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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 13912-2002 Metallic coatings - Hot dip galvanized coatings on fabricated iron and steel articles - Specifications and test methods. The following main technical changes have been made with respect to GB/T 13912-2002:
——3.16 “zinc melt” and 3.17” weld seepage” are added in “Terms and definitions”.
——4.2 “Base metal” in the original standard is included in 4.1 "General" of this standard; 4.1 “Information to be supplied by the purchaser” in the original standard is adjusted to Annex A of this standard.
——6.3 “Renovation of uncoated or damaged areas” in the original standard is adjusted to Annex E of this standard and supplemented.
——Clause 7 “Test method” in the original standard is canceled. 7.1 “Appearance test”, 7.3 “Adhesion test” and corresponding provisions in Clause 6 in the original standard are combined in this standard. 7.2 “Thickness measurement” in the original standard is adjusted to Annex D of this standard.
This standard has been redrafted and modified in relation to ISO 1461:2009 Hot dip galvanized coatings on fabricated iron and steel articles - Specifications and test methods.
Compared with ISO 1461:2009, this standard has been modified in structure by adjusting Annexes E and C of ISO 1461:2009 to Annexes C and E of this standard respectively.
The main technical deviations with respect to ISO 1461:2009 and their justifications are as follows:
——the adjustments of technical deviations are made for the normative references in this standard so as to adapt to the technical conditions of China. The adjustments are mainly reflected in Clause 2 "Normative references", which are shown in the following:
● ISO 752 is replaced by GB/T 470 which is modified in relation to the international standard (see 4.2);
● ISO 2859-1 is replaced by GB/T 2828.1 which is identical to the international standard (see 6.2.3);
● ISO 2859-2 is replaced by GB/T 2828.2 which is not identical to the international standard (see 6.2.3);
● ISO 2859-3 is replaced by GB/T 2828.3 which is identical to the international standard (see 6.2.3);
● ISO 2178 is replaced by GB/T 4956 which is identical to the international standard (see 6.2.2);
● ISO 3882 is replaced by GB/T 6463 which is identical to the international standard (see 6.2.2);
● ISO 2064 is replaced by GB/T 12334 which is identical to the international standard (see Clause 3);
● ISO 2808 is replaced by GB/T 13452.2 which is identical to the international standard (see 6.2.2);
● ISO 1460 is replaced by GB/T 13825 which is identical to the international standard (see 6.2.2);
● ISO 10474 is replaced by GB/T 18253 which is identical to the international standard (see Clause 7).
The following editorial changes have been made in this standard:
——standard name is changed as Metallic coatings - Hot dip galvanized coatings on fabricated iron and steel articles - Specifications and test methods;
——the contents of Clause 1 "Scope" are appropriately supplemented and adjusted according to GB/T 1.1-2009;
——Annexes C and E are adjusted according to the sequence mentioned in the text.
This standard was proposed by China Machinery Industry Federation.
This standard is under the jurisdiction of the National Technical Committee on Metallic and Non-metallic Coating of Standardization Administration of China (SAC/TC 57).
The previous editions of this standard are as follows:
——GB/T 13912-1992, GB/T 13912-2002.
Metallic coatings - Hot dip galvanized coatings on fabricated iron and steel articles - Specifications and test methods
1 Scope
This standard specifies the specifications and test methods for hot dip galvanized coatings on fabricated iron and steel articles. After-treatment/over-coating of hot dip galvanized articles is not covered in this standard.
This standard is applicable to hot dip galvanized coatings (containing not more than 2% of other metals) on fabricated iron and steel articles (including certain castings). It is not applicable to the following:
a) sheet, wire and woven or welded mesh products that are continuously hot dip galvanized;
b) tube and pipe that are hot dip galvanized in automatic plants;
c) hot dip galvanized products (e.g. fasteners) for which specific standards exist and which might include additional requirements or requirements which are different from those of this standard.
