Corrosion, galvanic action and service life
How a corrosion cell works, why a galvanic series is not a verdict, and why area ratio and copper runoff matter; atmospheric categories, coating thickness and how makers define coastal; and a documented review that ends in questions, not a promise of years.
4 lessons · about 49 min · 14 diagrams · 1 video
Version 1.0.0
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Lessons
0 of 4 complete
Lesson 1 · 13 min · 12 slides · 9 questions
Corrosion, galvanic action and service life: principles and terminology
The four parts of a corrosion cell and the three prerequisites of galvanic attack; what counts as an electrolyte; why a galvanic series is not a verdict; area ratio; deposition corrosion; and how zinc protects steel.
You will be able to: Name the parts of a corrosion cell, state the conditions galvanic corrosion needs, read a galvanic series with its limits, explain area ratio and deposition corrosion, and keep the safety boundary of inspecting at height.
Not startedStart →Lesson 2 · 14 min · 12 slides · 10 questions
Corrosion, galvanic action and service life: materials, standards and design constraints
Atmospheric corrosivity categories and their zinc rates; coating thickness and linear zinc loss; why batch-galvanizing charts do not transfer to sheet; aluminum-zinc coatings; warranty distances and exclusions; and UFGS 07 60 00 as a specification model.
You will be able to: Use the ISO 9223 categories and zinc rates, relate coating thickness to life without misusing batch-galvanizing charts, compare how makers define coastal, and read warranties and a guide specification as design checklists.
Not startedStart →Lesson 3 · 12 min · 11 slides · 8 questions
Corrosion, galvanic action and service life: methods and worked application
An eight-step review method; screening pairs with the Design Center and reading it against the sources; choosing separation; zinc-loss arithmetic, an area-ratio example and a site checked against four warranty and category documents.
You will be able to: Run a documented corrosion and service-life review on a flashing detail: define the site, map contact and drainage paths, screen pairs, choose separation, check warranties and record assumptions, with three worked examples.
Not startedStart →Lesson 4 · 10 min · 12 slides · 6 questions
Corrosion, galvanic action and service life: defects, verification and case study
Defects read as symptom, mechanism and evidence: fastener and crevice corrosion, copper-aluminum damage, rooftop-unit runoff, cut edges, treated wood and concrete; the evidence to capture; and an illustrative school re-roof case.
You will be able to: Diagnose a plausible corrosion defect from its symptom, name the likely mechanism and the evidence to capture, and work an illustrative school re-roof through the review to a list of requests for information.
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Practical task
Produce a corrosion and service-life review packet for one flashing detail of your own design (or a job you have worked on): the site, every metal and fastener, the contact and drainage paths, the separation you chose, the warranty checks, and the requests for information that remain.
Hand in
- A decision rationale that names each metal pair, which part is the small one, the separation chosen and the source for it
- A marked-up sketch of the detail showing every metal, every fastener, the contact paths and the drainage paths, with the moisture sources marked
- An assumptions sheet with units: site exposure evidence, the distance to salt water measured on the plan, and each coating thickness, each labelled as sourced, from a product document, or assumed
- A warranty check for each product: the document, its date, its distance condition and each exclusion read against the detail
- A defect analysis for one plausible failure: symptom, likely mechanism, the evidence you would capture, and who decides the fix
Rubric
| Criterion | Meets the standard when |
|---|---|
| Contact and drainage paths | Both kinds of path are drawn, including any place where water from one metal runs onto another, and each is checked against a source. |
| Area ratio | Every pair names which part is small, and no rate or years are invented from the ratio. |
| Separation | The separation breaks the metal path or the moisture path, does not rely on coating only the anode, and names the maker or specification that governs it. |
| Warranty and coastal checks | Each product document is read on its own terms, with its date, rather than by a general coastal rule. |
| Service-life statement | Any years are written as the designer's assumptions with sources, never as an AFS prediction or warranty. |
| Safety | Any plan to inspect a roof edge names the fall-protection duty and the training that covers it. |