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GB/T 37578-2019 English PDF (GBT37578-2019)

GB/T 37578-2019 English PDF (GBT37578-2019)

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GB/T 37578-2019: Urea grade ultra-low carbon austenitic seamless stainless steel tubes and pipes

This Standard stipulates the classification, code, order content, dimensions, shape and mass, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of urea grade ultra-low carbon austenitic seamless stainless steel tubes and pipes. This Standard is applicable to urea grade ultra-low carbon austenitic seamless stainless steel tubes and pipes.
GB/T 37578-2019
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.140.75
H 48
Urea Grade Ultra-low Carbon Austenitic Seamless
Stainless Steel Tubes and Pipes
ISSUED ON: JUNE 4, 2019
IMPLEMENTED ON: MAY 1, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Classification and Code ... 6
4 Order Content ... 6
5 Dimensions, Shapes and Masses ... 7
6 Technical Requirements ... 10
7 Test Methods ... 15
8 Inspection Rules ... 16
9 Packaging, Marking and Quality Certificate ... 17
Urea Grade Ultra-low Carbon Austenitic Seamless
Stainless Steel Tubes and Pipes
1 Scope
This Standard stipulates the classification, code, order content, dimensions, shape and mass, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of urea grade ultra-low carbon austenitic seamless stainless steel tubes and pipes.
This Standard is applicable to urea grade ultra-low carbon austenitic seamless stainless steel tubes and pipes (hereinafter referred to as ?€?steel tubes and pipes?€?). 2 Normative References
The following documents are indispensable to the application of this document. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document. GB/T 222 Permissible Tolerances for Chemical Composition of Steel Products; GB/T 223.5 Steel and Iron - Determination of Acid-soluble Silicon and Total Silicon Content - Reduced Molybdosilicate Spectrophotometric Method;
GB/T 223.11 Iron, Steel and Alloy - Determination of Chromium Content - Visual Titration or Potentiometric Titration Method;
GB/T 223.18 Methods for Chemical Analysis of Iron, Steel and Alloy - The Sodium Thiosulfate Separation Iodimetric Method for the Determination of Copper Content; GB/T 223.25 Methods for Chemical Analysis of Iron, Steel and Alloy - The Dimethylglyoxime Gravimetric Method for the Determination of Nickel Content; GB/T 223.28 Methods for Chemical Analysis of Iron, Steel and Alloy - The ???- benzoinoxime Gravimetric Method for the Determination of Molybdenum Content; GB/T 223.36 Methods for Chemical Analysis of Iron, Steel and Alloy - The Neutral Titration Method for the Determination of Nitrogen Content after Distillation Separation; GB/T 223.37 Methods for Chemical Analysis of Iron, Steel and Alloy - The Indophenol Blue Photometric Method for the Determination of Nitrogen Content after Distillation Separation;
Determination of Chemical Composition;
GB/T 20123 Steel and Iron - Determination of Total Carbon and Sulfur Content Infrared Absorption Method after Combustion in an Induction Furnace (routine method); GB/T 20124 Steel and Iron - Determination of Nitrogen Content - Thermal Conductimetric Method after Fusion in a Current of Inert Gas (routine method); GB/T 25151.2-2010 Fabrication and Inspection Method for High Pressure Urea Equipment - Part 2: Selective Corrosion Examination and Metallography Examination for Ultra Low-carbon Chromated Nickel Molybdenum Austenitic Stainless Steel of Urea Grade;
GB/T 25151.3-2010 Fabrication and Inspection Method for High Pressure Urea Equipment - Part 3: Intergranular Corrosion Tendency Test for Ultra Low-carbon Chromated Nickel Molybdenum Austenitic Stainless Steel of Urea Grade;
GB/T 25151.4-2010 Fabrication and Inspection Method for High Pressure Urea Equipment - Part 4: Intergranular Corrosion Tendency Test Specimen Preparation for Ultra Low-carbon Chromated Nickel Molybdenum Austenitic Stainless Steel of Urea Grade;
GB/T 34475-2017 Urea Grade Austenitic Stainless Steel Bars.
3 Classification and Code
3.1 In accordance with the manufacturing mode, the classification and code of steel tubes and pipes are as follows:
a) Hot-rolled (extruded) steel tubes and pipes, W-H;
b) Cold-drawn (rolled) steel tubes and pipes, W-C.
3.2 In accordance with the grade of dimensional accuracy, the classification and code of steel tubes and pipes are as follows:
a) Common grade, PA;
b) Superior grade, PC.
4 Order Content
Contract or order form which orders steel tubes and pipes in accordance with this Standard shall include the following content:
a) Serial No. of this Standard;
5.2 Length
5.2.1 General length
The general length of steel tubes and pipes shall comply with the following stipulations: a) Hot-rolled (extruded) steel tubes and pipes: 2,000 mm ~ 12,000 mm;
b) Cold-drawn (rolled) steel tubes and pipes: 1,000 mm ~ 12,000 mm.
5.2.2 Specified length and multiple length
In accordance with the demand-side?€?s requirements, through the negotiation between the demand-side and the supply-side, and statement in the contract, steel tubes and pipes may be delivered in accordance with specified length or multiple length. Specified length and multiple length shall be within the general range of length; the allowable deviation of total length shall be . In terms of steel tubes and pipes which are delivered in accordance with multiple length, the allowance of each incision shall comply with the following stipulations:
