Zhuojin Pipe Fitting Co., LtdApplication of Domestic Single-Layer Strip Electrode Electroslag Cladding in Hydrogenation Reactors
Literature Overview
This technical paper by Liu Baojian, Kong Fanhong, Wang Tianxian, and Fan Xibin from Qingdao Lanshi Heavy Equipment Co., Ltd., published in Pressure Vessel Technology (Yali Rongqi) in 2019, Volume 36, Issue 9, pages 70–77, documents the qualification and industrial application of domestically produced single-layer strip electrode electroslag cladding consumables for hydrogenation reactors. The study addresses a critical challenge in the Chinese pressure vessel manufacturing industry: the reliance on imported consumables for hydrogen service applications, which poses supply chain security and cost concerns.
Electroslag Cladding Process and Consumable Specification
The process qualification employed a 75 mm × 0.4 mm steel strip as the electrode material, paired with a matching flux composition. Single-layer strip electrode electroslag cladding (SS-ESC) is a specialized variant of electroslag welding adapted for surface cladding rather than joint fabrication. The 75 mm strip width provides a wide cladding band, which significantly improves productivity compared to conventional wire-based cladding methods. The 0.4 mm strip thickness ensures adequate mechanical strength during feeding while maintaining a consistent melting rate.
| Parameter | Specification |
|---|---|
| Strip electrode dimensions | 75 mm × 0.4 mm |
| Cladding process | Single-layer strip electrode electroslag cladding |
| Application | Inner wall cladding of hydrogenation reactor |
| Qualification standard | Welding Procedure Qualification (WPQ) |
| Acceptance criteria | Product inspection and acceptance |
| Status | Qualified and approved for production |
Welding Procedure Qualification and Product Acceptance
The welding procedure qualification followed the standard qualification protocol, which typically involves welding test coupons under the proposed parameters, performing destructive and non-destructive testing, and verifying that the results meet the acceptance criteria specified in the applicable codes. For hydrogenation reactors, the qualification must demonstrate compliance with requirements for hydrogen resistance, including resistance to hydrogen-induced cracking (HIC), sulfide stress cracking (SSC), and other hydrogen-related degradation mechanisms.
The product acceptance inspection included ultrasonic testing (UT) for lack of fusion and slag inclusions at the cladding-to-base interface, radiographic testing (RT) for porosity and internal defects, and potentially dye penetrant testing (PT) for surface defects. Mechanical property testing of the cladding layer verified hardness, tensile strength, and impact toughness within the required ranges. The successful qualification and acceptance of both the welding procedure and the manufactured product confirm that the domestic consumable system meets the performance requirements for hydrogen service.
Engineering Significance and Industry Impact
The successful application of domestic single-layer strip electrode electroslag cladding consumables in hydrogenation reactors represents a significant milestone for the Chinese pressure vessel industry. Hydrogenation reactors operate under severe conditions, including high temperatures, high pressures, and the presence of hydrogen and hydrogen sulfide, which demand stringent material and welding quality requirements. The qualification of domestic consumables reduces dependency on imported materials, lowers project costs, and ensures supply chain reliability.
From a process engineering perspective, the strip electrode electroslag cladding process offers several advantages over alternative cladding methods such as submerged arc welding (SAW) or plasma arc welding (PAW). The high deposition rate and deep penetration characteristic of electroslag cladding result in excellent metallurgical bonding with the base material and lower dilution rates. The single-layer approach simplifies the welding sequence and reduces the risk of interpass defects, which is particularly beneficial for large-diameter reactor shells where cladding coverage area is extensive.
Summary
This paper documents the successful qualification and industrial application of domestic single-layer strip electrode electroslag cladding consumables for hydrogenation reactor inner wall cladding. The use of 75 mm × 0.4 mm steel strip electrodes with matching flux provides a productive and reliable cladding solution that meets the stringent requirements of hydrogen service applications. This achievement promotes the localization of critical welding consumables in the Chinese pressure vessel industry and contributes to the overall competitiveness of domestic equipment manufacturing.