GB/T 8163-2018Seamless steel pipes for liquid service (English PDF)

4.2 Allowable deviation of outer diameter and wall thickness

4.2.1 The allowable deviation of the outer diameter of the steel pipe shall comply with the requirements of Table 1.

4.3 Length

4.3.1 Normal length The normal length of steel pipe is 3000mm~12000mm. According to the requirements of the purchaser, the steel pipe outside the normal length can be supplied through negotiation between the supplier and the purchaser.

4.3.2 Range length According to the requirements of the purchaser, after negotiation between the supplier and the purchaser, and indicated in the contract, the steel pipe can be delivered according to the range length.

4.3.3 Fixed length and multiple length

4.3.3.1 According to the requirements of the purchaser, after negotiation between the supplier and the purchaser, and indicated in the contract, the steel pipe can be delivered according to a fixed length or multiple length.

4.3.3.2 When the steel pipe is delivered in a fixed length or multiple length, the length tolerance shall comply with the following provisions.

4.3.3.3 After negotiated between the supplier and the purchaser, other steel pipes with other allowable deviation of the length can be supplied.

4.4 Curvature

4.4.1 The curvature per meter of steel pipe shall comply with the requirements of Table 4.

4.4.2 The full-length curvature of the steel pipe shall not exceed 0.15% of the total length of the steel pipe.

4.5 Un-roundness and uneven wall thickness According to the requirements of the purchaser, the supplier and the purchaser shall negotiate and indicate in the contract that the un-roundness and wall thickness of the steel pipe shall not exceed 80% of the nominal outer diameter tolerance and the nominal wall thickness tolerance respectively.

4.7 Weight

4.7.1 Steel pipes are delivered either according to actual weight or according to theoretical weight. The theoretical weight of steel pipe is calculated according to the provisions of GB/T 17395,

4.7.2 According to the requirements of the purchaser, the supplier and the purchaser shall negotiate and indicate in the contract that the allowable deviation of the actual weight of the delivered steel pipe from the theoretical weight shall comply with the following provisions.

5.1 Steel designation and chemical composition

5.1.1 The steel pipe is made of steels with designations of 10, 20, Q345, Q390, Q420 and Q460.

5.1.2 The chemical composition (melting analysis) of steels with designations of 10 and 20 shall comply with the requirements of Table 5.

5.1.3 The chemical composition (melting analysis) and carbon equivalent of the steels with designations of Q345, Q390, Q420 and Q460 shall comply with the requirements of Table

6.According to the requirements of the purchaser, steel pipes of other designations or chemical compositions may be supplied through negotiation between the supplier and the purchaser.

5.1.4 When the purchaser requests to do the finished product analysis, it shall be indicated in the contract. The chemical composition allowable deviation of the finished steel pipe shall comply with the provisions of GB/T 222.

5.2 Manufacturing method

5.2.1 Steel smelting method Steel shall be smelted by electric arc furnace plus furnace refining or oxygen converter plus furnace refining method. After negotiation between the supplier and the purchaser, other methods of higher requirements may also be used for smelting. When the purchaser specifies a certain smelting method, it shall be indicated in the contract.

5.3 Delivery status

5.3.1 Hot rolled (expanded) steel pipes can be delivered in hot rolled (expanded) or heat treated condition. When the purchaser requests the heat treatment status, it shall be indicated in the contract.

5.3.2 Cold drawn (rolled) steel pipes shall be delivered in an annealed or high temperature tempered condition.

5.4 Mechanical properties

5.4.1 Tensile properties The longitudinal tensile properties of the steel pipe in the delivery status shall comply with the requirements of Table 7.

5.4.2 Impact

5.4.2.1 The quality grades for steel pipes with designations of Q345, Q390, Q420, Q460 are B, C, D, E.

5.4.2.2 The impact absorption energy in Table 7 is the Charpy V-notch impact absorption energy requirement value of the standard size sample. When the size of the steel pipe cannot prepare a standard size sample, a small size sample can be prepared. When using small-sized impact sample, the minimum Charpy V-notch impact energy requirements shall be the standard-size sample impact energy requirements multiplied by the decreasing factor in Table

8.The size of the impact sample shall be preferentially selected to a larger size.

5.5 Process performance

5.5.1 Flattening For 10, 20, Q345, Q390 designations of steel pipes with an outer diameter greater than 22mm~600mm and a wall thickness to outer diameter ratio of not more than 10%, the flattening test shall be carried out. Flattening test plate spacing H is calculated according to formula (1).

5.5.2 Flaring According to the requirements of the purchaser, the supplier and the purchaser shall negotiate and indicate in the contract that 10, 20 and Q345 designations of steel pipes with an outer diameter of not more than 76 mm and a wall thickness of not more than 8 mm may be subject to the flaring test.

5.5.3 Bending According to the requirements of the purchaser, after negotiation between the supplier and the purchaser, and indicated in the contract, the steel pipe with an outer diameter of not more than 22mm can be bent.

5.6 Hydraulic pressure

5.6.1 Steel pipes shall be hydraulically tested one by one. The test pressure is calculated according to formula (2). The maximum test pressure does not exceed 19.0MPa. Under the test pressure, the voltage regulation time shall be no less than 5s, and the steel pipe shall not leak.

5.7 Surface quality The inner and outer surfaces of steel pipes shall be free from visible cracks, folds, crusting, rolling and separation. These defects shall be completely removed. The depth of removal shall not exceed the lower deviation of the nominal wall thickness.

5.8 Ultrasonic testing According to the requirements of the purchaser, after negotiation between the supplier and the purchaser, and indicated in the contract, the steel pipe can be ultrasonically tested, and the acceptance level is L4 in GB/T 5777-2008.

5.9 Galvanized layer According to the requirements of the purchaser, after negotiation between the supplier and the purchaser, and indicated in the contract, the steel pipe can be galvanized for delivery.

7.2 Batching rules

7.2.1 Steel pipes shall be inspected and accepted in batches.

7.2.2 If the steel pipe is not heat treated after being cut into individual pieces, all pipe sections taken from the steel pipe rolled by one tube shall be regarded as one.

7.2.3 Each batch shall consist of steel pipes of the same designation, the same heat number, the same specification, and the same heat treatment system (furnace number). The quantity of each batch of steel pipes shall not exceed the following provisions.

7.3 Sampling quantity The sampling quantity of each batch of steel pipe inspection shall comply with the provisions of Table 10.

7.4 Re-inspection and determination rules The re-inspection and determination rules of steel pipes shall comply with the provisions of GB/T 2102.