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GB/T 14251-2017 English PDF (GBT14251-2017)

GB/T 14251-2017 English PDF (GBT14251-2017)

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GB/T 14251-2017: General technical standard for metal container of canned food

This Standard specifies the method for determination of the specific surface area of metallic powder. This Standard applies to the determination of the specific surface area of metallic powder. The determination range is 0.1 m2/g~1000 m2/g. The determination of the specific surface area of non-metallic powder and microporous materials may also refer to it for use. The specific surface area determined in this Standard is the total specific surface area of the powder, including any open specific surface area where nitrogen molecules can enter the powder body. It is different from the specific surface area measured by the air permeation method, which refers to the envelope surface area.
GB/T 14251-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 67.250
A 82
Replacing GB/T 14251-1993
General technical standard for metal container of
canned food
ISSUED ON: SEPTEMBER 07, 2017
IMPLEMENTED ON: OCTOBER 01, 2018
Issued by: General Administration of Quality Supervision, Inspection and Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 Product classification ... 19
5 Quality requirements ... 20
6 Food safety requirements ... 25
7 Test method ... 25
8 Inspection rules ... 34
9 Marking, packaging, transportation, storage ... 39
Appendix A (Normative) Quality requirements for pure copper wire used for welding canned metal containers ... 41
Appendix B (Informative) Calculation method and table look-up method of overlap length and overlap percent ... 43
General technical standard for metal container of
canned food
1 Scope
This standard specifies the terms and definitions, product classification, quality requirements, food safety requirements, test methods, inspection rules, markings, packaging, transportation, storage requirements for metal container of canned food.
This standard applies to empty cans and full cans for canned food, which are made of tin-plated or chrome-plated sheet steel or aluminum alloy sheet. 2 Normative references
The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) is applicable to this standard.
GB/T 2828.1 Sampling procedures for inspection by attributes - Part 1:
Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection
GB 4806.9 National food safety standard - Food contact metal materials and articles
GB/T 5231-2012 Designation and chemical composition of wrought copper
and copper alloys
GB/T 6682 Water for analytical laboratory use - Specification and test
methods
QB/T 2763-2006 Coated tinplate (or ECCS)
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
5.2 Quality of empty cans and ends
5.2.1 Appearance quality
5.2.1.1 Empty cans shall be free of contamination, oil stain, odor; it shall be intact; it shall be free from deformation or obvious corrosion. There shall be no metal exposure, except for plain tinplate cans.
5.2.1.2 The main printed patterns and text are clear.
5.2.1.3 The scoring of the key open can shall be uniform. There shall be neither faulty score nor welding of the open key.
5.2.1.4 The stiffeners of the can body shall be uniform, smooth, complete. It shall be free from end-to-end non-connections, bumps and wrinkles, different depths. The welds at the stiffeners shall not have cracks.
5.2.1.5 The top and bottom cover shall be free of damage, obvious
contamination, surface rust, wrinkles and deformation on the hook edge; there is no glue build-up, broken glue, tailing or obvious blisters in the sealant. The pull ring of the easy open end shall be free from other defects, such as damages. 5.2.2 Weld quality
5.2.2.1 The welding seam is flat and smooth. The lap joint is even and
consistent. The soldering joints are evenly connected. There shall be no cold welding, missing welding, pin holes, puncture. There shall be no obvious corrosion and splash.
5.2.2.2 The overlap of welds shall meet the processing requirements of can making. The thickness of the weld shall not be greater than 1.5 times the thickness of the original plate.
5.2.2.3 Sealed iron end can: The sum of weld misalignment and tailing shall not exceed 0.5mm. Sealed aluminum cans: the sum of weld misalignment and
fishtail shall not exceed 0.2 mm.
5.2.2.4 The welding seam of the straight-wall can shall be able to be torn off in its entirety; there shall be no delamination or fracture.
5.2.2.5 There shall be no delamination or fracture in the deformed part of the weld.
5.2.3 Quality of stripe
5.2.3.1 The stripe of weld shall be smooth and uniform, which completely covers the weld and the uncoated part. There shall be no large blisters, browning, exposed tinplate points. The liquid stripe shall not have splash points. After the test, the inner wall of the can body and can cover shall be free of corrosion. The inner coating shall be free of whitening, peeling off, shedding, blistering. The outer coating shall be free from loss of gloss, peeling off, shedding, or blistering. The printed pattern shall not be significantly faded. 5.2.7.3 Acid resistance
After the test, the inner wall of the can body and can cover shall be free of corrosion. The inner coating shall be free of whitening, peeling off, shedding, blistering.
