NB/T 47019.1-2011Purchase technical specification for boiler and heat exchanger tubes/pipes - Part 1: General requirements (English PDF)

1.1

This part of NB/T 47019 specifies such purchase technical specifications as the tube size, shape, mass, technical requirements, inspection and test rules, quality certificates, and so on, AND defines the duties, rights and obligations of the relevant parties.

1.2

This part applies to the carbon steel, alloy steel, stainless steel, low temperature steel tube, and non-ferrous metal tube used for boilers, heat exchangers and other equipment.

1.3

Tubes for fluid delivery may refer to the requirements of this standard.

3.1 Seller (supplier)

It refers to the organization that provides the products and services complying with the requirements of this part, including manufacturers and suppliers.

3.2 Manufacturing company

It refers to the factory organization which manufactures the product complying with the requirements of this part, AND provides the products and services to the buyer (purchaser).

3.3 Supplier

It refers to the organization which provides the products and services produced by the manufacturing company AND complying with the requirements of this part to the buyer.

3.4 Buyer (purchaser)

It refers to the factory organization which purchases the products and services complying with the requirements of this part, AND uses them for the part & component manufacturing for boiler and heat exchanger.

4.1

It can, based on the manufacturing methods, be divided into the following categories:

a) Hot-rolled (extruded) tube;

b) Thermal expansion tube;

c) Forged boring tube:

d) Cold drawn (rolled) tube;

e) Welded tube;

f) Welded-rolled tube.

4.2

It can, based on the material types, be divided into the following categories:

6.1 Allowable deviation of outer diameter

When the tube is delivered based on the nominal outer diameter D, the allowable deviation of outer diameter shall comply with the requirements of

Table 1. If the allowable deviation level of the outer diameter of the tube is not specified, the allowable deviation of the outer diameter of the tube shall be as specified in the general level.

6.4.2

Along any cross section, the wall thickness unevenness shall be as below:

cold drawn tube does not exceed 16%; hot-rolled (extruded) tube does not exceed 18%.

6.5 Allowable length deviation

6.5.1

The supply length L of the tube is normally 3000 mm - 12000 mm.

However, if agreed between the seller and buyer, the tube of other lengths or fixed lengths can be supplied.

6.5.2

When the tube is to be supplied in fixed length or multiple length, the allowable length deviation is specified as follows:

a) D <= 57 mm:

L <= 6000 mm, the deviation is 0 mm ~ 4 mm;

6000 mm < L <= 9000 mm, the deviation is 0 mm ~ 6 mm;

If the length L exceeds 9000 mm, then ADD another 3 mm deviation for each 3000 mm or its remainder, BUT the maximum deviation will not exceed 13 mm.

b) 57 mm < D <= 159 mm:

L <= 6000 mm, the deviation is 0 mm ~ 10 mm;

6000 mm < L <= 9000 mm, the deviation is 0 mm ~ 15 mm;

L > 9000 mm, the deviation is 0 mm ~ 20 mm;

c) D > 159 mm, the deviation is 0 mm ~ 30 mm.

6.5.3

When the tube is to be supplied in fixed length or in multiple length, the length of each multiple length shall be reserved with the notch allowance as specified below:

c) D <= 159 mm, the deviation is 5 mm ~ 10 mm;

c) D > 159 mm, the notch allowance is 10 mm ~ 15 mm.

6.6 Out of roundness

6.6.1

The out of roundness of the tube shall not exceed 80% of the nominal outer diameter tolerance.

6.6.2

As for the thin wall tube for which the outer diameter D <= 50 mm, wall thickness S <= 2% D OR the outer diameter D > 50 mm and wall thickness S <= […]

6.9 Welded tube weld reinforcement

6.9.1

The outside weld reinforcement shall be removed to be level with the base

metal.

6.9.2

The inside weld reinforcement shall be removed through mechanical method. As for the welded tube for which the outer diameter D <= 38 mm, the maximum reinforcement of any point within the tube shall not exceed 0.15 mm;

as for the welded tube for which the outer diameter D > 38 mm, the maximum reinforcement of any point within the tube shall not exceed 0.25 mm

6.10 Mass

The tube can be supplied based on actual mass; however, if agreed between the buyer and seller AND noted in the contract, the tube can also be supplied based on theoretical mass.

6.11

The size, shape, and allowable deviation of the non-ferrous metal tube shall comply with the requirements of relevant parts of this standard.

7.1 Manufacturing methods

7.1.1 Smelting

The smelting of tube materials shall comply with the relevant parts of this standard.

