This study is a key reason why GMP became popular as an accelerated laboratory corrosion test for steel. In recent years GMP has been replaced by. of the reference specimens in the as-received condition are in Figure 3. The salt fog test used an abbreviated procedure (Table 3) of the standard GMP test. Find the most up-to-date version of GMP at Engineering
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Four 4 95440p thicknesses are available as shown in Table 2. One 1 test cycle is equal to 24 h, 1 phase is equal to 8 cycles. Test durations A and B can be used for quality control and validation procedures as appropriate. It requires a 16 h work day or an automatic cycling test chamber. Additional options can be customized to specific components or subsystems to increase the ability to conduct validation or development testing.
The mg of cycle repeats and therefore the test duration is variable. Corrosion coupons shall be removed and analyzed after each phase throughout the test to monitor the corrosion. To check test progress and assure that the test is being run correctly, assume a linear corrosion rate. If possible, mount test specimens in a production representative orientation simulating onvehicle inputs e. If the actual mass loss does not coincide with the targeted values listed in Table 2 the test should be repeated.
GM P Cyclic Accelerated Corrosion Analysis of Nonchromate Conversion – Google Books
Modifications to the test may or may not attain equivalent levels of mass loss. This method may involve hazardous materials, operations and equipment. Test samples shall be representative of production intent.
Repeat the cycle daily as necessary until the test duration requirements are met. Wipe the coupons free of grit and weigh to determine the coupon mass loss using the formula: Test durations C and D or any modified test are to be used for validation and development purposes.
If a test is conducted with ramp times different than described above, the number of cycles to reach coupon mass loss targets may increase or decrease. Garden dusters from the following manufacturers could be modified: Typically, the time from ambient to the wet condition should be approximately 1 h and the transition time between wet and dry conditions should be approximately 3 h.
The latest revisions include: These methods should be used when reporting test results unless stated otherwise on drawings or agreed upon by test requestor and testor. The temperature and humidity conditions are shown in Table 3. If a recorder is fm in use, written documentation should be provided indicating typical steady state conditions and the ramp times between steady states conditions. Test Conditions The test consists of alternating wet and dry cycles with precisely prepared salt solution.
This procedure describes an accelerated laboratory corrosion test method to evaluate assemblies and components. A cycle is made up of the daily events or test inputs prescribed in Table 4.
Test durations A and B can be hm as both QC tests and validation tests depending on the purpose of the test. The test is generally made up of 3 shifts: If gravelometer exposure is ym, test samples not coupons may be exposed to gravelometer testing per GMP before or during exposure. At the end of test the samples shall be rinsed with fresh tap water and allowed to dry before evaluating. See Appendix A for typical modifications.
Though believed to be accurate at the time of writing, this may change over time. However, thicker 9450p sizes should be used for tests with long durations. In addition to the sample data and 5940p results, reports must indicate the total number of cycles run, any modifications to the test see Appendix Athe Equipment and Test Record Form Appendix B and should include photographic documentation and the coupon mass loss values. A phase is made up of a predetermined number of cycles, 8 cycles constitute 1 phase.
Contact Ascott for Further Information. See Table 4 for the steps that comprise the test method. Garden dusters with an 8 mm diameter hole for dust application are recommended to achieve the appropriate level of dust application. Typically no modifications of this shift. At the option of the test requester, the test can be continued throughout weekends to decrease the bm all test time.
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The spray nozzle shall be such that the salt solution is atomized into a mist as required. The quantity of spray applied should be sufficient to rinse away any salt accumulation left from previous sprays.
Originally developed by General Motors the standard has gained popularity for corrosion tests within the automotive industry and hm also become the preferred corrosion test of the US Navy.
The test duration is dictated by the number of test cycles. The test consists of alternating wet and dry 9540o with precisely prepared salt solution.