US DOT Issues Emergency Testing Order For Transport Of Crude Oils
March 2014 – The US Department of Transportation (DOT) has issued an Emergency Testing Order that requires all shippers to test crude oil from the Bakken region to ensure the proper identification of the crude oil before it is transported by rail. The Emergency Testing Order is in response to a number of recent incidents involving the derailment of trains transporting crude oil from Canada to the United States.
Shippers are required to comply with Hazardous Materials Regulations (HMR) that include testing of vapor pressure and flashpoint to ensure proper transportation and packing. To meet these regulations, Petrolab Company offers specialized instrumentation to test crude oil vapor pressure under various filling levels and temperatures.
There has been a steep increase in the number of rail carriages transporting crude oil from Canada to the United States. The oil industry has found that building rail infrastructure for new shale oil and gas fields can be simpler and more flexible than pipelines. However this increased use of rail transport has resulted in an increase in the number of accidents and greater scrutiny, The estimated cost of the damages from these accidents has topped $1 billion US$ and caused significant environmental damage.
Accident investigations have highlighted the need for more accurate classification of crude oils. Classification has often been based solely on safety data sheets, many of them outdated. As a result of these investigations, US DOT issued several Emergency Testing Orders with the most recent amended version issued on March 6, 2014 and addressed to shippers of petroleum crude. The order specifically requires the flashpoint and boiling point testing of crude oils and endorses the requirement that crude oil shipments follow volatility testing defined by Hazardous Material Regulations (HMR).
In HMR, the testing of crude oil vapor pressure is critical in determining the requirements for safe packing for transport. A derailment can result from the boiling over of crude oils from too much pressure in a rail carriage. This risk increases significantly if the crude oil includes gaseous components.
When testing crude oil samples, it is of the utmost importance that the sample is properly handled to keep the light ends in the crude oil prior to vapor pressure testing. Crude oils may be misclassified if hazardous volatiles are allowed to evaporate prior to sampling. One solution is to ensure that the crude sample is pressurized when delivered to the vapor pressure tester.
AMETEK Grabner Instruments has developed a proven method for effectively testing pressurized crude oils under varying transport conditions. We offer a custom crude package for the safe, air-tight and pressurized transportation of crude oil to the vapor pressure tester. The crude oil with all of its light ends is captured in a high-quality floating piston cylinder (FPC). Once this cylinder is connected to our MINIVAP VPXpert vapor pressure instrument, testing can begin immediately. This versatile analyzer is able to test vapor pressures at temperatures ranging from 0 to 120°C, and to perform tests at vapor-to-liquid ratios (V/L) ranging from 0.02/1 to 4/1 to simulate the various fill levels encountered during transportation.
AMETEK Petrolab Company also offers a process version of its vapor pressure analyzer for online monitoring that operates using the same principle as the laboratory version. The Grabner analyzers provide a proven method for determining the True Vapor Pressure or Bubble Point Pressure of crude oils. Bubble Point Pressure is the most extreme condition in vapor pressure testing and occurs when a container is filled completely to the top.
The Grabner method of measuring crude oil was standardized in 2003 as ASTM D6377 Standard. Since its introduction, the D6377 standard has gained industry wide acceptance and quickly replaced the old manual Reid method ASTM D323. In 2013, the US Environmental Protection Agency approved ASTM D6377 as an alternative method of measuring the vapor pressure of crude oils.
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US EPA Confirms ASTM D6377 as an Alternative Test Method For Measuring Vapor Pressure of Crude Oils
October 2013 – A new method for measuring the True Vapor Pressure (TVP) of crude oils is spreading quickly within the oil and gas industry. At request of the American Petroleum Institute (API), the US Environmental Protection Agency (EPA) recently confirmed the use of the ASTM D6377-10 standard as an alternative test method for the determination of the True Vapor Pressure of high VP crude oils. Widely used by the industry, the new method is now included within the AMETEK Grabner Instruments vapor pressure testers provided by Petrolab Company.
As defined by International Maritime Organization, the True Vapor Pressure (TVP) or bubble point vapor pressure is the equilibrium vapor pressure of a mixture when the vapor/liquid ratio (V/L) is zero. A V/L =0 can be achieved if a container is filled to the top with crude oil. This condition is typical for floating roof tanks, where the roof is floating directly on the crude oil.
As clear as this definition seems, a correct interpretation of the TVP term always depends on the specification for which it is used. In refining, the term TVP often is used to reflect the specific conditions of storage or transport. For example, if a truck or a ship is filled 95% with crude oil and only 5% vapor space remains, the vapor pressure at a V/L = 0.053 may be referred to as TVP. Within US EPA title 40 regulations, the term TVP is used for a TVP estimate calculated from a D323 Reid Vapor Pressure measurement and the crude oil´s tank stock temperature.
In its letter dated May 28, 2013 and published at http://epa.gov/ttn/emc/approalt.html, the US EPA acknowledged the broad use of the ASTM D6377-10 standard for VP measurement of crude oils. It confirmed the use of D6377 as an alternative method for TVP measurement of volatile crude oils, as defined under title 40 CFR with the understanding that crude oil samples are delivered pressurized for measurement to prevent evaporation of light ends and that the TVP is measured at a V/L = 4.
ASTM D6377 method is very versatile. It allows measurement of the TVP at various V/L ratios to reflect different tank filling levels. In addition, Grabner analyzers include a method for Bubble Point determination. Sandia National Laboratories has used this Bubble Point / TVP extrapolation method successfully (see Lord & Rudeen, 2010): From three D6377 measurements at different V/L ratios, the TVP of crude oil at a V/L = 0 is extrapolated. The extrapolation function assumes that crude oil is composed of three components: very light gas components (e.g. methane or nitrogen), intermediate volatility components (e.g. C2 and higher) and a non-volatile fraction (Lord & Rudeen, 2010).
Grabner analyzers have used the TVP extrapolation method successfully around the world. The method was demonstrated on large number of crude oil samples at the US Strategic Petroleum Reserve, and a similar TVP extrapolation project is currently underway at the Canadian Crude Quality Technical Association (CCQTA).
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