PDF Actual Sample: GB/T 24591-2019
| Standard ID | GB/T 24591-2019 (GB/T24591-2019) |
| Description (Translated English) | Seamless steel tubes for high pressure feedwater heater |
| Sector / Industry | National Standard (Recommended) |
| Classification of Chinese Standard | H48 |
| Classification of International Standard | 77.140.75 |
| Word Count Estimation | 18,147 |
| Date of Issue | 2019-10-17 |
| Date of Implementation | 2020-09-01 |
| Older Standard (superseded by this standard) | GB/T 24591-2009 |
| Drafting Organization | Jiangsu Yinhuan Precision Steel Tube Co., Ltd., Shanghai Huagang Stainless Steel Co., Ltd., Harbin Boiler Factory Co., Ltd., Dongfang Electric Group Dongfang Boiler Co., Ltd., Metallurgical Industry Information Standards Institute |
| Administrative Organization | National Steel Standardization Technical Committee (SAC/TC 183) |
| Proposing organization | China Iron and Steel Association |
| Issuing agency(ies) | State Administration of Markets and China National Standardization Administration |
ENGLISH: GB/T 24591-2019 (Translated) GB/T 24591-2019
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.75
H 48
Replacing GB/T 24591-2009
Seamless Steel Tubes for
High Pressure Feedwater Heater
高压给水加热器用无缝钢管
ISSUED ON: OCTOBER 17, 2019
IMPLEMENTED ON: SEPTEMBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative References ... 6
3 Classification and Code ... 8
4 Ordering Contents ... 10
5 Size, Shape, Weight and Allowable Deviation ... 10
6 Technical Requirements ... 13
7 Anti-Rust ... 19
8 Test Methods ... 20
9 Inspection Rules ... 21
10 Package, Marking and Quality Certificate ... 21
Appendix A (Normative) High-Temperature Specified Plastic Elongation
Strength ... 23
Seamless Steel Tubes for
High Pressure Feedwater Heater
1 Scope
This Standard specifies the classification and code, ordering contents, size, shape,
weight and allowable deviation, technical requirements, anti-rust, test methods,
inspection rules, package, marking and quality certificate of seamless steel tubes for
high pressure feedwater heater.
This Standard is applicable to the straight tube, U-shaped tube and serpentine tube
(hereinafter referred to as “steel tube”) for high-pressure feedwater heater.
2 Normative References
The following documents are essential to the application of this document. For the
dated documents, only the versions with the dates indicated are applicable to this
document; for the undated documents, only the latest version (including all the
amendments) are 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 223.12 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 223.14 Methods for Chemical Analysis of Iron, Steel and Alloy - The N-
Benzoy-N-Phenylhydroxylamine Extraction Photometric Method for the
Determination of Vanadium Content
GB/T 223.19 Methods for Chemical Analysis of Iron, Steel and Alloy – The
Neocuproine-Chloroform Extraction Photometric Method for the Determination of
Copper Content
GB/T 4336 Standard Test Method for Spark Discharge Atomic Emission
Spectrometric Analysis of Carbon and Low-Alloy Steel (Routine Method)
GB/T 4340.1 Metallic Materials - Vickers Hardness Test - Part 1: Test Method
GB/T 5777-2019 Automated Full Peripheral Ultrasonic Testing of Seamless and
Welded (except Submerged Arc-Welded) Steel Tubes for the Detection of
Longitudinal and/or Transverse Imperfections
GB/T 7735-2016 Automated Eddy Current Testing of Seamless and Welded
(except Submerged Arc-Welded) Steel Tubes for Detection of Imperfections
GB/T 11170 Stainless Steel - Determination of Multi-Element Contents - Spark
Discharge Atomic Emission Spectrometric Method (Routine Method)
GB/T 20066 Steel and Iron - Sampling and Preparation of Samples for the
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
YB/T 5137 Round Blank of Hot-rolled and Forged Seamless Steel Tube for High
Pressure
3 Classification and Code
The steel tube can be divided into three types, such as straight tube, U-shaped tube
and serpentine tube according to the product shape. The outline diagram and size
code of U-shaped tube can refer to Figure 1; while the schematic diagram of serpentine
tube can refer to Figure 2.
Key:
1 – header;
2 – serpentine tube;
r – bending radius, in mm;
β – flatness, in mm.
NOTE: The header is the equipment component that connects with the serpentine tube, it does
not belong to the specified scope of this Standard.
Figure 2 – Serpentine Tube Schematic Diagram
4 Ordering Contents
The contract or ordering form ordering the steel tubes according to this Standard shall
include but not limited to the following contents:
a) This Standard number;
b) Product name;
c) Steel designation;
d) Product shape (straight tube, U-shaped tube or serpentine tube);
e) Drawing or size specification (nominal outer diameter × wall thickness × length
of straight tube section, bending radius, in mm);
f) Ordering quantity (total weight or total length);
g) Package requirements;
h) Special requirements.
