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Potential-pH Diagrams
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Intelligent Tools
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Corrosion Calculator
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Corrosion Economics Estimator
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TUTORIAL ON SEQEXPERTTM and the SEQUENTIAL IMMERSION TEST FOR SCREENING OF
NONMETALLIC MATERIALS
David C. Silverman
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Table of Contents
Using SEQEXPERT-a step-by-step procedure
This flow chart
provides an overview of your interaction with SEQEXPERT. This tutorial uses the following
example to give step-by-step instructions. Several non metallic elastomers were being
considered as gasket materials of construction to replace EPDM (ethylene propylene dimonomer)
exposed to a process fluid waste stream at a temperature of about 50°C. The reason
for the replacement was that periodic replacements were required for EPDM and less
maintenance was desired. EPDM was exposed to this process fluid and periodic changes
in mass were recorded following the protocol of the Sequential Immersion Test.
This figure
shows the resulting plot of mass change. In addition, the hardness
was recorded prior to starting the test and at the conclusion of the drying cycle.
Following is the procedure for using SEQEXPERT to make its prediction of the compatibility of
EPDM in this environment. The table below shows the values of the features that are to be used
by SEQEXPERT. They are explained in more detail in the section entitled "Features Useful for
Interpreting Sequential Immersion Test" as well as when you get to item 7 below.
When in SEQEXPERT, each of these items has a Help screen associated with it.
| Input Parameter |
Value |
| Weight ratio after soak cycle |
0.014 |
| Sign of weight ratio after soak cycle |
Positive |
| Weight ratio after dry cycle |
-0.02 |
| Sign of weight ratio after dry cycle |
Negative |
| Final curvature after soak cycle |
Far from equilibrium |
| Final Curvature after dry cycle |
Far from equilibrium |
| Hardness Change |
-10 (Shore Durometer A) |
Detailed Instructions
- SEQEXPERT is located at the web site www.argentumsolutions.com.
- Enter SEQEXPERT. On the left hand side of each page including this one is
a column with the heading “Intelligent Tools”. SEQEXPERT is the first icon listed.
Double left click on that icon. You are taken to an opening page which overlays the page
you are on. This page contains general information. When you have finished reading this
information, left click on the button labeled “Enter SEQEXPERT” at the top or bottom of the
page. This action takes you into the SEQEXPERT environment.
- If you wish, read the "Overview" and "Instructions" to get a brief introduction to
SEQEXPERT and what you are asked to do. If you wish to go immediately to the Instructions
click on the word "Instructions". Note that you can change an entry at any time before running
the tool.
- Enter your name, company affiliation, and email address. An example using Argentum
Solutions, Inc. is shown below. That information is only for internal identification and
will not be shared with anyone. It will aid in data retrieval in case you make an inquiry
about the results.
In SEQEXPERT:
- Fill in the type of material and any additional information about it you desire. For
this example EPDM is entered. Below this entry you are asked to examine mass fraction change
versus time plots that represent different degrees of approach to equilibrium for the soak and
dry cycles. Though four combinations of degree of approach (near or far) to equilibrium,
(e.g. soak near equilibrium and dry far from equilibrium, etc.) only two are shown (soak
and dry near equilibrium and soak and dry far from equilibrium). These plots are to be
used for guidance later in the program. You can come back to these diagrams at any point
when entering data.
In SEQEXPERT:
- Next you need to examine the specimen used in the test and select the condition that most
resembles the appearance after the experiment. This selection provides a consistency check,
between the prediction and the appearance of the specimen. In this case, the specimen
softened considerably from the original texture so the choice of "softened". If you select
"Help on this topic”, you are provided with some guidelines. If the appearance is other
than the descriptions is listed, type in the appearance. Selecting other only prevents
the consistency check from being made but still allows the prediction to be made.
In SEQEXPERT:
- At this point you are ready to enter the parameters that will be used as inputs to
the artificial neural network in SEQEXPERT. The values used for this example have been entered
in the spaces below. If you need additional information, a help window can be opened when
you select “Help on this topic” to provide more details. You can also scroll up to Step 2 and
expand the thumbnails to get more information. When filling in the final curvature, clicking
on “Figure showing behavior far from equilibrium” or Figure showing behavior near equilibrium”
will provide you with an idea of which selection to make with respect to curvature.
In SEQEXPERT:
- At this point, you are ready to run SEQEXPERT. If your inputs are as you want them,
click on the button labeled "Run SEQEXPERT" and the prediction will emerge on the next screen.
If you want to change one or several items, you can retype the entry or click on a different
selection depending on the step above. Only if you want to reenter ALL of your inputs should
you click on the button labeled "Start Over".
In SEQEXPERT:
- After you have clicked on "Run SEQEXPERT" a new screen appears which contains the
prediction and its consistency with the choice of the sample appearance. In this case,
EPDM is predicted not to be compatible with this environment in agreement with the
observations noted above. The wording also provides some additional information in
terms of watch-outs and possible additional testing the may be suggested from experience.
Farther down, the consistency check among the prediction, the scan appearance, and the
electrode appearance is provided. In this case, the material softened in agreement
with the prediction of the material not being compatible with the environment. Below
the predictions, you are asked to submit your comments. Your name, affiliation, and
email address information will already appear based on your original input in Step 1.
You are asked to fill in the space with any comments and click on the "Submit" button.
This information is optional but feedback would be appreciated especially if the prediction
is contrary to your experience. You can return to any of the pages on this web site by
clicking the appropriate tab.
In SEQEXPERT:
Previous Page: Overview of the Experimental Technique
Next Page: Sorption and Diffusion Effect on Sample Size and Test Duration
Return to Table of Contents
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David C. Silverman, Ph.D. - Primary Consultant
E-Mail: dcsilverman@argentumsolutions.com
Phone: 314-576-3586
Fax: 314-754-9825
Address: The Argentum House
14314 Strawbridge Ct.
Chesterfield, MO 63017
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