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结构用无缝钢管
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GBT 8162-2018
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标准编号: GB/T 8162-2018 (GB/T8162-2018)
中文名称: 结构用无缝钢管
英文名称: Seamless steel tubes for structural purposes
行业: 国家标准 (推荐)
中标分类: H48
国际标准分类: 77.140.75
字数估计: 20,218
发布日期: 2018-05-14
实施日期: 2019-02-01
旧标准 (被替代): GB/T 8162-2008
起草单位: 鞍钢股份有限公司、衡阳华菱钢管有限公司、浙江格洛斯无缝钢管有限公司、浙江金洲管道科技股份有限公司、浙江伦宝金属管业有限公司、景县质量技术监督检验所(国家塔桅产品质量监督检验中心)、冶金工业信息标准研究院
归口单位: 全国钢标准化技术委员会(SAC/TC 183)
标准依据: 国家标准公告2018年第6号
提出机构: 中国钢铁工业协会
发布机构: 国家市场监督管理总局、中国国家标准化管理委员会
GB/T 8162-2018: 结构用无缝钢管
GB/T 8162-2018 英文名称: Seamless steel tubes for structural purposes
1 范围
本标准规定了结构用无缝钢管的订货内容、尺寸、外形、重量、技术要求、试验方法、检验规则、包装、标志和质量证明书。
本标准适用于机械结构和一般工程结构用无缝钢管。
2 规范性引用文件
下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件,仅注日期的版本适用于本文
件。凡是不注日期的引用文件,其最新版本(包括所有的修改单)适用于本文件。
GB/T 222 钢的成品化学成分允许偏差
GB/T 223.5 钢铁 酸溶硅和全硅含量的测定 还原型硅钼酸盐分光光度法
GB/T 223.9 钢铁及合金 铝含量的测定 铬天青S分光光度法
GB/T 223.11 钢铁及合金 铬含量的测定 可视滴定或电位滴定法
GB/T 223.12 钢铁及合金化学分析方法 碳酸钠分离-二苯碳酰二肼光度法测定铬量
GB/T 223.14 钢铁及合金化学分析方法 钽试剂萃取光度法测定钒含量
GB/T 223.19 钢铁及合金化学分析方法 新亚铜灵-三氯甲烷萃取光度法测定铜量
GB/T 223.23 钢铁及合金 镍含量的测定 丁二酮肟分光光度法
GB/T 223.26 钢铁及合金 钼含量的测定 硫氰酸盐分光光度法
GB/T 223.37 钢铁及合金化学分析方法 蒸馏分离-靛酚蓝光度法测定氮量
GB/T 223.40 钢铁及合金 铌含量的测定 氯磺酚S分光光度法
GB/T 223.59 钢铁及合金 磷含量的测定 铋磷钼蓝分光光度法和锑磷钼蓝分光光度法
GB/T 223.60 钢铁及合金化学分析方法 高氯酸脱水重量法测定硅含量
GB/T 223.62 钢铁及合金化学分析方法 乙酸丁酯萃取光度法测定磷量
GB/T 223.63 钢铁及合金化学分析方法 高碘酸钠(钾)光度法测定锰量
GB/T 223.68 钢铁及合金化学分析方法 管式炉内燃烧后碘酸钾滴定法测定硫含量
GB/T 223.78 钢铁及合金化学分析方法 姜黄素直接光度法测定硼含量
GB/T 223.84 钢铁及合金 钛含量的测定 二安替比林甲烷分光光度法
GB/T 223.86 钢铁及合金 总碳含量的测定 感应炉燃烧后红外吸收法
GB/T 228.1 金属材料 拉伸试验 第1部分:室温试验方法
