Tubesheet Sealing Surface Spraying Technology

The tubesheet sealing surface utilizes High-Velocity Oxygen Fuel (HVOF) spraying technology. The WC-10Co4Cr coating achieves a hardness of over 1200HV and a porosity of <1%, significantly enhancing corrosion and wear resistance. Prior to spraying, sandblasting (Sa3 grade) is required, with roughness controlled within Ra6.3-12.5μm to ensure a bonding strength ≥70MPa.

Optimized process parameters include: spraying distance of 150-200mm, powder feed rate of 30-50g/min, and gas flow rate of 900-1200L/min. The coating thickness is typically 0.2-0.3mm, and the surface roughness after machining can reach Ra0.8μm.

Comparative tests show that the sprayed sealing surface has a lifespan 3 times longer than that of weld overlay in Cl⁻-containing media, and it can repair local defects. It is important to avoid the substrate temperature exceeding 150℃ to prevent thermal deformation.