9. Identification, Packaging, Transportation, and Storage

9.1 Safety Identification

Each gas spring product must be marked with a safety identification in an obvious position.

9.2 Product Identification

Each gas spring product shall be marked with the following contents agreed upon by the supplier and the demander in an obvious position:
a) The trademark of the demander or the supplier;
b) Product code, model, or part number;
c) The name, code of the supplier or the name of the demander;
d) Delivery date or production batch number.

9.3 Packaging Box Identification

The packaging box of the gas spring shall be marked with the following contents agreed upon by the supplier and the demander:
a) Product name, model, part number, order number, or bar code;
b) The name, code, or address of the supplier and the demander;
c) Quantity of products;
d) External dimensions, gross weight, net weight;
e) Production date;
f) Markings such as “Beware of High Temperature” and “Handle with Care”.

9.4 Packaging

• 9.4.1 There shall be flexible material protection between each gas spring in the packaging box.
• 9.4.2 The gross weight of each box shall not be greater than 30 kg.
• 9.4.3 The packaging box shall be accompanied by a certificate of conformity stamped by the quality department.
• 9.4.4 The material of the packaging box shall be agreed upon by the supplier and the demander.

9.5 Transportation

The gas springs shall be shipped by the transportation method agreed upon by the supplier and the demander.

9.6 Storage

Gas spring products shall be stored in a dry and ventilated warehouse, and there shall be no acid, alkali, or other corrosive gases around. Under normal storage conditions, there shall be no rust on the plating layer or peeling of the paint within one year, and the attenuation of the nominal force value shall not be greater than 5%.

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).

8.3 Inspection Classification

Product inspections are divided into factory inspections and type inspections.

• 8.3.1 Factory Inspections
  All products must undergo final inspections before delivery. The inspection items are shown in Table 5.
  | Inspection Items | Inspection Type | Inspection Methods and Requirements |
  |—|—|—|
  | Specified Force Value | Mandatory Inspection | Shall comply with the provisions of Table 2 |
  | Appearance | Mandatory Inspection | Conducted according to 7.1.2, shall comply with the provisions of 6.1.3 – 6.1.5 and 9.1 |
  | Extended Length | Sampling Inspection according to 8.2 | Conducted according to 7.1.1, shall comply with the provisions of 6.1.2 |
  | Force Characteristic Curve | Sampling Inspection according to 8.2 | Conducted according to 7.2, shall comply with the provisions of 6.2 |
• 8.3.2 Type Inspections
  Type inspections shall generally be carried out under any of the following circumstances:
  • a) When new products or old products are transferred to production and undergo finalization appraisal;
  • b) When there are major changes in product design, structure, materials, or processes;
  • c) When there are major changes in key process equipment or personnel;
  • d) After a certain period of normal production of series products;
  • e) When major quality problems occur in products;
  • f) When products are out of production for more than one year and then resume production;
  • g) When there are significant differences between the results of factory inspections and the previous type inspections;
  • h) When the national quality supervision agency requires type inspections.
    The type tests in d) and h) shall be carried out according to 8.2. Other type inspections shall be carried out in accordance with the provisions of GB/T 2829. 6 gas springs are sampled and divided into 3 groups, with 2 gas springs in each group. The inspections are carried out as shown in Table 6.
    | Group | 1 | 2 | 3 |
    |—|—|—|—|
    | Inspection Items | Force characteristics 6.2, High and low temperature resistance performance 6.4, Cycle life 6.5, Tensile resistance performance 6.6
    Corrosion resistance performance 6.7 | Dimensions 6.1.2
    Appearance quality 6.1.3, 6.1.4, 6.1.5
    Safety identification 9.1 | – |
    | Number of Samples | 2 | 2 | 2 |
    | Discrimination Level | I | I | I |
    | Judgment Array | [0,1] | [0,1] | [0,1] |
    | Unqualified Quality Level (RQL) | 40 | 40 | 40 |

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).

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).

7. Test Methods

7.1 Dimensions and Appearance

• 7.1.1 Dimensions shall be inspected using special or universal measuring tools with a scale division value not greater than 0.5 mm.
• 7.1.2 Appearance quality shall be inspected by visual inspection.

