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