5.2.7.4 Sulfur resistance
After the test, the inner wall of the can body and can cover shall be free of iron sulfide and sulfur spots. The inner coating shall be free of whitening, peeling off, shedding, blistering.
5.2.7.5 Salt resistance
After the test, there shall be no intensive corrosion points on the inner wall of the can body and can cover. The inner coating shall be free of whitening, peeling off, shedding, blistering.
Note: According to the characteristics of the content, it puts forward to the resistance to acid, sulfur, salt.
5.2.8 Sealant performance
5.2.8.1 Water resistance of sealant
After being boiled in water, the sealant shall not be curled, sticky, odorous, falling off, etc.
5.2.8.2 Moisture content of sealant
The moisture content is not more than 5%.
5.3 Quality of full can container
5.3.1 Appearance quality
The full can container shall be intact AND free of leaked can, swelled can, dent can, peaking.
5.3.2 Quality of inner wall of can
5.3.2.1 Inner wall of plain tinplate can
There is free from obvious oxidation circle, pitting, abnormally rapid detinning, The reagents used in this test method, unless otherwise specified, refer to analytical grade (AR). If there are special requirements, it needs to be clearly stipulated.
The solution used in this test refers to an aqueous solution, when the solvent is not specified.
7.2.2.1 Reagents
7.2.2.2.1 Copper sulfate (CuSO4·5H2O).
7.2.2.2.2 Hydrochloric acid (36% hydrochloric acid).
7.2.2.2 Preparation of copper sulfate hydrochloric acid solution [20%
(mass fraction) copper sulfate, 10% (volume fraction) hydrochloric acid] Weigh 250 g of copper sulfate (CuSO4·5H2O). Add 875 mL of water. Then add 100 mL of hydrochloric acid to the solution. Mix well. Use water to make its volume reach to 1000 mL.
7.2.3 Test procedure
7.2.3.1 Appearance
Visual test.
7.2.3.2 Curability
Add water to the can, until the liquid level is about 3 mm away from the can opening. Seal it. Put the sample into the cooking container. Determine the heating temperature and time, according to the sterilization process of the content. Take out the sample after heating. Place it in tap water to cool it. Open the can. Pour out the water. Visually inspect the stripe.
7.2.3.3 Integrity of stripe
After the inspection in 7.2.3.2, immerse the empty can's stripe in the copper sulfate hydrochloric acid solution. After 2 minutes, take out the empty can. Use tap water to rinse it clean. After drying it, use a 10X magnifying glass to make visual inspection.
7.2.3.4 Adhesion
Methods as below:
- Test method for powder stripe: As shown in Figure 20, cut the weld stripe, at a distance of 5 mm from the powder stripe. Cut symmetrical triangular small openings, on both sides of the stripe. Fold it back and forth along the 7.4.2.1 Method 1: Decompression test
Wash the container clean. Dry it upside down at 50 °C for 2 h. Fill the dried container with water, to 80% ~ 90% of the volume. Place a plexiglass plate, which has a rubber ring, on the seam of the open end of the can. Keep it sealed. Start the vacuum pump. Hold the cover plate with hand. Control the air
extraction, so that the vacuum meter's reading slowly rises to 0.068 MPa. Keep it for 2 minutes. Carefully observe whether there are air bubbles, at the seam of the can body and the weld. Where continuous air bubbles are generated in the same part, it is judged as a leak. Mark the leaking location.
7.4.2.2 Method 2: Pressure test (arbitration method)
Wash the container clean. Dry it upside down at 50 °C for 2 hours. Immerse the container in the water tank of the pressurized leak detector. Slowly pressurize it to 0.26 MPa. Keep it for 2 minutes. Carefully observe the can body, especially the weld of the seam, to see whether there is air bubble. If air bubbles are continuously generated in the same part, it is judged as a leak. Mark the leaking location. The test pressure of pasteurized samples can be 0.068 MPa.
Note: This tightness test does not apply to easy peelable end.
7.5 Performance of internal and external coating
7.5.1 Instruments and equipment
Pressure steam sterilizer, enamel rate value tester.
