QCNPC 38 double-layer fusion bonded epoxy powder (FBE/2FBE) anti-corrosion steel pipe

Technical standard for QCNPC 38 anti-corrosion steel pipe

The QCNPC 38 standard mainly proposes technical specifications for solvent-free liquid epoxy anti-corrosion coatings and double-layer fusion bonded epoxy powder coatings for buried steel pipelines. This standard requires that the anti-corrosion coating be divided into ordinary grade and reinforced grade. The ordinary grade has a small thickness of 400 μ m, and the reinforced grade is 600 μ m. It also specifies that the material should use two-component solvent-free epoxy coating with high solid content (≥ 95%) and excellent bonding strength (≥ 10MPa). At the same time, the standard sets strict indicators for key parameters such as gelation time and drying time of coatings, and the anti-corrosion layer forms a dense and stable protective film during construction.

Structure and material characteristics of anti-corrosion coating

QCNPC 38 anti-corrosion steel pipe adopts a double-layer fusion bonded epoxy powder (FBE/2FBE) structure, with the inner layer being the anti-corrosion functional layer and the outer layer being the anti mechanical damage layer. Epoxy powder coating is made by mixing solid epoxy resin, curing agent, and additives, and forms a continuous coating on the surface of preheated steel pipes through electrostatic spraying technology. This coating has resistance to cathodic delamination, soil stress, impact and bending properties, and is suitable for working environments ranging from -30 ℃ to 100 ℃, especially in corrosive soils or underwater environments such as acid, alkali, and salt.

Application scope and engineering adaptability

QCNPC 38 standard anti-corrosion steel pipes are widely used for underground transportation pipelines of crude oil, refined oil, natural gas, and water, and can also be extended to scenarios such as steel storage tanks and offshore facilities. Its anti-corrosion coating design meets domestic and international industry standards such as SY/T0315-2005, and has passed chemical resistance tests (such as 10% H ₂ SO ₄, 10% NaOH, etc.), ensuring long-term stable operation in complex media. In addition, the coating supports various construction methods such as airless spraying and brushing, adapting to different engineering requirements.

Construction technology and quality inspection requirements

Before construction, the steel pipes need to be shot blasted and preheated at medium frequency to achieve a surface cleanliness level of Sa2.5. During the coating process, real-time monitoring of the coating thickness, uniformity, and curing status is required, and the performance is verified through tests such as bending resistance, impact resistance, and cathodic stripping. The factory inspection includes visual inspection, thickness measurement, and electrical strength testing (≥ 30MV/m), while the type inspection includes a 2400 hour immersion test, with no defects such as bubbles or rust.

Performance advantages and industry recognition

QCNPC 38 anti-corrosion steel pipe has become the preferred anti-corrosion solution in the fields of petroleum, chemical, municipal, etc. due to the high adhesion, temperature resistance, and chemical inertness of epoxy resin. Its coating has excellent mechanical properties, with a soil stress resistance of over 24MPa, high construction efficiency, and environmental friendliness without pollution. This standard has been widely applied in large-scale energy projects such as PetroChina and Sinopec, and has been internationally certified for export to multiple markets in Europe, America, Southeast Asia, and other countries.