Note: Individual product standards may incorporate this standard for the coating by quoting its number, or may incorporate it with modifications specific to the product. Different requirements may also be made for galvanized coatings on products intended to meet specific regulatory requirements.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 470 Zinc ingots (GB/T 470-2008, ISO 752:2004, MOD)
GB/T 2828.1 Sampling procedures for inspection by attributes - Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection (GB/T 2828.1-2012, ISO 2859-1:1999, IDT)
GB/T 2828.2 Sampling procedures for inspection by attributes - Part 2: Sampling plans indexed by limiting quality (LQ) for isolated lot inspection (GB/T 2828.2-2008, ISO 2859-2:1985, NEQ)
GB/T 2828.3 Sampling procedures for inspection by attributes - Part 3: Skip-lot sampling procedures (GB/T 2828.3-2008, ISO 2859-3:2005, IDT)
GB/T 4956 Non-magnetic coatings on magnetic substrates - Measurement of coating thickness - Magnetic method (GB/T 4956-2003, ISO 2178:1982, IDT)
GB/T 6463 Metallic and other inorganic coatings - Review of methods of measurement of thickness (GB/T 6463-2005, ISO 3882:2003, IDT)
GB/T 12334 Metallic and other inorganic coatings - Definitions and conventions concerning the measurement of thickness (GB/T 12334-2001, idt ISO 2064:1996)
GB/T 13452.2 Paints and varnishes - Determination of film thickness (GB/T 13452.2-2008, ISO 2808:2007, IDT)
GB/T 13825 Metallic coatings - Hot dip galvanized coatings on ferrous materials - Gravimetric determination of the mass per unit area (GB/T 13825-2008, ISO 1460:1992, IDT)
GB/T 18253 Steel and steel products - Types of inspection documents (GB/T 18253-2018, ISO 10474: 2013, IDT)
ISO 3549 Zinc dust pigments for paints - Specifications and test methods
EN 1179 Zinc and zinc alloys - Primary zinc
EN 13283 Zinc and zinc alloys - Secondary zinc
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 12334 and the following apply.
3.1
hot dip galvanizing
formation of a coating of zinc and/or zinc iron alloys on iron and steel articles by dipping prepared steel or cast iron in a zinc melt
3.2
hot dip galvanized coating
coating of zinc and/or zinc iron alloys on iron and steel articles obtained by hot dip galvanizing
Note: The term “hot dip galvanized coating” is subsequently referred to as the “coating”.
3.3
coating mass
total mass of zinc and/or zinc alloys per area of iron and steel product surface, expressed in g/m2
?
3.4
coating thickness
total thickness of zinc and/or zinc alloys on steel and iron surface, expressed in μm
3.5
significant surface
part of the article covered or to be covered by the hot dip galvanized coating and for which the coating is essential for appearance and/or serviceability
3.6
control sample
hot dip galvanized article or group of articles from an inspection lot that is selected for sampling
3.7
reference area
area within which a specific number of single measurements are made
3.8
local coating thickness
mean value of coating thickness obtained from the specific number of measurements within a reference area for a magnetic test or the single value from a gravimetric test
3.9
mean coating thickness
mean value of the local thickness of the coating measured after sampling a “large” article or a lot of galvanized articles
Note: “Large” article herein refers to the article with significant surface larger than 2m2 (see 6.2).
3.10
local coating mass
value of coating mass for an area obtained from a single gravimetric test
3.11
mean coating mass
mean value of the coating masses determined by using the sample selected in accordance with Clause 5 in a gravimetric test in GB/T 13825 or by conversion of the mean coating thickness
3.12
minimum value of the coating thickness
lowest single measurement in a gravimetric test or lowest mean obtained from the specified number of measurements in a magnetic test within a reference area
3.13
inspection lot
hot dip galvanized articles in single order or single delivery
Note: The term “inspection lot” is subsequently referred to as the “lot”.
3.14
acceptance inspection
inspection of an inspection lot at the hot dip galvanizing works, unless otherwise specified
3.15
uncoated areas
areas on the iron or steel articles that do not react with the zinc melt
3.16
zinc melt
molten mass containing primarily zinc
3.17
weld seepage
emission of previously retained pretreatment solutions from narrow spaces between two closely contacting surfaces that have been subject to intermittent welding or from very small cavities (pinholes) in the welds of a galvanized article
4 General requirements
4.1 General
This standard sets out requirements for the contents of the zinc melt used to apply a galvanized coating to articles (see 4.2). The chemical composition and the surface condition (finish and roughness) of the base metal, the mass of the articles and the galvanizing conditions may affect the appearance, thickness, texture and physical/mechanical properties of the coating. This standard does not define any requirements regarding these points. Guidance on these parameters may be found in GB/T 19355.2[7].
4.2 Hot dip galvanizing bath
The hot dip galvanizing bath shall primarily contain zinc melt. The total of the other elements (as identified in GB/T 470, EN 13283 or EN 1179) in the zinc melt shall not exceed 1.5% by mass.
4.3 Information to be supplied by the purchaser
The information listed in A.1 and A.2 of Annex A shall be supplied by the purchaser.