GB/T 229 金属材料 夏比摆锤冲击试验方法
GB/T 231.1 金属材料 布氏硬度试验 第1部分:试验方法
GB/T 244 金属管 弯曲试验方法
GB/T 246 金属材料 管 压扁试验方法
GB/T 699 优质碳素结构钢
GB/T 2102 钢管的验收、包装、标志和质量证明书
GB/T 2975 钢及钢产品 力学性能试验取样位置及试样制备
GB/T 3077 合金结构钢
GB/T 4336 碳素钢和中低合金钢 多元素含量的测定 火花放电原子发射光谱法(常规法)
GB/T 5777-2008 无缝钢管超声波探伤检验方法
GB/T 7735-2016 无缝和焊接(埋弧焊除外)钢管缺欠的自动涡流检测
GB/T 12606-2016 无缝和焊接(埋弧焊除外)铁磁性钢管纵向和/或横向缺欠的全圆周自动漏磁
检测
GB/T 17395 无缝钢管尺寸、外形、重量及允许偏差
GB/T 20066 钢和铁 化学成分测定用试样的取样和制样方法
GB/T 20123 钢铁 总碳硫含量的测定 高频感应炉燃烧后红外吸收法(常规方法)
GB/T 20124 钢铁 氮含量的测定 惰性气体熔融热导法(常规方法)
GB/T 20125 低合金钢 多元素的测定 电感耦合等离子体发射光谱法
YB/T 4149 连铸圆管坯
YB/T 5221 合金结构钢热轧和锻制圆管坯
YB/T 5222 优质碳素结构钢热轧和锻制圆管坯
3 订货内容
按本标准订购钢管的合同或订单应包括下列内容:
a) 标准编号;
b) 产品名称;
c) 钢的牌号,有质量等级的应包括质量等级;
d) 尺寸规格;
e) 订购的数量(总重量或总长度);
f) 交货状态;
g) 特殊要求。
4 尺寸、外形和重量
4.1 外径和壁厚
钢管的公称外径(D)和公称壁厚(S)应符合GB/T 17395的规定。根据需方要求,经供需双方协
商,可供应其他外径和壁厚的钢管。
4.2 外径和壁厚的允许偏差
4.2.1 钢管的外径允许偏差应符合表1的规定。
4.2.2 热轧(扩)钢管的壁厚允许偏差应符合表2的规定。
4.2.3 冷拔(轧)钢管的壁厚允许偏差应符合表3的规定。
4.2.4 根据需方要求,经供需双方协商,并在合同中注明,可供应表1、表2、表3规定以外尺寸允许偏差的钢管。
4.3 长度
4.3.1 通常长度
钢管的通常长度为3000mm~12000mm。根据需方要求,经供需双方协商,可供应通常长度以
外的钢管。
4.3.2 范围长度
根据需方要求,经供需双方协商,并在合同中注明,钢管可按范围长度交货。
4.3.3 定尺长度和倍尺长度
4.3.3.1 根据需方要求,经供需双方协商,并在合同中注明,钢管可按定尺长度或倍尺长度交货。
4.3.3.2 钢管以定尺长度或倍尺长度交货时,其长度允许偏差应符合如下规定:
a) 定尺长度或倍尺长度不大于6000mm时,其允许偏差为+30 0 mm;
b) 定尺长度或倍尺长度大于6000mm时,其允许偏差为+50 0 mm。
4.4 弯曲度
4.4.1 钢管的每米弯曲度应符合表4的规定。
4.5 不圆度和壁厚不均
根据需方要求,经供需双方协商,并在合同中注明,钢管的不圆度和壁厚不均应分别不超过公称外
径公差和公称壁厚公差的80%。
4.6 端头外形
4.6.1 公称外径不大于60mm的钢管,管端切斜应不超过1.5mm;公称外径大于60mm的钢管,管端
切斜应不超过钢管公称外径的2.5%,但最大应不超过6mm。钢管的切斜见图1所示。
4.6.2 钢管的端头切口毛刺应予清除。
4.7 重量
4.7.1 钢管按实际重量交货,亦可按理论重量交货。钢管理论重量按GB/T 17395的规定进行计算,钢的密度取7.85kg/dm3。
5 技术要求
5.1 钢的牌号和化学成分
5.1.1 优质碳素结构钢的牌号和化学成分(熔炼分析)应符合GB/T 699的规定。
5.1.2 低合金高强度结构钢的牌号和化学成分(熔炼分析)应符合表5的规定。除质量等级A外,各牌
