I. Basic Judgment Criteria and Methods
1. Visual Inspection Method
No Oil Residue: After cleaning, the inner surface of the tin should be free of any visible oil stains or film, and should be clean enough to act as a mirror. Hard-to-see corners can be inspected using specialized instruments such as an endoscope.
No Impurity Precipitation: Invert the tin to check for sediment, such as sand, metal shavings, and other deposits on the bottom to ensure complete cleanliness.
Surface Hydrophilicity Test: Immerse the cleaned tin in clean water and remove it. If a uniform film of water forms on the surface, rather than water droplets, the oil has been removed.
2. Physical Inspection Methods
White Cloth/Filter Paper Wipe Method: Repeatedly wipe the inner surface with a clean white cloth or filter paper. No residual stains are present.
Water Drop Test: Spray water mist into the tin. A continuous film of water indicates cleanliness; discontinuous water droplets indicate residual oil.
Thin Paper Test: Repeatedly wipe with thin paper to ensure no oil seepage indicates cleanliness.
II. Acceptance Criteria for Different Scenarios
1. Simple Home Cleaning Acceptance
Sensory Criteria:
No oily deposits
No residual odor of detergent or other cleaning agents
Inner surface feels smooth and not sticky
Simple Test:
No cloudiness or oily spots appear after shaking with clean water
No iridescent oil film reflects from the inner surface when observed under sunlight
2. Industrial Cleaning Acceptance
Professional Testing Criteria:
No fluorescence under UV light (indicating no organic residue)
Dyne test value meets the standard (depending on the material, generally ≥38 dynes)
Effluent oil content is less than 50 mg/L (for circulating cleaning systems)
Recordset Requirements:
Detailed records of cleaning time, cleaning agents used, operator, and other information are required.
Save an acceptance report including all test data.
III. Identification Methods for Special-Purpose Engine Oil Tin Cans
1. Food-Grade Containers
Hygiene Standards:
No visible impurities (e.g., rust, fibers) on the inner surface
No odor, confirmed by olfactory testing
Blank verification: Fill with a small amount of food-grade liquid to test for contamination
Special Testing:
Use food-grade test strips to confirm the absence of harmful residues
Inner surface roughness test (Ra ≤ 0.8 μm)
2. Hazardous Goods Containers
Safety Standards:
Combustible gas concentration testing must meet standards (typically ≤ 25% of the lower explosive limit)
No residual toxic gases, such as hydrogen sulfide
No leaks in welds and joints
Professional Acceptance:
A check report signed by professionals from both parties
Immediately seal the manhole and restore it to its original condition
