Research and Application of Wear-Resistant Material Cladding on Equipment Flange RJ Sealing Surface

Literature Overview

This 2023 technical paper by Wei Xianyong from Shandong Tianli Energy Co., Ltd. and Liu Haifeng from Shandong Hongda Technology Group Co., Ltd. addresses the research and application of wear-resistant material cladding on equipment flange RJ (Ring Joint) sealing surfaces. RJ flanges are widely used in high-pressure, high-temperature process systems in the petrochemical, oil and gas, and power generation industries. The sealing surface of RJ flanges is subjected to severe wear during assembly, disassembly, and operation, leading to reduced sealing performance and potential leakage. This research investigates the application of wear-resistant cladding materials to extend the service life of RJ flange sealing surfaces while maintaining the critical sealing geometry and surface finish requirements.

RJ Flange Sealing Surface Requirements

The RJ flange sealing surface must meet stringent geometric and surface quality requirements:

Parameter	Specification	Tolerance
Surface roughness	Ra ≤ 1.6 μm	Critical for sealing
Flatness	≤ 0.1 mm	Prevent uneven loading
Surface hardness	250–350 HV	Original material
Sealing groove depth	3.0–4.0 mm	Per ASME B16.5
Sealing groove width	8.0–10.0 mm	Per ASME B16.5
Surface finish after cladding	Ra ≤ 1.6 μm	Must maintain
Hardness after cladding	500–700 HV	Wear resistance

The challenge of cladding RJ flange sealing surfaces lies in maintaining the precise geometry and surface finish while achieving significant hardness improvement. Conventional cladding methods often result in surface roughness that exceeds acceptable limits, requiring extensive post-weld machining that can compromise the cladding integrity.

Cladding Material Selection

The research evaluated several wear-resistant cladding materials for RJ flange applications:

Material	Hardness (HV)	Toughness	Weldability	Cost	Suitability
Cr-C-Mo martensite	600–700	Good	Good	Medium	High
High-silicon alloy	700–900	Poor	Fair	Medium	Low
Carbide composite	800–1000	Poor	Poor	High	Low
Stellite 6	400–500	Excellent	Good	High	Medium
Cr-C-Mo-Ti alloy	650–750	Good	Good	Medium-High	High

The selected material was a Cr-C-Mo-Ti alloy wire (1.6 mm diameter) that provides an optimal balance of hardness, toughness, and weldability for RJ flange applications. The titanium addition promotes fine grain structure and improves hot ductility, reducing the risk of cracking during welding.

Cladding Process Development

Process Route

The cladding process for RJ flange sealing surfaces was developed as follows:

Surface preparation: Mechanical grinding to Ra ≤ 3.2 μm, followed by solvent cleaning.
Preheating: 150–200°C to reduce residual stress and prevent cracking.
Submerged arc welding: Single pass with 1.6 mm wire, controlled parameters.
Post-weld heat treatment: 600°C for 1 hour to relieve stresses and refine grain structure.
Machining: Precision turning to achieve final dimensions and surface finish.
Final inspection: Surface roughness, hardness, and dimensional verification.

Optimized Process Parameters

Parameter	Value	Notes
Shielding gas	Argon + 2% CO2	Low dilution, stable arc
Travel speed	100–150 mm/min	Controlled heat input
Current	250–300 A	Adequate penetration
Voltage	25–28 V	Stable arc
Wire feed speed	6–8 m/min	Consistent deposition
Preheat temperature	180°C	Reduce cracking risk
Interpass temperature	≤ 200°C	Prevent grain growth
Post-weld temperature	600°C / 1h	Stress relief
Final machining allowance	1.0–1.5 mm	Maintain cladding layer

Performance Verification

The cladding process was verified through laboratory testing and field trials:

Metric	Original	Clad	Improvement
Surface hardness	250 HV	650 HV	2.6×
Wear life (cycles)	50–100	300–500	5–10×
Surface roughness	Ra 1.6 μm	Ra 1.4 μm	Maintained
Leakage rate	Baseline	No increase	Sealing maintained
Crack rate	—	0%	Reliable
Cost per service life	1.0	0.3–0.4	60–70% savings

Application Cases

The cladding technology has been successfully applied to:

Application	Flange Size	Pressure Rating	Temperature	Service Life Extension
Hydrocracker	DN500	42 MPa	400°C	3.5×
Refinery unit	DN300	25 MPa	350°C	4.0×
Power plant	DN400	15 MPa	300°C	5.0×
Chemical plant	DN200	10 MPa	200°C	6.0×

Engineering Practice Implications

The application of wear-resistant cladding to RJ flange sealing surfaces requires careful attention to maintaining the critical sealing geometry and surface finish. The post-weld machining step is essential for achieving the required surface roughness, but excessive machining can remove too much of the cladding layer, reducing the wear resistance benefit. Engineers should develop application-specific cladding specifications that account for the flange size, pressure rating, and operating conditions to optimize the cladding thickness and machining allowance.

Study Insights and Conclusions

This research demonstrates that wear-resistant cladding can significantly extend the service life of RJ flange sealing surfaces while maintaining the critical sealing performance. The key to successful application is the careful balance between cladding thickness, machining allowance, and final surface finish requirements. The Cr-C-Mo-Ti alloy material provides an excellent combination of hardness, toughness, and weldability for this application. Future development should focus on developing thinner cladding layers with higher hardness to minimize machining requirements while maximizing wear resistance, potentially through advanced processes such as plasma transferred arc welding or laser cladding.