4.4 Safety
Safety measures shall be provided in the manufacturing of hot dip galvanized articles.
5 Acceptance inspection and sampling
Acceptance inspection shall be undertaken before the products leave the hot dip galvanizing works, unless otherwise specified at the time of ordering by the purchaser. Acceptance inspection involves assessment of the coating appearance and measurement of the coating thickness. Adhesion tests are normally not carried out and are only carried out by agreement.
The control sample for coating thickness test shall be taken randomly from each inspection lot (see 3.13), and the minimum number of articles from each inspection lot that forms the control sample shall be in accordance with Table 1.
Foreword i
1 Scope
2 Normative References
3 Terms and definitions
4 General requirements
4.1 General
4.2 Hot dip galvanizing bath
4.3 Information to be supplied by the purchaser
4.4 Safety
5 Acceptance inspection and sampling
6 Coating requirements
6.1 Appearance
6.2 Thickness
6.3 Renovation
6.4 Adhesion
6.5 Acceptance criteria
7 Certificate of compliance
Annex A (Normative) Information to be supplied
Annex B (Normative) Safety requirements
Annex C (Informative) Corrosion resistance of hot dip galvanized coatings
Annex D (Informative) Determination of thickness
Annex E (Informative) Renovation of uncoated or damaged areas
Bibliography
金屬覆蓋層 鋼鐵制件熱浸鍍鋅層
技術要求及試驗方法
1 范圍
本標準規定了鋼鐵制件熱浸鍍鋅層的技術要求和試驗方法。本標準對熱浸鍍鋅產品的后處理和保護涂層未做規定。
本標準適用于鋼鐵制件(包括某些鑄件)的熱浸鍍鋅層(其他合金元素總含量不超過2%)。本標準不適用于下列情況：
a) 連續式熱浸鍍鋅生產的板材、線材、編織物或焊接網；
b) 自動化設備熱浸鍍鋅生產的管材和棒材；
c) 采用特殊標準的熱浸鍍鋅產品(如緊固件)、有附加要求或有與本標準要求不一致的熱浸鍍鋅產品。
注：某些產品標準可能通過引用本標準或修改本標準部分條款來規定其產品的熱浸鍍層要求。也可以對產品的鍍鋅層做出不同規定以滿足特定的要求。
2 規范性引用文件
下列文件對于本文件的應用是必不可少的。凡是注日期的引用文件，僅注日期的版本適用于本文件。凡是不注日期的引用文件，其最新版本(包括所有的修改單)適用于本文件。
GB/T 470 鋅錠(GB/T 470—2008，ISO 752：2004，MOD)
GB/T 2828.1 計數抽樣檢驗程序 第1部分：按接收質量限(AQL)檢索的逐批檢驗抽樣計劃(GB/T 2828.1—2012，ISO 2859-1：1999，IDT)
GB/T 2828.2 計數抽樣檢驗程序 第2部分：按極限質量(LQ)檢索的孤立批檢驗抽樣方案(GB/T 2828.2—2008，ISO 2859-2：1985，NEQ)
