GB/T 5310-2023Seamless steel tubes and pipes for high pressure boiler (English PDF)

6.1 Outside diameter and wall thickness

6.1.1 Unless otherwise specified in the contract, steel tubes and pipes shall be delivered according to the nominal outside diameter and the nominal wall thickness. According to the requirements of the buyer and through negotiation between the supplier and the buyer, steel tubes and pipes can be delivered according to the nominal outside diameter and minimum wall thickness, nominal inside diameter and nominal wall thickness, or other size specifications.

6.1.2 The nominal outside diameter and wall thickness of steel tubes and pipes shall comply with the provisions of GB/T 17395. As required by the buyer, and negotiated between the supplier and the buyer, steel tubes and pipes with dimensions other than those specified in GB/T 17395 can be supplied. When steels tubes and pipes are delivered according to the nominal inside diameter and nominal wall thickness, the size specifications shall be determined by negotiation between the supplier and the buyer.

6.1.3 When steel tubes and pipes are delivered according to the nominal outside diameter and nominal wall thickness, the allowable deviations of the nominal outside diameter and nominal wall thickness shall comply with the provisions of Table 1.

6.1.4 When steel tubes and pipes are delivered according to the nominal outside diameter and minimum wall thickness, the allowable deviation of the nominal outside diameter shall comply with the provisions of Table 1, and the allowable deviation of the wall thickness shall comply with the provisions of Table 2.

6.1.5 When steel tubes and pipes are delivered according to the nominal inside diameter and nominal wall thickness, the allowable deviation of the nominal inside diameter of hot-expanded steel tubes and pipes is ±0.75%d, and the allowable deviation of the nominal inside diameter of the other steel tubes and pipes is ±1%d. The allowable deviation of the nominal wall thickness shall comply with the provisions of Table 1.

6.1.6 Where the buyer does not indicate the allowable deviation level of the size of steel tubes and pipes in the contract, the allowable deviation of the outside diameter and wall thickness of steel tubes and pipes shall comply with the requirements for the ordinary grade. According to the requirements of the buyer, as negotiated between the supplier and the buyer, and indicated in the contract, steel tubes and pipes with allowable deviations in dimensions other than those specified in Table 1 and Table 2, or steel tubes and pipes of other allowable deviations in inside diameter, can be supplied.

6.2 Length

6.2.1 Normal length

6.2.1.1 The random length of the steel tubes and pipes is 4 000 mm ~ 12 000 mm.

6.2.1.2 As negotiated between the supplier and the buyer, and indicated in the contract, steel tubes and pipes with a length of more than 12 000 mm or less than 4 000 mm but not less than 3 000 mm can be delivered; the number of steel tubes and pipes with a length less than 4 000 mm but not less than 3 000 mm shall not exceed 5% of the total quantity of this batch delivered.

6.2.2 Specific length and multiple length

6.3 Curvature

6.3.1 The curvature per meter of steel tubes and pipes shall comply with the following regulations.

a) When S<=15 mm, not greater than 1.5 mm/m;

b) When 15 mm < S <= 30 mm, not greater than 2.0 mm/m;

c) When S >30 mm, not greater than 3.0 mm/m.

6.3.2 For steel tubes and pipes with D >=127 mm, the curvature in total length shall not be greater than 0.10% of the length of the steel pipe.

6.3.3 According to the requirements of the buyer, if it is negotiated between the buyer and the supplier AND indicated in the contract, other provisions may be imposed for the curvature per meter and the curvature in total length of the steel pipe.

6.4 Out-of-roundness and unevenness in wall thickness

As required by the buyer, after it is negotiated between the supplier and the buyer AND indicated in the contract, the out-of-roundness and wall unevenness of steel tubes and pipes shall not exceed 80% of the outside diameter (inside diameter) and wall thickness tolerance, respectively.

6.5 End shape

The end faces of the steel tube shall be perpendicular to the axis of the steel tube; the burrs of the cut shall be removed.

6.6 Weight

6.6.1 Delivery weight

6.6.1.1 When steel tubes and pipes are delivered according to the nominal outside diameter and nominal wall thickness or the nominal inside diameter and nominal wall thickness, steel tubes and pipes can be delivered according to the actual weight or the theoretical weight.

6.6.1.2 When steel tubes pipes are delivered according to the nominal outside diameter and minimum wall thickness, steel tubes and pipes shall be delivered according to the actual weight; as negotiated between the supplier and the buyer, AND indicated in the contract, steel tubes and pipes can also be delivered according to the theoretical weight.

7.1 Steel designation and chemical composition

7.1.1 The steel designation and chemical composition (smelting composition) shall comply with the requirements in Table 1. Refer to Appendix B for comparison of designations in relevant domestic and foreign standards.