a) Nominal outer diameter not more than 159 mm, 5 mm ~ 10 mm;
b) Nominal outer diameter more than 159 mm, 10 mm ~ 15 mm.
5.3 Curvature
5.3.1 Per meter curvature
Per meter curvature of steel tubes and pipes shall be not more than what is stipulated below:
a) Wall thickness not more than 15 mm, 1.5 mm/m;
b) Wall thickness more than 15 mm, 2.0 mm/m.
5.3.2 Full length curvature
Full length curvature of steel tubes and pipes shall be not more than 0.15% of total length of steel tubes and pipes.
5.4 End Shape
Both end faces of steel tubes and pipes shall be vertical to the axis of steel tubes and pipes. The incision shall not have any burrs.
5.5 Out-of-roundness
In accordance with the demand-side?€?s requirements, through the negotiation between with the stipulations in Chapter 4 in GB/T 25151.2-2010. Corrosion depth shall comply with the stipulations in Table 5.
6.9 Surface Quality
6.9.1 The internal and external surface of steel tubes and pipes shall not have cracking, folding, rolling, separation or crusting. These defects shall be completely eliminated. The actual wall thickness of the area of elimination shall be not less than the minimum allowable value of wall thickness.
6.9.2 On the internal and external surface of steel tubes and pipes, straight allowable depth shall comply with the following stipulations:
a) Hot-rolled (extruded) steel tubes and pipes: not more than 5% of wall thickness, and not more than 0.4 mm;
b) Cold-drawn (rolled) steel tubes and pipes: not more than 4% of wall thickness, and not more than 0.2 mm.
6.9.3 Other partial defects that would not affect the minimum value of wall thickness are allowed to exist.
6.9.4 Roughness (Ra) of the internal and external surface of steel tubes and pipes shall be not more than 3.2 ???m.
6.10 Ultrasonic Testing
Steel tubes and pipes shall receive ultrasonic testing. In ultrasonic testing, the groove depth level of contrast tube shall comply with the stipulations of L2 in GB/T 5777-2008. When steel tubes and pipes are delivered in accordance with the minimum wall thickness, average wall thickness shall be adopted to calculate the groove depth. 7 Test Methods
7.1 The chemical composition analysis sampling of steel tubes and pipes shall comply with the rules in GB/T 20066. Generally speaking, chemical composition analysis shall be conducted in accordance with GB/T 11170, GB/T 20123, GB/T 20124 or other general methods. Arbitration shall comply with the stipulations in GB/T 223.5, GB/T 223.11, GB/T 223.18, GB/T 223.25, GB/T 223.28, GB/T 223.36, GB/T 223.37, GB/T 223.62, GB/T 223.63, GB/T 223.68, GB/T 223.85 and GB/T 223.86.
7.2 In metallographic test, along the steel tubes and pipes, longitudinally take strip samples. Sample size shall be: 50 mm ??? 10 mm (length ??? width). The sides of the sample shall be grinded and polished.
7.3 In terms of the dimensions and shape of steel tubes and pipes, measuring instruments that comply with the accuracy requirement shall be adopted for one-by- 8.2 Group Batch Rules
Steel tubes and pipes shall receive inspection and acceptance inspection by batches. Each batch shall be constituted of steel tubes and pipes of the same designation, the same furnace No. (in terms of electroslag re-melting steel, under the condition of stable process and compliance with the various requirements in this Standard, it can be master smelting furnace No. of consumable electrode), the same specification and the same thermal treatment system (heat). The quantity of steel tubes and pipes in each batch shall not exceed the following stipulations:
a) Outer diameter not more than 76 mm and wall thickness not more than 3 mm: 500 PCS;
b) Outer diameter more than 351 mm: 50 PCS;
c) Other dimensions: 200 PCS.
8.3 Sampling Size
Sampling size of various inspections of each batch of steel tubes and pipes shall comply with the stipulations in Table 6.
8.4 Re-inspection and Determination Rules
8.4.1 Re-inspection and determination rules of corrosion resistance test shall comply with the following stipulations:
a) If corrosion rate exceeds the stipulated value in Table 5, or, corrosion rate of the 5th cycle exceeds 50% of the 4th cycle, then, take another sample from the same steel tube/pipe; adopt the same procedures for re-inspection;
b) When 015Cr25Ni22Mo2N steel tubes and pipes are under 10 cycles of test in accordance with the demand-side?€?s requirements, if corrosion rate exceeds the stipulated value in Table 5, or, corrosion rate of the 10th cycle exceeds 50% of the 9th cycle, then, take another sample from the same steel tube/pipe; adopt the same procedures for re-inspection;
c) Re-inspection can only be conducted once.
8.4.2 Re-inspection and determination rules of the remaining inspection items of steel tubes and pipes shall comply with the stipulations in GB/T 2102.
9 Packaging, Marking and Quality Certificate
Packaging, marking and quality certificate of steel tubes and pipes shall comply with the stipulations in GB/T 2102.

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