The installation and construction of SSAW Steel Pipes is related to their subsequent performance and safety, and attention should be paid to multiple aspects.

Preparation before construction

Pipe quality inspection: For the SSAW steel pipes entering the site, the quality certification documents should be strictly checked, including whether the material, specifications, mechanical properties and other parameters of the steel pipes meet the design requirements. Through appearance inspection, check whether there are cracks, holes, scratches, folds and other defects on the surface of the steel pipe. For steel pipes with large diameters or used in important projects, sampling physical and chemical performance tests, such as tensile tests, impact tests, hardness tests, etc., can be carried out when necessary to ensure that the quality of the pipes meets the standards.

Construction site layout: Reasonably plan the construction site to ensure that there is enough space for steel pipe stacking, processing and construction equipment parking. The site should be flat and solid to avoid deformation of steel pipes due to foundation settlement. Set up a special pipe stacking area, store them according to pipe diameter, wall thickness, material, etc., and take moisture-proof and rain-proof measures to prevent steel pipes from rusting and corrosion.

Construction equipment commissioning: All kinds of equipment used in the construction process, such as cranes, electric welders, cutting machines, and mouthpieces, are fully debugged and inspected before construction. Ensure that the equipment has good performance, stable operation, and correct settings of various parameters. For example, the current and voltage adjustment of the electric welder must be accurate to ensure the welding quality; the lifting capacity and limit devices of the crane must be reliable to ensure the safety of lifting.

Lifting and installation

Lifting tool selection: According to the diameter, length, and weight of the SSAW steel pipe, select appropriate lifting tools, such as cranes and slings. The strength and specifications of the slings must meet the lifting requirements and have no defects such as broken wires, wear, and deformation. During the lifting process, the correct lifting method must be used to avoid single-point force on the steel pipe or excessive bending stress, and prevent the steel pipe from being deformed or damaged.

Accurate installation positioning: When installing the steel pipe, it must be positioned strictly in accordance with the design drawings. Use measuring instruments, such as total stations and levels, to accurately measure the center line, elevation, and slope of the pipeline. Ensure that the connection position between each pipe section is accurate to avoid installation deviations that may cause subsequent welding difficulties or affect the operating performance of the pipeline system.

Avoid collision damage: During the lifting and installation process, care should be taken to avoid collisions between steel pipes and other objects. Especially in narrow spaces or multi-pipeline cross-construction areas, on-site command and safety protection should be strengthened to prevent damage to the surface coating of the steel pipe or defects such as dents and cracks on the steel pipe itself, which will affect its service life and anti-corrosion performance.

Welding operation

Welding process assessment: Before formal welding, welding process assessment is carried out based on the material, specifications and welding position of the steel pipe. Determine appropriate welding parameters such as welding current, voltage, welding speed, number of welding layers, etc. through experiments, and formulate detailed welding process regulations. Welders must strictly follow the process regulations to ensure welding quality.

Welding environment control: Welding operations should be carried out under appropriate environmental conditions. When the ambient temperature is lower than 5°C, the steel pipe needs to be preheated. The preheating temperature is determined according to the material and wall thickness, generally between 100-200°C, to prevent cracks in the welded joints. At the same time, open-air welding should be avoided in rainy and windy weather. If it cannot be avoided, effective protective measures should be taken, such as setting up rain shelters and wind shields, to ensure the stability of the environment in the welding area.

Weld quality inspection: After welding is completed, the weld should be inspected in time to check whether the weld surface is flat and smooth, and whether there are defects such as pores, slag inclusions, undercuts, cracks, etc. According to the design requirements and relevant standards, non-destructive testing methods such as ultrasonic testing and radiographic testing are used to test the internal quality of the weld. For unqualified welds, they should be repaired in time, and the repaired welds should be tested again until they are qualified.

Anti-corrosion treatment

Surface pretreatment: Before the anti-corrosion coating is applied, the steel pipe surface must be strictly pretreated. Sand blasting, shot blasting and other methods are used to remove impurities such as rust, oil stains, oxide scale, etc. on the surface of the steel pipe, so that the surface of the steel pipe meets a certain roughness requirement to enhance the adhesion of the anti-corrosion coating to the surface of the steel pipe. The quality of surface pretreatment should meet the relevant standards, such as Sa2.5 or above.

Anti-corrosion coating construction: According to the design requirements, select appropriate anti-corrosion coating materials and construction processes. Common anti-corrosion coatings include epoxy coal tar coatings, 3LPE coatings, etc. During the construction process, the thickness, number of times the coating is applied, and the curing time of the coating must be strictly controlled. For example, epoxy coal tar coatings generally require multiple layers of application, each layer has a uniform thickness, and the total thickness meets the design requirements. After the coating construction is completed, quality inspections should be carried out, such as coating thickness detection, pinhole detection, etc., to ensure that the quality of the anti-corrosion coating is qualified.

Patching and repairing treatment: For the patching of steel pipe welding and the coating damage caused during transportation and installation, patching and repairing treatment should be carried out in time. The patching and repairing materials should match the original anti-corrosion coating materials, and the construction process and quality requirements should be consistent with the overall anti-corrosion coating. After the patching and repairing are completed, quality inspections should also be carried out to ensure the anti-corrosion performance of the patching and repairing parts.

Quality inspection

Installation quality inspection: During and after the installation of SSAW steel pipes, a comprehensive inspection of the installation quality should be carried out. The inspection contents include the centerline deviation, elevation deviation, slope deviation, joint gap, misalignment, etc. of the pipeline. Each deviation should meet the requirements of the design documents and relevant construction specifications, such as the centerline deviation generally does not exceed ±20mm, the elevation deviation does not exceed ±10mm, etc.

Pressure test: After the pipeline system is installed, a pressure test is required to test the strength and tightness of the pipeline. Determine the test pressure and test medium according to the design pressure and working medium of the pipeline. Generally, a water pressure test is used, and the test pressure is 1.5 times the design pressure. During the test, the pressure is slowly increased. After reaching the test pressure, the pressure is stabilized for a certain period of time to check whether the pipeline has leakage, deformation, etc. After the test is qualified, the pressure is slowly reduced to discharge the test medium in the pipeline.

Completion data collation: During the construction process, various construction materials should be collected and collated in a timely manner, including pipe quality certification documents, welding process assessment reports, non-destructive testing reports, pressure test reports, hidden project acceptance records, etc. The completion data should be true, complete, and accurate, consistent with the actual situation of the project, and provide a basis for the completion acceptance and subsequent maintenance management of the project.