AMPP Pipeline Coatings flashcards
AMPP Pipeline Coatings · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Corrosion cell elements
- Four components are needed: an anode where metal dissolves, a cathode where reduction occurs, an electrolyte that conducts ions, and a metallic path for electrons.
- Anodic reaction for steel
- Iron dissolves at the anode as Fe → Fe²⁺ + 2e⁻; this oxidation releases electrons that travel through the steel to the cathode.
- Cathodic disbondment mechanism
- At a coating holiday, cathodic protection generates hydroxide ions that raise pH and break the coating-to-steel bond, producing a disbonded ring around the defect.
- Coating barrier mechanism
- A coating slows corrosion mainly by blocking water, oxygen, and ions from reaching the steel; high electrical resistance further limits the galvanic current that drives corrosion.
- CP current demand
- Cathodic protection current decreases as coating resistance increases; a damaged coating exposes bare steel, sharply raising current demand and the number of anodes required.
- Fusion-bonded epoxy (FBE)
- FBE is a heat-applied powder coating, usually 250–500 µm thick, with strong adhesion and good high-temperature performance; it is vulnerable to cathodic disbondment at damage.
- Three-layer polyethylene (3LPE)
- 3LPE combines an FBE primer, a copolymer adhesive, and an extruded polyethylene topcoat; it is widely used on buried pipelines, typically up to about 60–85 °C.
- Three-layer polypropylene (3LPP)
- 3LPP uses an FBE primer, adhesive, and polypropylene topcoat, giving higher service temperature and better abrasion resistance than polyethylene systems.
- Concrete weight coating
- Concrete weight coating provides negative buoyancy and mechanical protection for subsea or river-crossing pipelines; it is not the corrosion barrier, so the coating beneath is essential.
- Coal tar enamel coating
- Coal tar enamel is a legacy hot-applied coating with good water resistance but contains polycyclic aromatic hydrocarbons, so it is largely phased out for health and environmental reasons.
- Heat-shrink sleeve
- A heat-shrink sleeve is a crosslinked polyolefin field-joint coating with a mastic or adhesive backing; it shrinks onto the pipe when heated and bonds to the mainline coating.
- SSPC-SP 10 / NACE No. 2
- Near-white blast cleaning removes all visible oil, grease, dirt, mill scale, rust, and coating, leaving only very light staining; it is a common pipeline specification.
- Anchor profile
- The anchor profile is the microscopic roughness created by blasting; FBE typically requires about 40–100 µm, measured by comparator or replica tape.
- Bresle salt test
- The Bresle method extracts soluble salts from a defined area with a patch and measured water, then conductivity indicates chloride concentration in mg/m².
- Dew point rule
- Blasting or coating should not proceed unless the steel surface is at least 3 °C (5 °F) above the dew point, preventing condensation that ruins adhesion.
- Mill scale removal
- Mill scale is a cathodic oxide layer; if left on steel it forms a galvanic couple with the steel and promotes localized corrosion under the coating.
- FBE electrostatic spray
- Charged epoxy powder is sprayed onto heated steel, usually at 200–260 °C; the particles melt, flow, and cure into a continuous film.
- Wet film thickness formula
- Wet film thickness equals dry film thickness divided by the volume solids fraction; for 400 µm DFT at 60% solids, the required wet film is about 667 µm.
- Plural-component spray mixing
- Two-component coatings must be mixed at the specified ratio; incorrect ratio, expired material, or insufficient induction causes poor cure and adhesion failure.
- Heat-shrink installation
- Heat-shrink sleeves need preheat, adequate overlap on the mainline coating, and even heating until the adhesive melts and the sleeve shrinks tightly.
- Amine blush
- Amine blush is a waxy surface film formed when epoxy or polyurethane cures in cool, humid conditions; it must be removed before recoating.
- Field joint coating
- A field joint coating restores corrosion protection at girth welds; it must be compatible with the mainline coating and receive the same surface preparation.
- Dry film thickness gauge
- Magnetic pull-off and eddy-current gauges measure DFT; SSPC-PA 2 defines the number and pattern of readings and the acceptance limits.
- Holiday detection
- Holiday testing finds pinholes and thin spots: low-voltage wet sponge for thin films, high-voltage spark testers for thicker coatings, per NACE SP0188/SP0490.
- Pull-off adhesion test
- ASTM D4541 pulls a loaded dolly from the coating and reports bond strength plus failure mode, either adhesive (coating-steel) or cohesive (within coating).
- Cathodic disbondment test
- ASTM G8/G95 and CSA Z245.20 measure the disbonded radius around an artificial holiday under cathodic protection at elevated temperature, typically 28 days at 65 °C.
- Impact resistance test
- ASTM G14 drops a weight onto a coated panel and records the energy that causes coating failure, indicating resistance to handling and installation damage.
- ISO 21809 coating standards
- ISO 21809-1 covers three-layer polyethylene, -2 covers fusion-bonded epoxy, and -3 covers three-layer polypropylene for pipeline external coatings.
- NACE SP0169
- NACE/AMPP SP0169 gives cathodic protection criteria for buried metallic piping, including the −850 mV versus copper-copper sulfate reference electrode criterion.
- Silica dust hazard
- Abrasive blasting generates crystalline silica dust that causes silicosis; controls include supplied-air respirators, ventilation, and air monitoring.
- Holiday tester electrical safety
- High-voltage holiday testers are electrical hazards; operators must be trained, equipment grounded, and contact with workers or wet ground avoided.
- Blast waste disposal
- Spent abrasive and removed coating may be hazardous waste containing lead, chromium, or PAHs; containment, testing, and regulated disposal are required.