GB/T 8162-2018Seamless Steel Tubes for Structural Purpose (English PDF)

4.1 Outside Diameter and Wall Thickness

Steel tube’s nominal outside diameter (D) and nominal wall thickness (S) shall comply with the provisions of GB/T 17395. According to the requirements of the requester, after the negotiation of both supply-demand parties, steel tubes in other outside diameters and wall thickness can be supplied.

4.2.1 Allowable deviation of steel tube’s outside diameter shall comply with the requirements of Unit: mm Type of Steel Tube Allowable Deviation Hot Rolled (Expanding) Steel Tube ±1%D OR ±0.5; Take the larger one Cold Drawn (Rolled) Steel Tube ±0.75%D OR ±0.3; Take the larger one

4.2.2 Allowable deviation of hot rolled (expanding) steel tube’s wall thickness shall comply with the requirements of Table 2.

4.2.3 Allowable deviation of cold drawn (rolled) steel tube’s wall thickness shall comply with the requirements of Table 3.

4.2.4 According to the requirements of the requester, which shall be indicated in the contract, deviation is outside the scope of the dimension in Table 1, Table 2 and Table 3, it can be supplied.

4.3 Length

4.3.1 Usual Length

Usual length of steel tube is 3000mm~12000mm. According to the requirements of the requester, after the negotiation of both supply-demand parties, for the steel tube which is

outside the scope of usual length, it can be supplied.

4.3.2 Range Length

According to the requirements of the requester, which shall be indicated in the contract, after the negotiation of both supply-demand parties, steel tubes can be delivered according to range length.

4.5 Out-of-roundness and Uneven Wall Thickness

According to the requirements of the requester, which shall be indicated in the contract, after the negotiation of both supply-demand parties, steel tube’s out-of-roundness and uneven wall thickness shall respectively not exceed 80% of the nominal outside diameter’s tolerance and nominal wall thickness’s tolerance. […]

4.6 Shape of End

4.6.1 For the steel tube whose nominal outside diameter is not more than 60 mm, tube end’s cut-oblique shall not exceed 1.5mm; for the steel tube whose nominal outside diameter is greater than 60mm, tube end’s cut-oblique shall not exceed 2.5% of tube end’s outside’s diameter, however, its maximum value shall not exceed 6mm. Steel tube’s cut-oblique is shown Chinastandards.org Cut-oblique in Figure 1.

4.6.2 Burrs on steel tube’s end notch shall be removed.

4.7 Weight

4.7.1 Steel tubes shall be delivered according to the actual weight and can also be delivered according to the theoretical weight. Steel tube’s theoretical weight shall be calculated according 4.7. […]

5.1 Steel’s Designation and Chemical Composition

structural steel shall comply with the provisions of GB/T 699. structural steel shall comply with the requirements of Table 5. Except that the quality grade is A, carbon equivalent of each designation shall comply with the requirements of Table 6. Carbon equivalent (CEV) shall be calculated, based on smelting analysis component, according to formula (1). 5.1.3 Designation and chemical composition (smelting analysis) of alloy structural steel shall comply with the provisions of GB/T 3077. 5.1.4 According to the requirements of the requester, after the negotiation of both supply- demand parties, for the steel which has other designation and chemical composition, it can be supplied. 5.1.5 When the requester requests to conduct the finished-product analysis, it shall be indicated with the provisions of GB/T 222. a Except for the designation - Q345A and Q345B, steel shall at least contain one of the refined grain elements - Al, Nb, V and Ti. […]

5.2 Manufacturing Methods

5.2.1 Smelting Method for Steel

Steel shall be smelted by the method of electric arc furnace plus external-furnace-refining or oxygen converter plus external-furnace-refining. […]

5.2.3 Manufacturing Method for Steel Tube

Steel tube shall be manufactured by a hot rolled (expanding) or cold drawn (rolled) seamless method. When the requester specifies a certain manufacturing method for steel tube, it shall be indicated in the contract.

5.3 Delivery Status

5.3.1 Hot rolled (expanding) steel tubes shall be delivered in hot-rolled (expanding) or heat treatment status. When the requester specifies the delivery status of heat treatment status, it shall be indicated in the contract.

