Write from 6 o'clock. The letter of authorization for witnessing and sampling of anti-corrosion coatings should be written from 6 o'clock:

1. The witness unit and witness authorization letter is a form used by the construction unit or the supervision unit entrusted by the construction unit to report to the quality supervision department supervising the project for filing. It is also used to notify the construction unit and the testing unit entrusted to conduct test inspections.

2. This form is to be filled in by the construction (supervision) unit, stamped by the unit and filled in with the date. One copy will be reported to the measurement and supervision station, and one copy will be notified to the laboratory by the construction unit. Witnesses should be professional technicians from the supervision unit or construction unit of the project who have construction knowledge and witness qualifications.

3. Witness the sampling and delivery procedures.

4. The witness should monitor the sample and hand it over to the testing personnel together with the sampler or take effective measures to seal the sample before sending it.

5. When the testing unit accepts the entrusted inspection task, the inspection unit must fill in the entrustment form, and the witness shall check the signature on the entrustment form.

6. The testing unit should indicate the name of the witnessing unit and witness in the remarks column of the inspection report. If a sample is found to be unqualified, the witnessing unit must be notified first.