Rolling and shaping muscles and bones, cutting into customized products

In the seamless steel pipe manufacturing chain, precision cutting of pipe ends belongs to the closed-loop control process of finished geometric shape. Its dimensional tolerance and end face positional accuracy directly determine the coaxiality of pressure bearing pipeline assembly, metallurgical quality of ring welded joints, and structural integrity under service conditions. For products with strict requirements for fixed length and pipe end geometric accuracy, such as boiler heat exchange pipes that comply with NB/T 47019.1-2021 "Heat exchange pipes for boilers and heat exchangers - Part 1: General rules", and marine pressure pipes that comply with current standards such as GB/T 5312-2025 "Seamless steel pipes for ships", Kanghong relies on full process capability control to achieve stable performance of micrometer level form and position tolerances.

Human, machine, material, method, environment, and measurement are the six major elements in the production process, and measurement is the basic work of internal management in enterprises. Need to achieve:

Measurement tool: Accurate and calibrated;

Measurement method: The measurement method is scientific and reasonable;

Data recording: Accurate and complete measurement data, standardized recording;

Frequency: Measuring the frequency appropriately can detect problems in a timely manner;

Data analysis: Conduct thorough analysis and interpretation of measurement data to ensure consistency, and ensure that measurement errors between different personnel are within an acceptable range.

Taking the ruler as a rule, precise control of the ruler, and strict adherence to the axial length tolerance system, dimensional accuracy is the core lifeline of seamless steel pipes. Taking the boiler heat exchange pipe NB/T 47019.1-2021 specification as an example, the allowable deviation of the axial dimension of the heat exchange pipe is: when the length of the ruler L ≤ 6m, the tolerance range is 0~+5mm; when L>6m, the tolerance range is 0~+10mm. For high-end pressure bearing and marine projects, internal control is implemented to tighten the tolerance of 0~+3mm, which is stricter than the standard basic tolerance zone. The control process of "pre measurement multi-point retest marking positioning" is implemented for homework execution. For large-diameter and thick walled pipes, circumferential multi-point collection is carried out to compensate for systematic errors caused by longitudinal bending of pipes and fixture positioning offset, and to lock the cutting reference. Ensure that the axial dimensions of the finished product meet the requirements of standard specifications, classification society supervision, and order technical agreement boundaries.

Steel pipe cutting is a comprehensive test of technology, experience, and mentality. According to the standard NB/T47019.1-2021 B.6, the cutting angle limit of steel pipe ends should not exceed 0.01 times the outer diameter of the steel pipe, and the maximum value should not exceed 3mm. The standard GB/T5312-2025 synchronously requires the end face to be perpendicular to the axis of the steel pipe and controls the geometric deviation of the pipe end. Excessive cutting deviation will lead to excessive misalignment, resulting in an increase in stress concentration factor of the circumferential weld and deterioration of the fatigue performance of the pressure bearing joint. According to the matching cutting process parameters of steel grade, outer diameter, and wall thickness, the feed rate, linear velocity, and cooling medium flow rate are synergistically controlled to avoid non allowable defects such as end face plastic distortion, incision tearing, and edge burrs. The operators dynamically monitor the cutting steady state, achieve consistency in the shape and position of the same batch of pipes, reduce the rate of non-conforming products in the process, and adapt to harsh working conditions such as Class I marine pressure pipes and high-temperature heat exchange pipelines.

Grinding is the precision, carving the pipe mouth to meet the standard surface quality criteria for pipe ends. Cutting and forming the pipe end is not the end of the process. Pipe mouth finishing is a key step in eliminating service hazards and ensuring compliance with subsequent non-destructive testing and welding assembly. For the end morphology of heat exchange and marine pipes, strict quality thresholds are set by current standards: according to clause 6.8.1 of NB/T 47019.1-2021, the pipe end face must be flat and free from harmful defects such as cracks, burrs, notches, and melting nodules; GB/T 5312-2025 for marine pipes specifies the requirement to remove burrs from cut edges and carry out pipe end groove processing as needed. Residual burrs, sharp corners, and oxide scales at the pipe end can cause false defect signals in ET/UT non-destructive testing, disrupt the continuity of the fusion of the docking groove, and form a stress concentration source under alternating pressure loads. The pipe end finishing process quantitatively controls the amount of material removal, removes burrs and oxide layers on the inner and outer walls of the pipe end, and protects the substrate wall thickness and original geometric features from damage throughout the process.

The square workstation follows the standard, and the shape and position are precisely controlled for variation. The cutting process has high repeatability characteristics, but it directly determines the service reliability of pressure bearing components and the conclusion of third-party supervision and acceptance. The Kanghong cutting position will benchmark indicators such as axial length, cutting slope, and surface quality of pipe ends against NB/T 47019.1, GB/T5312-2025, and customer specific stricter clauses to maintain the quality threshold for pipe production.

Craftsmanship in pressure bearing pipe fittings, standardized performance and commitment. Full process capability control ensures the smooth passing of seamless steel pipes through classification societies, third-party supervision, and project entry inspections, fulfilling the technical performance commitments of high-end pressure equipment customers, and consolidating the core competitiveness of the enterprise's high-end pipe manufacturing.