GM 9540P PDF
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 In recent years GMP has been replaced by.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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Any option changes not called out specifically in this Appendix must be included on the engineering drawing.
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A siphon spray powered by oil-free regulated air or a hand operated pump spray may also be used. The bolt, nut and washers shall be made from a non black 99540p material, preferably nylon. 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 9540; Navy. Modify a garden duster to accept an air 940p connection where the manual pump lever is located remove the manual pump lever and attach a fitting to accept the air line.
The coupons serve to monitor the average general bare steel corrosion produced by the test environment. Engineering drawings and material specifications that reference this test procedure must specify the test duration, A, B, C or D or the number of test cycles as indicated in Table 1.
However, thicker coupon sizes should be used for tests with long durations. The ambient tm can be modified to include additional test inputs such as dust, grit sprays, mechanical cycling, electrical cycling, thermal inputs, grayelometer and acid rain spray.
The quantity of spray applied should be sufficient to rinse away any salt accumulation left from previous sprays. The test duration can be individually tailored to achieve g, desired level of corrosion exposure. The weight, in milligrams mgshall be recorded and retained for future reference. The humidity cabinet shall be as specified by GMP and Table 3. Test durations C and D or any modified test are to be used for validation and development purposes.
Four 4 coupon thicknesses are available 9540l shown in Table 2. See Table 4 for the steps that comprise the test method. Method Test specimens in the 5940p chamber are exposed to a changing climate that generally comprises of the following 3 part repeating cycle variations to this cycle are permitted depending on the type of component under test — refer to the full test standard for further guidance.
To analyze coupons remove 1 coupon from each end of the rack and prepare for weighing and gn loss determination. In recent years GMP has been replaced by its successor; GMW, but this is all but identical in terms of the test conditions required. A phase is made up of a predetermined number of cycles, 8 cycles constitute 1 phase. These methods should be used when reporting test results unless stated otherwise on drawings or agreed 954p by test requestor vm testor.
Garden dusters with an 8 mm diameter hole for dust application are recommended to achieve the appropriate level of dust application. Prior to start of test, prepare the coupon rack with sufficient coupons to monitor the test 4.
You need to upgrade your browser You are using Internet Explorer 8 This is considered an out of date browser. 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 gmm during this transition period.
If gravelometer exposure is required, test samples not coupons may be exposed to gravelometer testing per GMP before or during 95440p. A cycle normally requires 1 day to complete. 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 h, 1 phase is equal to 8 cycles. Additional options g be customized to specific components or subsystems to increase the ability to conduct validation or development testing.
Ambient Soak 8 h. Water fog or visible water droplets on parts – continuous after equilibrium is reached. Expected test duration to evaluate functional corrosion is 10 phases. Garden dusters from the following manufacturers could be modified: The latest revisions include: The number of cycle repeats and therefore the test duration is variable.
The dryoff 940p area shall be maintained 95540p sufficient air circulation to prevent temperature stratification, and also allow thorough drying of the material. The test can be started at any time with the understanding that 24 h constitutes 1 cycle. This method may involve hazardous materials, operations and equipment.
This process can be aided by using a commercial grade degreaser prior to methanol or acetone clean. Longer test durations C and D and tests involving modifications are to be used for validation purposes only. The solution shall be sprayed as a mist for example, from a plastic bottle onto the test samples and 5940p. Also, the reasons why the targeted value s was not obtained should be investigated and corrected before resuming the test.
The number of coupons required for different test durations are shown in Table 1.
GM P Cyclic Accelerated Corrosion Analysis of Nonchromate Conversion – Google Books
Refer to Table 2 for targeted mass loss values, in milligrams, for various test durations as a function of the coupon’s original thickness. Typical test duration is 4 cycles for tm dash mid to high mount locations and 12 cycles for floorpan low mount locations which approximately equals 10 yearscosmetic corrosion exposure. Wipe the coupons free of grit and weigh to determine the coupon mass loss using the formula: Test specimens in the enclosed chamber are exposed to a changing climate that generally comprises of the following 3 part repeating cycle variations to this cycle 95400p permitted depending on the type of component under test — refer to the full test standard for further guidance.
Typical Application 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. To check test progress and assure that the test is being run correctly, assume a linear corrosion rate.
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. Corrosion coupons shall be removed and analyzed after each phase throughout the test to monitor the corrosion. 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.
Though believed to be accurate at the time of writing, this may change over time.