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Shijiazhuang Faith Machinery Co.,Ltd’s steel welded pipe mill solutions are engineered to produce longitudinally welded steel pipes used in structural applications, fluid conveyance, and mechanical systems. With a focus on efficiency, weld integrity, and process traceability, these pipe mills support a range of materials—from mild carbon steels to high‐strength alloys—and deliver pipes that comply with industry standards such as ASTM, EN, and JIS.
A steel welded pipe mill typically comprises the following modules, each optimized for pipe production:
Payoff/Coil Loading
Mandrel decoilers equipped with hydraulic brakes manage coil weights up to 25 tons, feeding strip into the line at controlled tension.
Coil cars with precision positioning ensure exact alignment of strip entry, minimizing lateral strip wander that can compromise seam alignment.
Tension Leveler and Strip Preparation
A multi-bar tension leveler removes catenary curvature and camber, providing a flat strip for precise forming.
Load‐cell feedback monitors tension, and the PLC adjusts decoiler and leveler drives to maintain consistent strip entry conditions.
Forming Section
Progressive forming stands—typically 8 to 14 stands—gradually bend strip from flat to an open “U” shape, then to a closed tubular profile.
Forming rolls, machined from forged or heat-treated steel, are selected based on strip thickness (ranging from 1.2 mm to 12 mm) and desired pipe diameter (20 mm to 273 mm).
Stand housings feature shim packs or motorized adjustment to accommodate quick roll‐gap settings for different pipe sizes.
Welding Station (ERW)
Electric resistance welding (ERW) heads use high-frequency induction to heat strip edges to a forging temperature (1,000 °C–1,300 °C).
After heating, weld rolls apply forging pressure to create a solid‐state bond with minimal weld flash. Welding parameters—current, voltage, coil speed—are programmable via the PLC to match material grade and thickness.
Water-cooled induction coils dissolve heat directly into strip edges, minimizing the heat-affected zone (HAZ) and preserving parent material properties.
Weld Bead Treatment
Inline weld bead scarfing units remove residual flash on both the inside and outside surfaces. Rotary knives, synchronized with line speed, trim the bead, and vacuum extraction collects waste chips.
Roll brushing units may be added to polish the seam area, improving surface finish and preparing the pipe for downstream coating or galvanizing.
Sizing and Calibration
Tubes pass through sizing stands that refine outer diameter and circularity to meet tolerances (typically ±0.5% of nominal diameter).
Laser micrometers measure diameter continuously, providing feedback to the PLC for dynamic roll adjustment.
Stretch forming modules downstream apply axial tension (5%–8% of yield strength) to reduce ovality to less than 1% and improve straightness (targeting <1 mm deviation over 6 m).
Cutoff and Chain-Shot Systems
Flying cutoff saws, driven by servo motors, shear pipes at programmed lengths—ranging from 3 m to 12 m—with ±5 mm accuracy at speeds up to 100 m/min for thin-wall pipes.
For heavy-gauge pipes, hydraulic cutoff shears produce burr-free ends.
Chain-shot scrap conveyors capture pipe remnants, ensuring a clean and organized production environment.
Downstream Finishing Options
End Forming: Chamfering, beveling, or upset forming prepares pipe ends for welding, threading, or flange insertion.
Hydrostatic Testing: Inline hydrostatic stations test pipe integrity at pressures up to 10 MPa, verifying seam quality and wall strength.
Coating and Galvanizing: After welding, pipes can be routed through inline shot blasting, preheating, and coating stations or through continuous galvanizing lines for corrosion protection.
Shijiazhuang Faith’s steel welded pipe mills accommodate a variety of materials and pipe dimensions:
Carbon Steel Pipes:
Diameters from 20 mm to 273 mm, wall thicknesses from 1.2 mm to 12 mm.
Common grades: ASTM A53, API 5L (Grade B and X42), EN 10219 (S235JR, S355JR), JIS G3452. Applications include structural tubing, fluid conveyance, and mechanical systems.
High-Strength Low-Alloy (HSLA) Pipes:
Grades such as ASTM A500, API 5CT, with yield strengths up to 485 MPa.
Post-weld cooling modules (water quench or forced-air) help achieve targeted mechanical properties in the weld seam and HAZ.
Alloy Steel Pipes:
Medium-alloy grades (e.g., 4140, 4340) require precise control of weld heat input and HAZ cooling to ensure toughness and avoid martensitic brittleness.
Induction tempering units may be added for normalized or tempered finishes downstream of welding.
Stainless Steel Pipes (Selective Lines):
When needed, lines can be configured to handle stainless strip (e.g., 304, 316, 321) up to 4 mm thickness. Passivation stations and careful handling protocols maintain corrosion resistance post-weld.
To ensure reliable, high-quality welded pipe production, Shijiazhuang Faith Machinery Co.,Ltd integrates advanced automation and inspection systems into each mill:
Distributed PLC Control:
A master PLC (e.g., Siemens S7 or Allen-Bradley ControlLogix) manages all drive axes, welding power supplies, and safety interlocks.
EtherCAT or ProfiNet communication between modules ensures deterministic control for high-speed pipe production.
Human-Machine Interface (HMI):
Touchscreen HMIs present live process data—coil ID, strip thickness, weld current and voltage, pipe diameter, wall thickness, cut-to-length counts.
Operators select pipe size and grade via preloaded recipes, which automatically configure welding power levels, roll stand positions, and tension setpoints.
Weld Seam Inspection:
Surface Inspection Cameras: High-resolution cameras capture weld bead profile; image analysis algorithms flag undercut, excessive flash, or bead discontinuities.
