SSAW Steel Pipe is a spiral seam submerged arc welded steel pipe, and HSAW Steel Pipe is a spiral submerged arc welded steel pipe. In fact, the two are the same type of steel pipe. The following are their similarities and differences:

Commonalities

Welding process basis: Both use submerged arc welding technology. During the welding process, the arc burns under the flux layer. The arc heat between the welding wire and the weldment is used to melt the edges of the welding wire and the weldment to form a weld. This welding method can ensure the quality and stability of the weld, and the weld metal composition and performance are relatively stable.

Raw materials and forming methods: Both use steel strips or steel plates as raw materials, and the raw materials are processed into tubes by curling or spiral rolling, and then welded. In this way, large-diameter steel pipes can be produced using narrower steel strips or steel plates. The raw materials are highly adaptable and can produce steel pipes with different wall thicknesses.

Application fields: It is widely used in the oil, natural gas, chemical, electric power, construction and other industries. It is mainly used to transport various fluid media, such as oil, natural gas, water, chemicals, etc. It can also be used for structural pipes, such as support columns in building structures, pipe piles in bridge structures, etc.

Difference

Name usage habits: SSAW is a more formal and common name, and it is usually used in international standards and domestic related standards and industries; HSAW is sometimes used in some specific areas or within enterprises, but it is relatively not as widespread and formal as SSAW.

Weld mark and appearance: The weld of SSAW steel pipe is obviously spiral, extending from one end of the steel pipe to the other end, and the weld has a certain angle with the axis of the steel pipe; the spiral angle of HSAW steel pipe weld may vary due to different production processes and equipment, but it is generally distributed in a spiral, but the appearance may be slightly different from the weld appearance details of SSAW steel pipe due to specific production conditions.

Production efficiency and cost: Under the same production scale and equipment conditions, due to the more mature and common production process of SSAW steel pipes, its production efficiency is relatively high and the cost is relatively low; while the production process of HSAW steel pipes requires higher precision and stability of equipment, and the production efficiency may be slightly lower than that of SSAW steel pipes, and the cost may also be slightly higher.

Mechanical performance: Due to the spiral distribution of the weld, when the SSAW steel pipe is subjected to internal pressure and external load, the spiral weld has a certain angle with the main stress direction, which makes the stress distribution at the weld relatively complex, but the overall strength and toughness can meet most conventional engineering needs; HSAW steel pipes can optimize the welding process and parameters during the production process to make the mechanical properties of the weld better match the parent material, and have more advantages in some specific application scenarios that require higher mechanical properties of steel pipes.

SSAW steel pipes (spiral seam submerged arc welded steel pipes) and HSAW steel pipes (spiral submerged arc welded steel pipes) are essentially the same type of steel pipes, and their production process is basically the same. The following is a detailed introduction:

1. Raw material preparation

Select standard hot-rolled steel strips or steel plates as production raw materials. The quality of these raw materials directly affects the performance of the steel pipe. Its chemical composition, mechanical properties (such as yield strength, tensile strength, elongation, etc.) and surface quality must be strictly inspected to ensure that there are no defects such as cracks, scars, folds, etc.

2. Strip pretreatment

Leveling: Since the steel strip may bend and deform to a certain extent during rolling and transportation, the steel strip is leveled by a leveling machine to eliminate the shape defects of the steel strip, so that it can meet the flatness requirements required for subsequent processing and ensure the quality of steel pipe forming.

Edge trimming: The edge of the steel strip may be uneven, burred or uneven in thickness during the production process. The edge trimming machine is used to shear both sides of the steel strip to remove the irregular parts of the edge, ensure the flatness and verticality of the edge of the steel strip, and control the width dimensional accuracy of the steel strip to provide good conditions for subsequent steel pipe forming.

Bevel milling: In order to ensure the welding quality of the steel pipe, a suitable bevel shape is milled on the edge of the steel strip. Common bevel forms include V-type and X-type. The purpose of milling groove is to increase the amount of deposited metal during welding, improve the strength and sealing of the weld, and enable the arc to penetrate the root of the groove better, ensure the root penetration, and reduce the occurrence of welding defects.

3. Forming welding

Forming: The pre-treated steel strip passes through the forming machine and is wound into a tubular blank according to the set spiral angle. During the forming process, the roundness, diameter dimensional accuracy of the tube blank, and the uniformity and stability of the spiral weld are guaranteed by adjusting the position and pressure of each roller of the forming machine. At the same time, in order to prevent the tube blank from deformation or instability during the forming process, a supporting device such as an internal expansion mandrel or a supporting roller is usually set inside the tube blank to provide the necessary support force to ensure the forming quality.

