Inhibitors Flashcards
AKA Gunkers
Ohmic inhibitors
Scale formation over the entire surface. Most common types: Silicates Phosphates
Precipitation inducing Inhibitors
AKA volatile corrosion Inhibitors Inhibitors is vaporized into a gaseous form Inhibits corrosion by making the environment alkaline
Vapor Phase Inhibitors
Can reduce the effectiveness of inhibitors
Bicarbonates Metal cations
The corrosion Investigator’s first job on-site is to:
Protect all evidence
the Corrosion Investigator’s second job on-site is to:
Collect all evidence
The presence of water can be confirmed in a sample by using ….
Hydrion paper
Which gas analysis test cannot be collected with a stain tube?
Pressure
A procedure that penetrates and preserves the scale, corrosion product, microbes and deposits that are present on an internally corroded pipe is:
Embedment
The temperature of liquid samples is measured in the field using:
Common laboratory thermometer and with an electronic temperature probe.
The pH of aqueous samples is measured using:
pH Meter and pH Test Paper
These samples must be taken where there are differences in color, texture, density or composition of materials in the pipe
Solid/Sludge sampling
These samples are normally collected in stainless steel sample bottles or Tedlar bags. Stain tubes can sometimes be used to replace some samplings.
Gas Sampling
Collect at least 500ml in two 250 ml sample containers at the site of the cut if possible. Samples should be filled to the top to exclude air and capped.
Liquid Sampling
This sample should be cut using a portable band saw or wheel-type cutter to prevent torch cutting debris from entering the sample.
Pipe Sampling
Common technique used to identify crystalline phases in unknown materials. These crystalline phases are described as compounds rather than elements which is beneficial in understanding corrosion.
XRD - X-Ray Diffraction (XRD)
This method provides elemental compositional analysis of very thin (3nm) surface layers.
AES - Auger Electron Spectroscopy
These two methods are used with microscopes to examine small areas or features. Both methods usually allow mapping of the surface and are used for bulk sample analysis.
FTIR and Raman Spectoscopy
A long established technique used to identify nearly 70 diff elements in liquid and solid samples down to parts per billion.
Atomic Absorption
This method is used to look for corrosion inhibitors, biocides, methanol, glycol and organic materials but the investigator must have some idea of the organic material for which they are searching.
Gas or Liquid Chromatography
These 2 methods can quantitatively identify over 70 elements in liquids, solids and particulates. They provide shorter analysis times than AAS.
DCP/ICP - Direct Current Plasma & Inductively Coupled Plasma
This procedure uses liquid chemistry data to calculate values which are simply indications as to the propensity for
Scaling Index
This term describes laboratory analysis techniques such as gravimetry, titrimetry and numerous separation methods. It is time consuming and methods vary widely
Wet Chemistry
This is a popular method for determining the concentrations of ionic species in aqueous samples. Typical results would identify sulfate, sulfite, nitrate, nitrite, phosphate, chloride, bromide and floride
Ion Chromatography
Pair of tests are some of the most popular techniques used for examining and analyzing elemental surface components of corrosion-related samples.
SEM/EDS - Scanning Electron Microscopy/Energy Dispersive Spectroscopy
This technique is used more frequently in the study of microorganisms than of corrosion.
TEM - Transmission Electron Microscopy
This method is like Auger as another method that analyzes atomic surface layers for elemental composition. It is more sensitive and has better spatial resolution than EDS
SIMS - Secondary Ion Mass Spectroscopy
What is the final and most important part of instituting a corrosion mitigation program?
Monitoring the effectiveness of the treatment
Step # 1
Physically arrange the investigation results in logical progression
Step # 2
Ask the 20 Questions
Step # 3
Look for the connections between the different types of data.
Step # 4
Develop a factual story of what happened to cause the failure using the results, observation and relationships.
Step # 5
Put the finding in writing.
Three methods for mitigating internal corrosion once the cause has been identified?
Remove the environment that provided corrosion. Change internal environment by altering operations or maintenance procedures, Chemical treatment with inhibitors.
Who should develop an investigative plan for an internal pipeline corrosion failure?
A Team
Which visual appearance may indicate the effects of historical liquid levels in the pipeline?
Corrosion in the longitudinal bands along both sides of the pipe
Which internal pipeline condition most indicates H2S presence?
Rotten egg smell
When collecting physical evidence of internal corrosion, cleaned pipe should be used primarily for ?
Dimensional Analysis
Which type of physical evidence is intended to capture the deposits and biofilm and their relation to the corrosion?
Embedments
Concentration cell corrosion within small areas isolated from the bulk fluid stream?
Crevice Corrosion at Joints
General etching over large continuous area that still contain isolated pitting or clusters of pits?
Isolated pitting with General Corrosion
Combined action of corrosion and metal loss due to rapidly moving fluids and/or solid particles?
Erosion Corrosion