7.1.2 The residual element (smelting component) content in steel shall comply with the requirements in Table 5.

7.1.3 The chemical composition of finished steel tubes and pipes of 10Cr9Mo1VNbN (A31108), 08Cr9W3Co3VNbCuBN (A32088), and 07Cr23Ni15Cu4NbN (S30989) shall comply with the provisions of Table 4. The allowable deviation of chemical composition of finished steel tubes and pipes of other designations shall comply with the provisions of Table 6. The relevant terms, definitions and determination methods of chemical composition of finished products shall comply with the provisions of GB/T 222.

7.2 Manufacturing method

7.2.1 Smelting method of steels

7.2.1.1 Quality carbon steel and alloy steel shall be treated by using electric arc furnace plus out-of-furnace refining and vacuum refining, or oxygen converter plus out-of-furnace refining and vacuum refining, or electroslag remelting method.

7.2.1.2 Stainless (heat-resistant) steel shall be smelted by using electric arc furnace plus out-of-furnace refining, or converter plus out-of-furnace refining, or electroslag remelting method.

7.2.1.3 Other smelting methods with higher requirements may be adopted after negotiation between the supplier and the buyer and as indicated in the contract. When the buyer specifies a certain smelting method, it shall be stated in the contract.

7.2.2 Manufacturing methods and requirements for tube blanks

7.2.2.1 Tube blanks can be manufactured by continuous casting, die casting or hot rolling (forging).

7.2.2.2 Continuously cast tube blanks shall comply with the provisions of YB/T 4149, in which the grades of low-magnification structural defects such as central cracks, middle cracks, subcutaneous cracks and subcutaneous bubbles shall not be greater than grade 1 respectively, or shall comply with other higher quality requirements approved by relevant parties; hot-rolled (forged) tube blanks shall comply with the requirements of YB/T 5137; die-cast tube blanks (steel ingots) can be implemented with reference to the regulations for hot-rolled (forged) tube blanks.

7.2.3 Manufacturing method of steel tubes

7.2.3.1 Steel tubes and pipes of the designation 08Cr18Ni11NbFG shall be manufactured by cold-drawn (rolled) seamless methods, and other steel tubes and pipes shall be manufactured by hot-rolled (extruded, expanded) or cold-drawn (rolled) seamless methods.

7.2.3.2 For steel tubes and pipes directly rolled from continuous cast or die-cast steel billets, the total elongation coefficient of processing deformation shall not be less than 3.0. For steel tubes and pipes directly rolled by electroslag ingots, the total elongation coefficient of processing deformation shall not be less than 2.0.

7.3 Delivery state

7.3.1 Quality carbon steel and alloy steel tubes and pipes shall be delivered in a heat-treated state.

7.3.2 Stainless (heat-resistant) steel tubes and pipes shall be delivered in a heat-treated, pickled and passivated state. All steel tubes and pipes that have been wholly ground, bored or heat-treated in protective atmosphere can be delivered without pickling.

8.1 Tensile test sample

8.1.1 For steel tubes and pipes with D < 219 mm, the tensile test shall be conducted along the longitudinal direction of the steel pipe.

8.1.2 For steel tubes and pipes with D >= 219 mm, when the size of the steel pipe allows, a circular cross-section sample with a diameter of 10 mm shall be taken transversely along the steel pipe for the tensile test; when the size of the steel pipe is not sufficient to intercept a 10 mm sample, use the larger possible transverse circular cross-section sample with a diameter of 8 mm or 5 mm; when the size of the steel pipe is not sufficient to cut a 5 mm circular cross-section sample, samples shall be taken along the longitudinal direction of the steel pipe for the tensile test. Transverse circular cross-section test pieces shall be taken from un-flattened samples.

8.2 Impact test sample

For the impact test, priority shall be given to intercepting the sample along the transverse direction of the steel pipe. When the transverse sample cannot be intercepted, the sample shall be intercepted along the longitudinal direction of the steel pipe.

Regardless of whether it is cut transversely or longitudinally along the steel pipe, the impact test sample shall be a standard size sample with a thickness of 7.5 mm or a thickness of 5 mm, whichever is possibly larger.

8.3 Bending test sample

8.3.1 Sample preparation

The sample for the bending test shall be taken transversely along one end of the steel pipe, and the preparation of the sample shall comply with the provisions of GB/T 232.

When the sample is taken, the forward bending sample shall be as close as possible to the outer surface, and the reverse bending sample shall be as close as possible to the inner surface. There shall be no obvious scars and other defects on the surface of the sample under bending and tension deformation.

8.3.2 Sample size

The cross-sectional size of the sample after processing is 12.5 mm × 12.5 mm or 25 mm × 12.5 mm (width × thickness); the four corners on the cross section shall be processed into rounded corners, and the radius of the rounded corners shall not be greater than 1.6 mm; the length of the sample shall not be greater than 150 mm.