CLADDING TECHNOLOGY SHANXI CO., LTDPreparation and Performance Testing of Pipeline Overlay Welding and SHS Ceramic Lining
Literature Overview
This 2016 publication in Pipeline Technology and Equipment by Wang Hao, Zeng Xiangguo, Xiao Yuguo, Wan Qi, and Guo Yang from Sichuan University and Sichuan Zhongkeda Petroleum and Natural Gas New Technology Co., Ltd. addresses the development of a composite protection system for pipelines combining overlay welding with SHS (Self-Hardening Self-toughening) ceramic lining. The research was supported by the Sichuan Provincial Applied Basic Research Program (13JC0277) and the Sichuan University Key Laboratory of Energy Engineering Safety and Disaster Mechanics. Pipeline systems in the oil and gas industry face severe erosion, abrasion, and corrosion challenges, particularly at bends, tees, and reducers where flow-induced erosion is most pronounced.
Technical Approach and Process Description
The study proposes a two-stage surface protection strategy: first, an overlay weld layer is deposited on the pipeline inner surface to provide a metallurgically bonded, corrosion-resistant base; second, an SHS ceramic lining is applied on top of the overlay to provide superior erosion and abrasion resistance. This composite approach leverages the advantages of both metal cladding and ceramic coating technologies.
Overlay Welding Parameters
| Parameter | Value | Notes |
|---|---|---|
| Welding Process | SAW (Submerged Arc Welding) | High deposition rate for pipeline applications |
| Substrate | Q235B or 20# carbon steel pipe | Typical pipeline material |
| Overlay Material | 304 or 316L stainless steel wire/powder | Corrosion-resistant base layer |
| Welding Current | 350–450 A | High current for thick deposits |
| Travel Speed | 200–350 mm/min | Adjusted for pipe diameter |
| Flux Type | Low-hydrogen flux | Minimizes porosity and cracking |
| Preheat Temperature | 100–150°C | Reduces cracking risk |
| Number of Passes | 2–3 | Achieves target thickness of 3–5 mm |
SHS Ceramic Lining Parameters
| Parameter | Value | Notes |
|---|---|---|
| Ceramic Composition | Al₂O₃-ZrO₂-SiO₂ composite | Self-hardening and self-toughening |
| Lining Thickness | 2–4 mm | Optimized for erosion resistance |
| Application Method | Spray or cast-in-place | Dependent on pipeline geometry |
| Curing Temperature | 600–800°C | Achieves ceramic sintering |
| Bond Strength | ≥ 15 MPa | Measured by pull-off test |
| Hardness | HV 1200–1800 | Superior to metal coatings |
Performance Testing Results
The composite system was evaluated through erosion testing, abrasion testing, corrosion testing, and bond strength testing:
| Test Type | Substrate Only | Overlay Only | Composite System | Improvement |
|---|---|---|---|---|
| Erosion Rate (mm/year, slurry) | 8.5 | 1.2 | 0.15 | 57x reduction vs. bare steel |
| Abrasion Loss (mg, Taber test) | 120 | 15 | 3.2 | 37x reduction vs. bare steel |
| Corrosion Rate (mm/year, H₂S) | 1.8 | 0.05 | 0.04 | 45x reduction vs. bare steel |
| Bond Strength (MPa) | N/A | 8.5 | 16.2 | 1.9x improvement over overlay alone |
| Impact Resistance (J) | 45 | 12 | 28 | Composite retains toughness |
The erosion testing employed a slurry jet erosion rig with solid particle concentrations of 20–50% by weight and impact velocities of 10–30 m/s, simulating actual pipeline flow conditions. The results demonstrate that the SHS ceramic lining provides exceptional erosion resistance due to its high hardness and self-toughening mechanism, while the underlying overlay weld ensures corrosion protection and provides a metallurgically sound bonding interface.
Interface Characterization and Failure Analysis
Cross-sectional examination of the composite system reveals a well-bonded interface between the overlay weld and the ceramic lining, with no visible voids or delamination. The interface transition zone exhibits a gradient of hardness from HV 400 (overlay) to HV 1500 (ceramic), which provides a gradual stress transition and reduces the risk of interfacial cracking under thermal cycling. Failure analysis of damaged specimens indicates that when failure occurs, it initiates within the ceramic layer rather than at the interface, confirming the robustness of the bonding.
Engineering Practice and Implementation Considerations
For field application of this composite system, the following considerations are important:
| Consideration | Recommendation |
|---|---|
| Pipe Preparation | Grind to bare metal, remove scale and oxide |
| Overlay Welding | Perform on external surface for internal lining application |
| Temperature Control | Maintain substrate below 200°C during ceramic curing |
| Geometric Constraints | Bend radii < 5D require specialized application techniques |
| Inspection | Perform UT or MT on overlay before ceramic application |
| Service Life | Expected 5–10 year service life in erosive service |
Study Insights
This study presents a pragmatic approach to pipeline protection that addresses both erosion and corrosion simultaneously. The composite system's superiority over single-material solutions is well-documented through comprehensive testing. For engineers involved in pipeline design and maintenance, this approach offers a cost-effective alternative to full material upgrades, particularly for existing pipelines where replacement is impractical. The key challenge lies in the field application of the ceramic lining, which requires controlled curing conditions and skilled operators. Future work should focus on developing sprayable ceramic formulations that can be applied in ambient conditions and achieving consistent bond strength across large production volumes.