1、Designation: D7376 10a (Reapproved 2016)Standard Practice forOutdoor Evaluation of Wet Stack Storage Conditions onCoil-Coated Metals1This standard is issued under the fixed designation D7376; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice is used to determine the resistance tocorrosion and blistering of coil-coated metal
3、 products relativeto one another when stacked outdoors under direct weatheringconditions in which they are wetted by rain and dew.1.2 The coil-coated product variables evaluated mayinclude, but are not limited to, substrates, pretreatments,primers, topcoats, and backers.1.3 This test simulates a sta
4、cked building panel bundlestored at a job site in wet outdoor conditions. The results frompanels tested during the same time period at the same physicallocation may be used to compare products as an indicator ofrelative field performance. Environments with higher tempera-ture and moisture levels acc
5、elerate corrosion and blistering.1.4 This standard does not endorse the storage of level (thatis, 0 from horizontal) building panels stacks in wet outdoorconditions. Level storage of building panels is not recom-mended and is used in this standard for evaluation only.1.5 The values stated in SI unit
6、s are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health prac
7、tices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D610 Practice for Evaluating Degree of Rusting on PaintedSteel SurfacesD714 Test Method for Evaluating Degree of Blistering ofPaintsD1654 Test Method for Evaluation of Painted or
8、CoatedSpecimens Subjected to Corrosive EnvironmentsG7 Practice for Atmospheric Environmental Exposure Test-ing of Nonmetallic Materials3. Summary of Practice3.1 This practice is for the evaluation of relative resistanceto wet stack corrosion and blistering of coil-coated metal. Thetest is to be cond
9、ucted in an outdoor environment withcoil-coated panels placed on a flat surface while allowingexposure to direct weather conditions including rain, dew, andsolar radiation.3.2 It is necessary to expose negative controls in each testrun, that is, products with known resistance to corrosion andblister
10、ing in this location, at the same time as the test productto determine its resistance relative to controls.3.3 Panels are evaluated periodically for corrosion andblistering as specified in 6.7.4. Significance and Use4.1 This practice provides for periodic testing for resistanceto wet conditions duri
11、ng storage to compare the relativeperformance of specific combinations of coatings, substrates,and/or pretreatments used on coil-coated metal. The resultsmust be considered relative and do not indicate absoluteperformance.4.2 When stored improperly, coil-coated building panelstacks can be exposed to
12、 rainwater, which flows into gapsbetween panels by capillary action or gravity, and remains inthe gaps because of poor drainage conditions. Such a conditionis known as a “wet stack” and may cause blistering andcorrosion of the painted surfaces. This practice simulates suchimproper storage conditions
13、.4.3 Because the outdoor environment shows year-to-yearseasonal and geographic climate variation, the absolute amountof degradation based on corrosion and blistering may vary (seeAppendix X1).1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and
14、Applications and is the direct responsibility ofSubcommittee D01.53 on Coil Coated Metal.Current edition approved April 1, 2016. Published June 2016. Originallyapproved in 2007. Last previous edition approved in 2010 as D7376 10a. DOI:10.1520/D7376-10AR16.2For referenced ASTM standards, visit the AS
15、TM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Unite
16、d States14.4 Temperature, rain, humidity, and storage practices areimportant factors in wet stack corrosion. Corrosion and blis-tering will accelerate with increased temperature. The pre-ferred test location is south of 27N latitude in Florida. Otherlocations may be used, but differences in temperat
17、ure andmoisture must be considered, and the amount of corrosion andblistering are expected to vary considerably with climate. Testsites must have the instrumentation to measure and recordambient temperature and rainfall as in Practice G7.4.5 This practice is not meant to support the field storage of
18、coil-coated metal in any way other than what is recommendedby the manufacturer.5. Apparatus5.1 The use of a wooden or plastic pallet to stack the testpanels in a horizontal position is one way to ensure rain doesnot puddle around the panels. Rainwater and condensation flowdown the sides of the stack
19、s, and water is drawn betweenpanels by capillary action. Excess water will drain through theslats in the pallet (see Fig. 1).5.2 The pallet is recommended to be 61 cm to 91 cm (24 in.to 36 in.) from the ground and all foliage should be maintainedso that it does not create shade on or contact with th
20、e testpanels.5.3 Wooden two by four boards of approximate cross-sectional dimensions, 4 cm by 9 cm (1.5 in by 3.5 in.) and ofthe required length are placed on top of the stacks (see Fig. 1).The pallets and boards shall be composed of untreated wood toavoid any influence from the treatment.5.4 The ap
21、paratus shall be placed in an unsheltered locationthat is subject to direct weathering conditions including rain,dew, and solar radiation.6. Procedure6.1 A wooden pallet or some flat surface with slats for waterdrainage is assembled in the required location. See Section 5.6.2 Test panels shall be ga
22、thered and cut to the required size.A size of at least 15 cm by 15 cm (6 in. by 6 in.) is required.Duplicates of each panel are required to allow contact betweenthe topside and backside of the same sample Panels to becompared must be cut on the same metal shear with edge burrsoriented in the same di
23、rection. Edge results may be signifi-cantly influenced by burr differences. Corrosion ratings shallinclude any visible red or white corrosion products.6.3 A minimum of two extra panels shall be placed at thetop and two at the bottom of the stack to act as a barrier to anyinfluences from the wood or
