For supervisory spot checks, samples are selected at random from products intended for sale. For each batch, 10 units-each measuring 1 meter in length by the product's original width-are collected; 5 of these serve as test samples, while the remaining 5 are held as reserve samples.
The inspection criteria cover parameters such as the thickness of the color-coated steel sheet and the profiled steel sheet, peel performance, surface quality, dimensions and allowable deviations, and bond strength. According to the determination rules, a product is considered to have no non-conformities only if it passes all inspection items; failure in one or more items results in an overall determination of non-conformity. If the quality requirements explicitly stated for a product are more stringent than the applicable inspection standards, the stated requirements shall take precedence; conversely, if the stated requirements are less stringent than those mandated by compulsory standards, the compulsory standards shall apply.