号的碳当量应符合表6的规定。碳当量(CEV)应由熔炼分析成分按式(1)计算。
5.1.3 合金结构钢的牌号和化学成分(熔炼分析)应符合GB/T 3077的规定。
5.1.4 根据需方要求,经供需双方协商,可供应其他牌号或化学成分的钢管。
5.1.5 当需方要求做成品分析时,应在合同中注明。钢管的成品化学成分允许偏差应符合GB/T 222
的规定。
5.2.1 钢的冶炼方法
钢应采用电弧炉加炉外精炼或氧气转炉加炉外精炼方法冶炼。经供需双方协商,也可采用较高要
求的其他方法冶炼。需方指定某一种冶炼方法时,应在合同中注明。
5.2.2 管坯的制造方法
5.2.2.1 管坯可采用连铸、模铸或热轧(锻)方法制造。
5.2.2.2 连铸管坯应符合YB/T 4149的规定;热轧(锻)管坯应符合YB/T 5221或YB/T 5222的规定;
模铸管坯可参照热轧(锻)管坯的规定执行。
5.2.3 钢管的制造方法
钢管应采用热轧(扩)或冷拔(轧)无缝方法制造。需方指定某一种方法制造钢管时,应在合同中
5.3 交货状态
5.3.1 热轧(扩)钢管以热轧(扩)或热处理状态交货。需方要求热处理状态交货时,应在合同中注明。
5.3.2 冷拔(轧)钢管应以退火或高温回火状态交货。根据需方要求,经供需双方协商,并在合同中注
明,冷拔(轧)钢管也可以冷拔(轧)或其他热处理状态交货。
5.4 力学性能
5.4.1 拉伸性能
5.4.1.1 优质碳素结构钢、低合金高强度结构钢的钢管,其交货状态的拉伸性能应符合表7的规定。
5.4.1.2 合金结构钢钢管试样毛坯按表8推荐热处理制度进行热处理后制成试样测出的拉伸性能应符合表8的规定。
5.4.1.3 冷拔(轧)状态交货钢管的力学性能由供需双方协商确定。
5.4.3.1 低合金高强度结构钢钢管,当外径不小于70mm,且壁厚不小于6.5mm时,应进行纵向冲击
试验,其夏比V型缺口冲击试验的试验温度和冲击吸收能量应符合表7的规定。冲击吸收能量按一组3个试样的算术平均值计算,允许其中一个试样的单个值低于规定值,但应不低于规定值的70%。
5.4.3.2 表7中的冲击吸收能量为标准尺寸试样夏比V型缺口冲击吸收能量要求值。当钢管尺寸不
能制备标准尺寸试样时,可制备小尺寸试样。当采用小尺寸冲击试样时,其最小夏比V型缺口冲击吸收能量要求值应为标准尺寸试样冲击吸收能量要求值乘以表9中的递减系数。冲击试样尺寸应优先选择较大的尺寸。
5.4.3.3 根据需方要求,经供需双方协商,并在合同中注明,其他牌号的钢管也可进行夏比V型缺口冲
击试验,其试验温度、试验尺寸、冲击吸收能量由供需双方协商确定。
5.5 工艺性能
5.5.1 压扁
牌号为10、15、20、25、20Mn、25Mn、Q345、Q390,公称外径D >22mm~600mm,并且壁厚与外径比值不大于10%的钢管应进行压扁试验,钢管压扁后平板间距离应符合表10的规定。压扁后,试样上不应出现裂缝或裂口。
根据需方要求,经供需双方协商,并在合同中注明,外径不大于22mm的钢管可做弯曲试验,弯曲
角度为90°,弯芯半径为钢管外径的6倍,弯曲后试样弯曲处不应出现裂缝或裂口。
5.6 表面质量
钢管的内外表面不应有目视可见的裂纹、折叠、结疤、轧折和离层。这些缺陷应完全清除,清除深度应不超过公称壁厚的下偏差,清理处的实际壁厚应不小于壁厚所允许的最小值。不超过壁厚下偏差的其他局部缺欠允许存在。
5.7 无损检测
根据需方要求,经供需双方协商,并在合同中注明,钢管可采用以下一种或多种方法进行无损检测:
a) 按GB/T 5777-2008的规定进行超声检测时,对比样管刻槽深度等级:冷拔(轧)管为L3,热
轧(扩)钢管为L4;
b) 按GB/T 7735-2016的规定进行涡流检验,验收等级E4H或E4;
5.8 镀锌层
根据需方要求,经供需双方协商,并在合同中注明,钢管可镀锌交货。当钢管镀锌交货时,镀锌层的