5 Size, Shape, Weight and Allowable Deviation
5.1 Outer diameter
5.1.1 The nominal diameter of the steel tube is generally 12mm~32mm.
5.1.2 The allowable deviation for the outer diameter of the straight section of steel tube
shall conform to the provisions of Table 1.
ring gauge shall be the maximum allowable outer diameter of the steel tube; its
allowable deviation is +0.05 0 mm; its length shall be no less than 50mm. The degree of
bending for the straight section of other shape of steel tube shall be no more than
1.5mm/m. Through the negotiation between the supplier and the purchaser, indicated
in the contract, take other methods to check the degree of bending of the steel tube.
5.4.6 For U-shaped tube, the flatness β of the elbow measured at the two tangent
points shall not exceed 1.5mm (see Figure 1). For serpentine tube, unless otherwise
is specified, the flatness β of the elbow shall not exceed 4.0mm.
5.4.7 The actual size and shape of the serpentine tube shall conform to the provisions
of the drawings.
5.5 Weight
The steel tube shall be delivered according to the theoretical weight. The theoretical
weight per square meter of the steel tube shall be calculated as per Formula (2):
Where:
W – theoretical weight of steel tube per meter, in kg/m;
π- 3.1416;
ρ – the density of the steel, in kg/dm3; austenitic stainless steel is 7.93, other steel is
7.85;
S – wall thickness of steel tube, in mm; the steel tube delivered by the minimum wall
thickness shall take the average value between the allowable max. wall thickness and
the allowable min. wall thickness;
D – nominal outer diameter of the steel tube, in mm.
6 Technical Requirements
6.1 Designations and chemical compositions of steel
6.1.1 The designations and chemical compositions (smelting analysis) of steel shall
conform to the provisions of Table 5. According to the requirements of the purchaser,
through the negotiation between the supplier and the purchaser, indicated in the
contract, the steel tubes with other requirements of chemical compositions may be
supplied.
6.5.3 The blind area on the tube end during the hydraulic test shall be removed.
6.6 Process performance
6.6.1 Flattening
The steel tube shall be conducted the flattening test. The flattening test shall be carried
out as per the following two steps:
a) The first step is ductility test. Press the specimen till the distance between two
plates is H; the Value-H shall be calculated as per Formula (4). When the
specimen is pressed to the distance H between two plates, there shall be no
cracks or breakages on the specimen.
Where:
H – distance between two plates, in mm;
α – deformation coefficient per unit length; 0.09 for austenitic stainless-steel, and
0.08 for other steels;
S – wall thickness of steel tube, in mm;
D – nominal outer diameter of steel tube, in mm.
b) The second step is integrity test (closed flattening). The flattening shall be
continued till the specimen breaks or the two opposite walls of the specimen
collide. During the whole flattening test period, the specimen shall not appear
visible delamination, white spots and inclusions.
6.6.2 Flaring
The steel tube shall be conducted the flaring test. The top core taper of the flaring test
is 60°. The flaring ratio of the outer diameter of the specimen after flaring shall conform
to the provisions of Table 8. After flaring, the specimen shall not appear cracks or
breaches.
determined by the supplier; or determined through the negotiation between the
supplier and the purchaser; and indicated in the contract.
8 Test Methods
8.1 The analysis sampling for the chemical compositions of the steel tube shall be
conducted as per the rules specified in GB/T 20066. The analysis of chemical
compositions is generally conducted as per GB/T 4336, GB/T 11170, GB/T 20123,
GB/T 20124 or other general methods. The arbitration shall be conducted as per the
provisions of GB/T 223.5, GB/T 223.11, GB/T 223.12, GB/T 223.14, GB/T 223.19,
GB/T 223.23, GB/T 223.25, GB/T 223.26, GB/T 223.36, GB/T 223.59, GB/T 223.63,
GB/T 223.85, GB/T 223.86.
8.2 The dimensions of steel tubes shall be measure one by one by the measuring
gauges that meet the accuracy requirements.
8.3 The inner and outer surfaces of the steel tubes shall be visually inspected one by
one under full lighting conditions.
8.4 The sampling quantity, sampling method and test methods of other inspection
items of the steel tubes shall conform to the provisions of Table 10.
Table 10 – Sampling Quantity, Sampling Method and Test Methods for
Inspection items of Steel Tubes
SN Inspection items Sampling quantity
Sampling
method Test methods
1 Chemical composition 1 specimen for each furnace GB/T 20066 See 8.1
2 Tensile at room temperature
Take 1 specimen from each two steel
tubes per batch GB/T 2975 GB/T 228.1
3 Tensile at high temperature
Take 1 specimen from each two steel
tubes per batch GB/T 2975 GB/T 228.2
4 Hardness Take 1 specimen from each two steel tubes per batch
GB/T 230.1,
GB/T 4340.1
GB/T 230.1,
GB/T 4340.1
5 Hydraulic pressure One by one --- GB/T 241
6 Flattening Take 1 specimen from each two steel tubes per batch GB/T 246 GB/T 246
7 Flaring Take 1 specimen from each two steel tubes per batch GB/T 242 GB/T 242
8 Decarburization layer
Take 1 specimen from each two steel
tubes per batch GB/T 224 GB/T 224
9 Intergranular Straight tube: take 1 specimen from GB/T 4334- Method-E in
......