7.5.2 Reagents and solutions
7.5.2.1 Citric acid (C6H8O7·H2O).
7.5.2.2 L-cysteine hydrochloride (0.5 g/L).
7.5.2.3 Potassium dihydrogen phosphate (3.6 g/L).
7.5.2.4 Disodium hydrogen phosphate (7.2 g/L).
7.5.2.5 Sodium chloride (3% mass fraction).
7.5.2.6 Sodium sulfate (2% mass fraction).
7.5.3 Test procedure
7.5.3.1 Enamel rate value
After simulating the sterilization of the empty can at 121 °C/30 min, add 2% (mass fraction) sodium sulfate solution in the can (weigh 20 g of sodium sulfate; use water to dissolve and dilute it to 1000 mL). The liquid level is 3 mm away from the can opening. Use 6.3V enamel rate value tester. Connect the can body to the positive electrode. Connect the inserted stainless steel rod to the negative electrode. Read the current value of the coating defect at the 4th second. 7.5.3.2 Curability test of internal and external coating
Put the whole can or whole cover into a high-pressure sterilizer. Add distilled water to immerse the specimen and seal it. Determine the sterilization
temperature and time, according to the sterilization process of the content. Take it out after the test. Cool it in cold water. Visually inspect it after drying. 7.5.3.3 Acid resistance
Add the 2% (mass fraction) citric acid solution [weigh 20 g of citric acid monohydrate (C6H8O7 • H2O); use water to dissolve and dilute it to 1000 mL], into an empty can, until it is about 3 mm away from the liquid surface. Seal it. Place the can cover in an inert container. Add the solution. Seal it. Determine the heating temperature and time, according to the sterilization process of the content. Take it out after the test. Cool it in tap water. Open the can and rinse it with water. Visually inspect it after drying.
7.5.3.4 Sulfur resistance
Mixed solution of L-cysteine hydrochloride (0.5 g/L), potassium dihydrogen phosphate (3.6 g/L), disodium hydrogen phosphate (7.2 g/L):
Weigh 0.50 g of L-cysteine hydrochloride (C3H8NO2SCl), or 0.56 g of L-cysteine hydrochloride monohydrate (C3H8NO2SCl • H2O), 3.6 g of potassium
dihydrogen phosphate dodecahydrate (KH2PO4 • 12H2O), 7.2 g of disodium
hydrogen phosphate dodecahydrate (Na2HPO4 • 12H2O). Use water to dissolve them respectively. Mix and dilute it to 1000 mL. The mixed solution shall be used within 4 h after preparation.
Add the solution to the empty can, to about 3 mm away from the liquid surface. Seal it. Place the can cover in an inert container. Add the solution and seal it. Determine the heating temperature and time, according to the sterilization process of content. Take out the container after the test. Place it in tap water to cool it. Open the can and rinse with clean water. Visually inspect it after drying. 7.5.3.5 Salt resistance
Add 3% (mass fraction) sodium chloride solution (weigh 30 g of sodium chloride; make its volume reach to 1000 mL; shake well), into an empty can, to about 3 mm from the liquid surface. Seal it. Place the can cover in an inert container. Add the solution and seal it. Determine the sterilization temperature and time, according to the sterilization process of content. Take out the container after the test. Place it in cold water to cool it. Open the can and rinse with clean water. Visually inspect it after drying.
7.6 Sealant performance
7.6.1 Instruments and equipment
Analytical balance: The accuracy is 0.001 g.
7.6.2 Test procedure
7.6.2.1 Water resistance of sealant
Put the sample cover into a glass container, which is filled with water. The water level is about 50 mm above the sample cover. Put the glass container into the pressure cooker. After boiling at 100 °C for 20 min, take out the sample cover. Observe the sealant performance.
7.6.2.2 Moisture content of sealant
Take the sealant off the scale. Record the mass as m1. Put it in an oven at 125 °C for 30 min, to make it reach to constant weight. Record the mass, after taking out, as m2. The moisture content of the sealant is calculated according to formula (5):
Where:
W - The moisture content of the sealant, %;
m1 - The mass of the sealant before drying;
m2 - The mass of the sealant after baking at 125 °C for 30 minutes.
8 Inspection rules
8.1 The inspection shall be carried out according to the batch or group of goods. The product of the same specification delivered at one time is a batch. The same batch of products can be divided in several batch groups, after negotiation between the two parties; however, the product groups shall be packages of integer multiples.
8.2 Product inspection includes exit-factory inspection and type inspection items.

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