相关要求应符合附录A的规定。
6 试验方法
6.1 钢管的化学成分分析取样按 GB/T 20066 的规则进行。化学成分分析通常按 GB/T 4336、
GB/T 20123、GB/T 20124、GB/T 20125或其他通用的方法进行,仲裁时应按GB/T 223.5、GB/T 223.9、GB/T 223.11、GB/T 223.12、GB/T 223.14、GB/T 223.19、GB/T 223.23、GB/T 223.26、GB/T 223.37、GB/T 223.40、GB/T 223.59、GB/T 223.60、GB/T 223.62、GB/T 223.63、GB/T 223.68、GB/T 223.78、GB/T 223.84、GB/T 223.86、GB/T 20125的规定进行。
6.2 钢管的尺寸和外形应采用符合精度要求的量具进行测量。
6.3 钢管的内外表面应在充分照明条件下进行目视检查。
6.4 钢管其他检验项目的取样方法和试验方法应符合表11的规定。
7.1 检查和验收
钢管的检查和验收由供方质量技术监督部门进行。
7.2 组批规则
7.2.1 钢管按批进行检查和验收。
7.2.2 若钢管在切成单根后不再进行热处理,则从一根管坯轧制的钢管截取的所有管段都应视为
一根。
7.2.3 每批应由同一牌号、同一炉号、同一规格和同一热处理制度(炉次)的钢管组成。每批钢管的数量应不超过如下规定:
a) 外径不大于76mm,并且壁厚不大于3mm:400根。
b) 外径大于351mm:50根。
d) 剩余钢管的根数,如不少于上述规定的50%时则单独列为一批,少于上述规定的50%时可并
入同一牌号、同一炉号和同一规格的相邻一批中。
7.3 取样数量
每批钢管各项检验的取样数量应符合表11的规定。
7.4 复验与判定规则
钢管的复验与判定规则应符合GB/T 2102的规定。
8 包装、标志和质量证明书
钢管的包装、标志和质量证明书应符合GB/T 2102的规定。
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.75 H 48
GB/T 8162-2018
Replacing GB/T 8162-2008
Seamless Steel Tubes for Structural Purpose
Issued on. May 14, 2018 Implemented on. February 1, 2019 Issued by. State Administration for Market Regulation; Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Order Contents ... 8
4 Dimensions, Shape and Weight ... 8
5 Technical Requirements ... 11
6 Test Methods... 19
7 Inspection Rules ... 21
8 Packaging, Signs and Quality Certificates ... 21
Appendix A (Normative) Galvanized Coatings ... 22
Seamless Steel Tubes for Structural Purposes
1 Scope
This Standard specifies the order content, dimension, shape, weight, technical requirements, test methods, inspection rules, packaging and quality certification for seamless steel tube.