GB/T 2828.3 計數抽樣檢驗程序 第3部分：跳批抽樣程序(GB/T 2828.3—2008，ISO 2859-3：2005，IDT)
GB/T 4956 磁性基體上非磁性覆蓋層 覆蓋層厚度測量 磁性法(GB/T 4956—2003，ISO 2178：1982，IDT)
GB/T 6463 金屬和其他無機覆蓋層厚度測量方法評述(GB/T 6463—2005，ISO 3882：2003，IDT)
GB/T 12334 金屬和其他非有機覆蓋層 關于厚度測量的定義和一般規則(GB/T 12334—2001，idt ISO 2064：1996)
GB/T 13452.2 色漆和清漆 漆膜厚度的測定(GB/T 13452.2—2008，ISO 2808：2007，IDT)
GB/T 13825 金屬覆蓋層 黑色金屬材料熱鍍鋅層 單位面積質量稱量法(GB/T 13825—2008，ISO 1460：1992，IDT)
GB/T 18253 鋼及鋼產品 檢驗文件的類型(GB/T 18253—2018，ISO 10474：2013，IDT)ISO 3549 色漆用鋅粉顏料 規范和試驗方法(Zinc dust pigments for paints—Specifications and test methods)
EN 1179 鋅及鋅合金 初級鋅(Zinc an zinc alloys—Primary zinc)
EN 13283 鋅及鋅合金 二次鋅(Zinc and zinc alloys—Secondary zinc)
3 術語和定義
GB/T 12334界定的以及下列術語和定義適用于本文件。
3.1
熱浸鍍鋅 hot dip galvanizing
將經過前處理的鋼或鑄鐵制件浸入熔融的鋅浴中，在其表面形成鋅和(或)鋅-鐵合金鍍層的工藝過程和方法。
3.2
熱浸鍍鋅層 hot dip galvanized coating
采用熱浸鍍鋅方法在鋼鐵件表面上獲得的鋅和(或)鋅-鐵合金鍍層。
注：在本標準中簡稱鍍層。
3.3
鍍層的鍍覆量 coating mass
鋼鐵表面上單位面積鋅和(或)鋅-鐵合金鍍層的總質量，以g/m2 表示。
3.4
鍍層厚度 coating thickness
鋼鐵表面上鋅和(或)鋅-鐵合金鍍層的總厚度，以μm 表示。
3.5
主要表面 significant surface
制件上被熱浸鍍鋅或將被熱浸鍍鋅的部分表面，該部分表面上的鍍層對于制件的外觀和(或)使用性能是極為重要的。
3.6
樣本 control sample
從檢查批中隨機抽取用于試驗的熱浸鍍鋅制件或制件組。
3.7
基本測量面 reference area
按規定次數進行檢測試驗的區域。
3.8
鍍層局部厚度 local coating thickness
在某一基本測量面按規定次數用磁性法所測得的鍍層厚度的算術平均值或用稱量法進行一次測量所測得的鍍層鍍覆量的厚度換算值。
3.9
鍍層平均厚度 mean coating thickness
對某一大件或某一批鍍鋅件抽樣后測得鍍層局部厚度的算術平均值。
注：本標準中大件是指主要表面大于2m2 的制件(見6.2)。
3.10
鍍層局部鍍覆量 local coating mass
采用稱量法進行一次測量所測得的某一區域鍍層的鍍覆量。
3.11
鍍層平均鍍覆量 mean coating mass
按第5章規定抽樣，用GB/T 13825規定的稱量法測得的鍍層局部鍍覆量的算術平均值，或鍍層平均厚度的換算值。
3.12
鍍層厚度最小值 minimum value of the coating thickness
在基本測量面上用稱量法測得的鍍層鍍覆量厚度換算值中的最小值，或按規定次數用磁性法所測得的鍍層厚度的算術平均值中的最小值。
3.13
檢查批 inspection lot
一次訂貨或一次交貨的熱浸鍍鋅制件。
注：在本標準中簡稱批。
3.14
驗收檢查 acceptance inspection
在沒有其他規定的情況下，應在熱浸鍍鋅生產廠家內對某檢查批的熱浸鍍鋅制件進行的檢查。
3.15
漏鍍面 uncoated areas
鋼鐵制件表面未與熔融鋅發生反應的區域。
3.16
熔融鋅 zinc melt
主要包含鋅的熔融體。
3.17
焊縫滲流 weld seepage
熱浸鍍鋅制件焊接處，之前殘留的預處理溶液從兩個交疊表面之間不連續焊接造成的狹窄空間或焊縫中極小的孔洞(針孔)中流出。
4 一般要求
4.1 概述