7.2 Force Characteristics

• 7.2.1 Test Conditions
  The test shall be carried out in an environment of 20°C ± 2°C. Before the test, the gas spring shall always be in the extended state, and the piston rod shall not be pressed. The sample shall be placed in an environment of 20°C ± 2°C for

7.2 Force Characteristics

• 7.2.1 Test Conditions
  The test shall be carried out in an environment of 20°C ± 2°C. Before the test, the gas spring shall always be in the extended state, and the piston rod shall not be pressed. The sample shall be placed in an environment of 20°C ± 2°C for more than 2 hours. The test measurement speed is 400 mm/min, and the force measurement accuracy is not lower than 1%.
  Note: For variable – damping gas springs and pressure – damping gas springs, the test speed is 100 mm/min – 300 mm/min.
• 7.2.2 Test Methods
  The test methods for force characteristics are divided into dynamic tests and static tests. The dynamic test method should be used as much as possible.
  • 7.2.2.1 Dynamic Test
    Install the piston rod of the gas spring vertically upward on the testing machine. In the first cycle of starting the machine, record the starting force. In the second cycle, record the extension force and compression force , , ,  at the force – measuring point , and calculate the nominal force, dynamic friction force and force ratio, and draw the force – displacement curve. At the same time, observe whether there is any jamming or obvious jitter of the gas spring piston rod.
  • 7.2.2.2 Static Test
    Install the piston rod of the gas spring vertically upward on the testing machine. In the first cycle of starting the machine, record the starting force. In the second cycle, record the extension force and compression force , , ,  at the force – measuring point , and calculate the nominal force and force ratio, and draw the force – displacement curve. The static test stays at the force – measuring point  for 3 s. At the same time, observe whether there is any jamming or obvious jitter of the gas spring piston rod.

7.3 Extension Speed

• 7.3.1 Test Conditions
  The test shall be carried out in an environment of 20°C ± 2°C. Before the test, the sample shall be placed in an environment of 20°C ± 2°C for more than 2 hours. The scale division value of the timer is not greater than 1/100 s.
• 7.3.2 Test Methods
  Install the piston rod of the gas spring vertically downward on the testing machine. Start the testing machine, press the piston rod into the specified stroke, and then remove the external force to allow the piston rod to extend freely. Measure the extension time  and the extended stroke , and calculate the extension speed (average speed)  according to the following formula:
  
  Where:
   – Extension speed, in millimeters per second (mm/s);
   – Stroke, in millimeters (mm);
   – Extension time, in seconds (s).

7.4 High and Low Temperature Resistance Performance

Place the gas spring in a high – temperature test chamber at 110°C ± 5°C for 1 hour, then take it out and place it in a normal – temperature environment for 2 hours. Then place the gas spring in an environment of – 40°C ± 2°C, and then place it in an environment of 80°C ± 5°C for 4 hours. The above is a high – low temperature cycle test. Test the force characteristics of the gas spring after the high – low temperature test according to 7.2, and calculate the attenuation of the nominal force .

7.5 Cycle Life

• 7.5.1 Normal Temperature Cycle Life
  Install the piston rod of the gas spring after the high – low temperature test downward on a testing machine equipped with an oil – collecting device, and conduct a cycle life test at a frequency of 4 times/min – 6 times/min (for variable – damping gas springs and pressure – damping gas springs, it is 3 times/min – 5 times/min). During the test, the piston rod should extend freely. After 25,000 cycles, test the force characteristics according to 7.2, calculate the attenuation of the nominal force , and then weigh the amount of oil brought out on an electronic scale with an accuracy of not less than 0.01 g.
• 7.5.2 Environmental Cycle Life
  Install the piston rod of the gas spring downward on a high – low temperature dynamic cycle testing machine equipped with an oil – collecting device. Lower the test environment temperature to – 40°C, and conduct a cycle life test at a frequency of 2 times/min – 4 times/min for 1,000 cycles. Take it out and test the force characteristics according to 7.2, and calculate the attenuation of the nominal force . Then install the gas spring on the testing machine, adjust the test environment temperature to 80°C ± 5°C, and conduct a cycle life test at a frequency of 4 times/min – 6 times/min (for variable – damping gas springs and pressure – damping gas springs, it is 2 times/min – 5 times/min) for 1,000 cycles. Take it out and test the force characteristics according to 7.2, and calculate the attenuation of the nominal force . Then weigh the amount of oil brought out on an electronic scale with an accuracy of not less than 0.01 g. After the high – low temperature dynamic cycle test, the gas spring is subjected to a normal – temperature cycle life test of 18,000 times. Test the force characteristics according to 7.2, calculate the attenuation of the nominal force , and then weigh the amount of oil brought out on an electronic scale with an accuracy of not less than 0.01 g.

7.6 Tensile Resistance Performance

Fix the extended gas spring on the testing machine, and load it at a speed of 1 mm/min – 2 mm/min according to the specified value in Table 3, and keep it for 3 minutes. After unloading, test the force characteristics according to 7.2 or observe.

7.7 Corrosion Resistance Performance

The corrosion resistance test of the gas spring shall be carried out in accordance with the provisions of GB/T 1771 or GB/T 10125.

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).

6. Technical Requirements

Products shall meet the requirements of this standard and be manufactured in accordance with the product drawings and technical documents confirmed by both the supplier and the demander. The materials and coatings selected for manufacturing products shall comply with the safety and environmental protection regulations of the application area.

