etc.) | Each process requires separate qualification |
| Base material | Same steel type or same material group | Carbon steel, low-alloy steel, stainless steel, etc. |
| Overlay material | Same classification | Same grade of stainless steel or nickel alloy |
| Overlay thickness | 0.5 to 3× qualified thickness | For overlay thickness |
| Position | Same position | Flat, vertical, overhead, etc. |
| Test method | Visual, destructive (bond test), NDT | Bond test is mandatory for overlay |
| Dilution rate | Must be determined and documented | As specified by material or owner |
Comparison with International Standards
The following table compares TSG Z6002 with ASME IX and ISO 9606 for welder qualification:
| Aspect | TSG Z6002 | ASME IX | ISO 9606-1 |
|---|---|---|---|
| Validity period | 2 years | Indefinite (6-month inactivity rule) | 2 years |
| Test piece thickness | 0.5 to 3× | 0.5 to 3× | 0.5 to 3× |
| Position qualification | Separate for each position | Separate for each position | Separate for each position |
| Overlay qualification | Covered in TSG Z6002 | QW-451 | Annex of ISO 9606-1 |
| Material classification | Chinese steel grades | P-number and Group Number | ISO material groups |
| Test method | Destructive + NDT | Destructive + NDT | Destructive + NDT |
| Inspector involvement | Mandatory | Not required (unless specified) | Not required (unless specified) |
Practical Implementation in Chinese Projects
In practice, TSG Z6002 qualification requires careful attention to several China-specific considerations:
- Welder certificate management: TSG Z6002 requires that welder qualifications be documented in a welder certificate that is issued by the local market supervision authority. The certificate must be renewed every 2 years, and the welder must demonstrate continuous welding experience during the validity period. In practice, maintaining an up-to-date welder certificate database is essential for project planning.
- Inspector witnessing: TSG Z6002 requires that welder qualification tests be witnessed by a qualified inspector. The inspector must verify the test piece preparation, welding parameters, and test results. In practice, the inspector's interpretation of the standard may vary, and clear communication is essential.
- Material classification mapping: Chinese steel grades must be mapped to the appropriate TSG Z6002 material categories. For example, 16MnR (GB/T 713) is classified as a low-alloy steel, while 06Cr19Ni10 (GB/T 20878) is classified as an austenitic stainless steel. This mapping is critical for determining the qualification scope.
- Overlay qualification specifics: For overlay welding, TSG Z6002 requires a bond test in addition to the standard destructive tests. The bond test specimen must be machined to test the bond between the base metal and overlay layer. The minimum bond strength requirement is 100 ksi (690 MPa) for ferrous overlay on ferrous base metal, or as specified by the base material.
Reflections on TSG Z6002 Application
After working on several Chinese pressure vessel projects, I have found that TSG Z6002 provides a clear and prescriptive framework for welder qualification. The 2-year validity period is similar to ISO 9606 and requires active management of welder qualifications.
One significant challenge is the welder certificate management. TSG Z6002 requires that welder certificates be issued by the local market supervision authority, and the process can be time-consuming. In one project, we lost two weeks of schedule because the welder certificates were not issued in time, requiring us to find alternative qualified welders.
Another practical observation is that TSG Z6002 is more prescriptive than ASME IX in terms of test piece dimensions and test methods. The standard specifies specific test piece dimensions and test methods that must be followed exactly. This prescriptive approach can be beneficial for ensuring consistency but may limit flexibility in qualification design.
In one hydrogenation reactor project, we encountered a challenge with the overlay welder qualification for PTA welding of Inconel 625 on 16MnR. TSG Z6002 did not specifically address PTA welding qualification, and the inspector required a custom qualification procedure that included dilution rate testing and bond strength testing. This required close coordination with the inspector and the owner to develop an acceptable qualification procedure.
Summary
TSG Z6002 is the primary regulation for welder qualification in Chinese special equipment fabrication. It provides a clear and prescriptive framework that is largely compatible with international standards but includes China-specific requirements for certificate management, inspector involvement, and material classification. Engineers must carefully manage welder certificates, ensure compliance with the 2-year validity period, and maintain clear communication with inspectors. For international projects involving Chinese fabrication partners, understanding TSG Z6002 requirements is essential for ensuring compliance with Chinese regulatory requirements and maintaining project schedule.