Evaluating the Compatibility of PA11 Pipe with Oil Field Media Based on Tensile Tests
In recent years, a large number of thermoplastic pipes have been used in onshore oil fields of china in order to solve the corrosion problem of traditional carbon steel pipelines. However the domestic investigations on compatibility evaluation of thermoplastic materials with oil field media are just at the preliminary stage. Therefore, PA11 was chosen to study compatibility according to ISO 23936-1 standard. And influences of various factors on tensile test results were analyzed in order to optimize test parameters. Exposure tests were carried out in five kinds of simulated environments that were representative in the oil field service, and tensile tests were carry out in accordance with ISO 527 standard. The results showed that: ISO 23936-1 standard was confirmed to be an effective method of evaluating compatibilities of thermoplastic materials quantitatively; the tensile properties obtained from original PA11 material were in agreement with the data released by material supplier; the elongation of specimens decreased significantly after exposure tests, which indicates that the material’s toughness decreased; PA11 was compatible to all the test environments except the H2S-containing, judged by changes of tensile properties. RSDs (relative standard deviation) of test data showed that stress test precision of specimens was better than that of strain and modulus. And suggestions for tensile test were given as the following: (1) specimens should be flat and straight in order to ensure the precision of strain test; (2) low test speed, such as 1 mm/min should be used to ensure that modulus could be calculated precisely.
KeywordsPA11 Thermoplastic Compatibility Oil field Tensile test
The authors wish to thank ARKEM for supply sample pipes for this investigation.
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