This standard applies to the seamless steel tubes for mechanical structural purposes and general engineering structural purposes.
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 standard.
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 223.9 Iron Steel and Alloy - Determination of Aluminium Content -Chrom Azurol S Photometric 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 223.23 Iron, Steel and Alloy-Determination of Nickel Content -The Dimethylglyoxime GB/T 246 Metallic Materials - Tube - Flattening Test GB/T 699 Quality Carbon Structure Steels GB/T 2102 Acceptance Packing Marking and Quality Certification of Steel Pipe GB/T 2975 Steel and Steel Products - Location and Preparation of Samples and Test Pieces
for Mechanical Testing GB/T 3077 Alloy Structure Steels GB/T 4336 Carbon and Low-Alloy Steel -Determination of Multi-Element Contents - Spark
Discharge Atomic Emission Spectrometric Method (Routine Method) GB/T 5777-2008 Seamless Steel Pipe and Tubing Methods for Ultrasonic Testing GB/T 7735-2016 Automated Eddy Current Testing of Seamless and Welded (Except
Submerged Arc-Welded) Steel Tubes for Detection of Imperfections GB/T 12606-2016 Automated Full Peripheral Flux Leakage Testing of Seamless and Welded
(Except Submerged Arc-Welded) Ferromagnetic Steel Tubes for the Detection of Longitudinal and/or Transverse Imperfections GB/T 17395 Dimensions, Shapes, Masses and Tolerances of Seamless Steel Tubes 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
GB/T 20125 Low-Alloy Steel -Determination of Multi-Element Contents -Inductively Coupled Plasma Atomic Emission Spectrometric Method YB/T 4149 Continuously Cast Round Billet for Seamless Steel Tube Rolling YB/T 5221 Alloy Structure Steel Round Tube Blank Hot Rolled and Forged for Making
Seamless Tube YB/T 5222 Quality Hot Rolled and Forged Carbon Structural Steel Round Tube Blank the requester specifies a certain smelting method, it shall be indicated in the contract.
5.2.2 Smelting Method for Tube Blank
5.2.2.1 Tube blanks can be manufactured by continuous casting, die casting or hot rolled (forging)
5.2.2.2 Continuous casting tube blanks shall comply with the provisions of YB/T 4149; hot rolled (forging) tube blanks shall comply with the provisions of YB/T 5221 or YB/T 5222; die casting tube blank can be carried out in accordance with the provisions of the hot rolled (forging) tube blank.
5.2.3 Manufacturing Method for Steel Tube
Steel tube shall be manufactured by a hot rolled (expanding) or cold drawn (rolled) seamless method. When the requester specifies a certain manufacturing method for steel tube, it shall be indicated in the contract.
5.3 Delivery Status
5.3.1 Hot rolled (expanding) steel tubes shall be delivered in hot-rolled (expanding) or heat treatment status. When the requester specifies the delivery status of heat treatment status, it shall be indicated in the contract.
5.3.2 Cold drawn (rolled) steel tubes shall be delivered by annealing or high-temperature tempering. According to the requirements of the requester, which shall be indicated in the contract, after the negotiation of both supply-demand parties, cold drawn (rolled) steel tube can also be delivered by cold drawn (rolled) or other heat treatment status.
5.4 Mechanical Properties
5.4.1 Tensile Properties
5.4.1.1 For steel tubes of high-quality carbon structural steel and low-alloy high-strength structural steel, tensile properties of their delivery status shall comply with the provisions in Table 7.
5.4.1.2 For sample blank of alloy structural steel tube, conduct heat treatment on it according to the heat treatment system recommended in Table 8; made it into the sample; measure its tensile properties. The tensile properties shall comply with the requirements in Table 8.
5.4.1.3 For mechanical properties of steel tubes which is delivered by cold drawn (rolled) status, it shall be determined by both supply-demand parties.
