Test 3 study guided Flashcards
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 a pipeline?
Corrosion in longitudinal bands along both sides of the pipe
Which internal pipeline condition most indicates hydrogen sulfide presence?
Odor similar to rotten eggs
Which type of physical evidence is intended to capture the deposits and biofilm and their relation to the corrosion?
Embedements
Concentration cell corrosion within small areas isolated from the bulk fluid stream
Crevice corrosion of joints
When collecting physical evidence of internal corrosion, cleaned pip should be used primarily for
Dimensional analysis
General etching over large continuous areas that still contain isolated pitting or clusters of pits
Isolated pitting within general corrosion
Combined action of corrosion and metal loss due to rapidly moving fluids and/or particles
Erosion corrosion
Numerous small pits growing together or a few large pits that connect only after they have grown to a certain size
Interconnected pitting
Mechanisms which include SCC, Corrosion Fatigue, SSC, HIC, etc.
Environmental cracking
Etching or near uniform attack with just a few scattered pits
General metal loss with infrequent pits
Special features such as cup-type hemispherical pits, pits within pits, striations parallel to the longitudinal axis of the pipe, tunnels in the end walls of pits, etc.
Unique pit morphology
Uniform attack of the pipe wall
Interconnected pitting
Pits occur singularly or in groups but the pits are not interconnected
Isolated pitting
Preferential attack of the weld metal or heat affected zone of the parent metal
Selective attack at welds
Measurement of the deepest pit depth and the average pit depth
Maximum/average pit depth
Measurement of wall thickness every .25 inches along the longitudinal axis in the deepest areas of interconnected corrosion
Profile wall loss
Measurement of the deepest corrosion or thinnest wall cause by corrosion
Maximum wall loss
Measurement of the greatest pit diameter and average pit diameter
Maximum/Average pit diameter
Examining the typical length and width of pits to determine if there is a preferred orientation of the pitting
Pit length vs. Pit width
A description of how far the corrosion extends down the longitudinal axis of pipe
Longitudinal Extent
A description of how far the corrosion is present about the circumference of the pipe
Circumferential extent
Calculation of both average depth/average diameter and maximum depth/maximum diameter ratios
Depth/diameter ratio
List the 5 factors other than morphology or the physical appearance that the author says should be considered by a competent corrosion investigator before making a conclusion
Chemistry, Electrochemistry, Microbiology, Metalurgy, Physical conditions
List the 3 main areas of managing internal corrosion of pipelines according to the author
Detecting the corrosion, Determining the cause of corrosion, Mitigating the corrosion
Which 3 main areas of managing internal corrosion of pipelines is is the text concerned with?
Determining the cause
List the Who questions that are essential in an investigative plan
Who will do the investigation
Who will collect the samples at investigation site
Who is responsible for writing the report
Who will decide if the lab services are needed
Who will stock testing supplies
Who needs to receive information about investigation
List the 4 What questions that must be answered for an investigative plan
What types of testing will be done?
What samples need to be collected
What tools and supplies are needed
What are health and safety precautions
List the 3 where questions essential to an investigative plan
Where will investigation be performed
Where will field supplies be stored
Where do samples need to be sent
List the 3 When questions for an investigative plan
When corrosion detectives be called to the scene
When are certain tests performed
When does the cause need to be determined
List the Why question that must be determined in an investigative plan
Why are we conducting the experiment
List the 2 How questions that must be determined when developing an investigative plan
How do we collect and analyze samples
How do you interpret test data and reach a conclusion
List the 3 main categories of evidence to consider when gaining a perspective on internal pipeline corrosion
Visual evidence
Physical evidence
Circumstantial evidence
List the 5 measurement tools the author suggests to collect measurable visual evidence
Steel tape measure Small finely divided tape measure Pit gauge Pipe micrometer UT gauge
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 the 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
These samples must be taken where there are differences in color, texture, density, or composition of materials in the pipe. These samples must be taken carefully to avoid damaging other corrosion evidence and must be carefully identified in terms of physical location
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 500 mL in 2 250 mL sample containers at the site of the cut if possible. Samples should be filled up to the top to exclude air and capped. Samples should be kept in a cool dark place if possible
Liquid sampling
This sample should be cut using a portable band saw or wheel type cutter to prevent torch cutting debris from entering the samples.
Pipe sampling
What is the final and most important part of instituting a corrosion mitigation program?
Monitoring the effectiveness of the treatment
Ask the 20 Questions
Step 2
Look for the connections between the different types of data
Step 3
Physically arrange the investigation results in logical progression
Step 1
Develop a factual story of what happened to cause the failure using the results, observations, and relationship
Step 4
Put the findings in writing
Step 5
List the 5 steps of reviewing the results
Get organized
20 questions to answer
Make connections
What are the 3 major methods for mitigating internal corrosion once the cause has been identified?
Remove the environment to prevent corrosion
Chemical treatment
Maintaining effectiveness of treatment