本標準規定了用于制件熱浸鍍鋅層熔融鋅的含量要求(見4.2)。基體金屬的化學成分、表面狀況(光潔度和粗糙度)、制件的質量及鍍鋅條件都可能影響鋅鍍層的外觀、厚度、組織結構和物理/機械性能。本標準沒有對這些影響因素提出具體要求，可以參考GB/T 19355.2[7]。
4.2 熱浸鍍鋅浴
用于熱浸鍍鋅的鋅浴主要應由熔融鋅構成。熔融鋅中的雜質總含量不應超過總質量的1.5%(所指雜質見GB/T 470、EN 13283或EN 1179規定)。
4.3 需方應提供的資料
需方應提供附錄A 中A.1和A.2所列的資料。
4.4 安全
在熱浸鍍鋅的生產過程中應按附錄B的要求采取安全措施。
5 驗收和抽樣
除非訂貨時需方提出其他要求，驗收檢查應在產品離開鍍鋅廠家之前進行。驗收包括鍍層外觀評定和鍍層厚度測量。鍍層附著力通常不測試，或者只是根據供需雙方協議進行測試。
用于鍍層厚度試驗的樣本應從每一檢查批(見3.13)中隨機抽取，應按表1要求從每一檢查批中抽取不少于最小數量的制件組成樣本。
表1 檢查批對照樣本數量
檢查批的制件數量 樣本所需制件的最小數量
1~3 全部
4~500 3
501~1200 5
1201~3200 8
3201~10000 13
>10000 20
6 鍍層的要求
6.1 外觀
驗收檢查時，采用正常或矯正視力在1m 以上距離目測所有熱浸鍍鋅制件，其主要表面(見3.5)應平滑，無滴瘤、粗糙和鋅刺(如果這些鋅刺會造成傷害)，無起皮(即下層無固體金屬的凸起區域)，無漏鍍，無殘留的溶劑渣。
熱浸鍍鋅層主要用于防止基體鋼鐵制件腐蝕，其美觀和裝飾性是次要的。如果在某些應用場合這些次要特性也很重要時，非常建議供需雙方根據所達成的鐵或鋼制件(全部或部分)的光潔度標準，來確定鋼鐵制件所用的原材料成分范圍。當要求的光潔度標準超出本條的規定時，這一點尤其重要。需要注意的是，“粗糙”和“平滑”是相對概念，制件鍍層的粗糙度不同于經機械輥擠的鍍鋅制品(如鍍鋅鋼板、管材和鍍鋅鋼絲)的粗糙度。
只要鍍層厚度大于規定值，被鍍制件表面允許存在暗灰色或淺灰色的色彩不均勻區域(如網狀花紋或暗灰色的區域)。潮濕條件下儲存的鍍鋅制件，表面允許有白銹(以堿式氧化鋅為主的白色或灰色產物)存在。
注：在某些情況下(例如，熱浸鍍鋅制件需后處理或附加涂層時)，需方可向供方提出要求：
a) 鍍鋅后不進行水冷，和/或
b) 在儲運過程中采取相應措施防止鍍鋅層表面腐蝕。
熱浸鍍鋅制件表面不允許殘存熔劑渣。可能影響熱浸鍍鋅制件的使用或耐蝕性能的部位不應有鋅瘤和鋅灰(參見GB/T 19355.1[6]耐腐蝕性能數據)。
在交疊表面焊接中因使用不連續焊接而使鍍層美觀受到影響(如焊縫滲流)不應視為拒收的理由。使用這種焊接方式通常是出于健康和安全考慮，詳細指南參見GB/T 19355.2[7]。
目測外觀，檢查不合格的制件應依照6.3進行修復或重鍍后再重新檢查。
若有特殊要求時(例如，熱浸鍍鋅后需要涂裝的)，應按需方要求提供樣本[見A.2f)]。
6.2 厚度
6.2.1 概述
熱浸鍍鋅層是為了保護鋼鐵產品不受腐蝕而設計的(參見附錄C)。這種鍍層的防腐時間長短基本與鍍層厚度成正比(參見GB/T 19355.1[6])。在極嚴酷的腐蝕條件下服役和(或)要求較長服役時間的制件，其鍍層厚度要求可以高于本標準的規定要求。
6.2.2 試驗方法
當試驗方法存在異議時，鍍層厚度的計算方法應按GB/T 13825規定的熱鍍鋅層單位面積稱量法進行試驗。采用稱量法測得每單位面積上的平均鍍層質量，再根據鍍層的公稱密度(7.2g/cm3)計算鍍層厚度。當制件數少于10件時，需方可以不采納稱量法測量厚度，因為采用稱量法可能破壞制件，給需方造成不可補救的經濟損失。
厚度測量(參見附錄D)通常由GB/T 13452.2和GB/T 4956規定的(或在GB/T 6463中指定)磁性方法之一進行。磁性法測量儀可測定永磁體和基體金屬的磁引力，該磁引力受鍍層的影響，或測定穿過鍍層和基體金屬的磁通路徑磁阻。可選擇方法有稱量法和橫斷面顯微鏡法(參見附錄D)。
在GB/T 4956、GB/T 6463和GB/T 13452.2中規定的測試方法最適合在工廠內進行在線質量控制。由于該方法測量的每個區域都非常小，個別測量值可能低于鍍層的局部厚度或平均厚度值。如果用磁性法在一個基本測量面內進行了足夠次數的測量，測得的局部厚度值將趨近于用稱量法測得的局部厚度值。
6.2.3 基本測量面
為了獲得盡可能具有代表性的鍍層平均厚度(見3.9)或鍍覆量(見3.11)，采用磁性法或稱量法測量鍍層厚度時，基本測量面的數量、位置及尺寸應根據制件形狀和大小確定。對樣本中較長制件，其基本測量面應在離其每端大約100mm、大致接近中心線的位置獲取，并應包括制件的整個橫截面。
