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Precautions for Seamless Line Pipe Production Process

Date:2021-08-25    keywords:seamless line pipe production process

Precautions for seamless line pipe production process:


1. Raw material inspection and inspection
The raw material manufacturer's product quality certificate, the raw material is sampled in batches, and the steel pipe manufacturer will conduct various inspections and issue an inspection report.

2. Hydrostatic pressure test

Each steel pipe shall be subjected to hydrostatic pressure test without leakage, and the test pressure shall be at least not lower than the requirements in API 5L. The test pressure holding time for seamless steel pipes of various sizes shall be no less than 5 seconds. In order to ensure that each steel pipe can reach the required test pressure, each testing machine should be equipped with a recorder to record the test pressure and holding time of each steel pipe. If there is a representative of the purchaser in the factory for inspection, these records or charts should be available for inspection by the inspector of the purchaser. The test pressure test device is checked every 4 months. The storage of verification records shall comply with the provisions of the API 5L standard.


seamless steel pipe


3. Non-destructive testing
For all seamless steel pipes, non-destructive inspection should be carried out in accordance with the provisions of the API 5L standard.

4. Tensile test
A complete tensile test should include the determination of yield strength, ultimate tensile strength and elongation.

3. Non-destructive testing
For all seamless steel pipes, non-destructive inspection should be carried out in accordance with the provisions of the API 5L stand

4. Tensile test
A complete tensile test should include the determination of yield strength, ultimate tensile strength and elongation.

5. Charpy impact test
Charpy impact test is not required for PSL1 products;
Charpy impact test of PSL2 is sampling test according to API 5L standard.

6. Appearance and surface inspection
There should be no cracks, folds, folds, scars and delamination on the inner and outer surfaces of the steel pipe, and these defects should be completely removed. The cleaning depth should not exceed the negative deviation of the nominal wall thickness, and the actual wall thickness at the cleaning site should not be less than the minimum allowable wall thickness deviation.

On the inner and outer surface of the steel pipe, the allowable depth of the straight line is as follows:
Cold drawn steel pipe: not more than 4% of the wall thickness, and the maximum depth is 0.3mm;
Hot-rolled steel pipe: not more than 5% of the wall thickness, and the maximum depth is 0.5mm.

Other local defects that do not exceed the negative deviation of the wall thickness are allowed to exist.


Tips:API seamless pipe is a steel pipe that belongs to the American petroleum standard. The steel pipe has a hollow section and is used as a pipeline for transporting fluids. For example, steel pipes for transporting oil, natural gas, gas, and water are used to make ring parts, which can improve the utilization rate of materials and simplify the manufacturing process. Saving materials and processing man-hours, such as rolling bearing rings, jack sleeves, etc., has been widely used in seamless steel pipe manufacturing.

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