GB/T18570 "Surface cleanliness assessment test for steel surface treatment before coating" is divided into 12 parts. This part is part 12 of GB/T18570. This part specifies the on-site titration method for the determination of soluble iron ions on the surface of steel before and after surface treatment. This method is mainly suitable for the evaluation of surface impurities. It is easy to operate for non-professionals and the accuracy can meet most practical purposes. This part is equivalent to ISO8502-12:2003 "Surface cleanliness assessment test for steel surface treatment before coating Part 12: On-site titration method for water-soluble iron ions" (English version). GB/T 18570.12-2008 Surface cleanliness assessment test for steel substrates before coating Part 12: On-site titration method for water-soluble iron ions GB/T18570.12-2008 Standard download decompression password: www.bzxz.net
GB/T18570 "Surface cleanliness assessment test for steel substrates before coating" is divided into 12 parts. This part is the 12th part of GB/T18570. This part specifies the on-site titration method for soluble iron ions on the surface of steel substrates before and after surface treatment. This method is mainly suitable for the evaluation of surface impurities. It is easy for non-professionals to operate and the accuracy can meet most practical purposes. This part is equivalent to ISO8502-12:2003 "Surface cleanliness assessment test for steel substrates before coating Part 12: On-site titration method for water-soluble iron ions" (English version).
class="f14" style="padding-top:10px; padding-left:12px; padding-bottom:10px;"> GB/T18570 "Surface preparation of steel before coating - Tests for the assessment of surface cleanliness" is divided into the following parts:
--- Part 1: Field test for soluble iron corrosion products (technical report);
--- Part 2: Laboratory determination of chloride on cleaned surfaces;
--- Part 3: Assessment of dust on steel surfaces before coating (pressure-sensitive adhesive tape method);
--- Part 4: Guidelines for the assessment of the possibility of condensation before coating;
--- Part 5: Determination of chloride on steel surfaces before coating (ion detector tube method);
--- Part 6: Bresle method for sampling soluble impurities;
---Part 7: Field determination of oils and fats;
---Part 8: Field refractometry of moisture;
---Part 9: Field conductivity determination of water-soluble salts;
---Part 10: Field titration of water-soluble chlorides;
---Part 11: Field turbidity determination of water-soluble sulfides;
---Part 12: Field titration of water-soluble iron ions;
---Part 13: Field conductivity determination of soluble salts. This part
is Part 12 of GB/T 18570.
This part is equivalent to ISO 8502-12:2003 "Surface preparation of steel before application of paint - Tests for the assessment of surface cleanliness - Part 12: Field titration of water-soluble iron ions" (English version).
This part is equivalent to ISO8502?12:2003.
For ease of use, the following editorial changes have been made to this part:
--- The term "this international standard" is changed to "this part";
--- The comma used as a decimal point is replaced by a decimal point.; ---
The comma used as a sub-statement is replaced by a semicolon,;
--- The table of contents, foreword and introduction of the international standard are deleted;
--- For clarity, add the number 4.1 and the title overview in the first paragraph of Chapter 4, and the subsequent number is modified accordingly; add the number and item number in Chapter 7.
This part is proposed by China State Shipbuilding Corporation.
This part is under the jurisdiction of the Technical Committee on Metal Surface Treatment Before Painting and Painting Technology of the National Technical Committee on Standardization of Paints and Pigments.
This part was drafted by China Shipbuilding Industry Comprehensive Technology and Economic Research Institute and the 11th Research Institute of China Shipbuilding Industry.
The main drafters of this part: Song Yanyuan, Liu Bingyang, Fu Jianhua.
The clauses in the following documents become clauses of this part through reference in this part of GB/T 18570. For any dated referenced document, all subsequent amendments (excluding errata) or revisions are not applicable to this part. However, parties to an agreement based on this part are encouraged to investigate whether the latest versions of these documents can be used. For any undated referenced document, the latest version applies to this part.
