1、SSPC-PA 16September 25, 20121SSPC: The Society for Protective CoatingsMethod for Evaluating Scribe Undercutting on Coated Steel Test Panels Following Corrosion Testing1. Scope1.1 This standard allows the user to determine average undercutting values on coated steel test panels scribed in accordance
2、with Section 6 of ASTM D 1654. The standard includes requirements for data collection, analysis, and reporting. 1.2 This standard is applicable for evaluation of most types of protective coatings for use on steel. This standard is not applicable to evaluation of thermal sprayed metals and ceramic co
3、atings, hot-dip and electro-coated metal coatings, and tapes. 2. Referenced Standards2.1 The latest issue, revision, or amendment of the refer-enced standards in effect on the date of invitation to bid shall govern, unless otherwise specified. 2.2 If there is a conflict between the requirements of a
4、ny of the cited reference standards and this standard, the require-ments of this standard shall prevail.2.3 ASTM INTERNATIONAL STANDARDS:1D 1654 Standard Test Method for Evalua-tion of Painted or Coated Specimens Subjected to Corrosive EnvironmentsD 7087 Standard Test Method for An Imaging Technique
5、 to Measure Rust Creepage at Scribe on Coated Test Panels Subjected to Corrosive Environments3. Undercutting Evaluation ProceduresTwo procedures for measuring undercutting are allowed by this method. Data analysis and reporting requirements are identical for each procedure. 3.1 PROCEDURE 1: Nondestr
6、uctive method for interim measurements only. Undercutting is determined by measuring areas of rust creepage or missing, disbonding, or lifted coating along the scribe. Defects at the scribe having the appearance of a “blister” are also considered indicative of undercutting when using this standard.
7、Disregard corrosion products or 1 ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standards volume infor-mation, refer to the
8、 standards Document Summary page on the ASTM website.rust staining on the surface of the coating when making the measurements.3.2 PROCEDURE 2: Destructive method for final measure-ments. This procedure is suitable for evaluating coatings at the completion of testing. This is the default measurement
9、for final measurements unless Procedure 1 is specified. Undercutting is measured after removing the coating along the scribe by scraping or chiseling with a suitable instrument to completely expose the corroded area. Measure exposed areas of corrosion along the scribe. Disregard corrosion products o
10、r rust staining on the surface of the coating when making the measurements.4. Data Collection Procedures4.1 AVERAGE DISTANCE OF UNDERCUTTING CORROSION: Measure the distance of undercutting corro-sion along both the right side and the left side of each scribe, starting from the edge of the scribe. Ta
11、ke nine measurements on each side of each scribe at locations spaced at 10 mm inter-vals, disregarding the ends of the scribe line, such that a total of 18 data points (nine to the right of the scribe and nine to the left) are obtained for each scribe. Measured values shall be in whole millimeters u
12、nless otherwise specified. Measurement may be either direct using a ruled device, or indirect using cali-pers and a ruler.4.2 AREA OF UNDERCUTTING CORROSION: Unless otherwise specified, measure the total area of undercutting corrosion along the entire length of each scribe to the nearest whole milli
13、meter. To determine the area manually, overlay each scribe with a transparent grid (ruled in millimeters) and estimate the total area of undercutting corrosion to the nearest square millimeter. Alternatively, use digital imaging in accor-dance with ASTM D 7087 to directly or indirectly (using a trac
14、e of each area) measure the area of undercutting at each scribe. 5. Data Analysis and Reporting5.1 UNDERCUTTING CORROSION DISTANCE PARAM-ETER: Data points acquired according to the procedures in Section 4.1 are analyzed. Compute the mean (average), Xdand the standard deviation, 2Sdof the data. Compu
15、te the scribe undercutting distance parameter D, as the mean plus two standard deviations (D = Xd+ 2Sd). Report the number of data points, the value of each data point, mean undercut-ting distance, standard deviation, and undercutting distance parameter. SSPC-PA 16September 25, 20122Copyright SSPC s
16、tandards, guides, and technical reports are copyrighted world-wide by SSPC: The Society for Protective Coatings. Any photocopying, re-selling, or redistribution of these standards, guides, and technical reports by printed, electronic, or any other means is strictly prohibited without the express wri
17、tten consent of SSPC: The Society of Protective Coatings and a formal licensing agreement.5.2 UNDERCUTTING CORROSION AREA PARAM-ETER: Data points are acquired as described in Section 4.2 and analyzed. Compute the mean (average), and the standard deviation, 2Sa of the data. Compute the scribe undercu
18、tting area parameter A, as the mean plus two standard deviations (A = + 2Sa). Report the number of data points, the value of each data point, mean undercutting area, standard deviation, and undercutting area parameter. 6. Disclaimer6.1 While every precaution is taken to ensure that all information f
19、urnished in SSPC standards and specifications is as accurate, complete, and useful as possible, SSPC cannot assume responsibility nor incur any obligation resulting from the use of any materials, coatings, or methods specified herein, or of the specification or standard itself.6.2 This standard does
20、 not attempt to address prob-lems concerning safety associated with its use. The user of this standard, as well as the user of all products or practices described herein, is responsible for instituting appropriate health and safety practices and for ensuring compliance with all governmental regulations.XaXa
