Field Guide chpt 1-3 Flashcards
(35 cards)
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 longitudinal bands along both sides of the pipe.
Which internal pipeline condition most indicates hydrogen sulfide presence.
Odor similar to rotten eggs
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 bio-film and their relation to corrosion?
Embedments
Concentration cell corrosion within small areas isolated from the bulk fluid stream.
Crevice Corrosion at Joints
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 solid 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.
Etching or General Loss with No 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 of wall loss
Measurement of the deepest corrosion or thinnest wall caused 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 to the pitting.
Pit length Vs. Pit width
A description of how far the corrosion is present about the circumference of the pipe.
Circumferential extent
A description of how far the corrosion extends down the longitudinal axis of the pipe.
longitudinal 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 physical appearance that should be considered by a competent corrosion investigator before making a conclusion.
1 chemistry 2 electro-chemistry 3 microbiology 4 metallurgy 5 physical condition (temp, flow velocity, etc)