Table 7 -- Mechanical Properties for Steel Tubes of High-quality Carbon Structural Steel and Low-alloy High-strength Structural Steel
Designation Quality Tensile Lower Yield Strength ReL a/MPa Percentage Impact Test
10; 15; 20; 25 D×2/3
Q345; Q390; 20Mn; 25Mn D×7/8
a Minimum value for the distance between the flats of flattening test (H) shall be 5 times of steel tube's wall thickness.
5.5.2 Bending
According to the requirements of the requester, which shall be indicated in the contract, after the negotiation of both supply-demand parties, for the steel tube whose outside diameter is not more than 22mm, it can perform bending test. The bending angle shall be 90°, and bending core’s radius shall be 6 times of steel tube’s outside diameter. After bending, no cracks or chinks shall appear on the bending location.
5.6 Surface Quality
Inner and outer surfaces of steel tube shall not have visible cracks, folds, crusting, rolling and separation. These defects shall be completely cleaned out. Depth of cleaning place shall not exceed nominal wall thickness’s lower deviation. Actual wall thickness of the cleaning place shall not be less than the minimum allowed by the wall thickness. For other local imperfections which do not exceed wall thickness’s lower deviation, their existence is allowed.
5.7 Non-destructive testing
According to the requirements of the requester, which shall be indicated in the contract, after the negotiation of both supply-demand parties, for the steel tube, non-destructive testing can be performed by one or more of the following methods.
a) When performing ultrasonic testing according to the provisions of GB/T 5777-2008, compare the depth grade of sample tube’s groove. cold drawn (rolled) tube -L3; hot rolled (expanding) tube - L4;
b) Perform eddy current test according to GB/T 7735-2016. Acceptance level - E4H or E4;
c) Perform magnetic flux leakage detection according to the provisions of GB/T 12606-2016. Acceptance level - F4.
5.8 Galvanized Coatings
6 Test Methods
6.1 Sampling for steel tube’s chemical composition analysis shall be carried out according to
7 Inspection Rules
7.1 Inspection and Acceptance
Inspection and acceptance of steel tubes shall be carried out by the supplier's quality and technical supervision department.
7.2 Rules of Lot Grouping
7.2.1 Steel tube shall be inspected and accepted in batch.
7.2.2 After being cut into single piece, if the steel tube is not performed with heat treatment anymore, for all tube sections which are taken from steel tubes rolled from the same tube blank, they shall be deemed as the same one.
7.2.3 For each batch, it shall be composed of the steel tube which has the same designation, same furnace number, same specification AND same heat treatment system (furnace No.). Quantity of each batch’s steel tubes shall not exceed the following provisions.
b) The one whose outside diameter is greater than 351mm. 50 pieces.
c) The ones with other dimensions. 200 pieces.
d) For the quantity of the remaining steel tubes, when it is not less than 50% of the above specified quantity, these steel tubes shall be separately listed as one batch; when the quantity is less than 50% of the above specified quantity, these steel tubes shall be merged into the adjacent batch of steel tube which has the same designation, same furnace number AND same specification.
7.3 Quantity of Samplings
For sampling quantity for all tests of each batch’s steel tube, it shall comply with the provisions of Table 11.
7.4 Re-examination and Judgment Rules
Re-inspection and judgment rules of steel tubes shall comply with the provisions of GB/T 2102.
8 Packaging, Signs and Quality Certificates
Packaging, signs and quality certificate of steel tubes shall comply with the provisions of GB/T 2102.
After galvanization, steel tube’s galvanized coatings weight shall be measure. Take 2 steel pipes from each batch at random; take one 30mm~60mm (depending on specifications) tube section on each end of each steel tube; treat them as samples. Sample’s surface shall not have rough surface and zinc tumor. Sample’s surface shall be washed with pure solvent, such as benzene, petroleum benzene, trichloroethylene or carbon tetrachloride, etc. Then use ethanol to rinse it; use water to wash it out; coat the end faces of both ends of the sample with varnish (phenol); dry it adequately.