5.3.2 Cold drawn (rolled) steel tubes shall be delivered by annealing or high-temperature tempering. According to the requirements of the requester, which shall be indicated in the contract, after the negotiation of both supply-demand parties, cold drawn (rolled) steel tube can also be delivered by cold drawn (rolled) or other heat treatment status.

5.4 Mechanical Properties

5.4.2 Hardness

tempering status and whose wall thickness is not less than 5mm, its Brinell hardness shall comply with the requirements of Table 8.

5.4.3 Impact

5.4.3.1 For low-alloy high-strength structural steel tube, when its outside diameter is not less than 70mm and the wall thickness is not less than 6.5mm, longitudinal impact test shall be carried out. Its test temperature and impact energy of the Charpy V-notch impact test shall comply with the provisions of Table 7. For absorbed energy of impact, it shall be calculated by the arithmetic mean of the three samples from one group. […]

5.5 Process Performance

7.2 Rules of Lot Grouping

7.2.1 Steel tube shall be inspected and accepted in batch.

7.2.2 After being cut into single piece, if the steel tube is not performed with heat treatment anymore, for all tube sections which are taken from steel tubes rolled from the same tube blank, they shall be deemed as the same one.

7.2.3 For each batch, it shall be composed of the steel tube which has the same designation, same furnace number, same specification AND same heat treatment system (furnace No.).

Quantity of each batch’s steel tubes shall not exceed the following provisions:

d) For the quantity of the remaining steel tubes, when it is not less than 50% of the above specified quantity, these steel tubes shall be separately listed as one batch; when the quantity is less than 50% of the above specified quantity, these steel tubes shall be merged into the adjacent batch of steel tube which has the same designation, same furnace number AND same specification.

7.3 Quantity of Samplings

For sampling quantity for all tests of each batch’s steel tube, it shall comply with the provisions

7.4 Re-examination and Judgment Rules

Re-inspection and judgment rules of steel tubes shall comply with the provisions of GB/T 2102.

A.1 Range

This Appendix specifies the technical requirements for hot-dip galvanized coatings of seamless steel tubes for structural purpose.

A.4 Weight of Galvanized Coatings

A.4.1 For the tube, after hot-dip galvanization, weight of zinc-coating shall be measured. The measurement method shall comply with the provisions of A.5. Total weight per unit area of steel tube’s inner & outer surface’s galvanized coatings shall not be less than 300g/m2.

A.4.2 According to the requirements of the requester, which shall be indicated in the contract, & outer surface’s galvanized coatings’ total weight per unit area is not less than 500g/m2, it can be supplied. When the delivery is made according to that total weight per unit area of the galvanized coating is 500 g/m2, for the inner & outer surface of 1 sample therein, total weight per unit area of galvanized coating is allowed to be less than 500g/m2, however it shall not be Chinastandards.org

A.5.1 Preparation of Samples

After galvanization, steel tube’s galvanized coatings weight shall be measure. Take 2 steel pipes from each batch at random; take one 30mm~60mm (depending on specifications) tube section on each end of each steel tube; treat them as samples. […]

A.5.2 Preparation of Test Solution

Dissolve 32g of antimony trichloride (SbCl3) OR 20g of antimony trioxide (Sb2O3) in 1000mL of hydrochloric acid whose density is over 1.18kg/dm3 or more; prepare it as the stock solution.

Before the test, add 5mL of the stock solution into 100mL of hydrochloric acid whose density is over 1.18kg/dm3 or more; treat it as the test solution.

A.5.3 Test Procedure

A.5.3.1 Use balance to weigh sample’s weight by AND round off it to the nearest one - 0.01g.

level shall be higher than the sample. During the measurement, temperature of the solution shall not be higher than 38 °C.

coatings has disappeared, take out the sample. Use water to rinse the sample; use cotton or clean cloth to dry it. After it is completely dried, it shall be weighed on the balance AND round off it to the nearest one - 0.01g.

A.5.3.4 After sample’s zinc coatings is peeled off, on two mutually perpendicular directions at the end of the sample, outside diameter and inner diameter shall be measured. Respectively take their average values; treat them as the actual outside diameter and inner diameter; round off it to the nearest one - 0.01mm.

A.5.3.5 In the case where the zinc coatings can be easily removed, test solution can be reusable.

A.10 Inspection Before Galvanization