8. Inspection Rules

8.1 Defects

Gas springs that do not meet the technical requirements specified in the product technical standards and drawings are considered defective. According to the severity of the defects, they are divided into:
a) A – Critical defects;
b) B – Major defects;
c) C – Minor defects.
The defect items are shown in Table 4.

8.2 Sampling Methods

• 8.2.1 Inspection Lots
  • a) The inspection lot must be qualified gas spring products. 280 gas springs are regarded as one inspection lot. If the number of products is greater than 280, the inspectors shall arbitrarily divide them into several inspection lots of 280 pieces each, and then randomly select one inspection lot as the sampling object.
  • b) If the number of products is less than 280, it is not suitable to be sampled as an inspection lot. Instead, inventory products should be selected for sampling, or the corresponding code letter and sample should be selected in Table 1 of GB/T 2828.1 according to the actual lot size.
• 8.2.2 Sample Selection
  • 8.2.2.1 Non – destructive inspection items share one sample. If the number of products is greater than 150, according to the general inspection level I specified in GB/T 2828.1, with the sample size code letter E, and according to the normal inspection single – sampling plan, 13 gas springs are sampled. If the number of products is not more than 150, the sample shall be selected according to 8.2.1 b).
  • 8.2.2.2 High and low temperature resistance performance, cycle life, tensile resistance performance, and corrosion resistance tests are destructive tests and belong to type – test items. During inspection, according to the special inspection level S – 1 specified in GB/T 2828.1, with the sample size code letter B, and the normal inspection single – sampling plan, the force characteristics, high and low temperature resistance performance, cycle life, and tensile resistance performance tests share one set of samples, and the corrosion resistance performance test uses one set of samples. 3 gas springs are sampled for each.
• 8.2.3 Acceptable Quality Limit (AQL) and Acceptance Number (Ac)
  The acceptable quality limit for A – defect items and B – defect items is 4.0, and the acceptance number is 0.
  The acceptable quality limit for C – defect items is 6.5. When the code letter is E, the acceptance number is 2; when the code letter is D, the acceptance number is 1.
• 8.2.4 According to the stability of product quality, transfer can be carried out among normal inspection, relaxed inspection, and tightened inspection in accordance with the transfer rules of GB/T 2828.1. When conducting relaxed inspection, with the general inspection level I and the sample size code letter E, 5 gas springs are sampled according to the relaxed inspection single – sampling plan. When the sample size code letters are D and B, 3 and 2 gas springs are sampled respectively. When conducting tightened inspection, the number of samples is the same as that in 8.2.2.

Technical Specification for Compression Gas Springs (English version of national strandard, initiated by LeiYan Gas Springs), proposed and prepared by SAC/TC 235 (National Technical Committee 235 on Spring of Standardization Administration of China).