GB Translated English of Chinese Standard: GB NATIONAL STANDARD OF THE

Transcription

1 Translated English of Chinese Standard: GB GB NATIONAL STANDARD OF THE PEOPLE S REPUBLIC OF CHINA ICS H 48 GB Replacing GB Seamless Steel Tubes for Low and Medium Pressure Boiler 低中压锅炉用无缝钢管 (ISO :1989, NEQ) Issued on: October 24, 2008 Implemented on: October 1, 2009 Issued by: General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ); Standardization Administration (SAC) of the People's Republic of China. Page 1 of 18

2 Table of Contents Foreword Scope Normative References Ordering Information Dimension, Appearance and Weight Technical Requirements Test Methods Inspection Rules Packing, Marking and Quality Certificate Page 2 of 18

3 Foreword This standard is corresponding to ISO :1989 "Seamless Steel Tubes for Pressure Purposes - Technical Delivery Conditions - Part 1: Unalloyed Steels with Specified Room Temperature Properties" (English edition). This standard is not equivalent to ISO :1989. GB Seamless Steel Tubes for Low and Medium Pressure" shall be abolished, from the implementation data of this standard. And there have been some significant changes in this standard over GB in the following aspects: The application scope of steel tubes was modified; The "ordering information" was added; The allowable dimension deviations were modified; The requirements on full length flexibility were added; The requirements on oblique cutting of end socket were added; The marking examples were canceled; The smelting process of steel was modified; Provisions on the delivery condition of steel tubes were modified; Provisions on the specific manufacturing method of hot-extended steel tubes were added; Provisions on the mechanical properties of steel tubes were modified; The judgement rules for Point 6 (bottom) and Point 12 (top) of the flattening test sample of steel tube were added; Requirements on flanging test were canceled; The requirements on replacing hydraulic test with flaw detection were modified. Clauses 4.1, 4.2, 4.3, 4.5, 4.7, 5.1.3, 5.3.1, 5.4.2, and 5.9 in this standard are voluntary, and the rest are compulsory. This standard was proposed by China Iron & Steel Association. This standard shall be under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China. Page 3 of 18

4 Seamless Steel Tubes for Low and Medium Pressure Boiler 1 Scope This standard specifies the ordering information, dimension, appearance, weigh, technical requirements, test methods, inspection rules, packing, marking and quality certificate of the seamless steel tubes for low and medium pressure boilers. This standard is applicable to the seamless steel tubes that are made of quality carbon structural steels and used for manufacturing various low and medium pressure boilers. 2 Normative References The following standards contain provisions which, through reference in this text, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, the parties whose enter into agreement according to this standard are encouraged to research whether the latest editions of these labels are applied or not. For undated references, the latest edition of the normative document is applicable to this standard. GB/T 222 Permissible Tolerances for Chemical Composition of Steel Products GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Diantipyrylmethane Phosphomolybdate Gravimetric Method for the Determination of Phosphorus Content GB/T Steel and Iron - Determination of Acid-soluble Silicon and Total Silicon Content - Reduced Molybdosilicate Spectrophotometric Method GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Cupferron Separation-Chrome Azurol S Photometric Method for the Determination of Aluminium Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Sodium Carbonate Separation-diphenyl Carbazide Photometric Method for the Determination of Chromium Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Page 5 of 18

5 Sodium Thiosulfate Separation Iodimetric Method for the Determination of Copper Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Neocuproine-chloroform Extraction Photometric Method for the Determination of Copper Content GB/T Iron Steel and Alloy - Determination of Nickel Content - The Dimethylglyoxime Spectrophotometric Method GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Indophenal Blue Photometric Methods for the Determination of Nitrogen Content after Distillation Separation GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Sodium Arsenite-sodium Nitrite Titrimetric Method for the Determination of Manganese Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Reduced Molybdoantimonyl Phosphoric Acid Photometric Method for the Determination of Phosphorus Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Perchloric Acid Dehydration Gravimetric Method for the Determination of Silicon Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Ammonium Phosphomolybdate Volumetric Method for the Determination of Phosphorus Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Butyl Acetate Extraction Photometric Method for the Determination of Phosphorus Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Sodium(potassium)periodate Photometric Method for the Determination of Manganese Content GB/T Iron Steel and Alloy- Determination of Manganese Content - Flame Atomic Absorption Spectrometric Method GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Potassium Iodate Titration Method after Combustion in the Pipe Furnace for the Determination of Sulfur Content GB/T Iron Steel and Alloy - Determination of Carbon Contents - Page 6 of 18