Ultrasonic Testing (UT): Inline phased-array UT probes scan the entire weld seam at production speed, detecting lack of fusion, porosity, or cracks. Defective sections are automatically diverted to scrap conveyors without interrupting production flow.
Eddy-Current Testing (ECT): For alloy steels or coated pipes, ECT probes inspect surface and near-surface defects not visible to UT.
Dimensional Verification:
Laser micrometers measure outer diameter at multiple angles around the pipe, ensuring dimensional tolerance (commonly ±0.5% of nominal).
Ultrasonic wall-thickness gauges verify uniformity, particularly important for thicker pipes or those with tight wall tolerances (e.g., ±10% of nominal).
Tension and Speed Regulation:
VFD-controlled motors on the decoiler, leveler, and pull-through modules maintain constant strip tension, preventing seam misalignment.
Encoder feedback from the pull-through drive synchronizes forming roll speeds with strip feed, ensuring consistent forming geometry and reducing scrap rates.
Data Archiving and Traceability:
All production parameters—coil heat number, strip thickness, welding current, inspection results, dimensional readings—are logged to a centralized database.
Traceability reports can be generated for customer audits, detailing each pipe segment’s process history from coil entry to final cutoff.
Shijiazhuang Faith Machinery Co.,Ltd accommodates diverse customer needs by offering modular, configurable pipe mill solutions:
Forming Stand Configurations:
Fixed-gap stands for simple size ranges (e.g., 21.3 × 2 mm to 60.3 × 3 mm), with manual shim adjustments between size changes.
Servo-driven stands for automated roll gap positioning, greatly reducing changeover time for frequent size variations.
Additional stands can be added for larger diameter ranges (above 114.3 mm) to ensure gradual forming and accurate shape control.
Welding Station Options:
Single-Head ERW: Suited for moderate production rates (up to 60 m/min) and standard pipe diameters.
Dual-Head ERW (Tandem Welding): Two induction heads in series allow higher throughput (up to 120 m/min) for high-volume production of common sizes.
SAW Units: For pipes above 114.3 mm in diameter or wall thicknesses above 8 mm, SAW heads provide deeper penetration and robust weld profiles.
Cooling and Heat Treatment Modules:
Water Quench Boxes: Control weld seam cooling rates to achieve desired mechanical properties for HSLA and alloy steels.
Induction Tempering Ovens: Following welding, induction tempering refines HAZ microstructure to ensure consistent hardness and toughness.
Cutoff Options:
Flying Cutoff Saws: Produce pipe lengths up to 12 m with ±5 mm accuracy at line speeds to 100 m/min.
Hydraulic Cutoff Shears: For heavy pipes (wall thickness above 8 mm), hydraulic shears deliver burr-free ends suitable for immediate downstream fabrication.
Downstream Finishing:
Chamfering and Beveling Units: Prepare pipe ends for welding or threading.
Hydrostatic Testing Stations: Inline hydrostatic tests at pressures up to 10 MPa verify seam integrity and detect leaks.
Coating and Galvanizing: Finished pipes can be routed through shot blasting, preheating, and coating booths, or through continuous galvanizing lines for corrosion protection.
Layout Configurations:
Straight-Line Layout: Ideal for facilities with sufficient linear space, minimizing material transfer distances.
L-Shaped or U-Shaped Layout: Optimized for plants with limited length; modules are positioned to maximize floor usage while maintaining logical process sequencing.
To ensure sustained performance and minimal downtime, Shijiazhuang Faith Machinery Co.,Ltd provides comprehensive support services for steel welded pipe mills:
Turnkey Project Management:
From the initial feasibility study through detailed 3D layout design, equipment fabrication, and site preparation, Faith Machinery’s team oversees every phase. Detailed utility requirements (power, compressed air, cooling water) are specified to streamline installation.
Installation and Commissioning:
On-site mechanical alignment, PLC wiring, and system calibration are conducted by Faith Machinery’s engineers. Trial runs with customer-supplied strip verify machine performance, weld quality, and dimensional tolerances.
Commissioning reports document test results for client validation, ensuring the mill meets agreed-upon specifications.
Operator and Maintenance Training:
Comprehensive training covers safe operation, HMI navigation, preventive maintenance routines (roll inspection, bearing lubrication, welding power supply checks), and weld parameter adjustments.
Training manuals, maintenance schedules, and troubleshooting guides are provided for ongoing reference.
Spare Parts and Consumables:
A recommended spare parts kit—form roll bearings, welding power supply capacitors, hydraulic seals, shear blades, and NDT probe assemblies—is available for immediate dispatch.
Customers can choose from standard kits or customize based on their production schedules and wear patterns.
Remote Diagnostics and Software Support:
Secure remote access modules permit Faith Machinery’s technical experts to review PLC programs, analyze alarm logs, and propose parameter optimizations without an on-site visit.
Periodic software updates ensure compatibility with evolving hardware platforms, cybersecurity standards, and HMI advancements.
Field Service and Upgrades:
Scheduled field service visits include alignment checks, weld head tuning, and NDT calibration.
Retrofit packages—adding extra forming stands, upgrading welding power supplies to higher efficiency IGBT models, and integrating AI-based defect recognition—enable existing mills to increase capacity, process new materials, or improve quality inspection.
By combining rugged mechanical construction, precise welding control, and comprehensive process traceability, Shijiazhuang Faith Machinery Co.,Ltd’s steel welded pipe mills provide pipe producers with reliable, efficient, and fully supported solutions—ensuring that every pipe meets stringent quality standards for structural integrity and dimensional accuracy.
