Quality Control Measures for Stainless Steel Seamless Pipe

Quality control in the production of Stainless steel pipe is essential to ensure their strength, durability, and reliability. From raw material inspection to final packaging, each step is meticulously monitored to meet industry standards and customer requirements.

Raw material quality control

(1) Chemical composition testing: Strictly test the chemical composition of raw materials, such as carbon, silicon, manganese, sulfur, phosphorus, etc., to ensure that they meet the design requirements.

(2) Dimension and defect inspection: Check the dimensional tolerance and surface defects of the billet or tube, such as cracks, pores, inclusions, etc., to ensure that there are no obvious defects.

(3) Heat treatment: Preheat the raw materials (such as annealing, normalizing) to eliminate internal stress and improve plasticity and uniformity.

Quality control during production

(1) Temperature:

- Strictly control the temperature of the heating furnace to avoid local overheating or overcooling.

- The cooling speed needs to be controlled during the cooling stage to avoid affecting the performance of the steel pipe.

(2) Forming:

- During the perforation process, the perforation must be uniform to avoid "fire mouth" or "skin and bone" phenomenon.

- During the cold rolling or cold drawing process, the gap between the rollers and the die is adjusted to ensure uniform wall thickness.

(3) Heat treatment:

- Annealing, normalizing, quenching and tempering are used to adjust the hardness, strength and toughness of the steel pipe.

- Strictly control the heat treatment temperature and time to ensure uniform metallographic structure.

(4) Size:

- The accuracy of the outer diameter, inner diameter and wall thickness is ensured by accurately controlling the rolling parameters (such as rolling force, speed and temperature).

- Use laser diameter gauges and other equipment to monitor the size in real time.

(5) Surface defects:

- The oxide scale is removed through pickling, phosphating and other processes to ensure a smooth surface.

- Use eddy current testing, ultrasonic testing and other equipment to detect surface and internal defects.

Final product inspection

• Appearance inspection: Check whether there are cracks, scratches, rust and other defects on the surface.

• Dimension inspection: Measure whether the outer diameter, wall thickness, length, etc. meet the standards.

• Mechanical property inspection: Ensure that the mechanical properties meet the standards through tensile, hardness, impact and other tests.

• Non-destructive testing: Use ultrasonic flaw detection, eddy current flaw detection and other technologies to detect internal defects.

• Packaging and labeling: Qualified products are oiled, packaged, and marked with specifications, production batch numbers and other information.

Quality traceability and recording

Establish a full-process quality traceability system to record the process parameters and test data of each steel pipe.