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 In recent years GMP has been replaced by.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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If gravelometer exposure is required, test samples not coupons may be exposed to gravelometer testing per GMP before or during exposure. The number of coupons required for different test durations are shown 9540o Table 1. Prior to start of test, prepare the coupon rack with sufficient coupons to monitor the test 4. Additional options can be customized to specific components or subsystems to increase the ability to conduct validation or development testing.
Any option changes not called out specifically in this Appendix must be included on the engineering drawing. 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.
Ramp time is to be included as part of the specified exposure period. See Table 4 for the steps that comprise the test method.
GMP | Standards | Ascott Analytical
If all solid materials are added dryan insoluble precipitate may result 3. Both are excellent browsers. The solution shall be sprayed as a mist for example, from a plastic bottle onto the test samples and coupons. 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. This website has been developed with modern browsers in mind to allow it to display at its best in a wide variety of viewing situations – including mobile viewing.
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. This is considered an out of date browser.
GM P Cyclic Accelerated Corrosion Analysis of Nonchromate Conversion – Google Books
These methods should be used when gn test results unless stated otherwise on drawings or agreed upon by test requestor and testor. 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.
However, thicker coupon sizes should be used for tests with long durations. A siphon spray powered by oil-free regulated air or a hand operated pump spray may also be used.
Bm note The test standard summaries are for general guidance only. It requires a 16 h work day or an automatic cycling test chamber. It is the responsibility of the user of this method to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Humidity ramp times between the ambient and wet condition and between the wet and gk conditions are critical to test acceleration this is gj corrosion rates are highest during this transition period.
The spray nozzle shall be such that the salt solution is atomized into a mist as required.
To analyze coupons remove 1 coupon from each end of the rack and prepare for weighing and mass loss determination. The bolt, nut and washers shall be made from a non gk plastic material, preferably nylon. The test consists of alternating wet and dry cycles with precisely prepared salt solution. The temperature and humidity conditions are shown in Table 3.
The test sample s shall be inspected for corrosion and photographed at the end of predetermined cycles. Four 4 coupon thicknesses are available as shown in Table 2.
This method also includes measurement of corrosion creepback from a scribe line, and describes how to evaluate corrosion formation in unscribed areas. These procedure modifications are based on field knowledge combined with engineering judgment to enhance the test’s ability to predict field performance.
See Appendix A for typical modifications. Bm dusters from the following manufacturers could be modified: Ambient Soak 8 h. This procedure describes an accelerated laboratory corrosion test method to evaluate assemblies and components. Though believed to be accurate at the time of writing, this may change over time.
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Test samples shall be representative of production intent. This process can be aided by using a commercial grade degreaser prior to methanol or acetone clean. Longer test 940p C and D and tests involving modifications are to be used for validation purposes only.
Do not intermix different coupon thickness on the same coupon rack. Typical Application Originally developed by General Motors the standard has gained popularity for corrosion tests within 950p automotive industry and has also become the preferred corrosion test of the US Navy.