7.1.2 Manufacturing methods of tube billet

The tube billet can be manufactured through molding, continuous casting, or hot rolling (forging).

7.1.3 Tube manufacturing methods

Steel tube can be manufactured through hot rolling (extrusion, thermal expansion), forged boring, cold rolling (drawing), welding, and so on. If the steel […]

7.4.1.1 Ductility test

PRESS the sample to the extent that the spacing between the two plates is H, which is calculated in accordance with the equation (2):

Where:

H - Spacing between the two plates, in the unit of mm;

S - Tube wall thickness, in the unit of mm;

D - Tube nominal outer diameter or calculated diameter, in the unit of mm;

a - Deformation coefficient of unit length, which is:

0.08 for high quality carbon structural steel and alloy structural steel;

0.09 for austenitic stainless steel;

0.07 for ferrite/austenitic duplex stainless steel;

When the S/D > 0.1, it can be reduced by 0.01 for high quality carbon structural steel and alloy structural steel.

7.4.1.2 Integrity test (closed flattening)

The flattening is continued until the sample breaks or the opposite two walls of the sample tube contact.

7.4.1.3

The following conditions shall not be used as the basis for determining whether the flattening test is satisfactory or not:

a) The cracks without metallic luster due to the sample surface defects;

b) When the S/D > 0.1, the cracks at the internal surfaces of the sample at 6 o'clock (bottom) and 12 o'clock (top) positions.

7.4.2 Flaring test

The tube flaring test shall be conducted at room temperature, with the sample length of more than 50 mm AND the top core taper of 60°. After flaring, the outer diameter flaring rate of the sample shall comply with the provisions of Table 5.

7.7 Non-destructive test

7.7.1

All non-destructive tests shall be conducted by qualified personnel.

7.7.2

Non-destructive test can be in the form of ultrasonic detection, eddy

current detection and magnetic flux leakage test. BUT the test methods shall comply with the relevant parts of this standard.

7.7.3

The manufacturer shall determine the length of the NDT blind spot at the tube end which cannot be tested. When specified in the contract, the manufacturer shall use artificial methods or other mechanical removal methods to remove the NDT blind spot, OR otherwise inform the buyer of the length of the blind spot.

7.8 Low magnification test

The low magnification test of the tube shall be in accordance with the relevant part of this standard.

7.9 Metallographic examination

The metallographic examination includes the inspection of non-metallic inclusions, decarburization layer, grain size, microstructure, and so on, which shall be conducted in accordance with the relevant parts of this standard.

7.10 Corrosion test

The corrosion test of the tube shall be conducted in accordance with the relevant parts of this standard.

7.11 Surface quality

7.11.1

The inner and outer surfaces of the tube shall, under sufficient lighting conditions, be visually inspected one by one for satisfactory surface quality.

7.11.2

The tube shall have a good surface quality, AND shall comply with the relevant parts of this standard.

7.11.3

It shall not be less than the minimum value as allowed by this standard.

7.11.4

It is not allowed for the defects in the base metal of the tube to be repaired by welding.

7.12 Dimensional inspection

7.12.1

The dimensions and straightness of the tube shall be measured one by one by the gauge which complies with the accuracy requirements.

7.12.2

The diameter of the tube shall be measured at any point on the tube; if the outer diameter of the tube exceeds 406.4 mm, it is allowed to use a tape to measure the outer diameter along the tube circumference.

7.12.3

The wall thickness of the tube shall be measured at any point on the tube.

7.12.4

The height of welds in welded tubes shall be measured on the flattened samples.

7.13 Material identification

USE appropriate method to conduct inspection and identification of the alloy steel tube, in order to ensure that the material is correct.

8.1 Inspection and test

The manufacturer shall, in accordance with the inspection and test scope as specified in relevant parts of this standard, conduct the exit-factory inspection and test of the tube, AND in the quality certificate, write the inspection and test results and data. The inspection and test are to be conducted by the manufacturer's quality supervision department.

8.2 Batching rules

The chemical composition of the steel tube is tested based on the furnace; the non-ferrous metal tube is tested based on the ingot; AND the other inspection and test items of the tube are conducted in batches. The batching rules of the tubes shall be in accordance with the relevant parts of this standard.

8.3 Sampling method and quantity

The sampling method and quantity for the tube inspection and test shall comply with the relevant parts of this standard.

8.4 Re-inspection and judgment rules

The purchaser may inspect and test every tube received, AND the re-inspection and judgment rules shall be as specified in the relevant parts of this standard.