Introduction%20to%20Internal%20Corrosion%20Sampling

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Introduction to Internal Corrosion Sampling

• October 6, 2009

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Pipeline Threats

• External Corrosion
• Internal Corrosion
• SCC
• Construction
• Manufacturing

• Third Party Damage
• Equipment
• Incorrect Operations
• Weather/Outside Forces

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Sampling and Monitoring Methods of Internal
Corrosion

• Visual Inspection
• Coupons and Probes
• Gas Samples
• Liquid Samples

• Bacteria Analysis
• Deposit Analysis
• In Line Inspections
• ICDA

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Causes Of Internal Corrosion

• H2S Influenced
• MIC
• CO2 Influenced
• O2
• Erosion Corrosion
• Galvanic Cells
• Combination Corrosion
• System Operation

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General guidelines when performing internal
corrosion evaluations

• All internal corrosion failures should be
  mechanically cut.
• The number one issue with follow up investigation
  is torch cutting pipe, rendering much of the data
  useless.
• Do not contaminate samples
• Have test kits on hand and ready
• Sample ASAP

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Mechanically Cutting of Drip
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DO NOT CONTAMINATE SAMPLES

• Use the correct sample kit.
• Clean valves, piping, or equipment used to sample
  if not provided
• Do not collect in used containers

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ASAP MEANS AS SOON AS POSSIBLE NOT AS CONVIENT

• pH changes dramatically with time (ex. pH 4.5
  to a pH 7 in 10 minutes).
• Bacteria must be sampled in the first 4 hours
  after exposure to the atmosphere, preferably the
  first hour.
• Every attempt should be made to limit the
  introduction of oxygen into the system before
  sampling.
• Sampling and data with known limitations is
  better than no sample at all.

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Not every sample location is in a field
sunny.
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Visual Inspections

• Failure orientation/clock position
• Seam orientation
• Deposits
• Photographs
• Pit Depth
• Number of pits
• Distance between pits

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Liquid Sampling Field Testing

• Presence of Water
• Temperature
• pH
• Dissolved Gases
• Alkalinity
• Bacteria

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Liquid Sampling Field Testing

• Other constituents that can be tested for
  on-site
• Chlorides
• Manganese
• Carbonate
• Sulfate
• Sulfide

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Bacteria Analysis

• planktonic bacteria culturing
• sessile bacteria culturing
• optical microscopy
• direct observation
• phase contrast examination
• epiflourescent microscopy

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Deposit Analysis

• Clays
• Quartz
• Carbonates
• Sulfates

• Sulfides
• Hydroxides
• Oxides
• Bacteria

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Chemical Kit Solids
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Deposit Analysis

• Give insight to mechanism causing corrosion
• Care should be taken to process samples as
  quickly as possible
• Deposits can be breeding ground for bacteria

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Deposit Analysis
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Gas Samples

• General gas composition
• Presence of Acid Gases
• Level of carbon dioxide
• Level of hydrogen sulfide
• Presence of oxygen
• Catalysis
• Water content

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Gas Samples

• What type of bottle do you need?
• Sulfur components require special bottle.
• Pressure rating of bottle needs to match system
• Pressure of system?
• Pressure of system is critical for calculating
  partial pressures
• Location to take samples?
• Be representative and consistent
• Care should be taken on sampling procedures
• Do not fill sample bottle with fluids

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Gas Sampling

• Field Screening Kit
• Direct Reading Tubes
• Tubes Come In
• Various Measuring Ranges
• Various Constituents
• Most Used Tubes
• Hydrogen Sulfide
• Carbon Dioxide
• Water Vapor

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Weight Loss Coupons

• Weight loss over time
• Corrosion Rate
• Type of Corrosion

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Other Coupons and Probes

• Oxygen coupon short term monitoring of
  concentration cells
• CID Copper Ion Displacement monitoring
  chemical distribution
• ER (Electrical Resistance) Probes on-line
  monitoring of vapors and gases
• LPR linear polarization resistance probe
  liquid service real time monitoring
• EM Coupon direct information about initiation
  mechanics and treatment effectiveness

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Summary

• Each sampling technique is a piece of the puzzle
• No technique is stand alone when
• All data must be considered when making decisions

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Question Answer
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