Internal welding: After the tube blank is formed, the internal weld is welded first. Using the submerged arc welding process, the welding wire is fed into the welding area through the wire feeding mechanism, and an arc is formed between the inside of the tube blank and the parent metal. The high temperature generated by the arc is used to melt the welding wire and the parent metal to form a weld. At the same time, a layer of granular flux is covered on the welding area, the arc burns under the flux layer, the flux melts at high temperature and participates in the metallurgical reaction, which protects, deoxidizes, and alloys the weld metal, thereby improving the quality and performance of the weld. Internal welding usually adopts multi-wire welding technology. By increasing the number of welding wires and adjusting the position of the welding wires, the welding speed and deposition efficiency can be improved, while the forming quality and internal quality of the weld can be improved.

External welding: After the internal weld is completed, the external weld of the pipe blank is welded. External welding also adopts submerged arc welding process, and its welding principle and process are basically the same as internal welding. When performing external welding, the pipe blank is first moved to the external welding station through the conveyor, and then the parameters of the welding equipment are adjusted, including welding current, voltage, welding speed, wire extension length, etc., to ensure the stability of the welding process and the reliability of the weld quality. External welding also usually adopts multi-wire welding technology, which can be combined with internal welding to further improve welding efficiency and weld quality. During the welding process, by real-time monitoring and control of welding parameters and inspection of weld appearance quality, problems that occur during welding can be discovered and corrected in time to ensure the stability and consistency of welding quality.

4. Weld inspection

Appearance inspection: After welding is completed, the steel pipe weld is first inspected for appearance. Check the weld surface for defects such as undercut, pores, slag inclusions, cracks, unfused, weld nodules, etc. by visual observation or with the help of tools such as low-power magnifying glasses. At the same time, measure the dimensional parameters such as the width, excess height, and misalignment of the weld to ensure that it meets the relevant standards and design requirements. Appearance inspection is a simple, intuitive and cost-effective inspection method that can quickly detect obvious defects on the weld surface and provide a basis for subsequent inspection and treatment.

Nondestructive testing: In addition to appearance inspection, nondestructive testing of steel pipe welds is also required to detect whether there are defects inside the weld. Commonly used nondestructive testing methods include ultrasonic testing (UT), radiographic testing (RT), magnetic particle testing (MT) and penetration testing (PT). Among them, ultrasonic testing and radiographic testing are mainly used to detect volume defects inside the weld, such as pores, slag inclusions, and incomplete penetration; magnetic particle testing and penetration testing are mainly used to detect open defects on the surface and near the surface of the weld, such as cracks and lack of fusion. In the actual inspection process, the appropriate non-destructive testing method or a combination of multiple methods is usually selected according to the material, specification, purpose of the steel pipe, and the form and characteristics of the weld to conduct a comprehensive and detailed inspection of the weld to ensure that the internal quality of the weld meets the relevant standards and requirements. Non-destructive testing technology has the advantages of not destroying the object being inspected, high detection sensitivity, and the ability to detect internal defects. It is one of the important means to ensure the quality of steel pipe welding.

5. Dimension and performance inspection Dimension inspection: Strictly measure and inspect the various dimensions of the steel pipe to ensure that it meets the relevant standards and ordering requirements. The main dimensional parameters inspected include the outer diameter, wall thickness, length, roundness, straightness, etc. of the steel pipe. The measurement of outer diameter and wall thickness is usually carried out with tools such as calipers, micrometers, and ultrasonic thickness gauges to ensure the accuracy and reliability of the measurement; the length measurement is carried out with equipment such as tape measures or laser rangefinders; the detection of roundness and straightness is usually carried out with special detection devices or instruments, such as roundness meters, straightness detectors, etc. Dimension inspection is one of the important links to ensure the quality of steel pipes. Excessive dimensional deviation may affect the installation and use performance of steel pipes in engineering, and even lead to safety accidents. Therefore, the dimensions of steel pipes must be inspected in strict accordance with relevant standards and inspection procedures to ensure that the dimensional deviation is within the allowable range.

