Corrosion control before, during and after hydrotesting for tanks, pipelines, pressure vessels and seawater systems.
| CORROSION THREAT TYPE | SCIENTIFIC CAUSE & CONSEQUENCES | TYPICAL AFFECTED LOCATIONS | RECOMMENDED VAPPRO SOLUTION |
|---|---|---|---|
| OXYGEN & WATERLINE CORROSION (General, Flash Rust, Waterline, Oxygen Cells) | Dissolved oxygen supports electrochemical reactions; alternating wet/dry conditions cause uniform wall thinning and rapid circumferential rust bands. | Entire wetted surfaces, tank shell-water interfaces, partially filled systems. | Vappro VBCI 844 (Add Vappro VBCI 849 CF for post-drain flash rust) |
| CHLORIDE & PITTING ATTACK (Chloride, Pitting, Industrial/Brackish Water) | High chloride concentrations increase electrolyte conductivity and locally destroy passive oxide films, causing deep localized penetration | Tank bottoms, stagnant water zones, coastal facilities, seawater/brackish hydrotests. | Vappro VBCI 849 CF
(Base treatment: Vappro VBCI 844) |
| MICROBIAL CORROSION (MIC) (MIC, SRB Attack, River Water) | Bacterial growth and Sulfate Reducing Bacteria (SRB) produce corrosive metabolites and biofilms, triggering severe pitting. | Water storage tanks, ballast tanks, river water sources, stagnant regions. | Vappro VBCI OP 529
(Integrated with Approved Biocide Programs) |
| CREVICE & JOINT ATTACK | Stagnant water becomes trapped in tight gaps, creating oxygen concentration cells and severe localized attack. | Flanges, gaskets, threaded joints. | Vappro VBCI 869 (Supported by Vappro VBCI 844) |
| UNDER-DEPOSIT CORROSION | Surface accumulations trap water and contaminants, establishing hidden, differential corrosion cells. | Tank bottoms, sludge accumulation areas. | Vappro VBCI 844 & Vappro VBCI 849 CF |
| GALVANIC CORROSION | Dissimilar metals immersed in conductive hydrotest water create electrochemical cells, accelerating attack on the anodic metal. | Mixed-metal systems, instrumentation interfaces, fittings. | Vappro VBCI 887 |
| POST-HYDROTEST RESIDUAL ATTACK (Residual water, post-drain, transport) | Trapped water in low points, residual humidity, or atmospheric oxygen attacks exposed steel after draining. | Low points, dead legs, drains, vapor spaces, upper shell regions. | Vappro VBCI 851 Fogging Fluid
(Augmented with Vappro VBCI 823, Vappro VBCI 849) |
| OPERATIONAL STAGE / ENVIRONMENT | WATER SOURCE & BASELINE RISK LEVEL | PRIMARY PRESERVATION CONCERN | RECOMMENDED VAPPRO TECHNOLOGY |
|---|---|---|---|
| PRE-HYDROTEST PREPARATION | N/A | Metal surface passivation prior to initial water exposure. | Vappro VBCI 887 |
| STANDARD FRESHWATER TESTING (Short Duration / Pipelines / Pressure Vessels) | Demineralized (Low Risk)
Potable (Moderate Risk) | Dissolved oxygen control, baseline uniform corrosion protection. | Vappro VBCI 844
(Add Vappro VBCI 851 for vessels/pipelines) |
| HIGH-RISK / ENVIRONMENTAL WATER TESTING (River, Industrial, Brackish Water) | River / Industrial (High Risk)
Brackish (Very High Risk) | Suspended solids, heavy contaminants, dissolved salts, and high chlorides. | Vappro VBCI 844, Vappro VBCI 849 CF
(Add Vappro VBCI OP 529 if using River Water) |
| SEAWATER & SEVERE TESTING
(Seawater / Ballast Tanks) | Seawater (Severe Risk) | Critical chloride mitigation, severe pitting, and immediate biological threats. | Vappro VBCI 849 CF Vappro VBCI 844 Vappro VBCI OP 529 (Use Vappro VBCI 867 for Ballast Tanks) |
| LONG-DURATION & DELAYED TESTING | Any water source left extended | Extended oxygen exposure, microbial escalation, and biofilm formation. | Vappro VBCI 844, Vappro VBCI OP 529 |
| POST-TEST DRAINING & LAY-UP
(Dry Preservation / Long-Term Storage) | System draining phase | Flash rusting on wet steel; long-term vapor-phase protection during storage. | Vappro VBCI 851 Fogging Fluid Vappro VBCI 849 |
| EQUIPMENT TRANSIT & SHIPPING | Drained & sealed system | Enclosed ambient humidity trapping and post-hydrotest shipping corrosion. | Vappro VBCI 823, Vappro VBCI 851 |