A.5.2 Preparation of Test Solution
Dissolve 32g of antimony trichloride (SbCl3) OR 20g of antimony trioxide (Sb2O3) in 1000mL of hydrochloric acid whose density is over 1.18kg/dm3 or more; prepare it as the stock solution. Before the test, add 5mL of the stock solution into 100mL of hydrochloric acid whose density is over 1.18kg/dm3 or more; treat it as the test solution.
A.5.3 Test Procedure
A.5.3.1 Use balance to weigh sample’s weight by AND round off it to the nearest one - 0.01g.
A.5.3.2 Immerse the sample into the test solution; immerse one sample at one time. Liquid level shall be higher than the sample. During the measurement, temperature of the solution shall not be higher than 38 °C.
A.5.3.3 In sample solution, when the generation of Hydrogen becomes less and the galvanized coatings has disappeared, take out the sample. Use water to rinse the sample; use cotton or clean cloth to dry it. After it is completely dried, it shall be weighed on the balance AND round off it to the nearest one - 0.01g.
A.5.3.4 After sample’s zinc coatings is peeled off, on two mutually perpendicular directions at the end of the sample, outside diameter and inner diameter shall be measured. Respectively take their average values; treat them as the actual outside diameter and inner diameter; round off it to the nearest one - 0.01mm.
A.5.3.5 In the case where the zinc coatings can be easily removed, test solution can be reusable.
A.5.4.1 Surface area of the sample shall be calculated according to formula (A.2).
e - Approximate value of galvanized coatings’ thickness. The unit is micrometers (μm);
mA - Weight of the galvanized coatings. The unit is grams per square meter (g/m2).
A.6 Uniformity of Galvanized Coatings
For galvanized steel tube, it shall perform galvanized coatings’ uniformity test. The test method shall comply with the provisions of A.7. During the test, the sample (except the weld seam) shall be continuously immersed for 5 times in copper sulfate solution without turning into red (color of copper plating).
A.7 Test Method for Uniformity Test of Galvanized Coatings (copper sulfate impregnation method)
A.7.1 Preparation of Samples
After the galvanization, the steel tube shall perform galvanized coatings’ uniformity test.
Take two steel tubes from each batch at random; take one tube section which is not less than 150mm on each end of each steel tube; treat them as samples. Oil contamination on sample’s surface shall be cleaned out firstly, then use clean soft cloth to wipe it off.
Dissolve 33g of crystalline copper sulfate (CuSO4·5H2O) OR about 36g of industrial copper sulfate in 100mL of distilled water; then add excessive powdered copper hydroxide [Cu (OH)2] or alkaline copper carbonate (chemically pure) [ CuCO3-Cu (OH)2] to neutralize the free acid. If add copper hydroxide, it shall be about 10g in each 10L solution; if add alkaline copper carbonate; it shall be about 12g in each 10L solution. Judge that whether it is excessive or not according to the precipitation at the bottom of the container. At the same time, stir it adequately; then place it for 24h; filter it. If use powder copper oxide (CuO) to replace copper hydroxide, it shall be about 8g in each 10L solution, however, it shall be placed for 48h firstly and then shall be filtered. At 15 °C, density of the prepared test solution shall be 1.170 kg/dm3.
A.7.3 Test Container
A.7.3.1 For test containers, it shall choose the materials which is inert to copper sulphate.
A.7.3.2 For container’s internal dimensions, after the sample is immersed in the solution, it shall maintain the gap of at least 25mm from any wall of the container.
A.7.4 Test Procedure
A.7.4.1 Sample shall be downward based on the cut end. For the length which is immersed in the solution, it shall not be less than 100 mm. It shall be continuously immersed in copper sulfate solution for 5 times. During the test, sample’s and solution’s temperature shall maintain at 15°C~21°C, and they shall not be stirred. Impregnation time of the sample shall last for 1 min
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