Field guide chpt 4 - 5 Flashcards
(23 cards)
The corrosion investigator’s first job on-site is to
protect all the evidence
The corrosion investigator’s second job on-sit 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 a common _______ _______ or with an _____ ______ .
Clean thermometer
electronic thermometer
The pH of aqueous samples is measured using a ______ _____ or ______ ______.
pH meter
pH paper
These samples must be taken where there are differences in color, texture, density or composition of material 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.
Pipe 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 250ml sample containers at the site of the cut if possible. Samples should be filled 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 sample. this sample should be marked with relevant operating information such as flow direction, top, bottom, mile post, wheel count, etc.
Solid/Sludge sampling
This method provides elemental compositional analysis of very thin (3nm) surface layers. It has better spatial resolution and sensitivity and is more quantitative than EDS. It is only appropriate for certain types of corrosion related samples such as selective corrosion and grain boundaries or other metallurgical features.
(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 Spectroscopy
FTIR (Fourier transform infrared spectroscopy)
This is a 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 reactions. It requires only a few grams of sample and non-crystalline components can also be identified.
(XRD) X-Ray Diffraction
A long established technique used to identify nearly 70 elements in liquid and solid samples down to parts per billion. This technique is used to identify metallic elements found in corrosion products that couldn’t be found using ion chromatography.
Atomic Absorption
This method is used to look for corrosion inhibitors, biocides, methanol, glycol, and other 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. Sample sizes of 100ml for liquids and 1 gram for solids are common.
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 deposition or dissolution of calcareous deposits.
Scaling Index
This term describes laboratory analysis techniques such as gravimetry, titrimetry, and numerous separation methods. It is time consuming and the methods vary widely with sample type and composition and often require some educated guesswork to describe a non homogeneous sample.
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 fluoride ions. It can also identify the organic acid present in an aqueous ample. Results are reported in either ppm or mg/L.
ION Chromatography
This pair of tests are some of the most popular techniques used for examining and analyzing elemental surface of corrosion-related samples. One test provides a high-resolution view of the corroded surface and corrosion products while the other provides elemental chemical composition data of both discrete particles and larger areas. This combination analysis is an investigative procedure that the corrosion investigator should directly observe and participate in when ever possible.
SEM/EDS
Scanning Electron Microscope /
Energy Dispersive Spectroscopy
This technique is used more frequently in the study of microorganisms than of corrosion. Histological embedments of corrosion products and bio films can be used in this process by taking thin sections from the embedment. The primary limitation of this procedure is the length of time required for sample preparation and the cost.
TEM
Transmission Electron Microscopy
This method is like Auger as another method that analyzes atomic surface layers for elemental compositions. It is more sensitive and has better spatial resolution than EDS. It is sensitive to trace elements in the parts per million and parts per billion range. It can characterize both inorganic and organic surface materials. It is used for compositional depth profiling, bulk impurity analysis, and examination of specific metallurgical features.
SIMS
Secondary Ion Mass Spectroscopy
