Copper strip corrosion

Finally, there are some limits regarding LPG fuels butadiene content (0.5 wt. % maximum, ISO 7941), the absence of hydrogen sulfide (ISO 8819) and copper strip corrosion (class 1, ISO 6251) which are not usually problems for the refiner. 

If sulfur is a contaminant, its content can be measured, but it may suffice to characterize its effects by the copper strip corrosion test, or by the doctor test". 

Composition is normally expressed by a distillation curve, and can be supplemented by compositional analyses such as those for aromatics content. Some physical properties such as density or vapor pressure are often added. The degree of purity is indicated by color or other appropriate test (copper strip corrosion, for example). 

Performance can be illustrated for example by the time necessary for deaeration or de-emulsification of oils, anti-rust properties, copper strip corrosion test, the flash point in closed or open cup, the cloud and pour points, the foaming characteristics, etc. 

Copper strip corrosion NFM 07-015 ISO 2160 ASTM D 130 Appearance of a copper blade after immersion... 

Specifications for the principal LPG products are summarized in Table 4. Detailed specifications and test methods for LPG are pubHshed by the Gas Processor s Association (GPA) (3) and ASTM (4). The ASTM specification for special-duty propane and GPA specification for propane HD-5 apply to propane that is intended primarily for engine fuel. Because most domestic U.S. LPG is handled through copper tubing, which could fail if corroded, all products must pass the copper strip corrosion test. A test value of No. 1 represents a LPG noncorrosive to the copper. 

The acid wash test consists of shaking a mixture of 96% sulfuric acid with benzene and comparing the color of the (lower) acid layer with a set of color standards. Other quaUtative tests include those for SO2 and H2S determination. The copper strip corrosion test indicates the presence of acidic or corrosive sulfur impurities. The test for thiophene is colorimetric. 

Amines remove the bulk of the H2S primary amines also remove the COj. Amine treating is not effective for removal of mercaptan. In addition, it cannot remove enough H2S to meet the copper strip corrosion test. For this reason, caustic treating is the final polishing step downstream of the amine units. Table 1-3 illustrates the chemistry of some of the important caustic reactions. 

D 1838 1984 Test method for copper strip corrosion by liquefied petroleum (LP) gases... 

Corrosive sulfnr componnds can be detected by their effect on copper and the form in which the general copper strip corrosion test (ASTM D1838) for petrolenm prodncts is applied to liqnefied petrolenm gas. Hydrogen sulfide can be detected by its action on moist lead acetate paper, and a procedure is also used as a measure of sulfur compounds. The method follows the principle of the standard Doctor test. 

Flash point Water content Kinematic viscosit Distillation Copper strip corrosion Cetane index Density Color... 

Thus visual observation of the copper strip can present an indication or a conclusion of the presence or absence of corrosive sulfur. There is also a copper strip corrosion method for liquefied petroleum gases (ASTM D-1838). 

The copper strip test methods are used to determine the corrosiveness to copper of gasoline, diesel fuel, lubricating oil, or other hydrocarbons. Most sulfur compounds in petroleum are removed during refining. However, some residual sulfur compounds can have a corroding action on various metals. This effect is dependent on the types of sulfur compounds present. The copper strip corrosion test measures the relative degree of corrosivity of a petroleum product. 

One method (ASTM D-130, IP 154) uses a polished copper strip immersed in a given quantity of sample and heated at a temperature and for a time period characteristic of the material being tested. At the end of this period the copper strip is removed, washed, and compared with the copper strip corrosion standards (ASTM, 2001). This is a pass/fail test. In another method (ASTM D-849), a polished copper strip is immersed in... 

The copper strip test methods are used to determine the corrosiveness to copper of diesel fuel and are a measure of the relative degree of corrosivity of diesel fuel. Most sulfur compounds in petroleum are removed during refining. However, some residual sulfur compounds can have a corroding action on various metals, and the effect is dependent on the types of sulfur compounds present. One method (ASTM D-130, IP 154) uses a polished copper strip immersed in a given quantity of sample and heated at a temperature for a time period characteristic of the material being tested. At the end of this period the copper strip is removed, washed, and compared with the copper strip corrosion standards (ASTM, 2000). This is a pass/fail test. In another method (ASTM D-849) a polished copper strip is immersed in 200 ml of specimen in a flask with a condenser and placed in boiling water for 30 min. At the end of this period, the copper strip is removed and compared with the ASTM copper strip corrosion standards. This is also a pass/fail test. 

Copper strip corrosion. This determines the ability to tarnish clean copper, indicating the presence of any corrosive sulfur compounds. 

Corrosiveness. Sulfur in the fuel facilitates corrosion. The combustion of sulfur containing fuels results in the formation of corrosive gases that attack the engine, the exhaust as well as the environment. Sulfur also adversely affects the alkyl lead octane response. Furthermore, it adversely affects the exhaust catalysts. However, the monolithic catalysts usually recover when the sulfur content of the fuel is reduced. In this case, sulfur is considered to be an inhibitor rather than a catalyst poison. The copper strip corrosion test and the sulfur content specification are used to ensure fuel quality. The copper strip test measures the active sulfur whereas the sulfur content reports the total sulfur present. 

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