24、water accumulation.6.4 The test panel numbers shall be recorded along withinformation such as coil line, paint code, substrate, primer,pretreatment, and date of test initiation.6.5 The test panels shall be stacked on top of one anotherwith the convex side facing upward against the backer of aduplica
25、te panel to form a panel pair. If available, a duplicatepair of panels is highly recommended. Negative controls arerequired in order to provide a reference point for test duration.6.6 Each stack of test panels shall be no greater than 5 cm(2 in.) in height and have no less than 8 panels and shall be
26、weighted down with a single wooden two by four withcross-sectional dimensions, 4 cm by 9 cm (1.5 in. by 3.5 in.) ontop of each stack or spanning two or more stacks. The negativecontrol shall be placed near the center of the stack.6.7 It is recommended that panels be evaluated for corrosionand bliste
27、ring monthly in accordance with Test Methods D610,D714, and D1654 Procedure B, until the negative controlshows blister failure. Longer test times will be required duringperiods of drought (see Appendix X1.) Evaluation of fieldcorrosion and blistering is considered to be the most appropri-ate for thi
28、s test, but edge results may also be assessed.7. Report7.1 The report section shall contain the following informa-tion when available. In many cases, specific information aboutthe materials used or preparation of the test specimens is notavailable to commercial testing agencies.7.1.1 Included in the
29、 test reports shall be the location wherethe test is performed, the start date of the test and the date ofthe evaluation.7.1.2 The test report shall include a measurement of totalrainfall and number of days with rain during the test period atthe test location. A rain day shall be considered any day
30、with0.8 mm (0.03 in.) or greater of rainfall accumulation.7.1.3 The test report shall include the average daily maxi-mum temperature and average daily minimum relative humid-ity during the test period.7.1.4 The test report shall include the manufacturer of theproduct and any experimental, raw materi
31、al, or coating processchanges for the product being tested.7.1.5 The test report shall include the coating paint code,substrate, primer, backer and pretreatment used. Dry filmcoating thickness (DFT) and pretreatment weight may also beimportant and should be reported, if available.7.1.6 Samples shall
32、 be evaluated for corrosion and blisters.Any notable changes shall be recorded. Corrosion and blisters,NoteLevel position for test purposes only. Level storage of building panels inwet conditions is not recommended.FIG. 1 Illustration of Wet Stack Test Placed Horizontally (Level)on a PalletD7376 10a
33、 (2016)2including any red or white corrosion products, shall be rated inaccordance with Test Methods D1654, Procedure B, D610, andD714. The results from duplicate pairs of panels shall bereported separately to illustrate test variability, if any.7.1.7 A statement of compliance shall be noted and any
34、exceptions to the procedure shall be noted in the report.8. Keywords8.1 blistering; coil-coated; corrosion; wet stackAPPENDIX(Nonmandatory Information)X1. DETERMINATION OF TEST DURATIONX1.1 Outdoor wet stack testing relies on rainfall to supplywater for absorption into the stacked metal by capillary
35、 action.To some extent, dew contributes to wetness, but the rain is theprimary source of water. Because rainfall plays a major role inoutdoor wet stack testing, the seasonal and interannual (year-to-year) variability of rainfall at a given location represents amajor influence on test results from ru
36、n-to-run. Although thestandard is concerned with the relative performance of coil-coated samples, and the inclusion of a negative control withknown performance is required (see 6.5), the influence ofrainfall cannot be ignored, especially during periods of droughtwhen little or no rainfall may occur
37、at a given location. Thiscommentary is intended to provide a benchmark for rainfall ina location where the test has been run successfully.X1.2 As an example of a preferred location and test period,Fort Myers, Florida is used. It is a location south of 27Nlatitude as recommended in Section 4. Based o
38、n 30-yearrainfall data from Fort Myers Page Field, the six-month periodwith the greatest rainfall is represented by the months of Maythrough October. During the 30-year time period from 1971 to2000, the total average rainfall for these six months was 42.16in. These six months also correspond to the
39、time period ofhighest average temperature, which is also an influence on therate of corrosion and blister formation. Hence, the preferredtest period is May through October in Florida, south of 27Nlatitude, and a benchmark for total rainfall during the testperiod is 42.16 in. If the test is run in a
40、different climate withdifferent rainfall and temperatures, the time to failure for thenegative control is expected to differ accordingly.X1.3 Because of the spatial variability of rainfall on thekilometer and even sub-kilometer scale, section 4.4 requiresthat test sites have instrumentation to measu
41、re rainfall. A“local” weather reporting station, for example, may be morethan 5 kilometers from a test site, and rainfall may differsignificantly between the two sites over short time periods. Theaccuracy of the measurements (for example, in hundredths) arenot as critical as the number of days with
42、rainfall in a giventime period. Section 7 requires that the total rainfall andnumber of days with rainfall be recorded for the test period.X1.4 If the test is to be run at a location other than southFlorida where no benchmark for rainfall exists, the use of anegative control to verify failure would
43、be the only means ofdetermining the appropriate test duration. The total test timeshall be defined by the time that it takes to observe blisteringon the negative control. This would be some minimum level offailure, such as few #8 blisters as defined by Test MethodD714.ASTM International takes no pos
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