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 In recent years GMP has been replaced by.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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Coupons consist of The ambient shift can be modified to include additional test inputs such as dust, grit sprays, mechanical cycling, electrical cycling, thermal inputs, grayelometer and acid rain spray. At the option of the test requester, the test can be continued throughout weekends to decrease the over all test time. In this context they can be considered to be equivalent and interchangeable terms. Test durations A and B can be used as both QC tests and validation tests depending on the purpose of the test.

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To analyze coupons remove 1 coupon from each end of the rack and prepare for weighing and mass loss determination. If the actual mass loss does not coincide with the targeted values listed in Table 2 the test should be repeated. A siphon spray powered by oil-free regulated air or a hand operated pump spray may also be used.

Ambient Soak 8 h. The number of cycle repeats and therefore the test duration is variable. Test durations A and B can be used for quality control and validation procedures as appropriate. The coupon mass loss values shown in Table 2 are used to verify that the correct amount of corrosion has been produced by the test.

Repeat the cycle daily as necessary until the test duration requirements are met. The test is generally made up of 3 shifts: This procedure describes an accelerated laboratory corrosion test method to evaluate assemblies and components. Humidity ramp times between the ambient and wet condition and between the wet and dry conditions are critical to test acceleration this is because corrosion rates are highest during this transition period. The salt mist solution shall be as specified in Table 3.


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If a recorder is not in use, written documentation should be provided indicating typical steady state conditions and the ramp times between steady states conditions.

The test procedure provides a combination of cyclic conditions salt solution, various temperatures, humidity, and ambient environment to accelerate metallic corrosion. Garden dusters from 9540pp following manufacturers could be modified: See Appendix A for typical modifications. Please note The test standard summaries are for general guidance only.

GM P Cyclic Accelerated Corrosion Analysis of Nonchromate Conversion – Google Books

Expected test duration to evaluate functional corrosion is 10 phases. But we haven’t supported older browsers like IE8. Additional options can be customized to specific components or subsystems to increase the ability to conduct validation or development 954p.

Longer test durations C and D and tests involving modifications are to be 9504p for validation purposes only. The mist application occurs while the samples and coupons are in the ambient environment.

Though believed to be accurate at the time of writing, this may change over time. The weight, in milligrams mgshall be recorded and retained for future reference.

Do not intermix different coupon thickness on the same coupon rack. To check test progress and assure that the test is being run correctly, assume a linear corrosion rate. Hudson Sprayer, Hudson 9504p. Contact Ascott for Further Information. The bolt, nut and washers shall be made from a non black plastic material, preferably 9540o.

Test samples shall be representative of production intent. This method does not propose to address all the safety problems associated with its use.

The humidity cabinet shall be as specified by GMP ggm Table 3. This method may involve hazardous materials, operations and equipment. Originally developed by General Motors the standard has gained popularity for corrosion tests within the automotive industry and has also become the preferred corrosion test of the US Navy.

This study is a key reason why GMP became popular as an accelerated laboratory corrosion test for steel.


At the end of test the samples shall be rinsed with fresh tap water and allowed to dry before evaluating. This procedure supersedes any old procedures that may have referenced an “A” or “B” Test Method Method A is eliminated. If gravelometer exposure is required, test samples not coupons may be exposed to gravelometer testing per GMP before or during exposure.

In addition to the sample data and test 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. Ramp time is to be included as part of the specified exposure period. A cycle normally requires 1 day to complete. The test consists of alternating wet and dry cycles with precisely prepared salt solution.

GMP | Standards | Ascott Analytical

Refer to Table 2 for targeted mass loss values, in milligrams, for various test durations as a function of the coupon’s original thickness. Wipe the coupons free of grit and weigh to determine the coupon mass loss using 99540p formula: Use Option IV – for door detents without weatherseal protection Use Option VI – for door detents with weatherseal protection 1 test cycle is equal to 24 940p, 1 phase is equal to 8 cycles. However, thicker coupon sizes should be used for tests with long durations.

See Table 4 for the steps that comprise the test method. The spray nozzle shall be such that the salt solution is atomized into a mist as required. Any option changes not called out specifically in this Appendix must be included on the engineering drawing.

Also, the reasons why the targeted value s was not obtained should be investigated and corrected before resuming the test. It requires a 16 h work day or an automatic cycling test chamber.