GB/T 18570.6-2005 Surface preparation of steel before coating - Tests for assessment of surface cleanliness - Part 6: Sampling of soluble impurities - Bresle method (ISO 8502?6:1995, IDT)
ISO 3696:19871)

ICS 25. 220. 10
National Standard of the People's Republic of China
GB/T18570.12—2008/IS0 8502-12.2003 Preparation of steel substrates before application of paints and related products --Tests for the assessment of surface cleanliness-Part 12: Ficld method for the titrimetric deternination ofwater-soluble ferrous ions
(IS0 GB/T 18570.12—2008/1S0 8502-12:2003 GB/T 18570 "Surface preparation of steel substrates before painting - Tests for the assessment of surface cleanliness" is divided into the following parts: Part 1, Field test of soluble iron corrosion products (technical report); Part 2: Laboratory determination of chloride on cleaned surfaces; Part 3: Assessment of dust on steel surfaces before painting (pressure-sensitive adhesive tape method); Part 4, Guidelines for the assessment of the possibility of condensation before painting; Part 5: Determination of chloride on steel surfaces before painting ( Ion detection tube method): Part 6: Bresle method for sampling soluble impurities; Part 7: On-site determination of oil and fat; Part 8: On-site refractometry of moisture; Part 9: On-site conductivity determination of water-soluble salts; ... Part 10: On-site titration determination of water-soluble chlorides; Part 11: On-site turbidity determination of water-soluble sulfides, Part 12: On-site titration determination of water-soluble iron ions; - Part 13: On-site conductivity determination of soluble salts. This part is Part 12 of GB/T18570. This part is equivalent to ISO8502-12:2003 "Surface cleanliness assessment test for steel surface treatment before coating Part 12
On-site titration determination of water-soluble iron ions" (English version): This part is equivalent to the translation of ISO8502-12:2003. For ease of use, the following editorial changes have been made to this part: the term "this international standard" has been changed to "this part" and the decimal point "\" has been used instead of the return sign "", and the comma "\\" has been used instead of the logical sign "," as a sub-statement; the table of contents, foreword and introduction of the international standard have been deleted: for clarity, the number "4.1\" and the title "Overview" have been added to the first paragraph of Chapter 4, and the subsequent numbering has been modified accordingly; the numbering and item numbering have been added to Chapter 7.
This part was proposed by China Shipbuilding Industry Corporation. This part was organized by the Technical Committee on Metal Surface Treatment Before Painting and Painting Technology of the National Technical Committee for the Promotion of Paint and Material Standards. The drafting units of this part are: China Shipbuilding Industry Comprehensive Technology and Economic Research Institute, China Shipbuilding Industry Tenth Research Institute. The main contributors to this part are: Rong Yanyuan, Liu Bingyang, and Fu Jianhua. (B/18570.12—2008/1S0 8502-12:2003 Surface preparation of steel before coating
Tests for assessment of surface cleanliness www.bzxz.net
Part 12: Determination of water-soluble iron ions by titration in situ
Notice: The method specified in this part of GB/T18570 requires titration with potassium dichromate solution. Although the small consumption and low concentration of this titrant are not sufficient to make it a hazard (if ingested), attention should be paid to relevant national or local regulations regarding the possible pollution and environmental hazards of this titrant.
1 Scope
This part of GB/118570 specifies the on-site titration method for the determination of water-soluble iron ions on the surface of steel before and after surface treatment. This method is mainly suitable for the evaluation of surface impurities, is easy for non-professionals to use, and can meet the needs of most people in practice. 2 Normative references
The clauses in the following documents become clauses of this part through reference in this part of GB/T 18570. For any dated referenced document, all subsequent amendments (excluding errors) or revisions are not applicable to this part. However, parties conducting research based on this part or the cooperation are encouraged to use the latest versions of these documents. For any undated referenced document, the latest version applies to this part.
GB/118570.6-2005 Test for assessment of surface cleanliness of steel surfaces before coating - Part 6: Surface cleanliness of soluble impurities - Sample Bressle method (ISO85026:1995.1DT) ISO3696:1987-3 Specification and test method for water for analytical tests 3 Principle
Use water as solvent and adopt the Bressle method (GB/T 18570.62C05) or other conventional methods to remove the surface of the material to be evaluated, after the impurities are removed, it is acidified with acid, and the iron ion concentration in the solution is determined by titration using dichromate solution as titrant and diphenylamine sulfonate as indicator. The appropriate titration volume, drop size and test surface area (usually 1250mm2) should be selected, so that the surface concentration of soluble iron ions can be obtained by multiplying the number of drops titrated by a simple conversion factor, reaction formula: Cr0,*GF14H+—-→2Cr-+6Fe-+7H,04 Reagents
4.1 Overview
During the analysis, the water used should meet the requirements of ISO3696:1987 for at least grade 3 purity. Note: Usually distilled water or cloud deionized water with a conductivity below 0.5mS/m5μS/cm meets this requirement. 4.2 Phosphoric acid solution (H:PO.)
