Flexible steel pipe structure has four-layer structure of the flexible steel pipe, the innermost layer is extruded thermoplastic tube, the transmission fluid from the seal; between two layers of lining of carbon-filled polyethylene tube, having a resistance to ultraviolet radiation of temporary ability, and to rule out external static. The outermost layer is extruded thick outer shield, for maintaining the bottom of the tube from external influences.

Specification of flexible steel pipe pressure rating applies comply with ANSI classification, such as grade 300 equivalent 5.15MPa; grade 400 equivalent .89MPa; 10.3MPa flexible steel grade 600 equivalent design basis is API17J17K and RP17B land Flexible pipe design specifications slightly within a deviation from the API specifications, use API17J classification methods and materials, pressure, tension and damage limits are prescribed range.

Test is designed in accordance with APIRP17B terminal fitting to meet the requirements to maintain structural integrity, to ensure that the inner and outer extruded layer sealing requirements, and can ensure that the tensile and compressive load is transmitted to the pipe structure. After blasting sample terminal fittings and axial tensile test.