When sampling raw materials of steel bars, 60T steel bars with the same batch number, specifications and dimensions are considered as a batch; when the quality is less than 60T, they are still counted as a batch. After the appearance quality inspection is qualified, two steel bars with qualified diameters are randomly selected, and a tensile specimen and a cold bending specimen are intercepted for inspection. It is not allowed to take more than two specimens with the same purpose from the same steel bar.

When sampling, 500mm should be cut off at the end of steel bar before sampling.

Requirements for sample retention:

Elongation ≥ 17% (diameter: 12-25)

Elongation ≥ 16% (diameter 28-40)

Elongation ≥ 15% (diameter ≥40)

Generally, three groups of specimens from a batch are sent to the laboratory, and the evaluation depends on laboratory testing.

Extended data:

Sampling and inspection procedures

approve

The engineering construction unit or supervision unit shall submit the Power of Attorney for Witness Units and Witnesses to the construction unit, engineering quality supervision station and engineering inspection unit. The power of attorney shall specify the name, certificate number and witness number of the witness unit and the witness of this project, and the number of witnesses shall not be less than 2.

sample

When sampling and making samples at the site, the sampling personnel of the construction enterprise must have witnesses present, monitor the samples, take effective measures to seal the samples together with the inspectors entrusted by the inspection, or send the samples to the testing unit.

check

When the inspection unit accepts the entrusted inspection task, it must fill in the entrustment form, and the witness shall produce the witness certificate and sign the inspection entrustment form. Testing units must implement a password management system.

laboratory report

The inspection unit shall affix the seal of "witness sampling inspection" on the inspection report. If there are unqualified samples, they should be reported to the quality supervision station within 24 hours, and the unqualified project account should be established.

Five requirements: ① the test report should be printed by computer; (2) The test report adopts a unified form at the provincial level; ③ The signature of the test report must be signed by hand; ④ The test report shall have a unified format and be stamped with the special seal of "Witness Inspection"; (5) Indicate the name of the witness.

Report collection

The first case: the inspection result is qualified, and the construction unit receives the report and handles the sign-in registration.

In the second case: if the test result is unqualified, the testing unit will notify the witness to report to the monitoring station. The witness received the test report.

To witness the test report of sampling for inspection, the laboratory shall indicate the witness in the remarks column of the report and affix the special seal of "Witness for Inspection", and shall not affix the seal of "Responsible only for incoming samples".

If the test is unqualified, it shall immediately notify the construction engineering quality supervision institutions and witness units that supervise the project. If the test is unqualified, it is necessary to double the sampling and retest according to relevant regulations, and follow the witness sampling inspection procedure.

The test report without witness and "witness inspection" shall not be used as quality assurance data and completion acceptance data.

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