6 Gas-volumetric Method after Combustion in the Pipe Furnace GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Gravimetric Method after Combustion in the Pipe Furnace for the Determination of Carbon Content GB/T Iron Steel and Alloy - Determination of Sulfur Content - Gravimetric Method GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Combustion Gravimetric/gas-volumetric Method for the Determination of Combined Carbon Content GB/T 226 Etch Test for Macrostructure and Defect of Steels GB/T 228 Metallic Materials - Tensile Testing at Ambient Temperature (GB/T , eqv ISO 6892:1998) GB/T 241 Metal Materials - Tube - Hydrostatic Pressure Test GB/T 242 Metal Materials - Tube - Drift-expending Test (GB/T , ISO 8493:1998, IDT) GB/T 244 Metallic Materials Tube - Bend Test (GB/T , ISO 8491:1998, IDT) GB/T 246 Metal Materials - Tube - Flattening Test (GB/T , ISO 8492:1998, IDT) GB/T 699 Quality Carbon Structural Steels GB/T 1979 Standard Diagrams for Macrostructure and Defect of Structural Steels GB/T 2102 Acceptance, Packing, Marking and Certification of Pipe GB/T 2975 Steel and Steel Products - Location and Preparation of Test Pieces for Mechanical Testing (GB/T , eqv ISO 377:1997) GB/T 4336 Standard Test Method for Spark Discharge Atomic Emission Spectrometric Analysis of Carbon and Low-alloy Steel (Routine Method) GB/T 4338 Metallic Materials - Tensile Testing at Elevated Temperature (GB/T , ISO 783:1999, MOD) GB/T Seamless Steel Pipe and Tubing Methods for Ultrasonic Testing (ISO 9303:1989(E), MOD) GB/T 7735 Steel Tubes - The Inspection Method on Eddy Current Test (GB/T Page 7 of 18

7 , ISO 9304:1989, MOD) GB/T Steel Tubes - The Testing Method of Magnetic Flux Leakage (GB/T , eqv ISO 9402:1989 and ISO 9598:1989) GB/T Dimensions, Shapes, Masses and Tolerances of Seamless Steel Tubes (GB/T , ISO 1127:1992, ISO 4200:1991 and ISO 5252:1991, MOD) GB/T Steel and Iron - Sampling and Preparation of Samples for the Determination of Chemical Composition (GB/T , ISO 14284:1996, IDT) GB/T Steel and Iron - Determination of Total Carbon and Sulfur Content Infrared Absorption Method after Combustion in an Induction Furnace (Routine Method) (GB/T , ISO 15350:2000, IDT) GB/T Steel and Iron - Determination of Nitrogen Content - Thermal Conductimetric Method after Fusion in a Current of Inert Gas (GB/T , ISO 15351:1999, IDT) 3 Ordering Information The contract or order for purchasing steel tubes according to this standard shall include, but not limited to the following contents: a) Serial number of standard; b) Product name; c) Grade of steel; d) Ordered quantity (total weight or total length); e) Delivery condition; f) Dimension specification; g) Special requirements. 4 Dimension, Appearance and Weight 4.1 Outside diameter and wall thickness The outside diameter (D) and wall thickness (S) of steel tube shall meet those specified in GB/T Page 8 of 18

8 4.3 Length General length The general length of steel tubes is 4000mm~12500mm. Based on the agreement of both the supplier and the purchaser and as noted in the contract, the steel tubes that are longer than 12500mm may be delivered Specified length and multiple length As required by the purchaser and noted in the contract, the steel tubes may be delivered according to specified length or multiple length. The specified length shall be within the range of general length, and the Permissible deviation for the full length shall meet the following requirements: a) 0~10mm if the specified length 6000mm; b) 0~15mm if the specified length >6000mm. The total multiple lengths of the steel tube shall be within the range of the general length, the Permissible deviation for the full length is 20 0 mm, and each multiple length shall be left with notch allowance according to the following requirements: a) The notch allowance is 5mm~10mm if the outside diameter 159mm; b) The notch allowance is 10mm~15mm if the outside diameter >159mm. 4.4 Flexibility The flexibility per meter of the steel tubes shall be in accordance with those specified in Table 4. Table 4 Flexibility per Meter of Steel Tubes Nominal wall thickness of steel tube /mm Flexibility per meter /(mm/m) >15~ >30 or the outside diameter The full length flexibility of the steel tube shall not be larger than 1.5 of its total length and the bent part along the full length shall not be larger than 12mm. 4.5 Out-of-roundness and wall unevenness As required by the purchaser, based on the agreement of both the supplier and the purchaser and also noted in the contract, the out-of-roundness and wall unevenness of steel tubes shall not exceed 80% of the tolerances of outside diameter and wall Page 10 of 18