6.1 Dimensions and Appearance Quality

• 6.1.1 The ratio of D₂/D₁ shall not be less than 1. The diameter and stroke of the gas spring piston rod shall be selected in accordance with GB/T 2348 and GB/T 2349. Special requirements shall be agreed upon by the supplier and the demander.
• 6.1.2 The tolerance of the extended length of the gas spring shall comply with the IT16 accuracy level specified in GB/T 1800.1.
• 6.1.3 The coating on the piston rod of the gas spring shall be uniform, and the surface shall be smooth, without defects such as scars, blisters, peeling, pitting, pinholes, and nodules.
• 6.1.4 The coatings on other exposed parts except the piston rod shall be uniform, without defects such as red rust, peeling, blisters, roughness, and missing plating (except for process holes and holes smaller than 1 mm).
• 6.1.5 The paint coating on the gas spring cylinder shall comply with the provisions of QC/T 484. The paint coating shall be uniform, without exposed substrate, obvious pitting, or serious sagging.

6.2 Force Characteristics

For gas springs with a specified force greater than 100 N, the force value shall be determined in integer multiples of 50 N. There shall be no jamming or obvious jitter during the compression and extension processes of the gas spring.

• 6.2.1 Specified Force F× and Dynamic Friction Force F,
  The limit deviation of the specified force value and the dynamic friction force shall comply with the provisions of Table 2. In case of special needs, it shall be agreed upon by the supplier and the demander.
  | Specified Force Value (N) | Limit Deviation of Specified Force Value (N) | Maximum Dynamic Friction Force F, (N) |
  |—|—|—|
  | ≤100 | ±5 | 25 |
  | 101 – 200 | +20 – 10 | 30 |
  | 201 – 400 | +30 – 15 | 40 |
  | 401 – 600 | +40 – 20 | 60 |
  | 601 – 800 | +50 – 25 | 80 |
  | 801 – 1000 | +60 – 30 | 100 |
  | 1001 – 1200 | +70 – 35 | 130 |
  | >1200 | +80 – 40 | 150 |
• 6.2.2 Start – up Force F₀
  The start – up force of the gas spring shall be less than 1.5F₃.
• 6.2.3 Force Ratio
  The force ratio of the gas spring shall be agreed upon by the supplier and the demander according to the usage situation.
• 6.2.4 Liquid Damper Part
  The length of the liquid damper part of the gas spring shall be agreed upon by the supplier and the demander according to the load situation.

6.3 Extension Speed

The extension speed of the gas spring shall be between 50 mm/s and 350 mm/s. In case of special needs, it shall be agreed upon by the supplier and the demander.

6.4 High and Low Temperature Resistance Performance

After the gas spring is stored at a high temperature of 110°C and then undergoes two high – low temperature cycle tests at – 40°C and 80°C, it shall not fail, and the attenuation of its nominal force F. shall not be greater than 5%.

6.5 Cycle Life

• 6.5.1 Normal Temperature Cycle Life
  After the gas spring undergoes high – low temperature tests, it shall undergo a cycle life test of 25,000 times (when the stroke ≤ 200 mm, the actual stroke shall be used; when the stroke > 200 mm, a stroke of 200 mm shall be used). After the test, the total attenuation of its nominal force F. shall not be greater than 13%, the dynamic friction force shall comply with the provisions of Table 2, and the amount of oil brought out shall be less than 0.5 g.
• 6.5.2 Environmental Cycle Life
  For gas springs used in harsh environments, after 1,000 high – low temperature dynamic cycle life tests at – 40°C and 1,000 tests at 80°C, the attenuation of their nominal force F. shall not be greater than 5%. After the gas springs undergo high – low temperature dynamic cycle life tests, they shall then undergo a normal temperature cycle life test of 18,000 times (when the stroke ≤ 200 mm, the actual stroke shall be used; when the stroke > 200 mm, a stroke of 200 mm shall be used). After the test, the total attenuation of their nominal force F. shall not be greater than 13%, the dynamic friction force shall comply with the provisions of Table 2, and the amount of oil brought out shall be less than 0.5 g.
  Note 1: 6.5.1 and 6.5.2 are not required simultaneously.
  Note 2: When 6.5.2 is required, 6.4 shall not be required.

6.6 Tensile Resistance Performance

The tensile resistance performance of gas spring products shall comply with the provisions of Table 3.

6.7 Corrosion Resistance Performance

• 6.7.1 After a 96 – hour neutral salt spray test, the gas spring shall have no blisters, peeling, or corrosion defects; the threads at the rod end and tube end and the hole openings shall have no blisters or peeling.
• 6.7.2 After a 48 – hour neutral salt spray test, the hard – chrome – plated piston rod shall have no blisters, peeling, or corrosion defects on its rod body; the threads at the rod end and the hole openings shall have no blisters or peeling.
• 6.7.3 The corrosion resistance performance of other exposed parts shall comply with the provisions of the corresponding coatings in QC/T 625. In case of special needs, it shall be agreed upon by the supplier and the demander.

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).