Performance inspection: In order to ensure the quality and performance of steel pipes, a series of performance inspections are required for steel pipes. The main performance indicators of the inspection include mechanical properties, process properties, chemical properties, etc. Mechanical performance inspection is one of the important contents of steel pipe performance inspection, mainly including tensile test, bending test, impact test, hardness test, etc. Through the tensile test, the yield strength, tensile strength, elongation and other mechanical performance indicators of the steel pipe can be determined, and the mechanical properties of the steel pipe under axial tension can be evaluated; the bending test is used to test the plastic deformation capacity and crack resistance of the steel pipe under bending load, and to determine whether the steel pipe has internal defects or uneven organization. The impact test is to determine the toughness and impact resistance of the steel pipe under impact load, and to evaluate the performance of the steel pipe under harsh working conditions such as low temperature and dynamic load; the hardness test indirectly evaluates the strength, wear resistance, corrosion resistance and other performance indicators of the steel pipe by measuring the hardness value of the steel pipe surface. It can also be used to check whether there are organizational defects such as decarburization and carburization on the surface of the steel pipe. The process performance test mainly includes flattening test, expansion test, curling test, etc., which are used to test the process adaptability and deformation capacity of the steel pipe during the processing process, and evaluate whether the steel pipe can meet the requirements of different processing technologies. Chemical performance testing mainly includes chemical composition analysis, intergranular corrosion test, stress corrosion cracking test, etc., which are used to determine the chemical composition of steel pipes, evaluate the corrosion resistance of steel pipes in different corrosion environments, and determine whether steel pipes have potential corrosion problems such as intergranular corrosion and stress corrosion cracking. Performance testing is an important means to comprehensively evaluate the quality and performance of steel pipes. Through the inspection and analysis of various performance indicators of steel pipes, quality problems existing in the production process of steel pipes can be discovered in time, and corresponding improvement measures can be taken to improve the quality and performance of steel pipes and ensure that steel pipes can meet the use requirements of different engineering fields.

6. Labeling and packaging

Labeling: Steel pipes that have passed the inspection need to be marked on their surface or specified positions. The content of the label usually includes the specifications and models of the steel pipes (such as outer diameter, wall thickness, length, etc.), materials, production batch numbers, implementation standard numbers, manufacturer names or trademarks, etc. The purpose of labeling is to facilitate the identification, management and traceability of steel pipes during production, transportation, storage and use, and to ensure that the quality information of each steel pipe can be accurately recorded and queried. The methods of labeling usually include spray printing, steel stamping, and labeling. The spray printing mark is to use a spray gun to spray special ink or paint on the surface of the steel pipe to form a clear and firm identification information; the steel stamp mark is to use a press to press the steel stamp mold with the identification content on the surface of the steel pipe to form a permanent identification mark; the label paste mark is to paste the pre-printed label on the specified position of the steel pipe, and the label content should be clear, complete, and not easy to fall off. When performing the identification operation, the appropriate identification method and identification material should be selected according to the material, surface state, use environment and other factors of the steel pipe to ensure the clarity, durability and reliability of the identification, and meet the identification requirements of the steel pipe in different use scenarios.

Packaging: In order to protect the steel pipe from damage during transportation and storage, it needs to be properly packaged. The packaging form and material are usually determined according to the specifications, quantity, transportation method, storage conditions and special requirements of the steel pipe. Common packaging forms include bundling packaging, pallet packaging, container packaging, wrapping film packaging, plastic bag packaging, paper bag packaging, wooden box packaging, iron box packaging, etc. Bundling packaging is to arrange multiple steel pipes neatly according to certain rules, and then use steel belts, steel wires, plastic ropes and other bundling materials to bundle the steel pipes into bundles. This form of packaging is suitable for the transportation and storage of small and medium-sized steel pipes; pallet packaging is to place the steel pipes on the pallet, and then use steel belts, steel wires, plastic ropes and other bundling materials to fix the steel pipes and the pallet together, or use stretch film to wrap the steel pipes and the pallet as a whole. This form of packaging is convenient for forklift loading and unloading and transportation, and is suitable for the transportation and storage of large quantities of steel pipes; container packaging is to load the steel pipes into the container, and then seal and fix the container. This form of packaging has good protective performance and transportation efficiency, and is suitable for steel pipes for long-distance transportation and sea transportation; stretch film packaging is to use a stretch film machine to Stretch wrapping film is wrapped around the steel pipe in multiple layers to form a tight and firm packaging. This packaging form can effectively protect the surface of the steel pipe from scratches and corrosion, and has good moisture and dust resistance. It is suitable for steel pipe packaging with high surface quality requirements; plastic bag packaging and paper bag packaging are to put a single or multiple steel pipes into a plastic bag or paper bag, and then seal the bag mouth. This packaging form is suitable for small-sized steel pipes or steel pipes with certain requirements for moisture and dust resistance; wooden box packaging and iron box packaging are to put the steel pipe into a special wooden box or iron box, and then seal the box cover. This packaging form has high strength and protective performance. It is suitable for steel pipe packaging with high safety requirements and easy to be collided and damaged during transportation. When performing packaging operations, the appropriate packaging form and packaging materials should be selected according to the actual situation of the steel pipe, and the firmness, sealing and protection of the packaging should be ensured to prevent the steel pipe from deformation, damage, corrosion and other problems during transportation and storage, and ensure the quality and integrity of the steel pipe. At the same time, the specifications, quantity, material, manufacturer and other relevant information of the steel pipe should be indicated on the packaging for easy identification and management.

The above is the complete production process of SSAW steel pipe and HSAW steel pipe.