9 with those specified in GB/T Where the purchaser requires doing product analysis, it shall be indicated in the contract. The permissible deviation for the chemical composition of finished steel tubes shall be in accordance with those specified in GB/T Manufacturing method Smelting process of steel Steels may be smelted by adopting with electric furnace and external refining or oxygen converter and external refining. Other smelting process of higher requirements may be adopted based on the agreement of both the supplier and the purchaser. If purchaser designates a certain smelting process, it shall be indicated in the contract Manufacturing method of tube blank The tube blank shall be manufactured by adopting with continuous casting or hot rolling (forging) method, and the steel ingot may also be used as tube blank directly Manufacturing method of steel tubes Steel tubes shall be manufactured by adopting with hot rolling (squeezing, extending) or cold drawing (rolling) seamless method. If purchaser designates a certain manufacturing method, it shall be indicated in the contract. The hot-extended steel tubes are the steel tubes of larger aperture made from the blank steel tubes through entire heating, extending and deforming. 5.3 Delivery condition The hot-rolled (squeezed, extended) steel tubes shall be delivered at the hot-rolled or normalized condition, and the finishing temperature of such steel tubes delivered at hot-rolled condition shall not be less than the critical phase transition temperature A r3. As required by the purchaser, the hot-rolled (squeezed, extended) steel tubes may be delivered by adopting normalized condition based on the agreement of both the supplier and the purchaser and indication in the contract. If the finishing temperature of hot-extended steel tubes is no less than the critical phase transition temperature A r3 and the steel tubes are air cooled, thus the steel tubes shall be considered as being normalized Cold-drawn (rolled) steel tubes shall be delivered at normalized condition. 5.4 Mechanical properties Page 12 of 18

10 P the test pressure, the unit is megapascal (MPa); S the nominal wall thickness of steel tube, the unit is millimeter (mm); D the nominal outside diameter of steel tube, the unit is millimeter (mm); R the allowable stress, which is 60% of the lower yield strength specified in Table 5, and the unit is megapascal (MPa). The supplier may replace the hydraulic test with eddy current test, magnetic flux leakage test or ultrasonic testing. If the purchaser has the requirement on the ultrasonic testing, the supplier shall not replace the hydraulic test with ultrasonic testing. When doing the eddy current test, the artificial defects of reference test tube shall comply with those specified on the acceptance level A in GB/T 7735; when doing the magnetic flux leakage testing, the longitudinal artificial defects on the external surface of reference test tube shall comply with those specified on the acceptance level L4 in GB/T 12606; when doing the ultrasonic testing, the longitudinal artificial defects on the external surface of reference test tube shall comply with those specified on the acceptance level L4 in GB/T Macroscopic examination For those steel tubes manufactured directly with continuously cast bloom or steel ingots, the supplier shall guarantee that the acid leached macrostructure test piece of the cross section of blanks or steel tubes shall have no white spots, inclusions, subsurface bubbles, skull patch and delamination. 5.8 Surface quality The internal and external surfaces of steel tubes shall be free from visible cracks, wrinkles, scars, creasing and delamination. These defects shall be completely removed and the removing depth shall not exceed 10% of the nominal wall thickness, the actual wall thickness at the cleared part shall not be less than the allowable minimum value of wall thickness deviation. The allowable depth of straight tube shall comply with the following requirements: a) For cold-drawn (rolled) steel tubes: not greater than 4% of the wall thickness; the maximum depth is 0.3mm; b) For hot-rolled (squeezed, extended) steel tubes: not greater than 5% of the wall thickness; the maximum depth is 0.5mm. The existence of other local defects not exceeding the negative deviation of wall thickness is allowed. 5.9 Nondestructive testing Page 15 of 18

11 As required by the purchaser, the steel tubes may be done with ultrasonic testing with the agreement of both the supplier and the purchaser and indication in the contract, and the longitudinal artificial defects of the reference test tube shall comply with those specified on the acceptance level L2.5 in GB/T Test Methods 6.1 The dimension and appearance of steel tubes may be measured with such measuring instruments meeting the precision requirements. 6.2 The internal and external surfaces of steel tubes shall be inspected visually one by one at sufficient lighting condition. 6.3 Other inspection items of steel tubes shall be in accordance with those specified in Table 8. Page 16 of 18

12 a) 400 sticks for the steel tube with outside diameter no larger than 76mm and wall thickness no larger than 3mm; b) 50 sticks for the steel tubes with outside diameter larger than 351mm; c) 200 sticks for the steel tubes of other dimensions. If the quantity of the residual steel tubes is not less than the 50% the aforementioned values, those steel tubes shall be grouped into a batch separately. Otherwise, those steel tubes may be grouped into the adjacent batch with the same designation, furnace number, specification and heat treating system (furnace number). 7.3 Sampling quantity The sampling quantity for the performance test of each batch of steel tubes shall be in accordance with those specified in Table Re-inspection and judgement rules The re-inspection and judgement rules of steel tubes shall comply with those specified in GB/T Packing, Marking and Quality Certificate The packing, marking and quality certificate of steel tubes shall comply with those specified in GB/T END Page 18 of 18