Phosphoric acid solution is a deionized water solution with a concentration of 85%, and the volume ratio is 1:2 (1 part of phosphoric acid corresponds to 2 parts of water). 4.3 Indicator solution
The indicator solution is a colorless, 0.5% concentration of sodium diphenylamine sulfonate deionized water solution (CII, NIICH.SO.Na), stored in bottle A (5.2).
1) GB/T6682---1992 is equivalent to TSO3596:19871
GB/T18570.12—2008/ISO8502-12.2003irKoNiKAca=
To determine whether the indicator is oxidized, it should be titrated once a year, that is, the solution is used to titrate a sulfate solution, such as ordinary white water. 4.4 Potassium dichromate solution
The concentration of potassium dichromate solution is c(K2Crz0,)=0.002m1/L, which is used for titration and stored in bottle B (5.3). 5 Equipment
5.1 Plastic beaker
The volume of the plastic beaker is appropriate, usually 20 ml. 5.2 Bottle A
The volume of bottle A is about 30 mL, and it is equipped with a device that can titrate the indicator solution (4.2) drop by drop, with each drop of about 0.05tmL. 5.3 Bottle B
The volume of bottle B is about 30 mL, and it is equipped with a device that can titrate the titration solution (4.3) drop by drop, with each drop of (0.050±0.002)mL: 6 Removal of water-soluble impurities on the surface of steel
The water-soluble impurities on the surface of steel are removed by the Bresle method specified in GB/T18570.62005 or other conventional methods. When using the Bresle method, if there are no other requirements: use a plastic bag of model A-1250 (cavity area is 1250 tarn2). Regardless of the size of the plastic bag: the volume of the water solvent injected into the cavity of the plastic bag is proportional to the area of ​​the cavity, which is (2.5±0.5) μ/tmm. 7 Steps
7.1 According to the steps specified in Chapter 5 of GB/T18570.62005, collect the solution containing iron ions to be analyzed in a plastic beaker (5.1).
7.2 Add about 1 mL of the indicator solution (4.3) and carefully shake the plastic beaker to mix the solution. 7.3 Determine the iron ion concentration according to the following titration requirements: a) Add 4 ml of phosphoric acid solution (4.2) and shake the plastic beaker carefully to mix the solution evenly; add 1 drop of E (0.050 ± 0.002) mL) titration solution (4.4): b)
Slowly add the titration solution. After each drop, shake the plastic beaker slightly to change the color of the solution from colorless to light gray c)
blue to purple. Record the number of titrations required for the color change (excluding the first drop added as a blank). Note: The color change is not very obvious and will not change more when more drops are added. 8 Results Table
If A-1250 adhesive bag is used, Table 1 shows the relationship between the number of titration drops specified in Chapter 7 and the surface concentration of iron ions. The conversion factor is 27tmg/mm2 per drop
Table 1 Titration results
Surface concentration of iron ions
Number of titrations required by Chapter 7
GB/T18570.12--2008/IS08502-12:2003 If the perforation area of ​​the adhesive bag actually used is not less than 1250mm, multiply the result by the ratio of 1250 and the actual cavity area of ​​the adhesive bag used (in m\). The measurement result is expressed as the surface concentration value of iron ions in milligrams per square meter (mg/m2). 9
Precision
The precision of this method is determined based on the concentration of iron ions on the surface of steel (see Table 1). 10
Test report
The test report shall at least include the following contents: a) the standard number of this part (GB/T18570,12--2008); b)
all details necessary to mark the test surface; the method of removing soluble impurities from the steel surface; the area of ​​the test device;
test results, the surface concentration of iron ions measured in accordance with Chapter 8; the test period.
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