Standard Test Method for Hydrogen Embrittlement Resistance for Steel Wire Hard-Drawn Used for Prestressed Concrete Pipe
A 16-inch-long sample of hand-straightened wire is prepared for the HE test. The wire straightened samples are fitted and sealed into a Pyrex T-shaped test cell that will be filled with a 20 percent (by weight) ammonium thiocyanate solution. The wire specimens are loaded in tension at a force equivalent to 70% of the specified minimum tensile strength.
A resistance heating coil wrapped around the outside of the test cell and connected to a proportioning temperature controller is employed to heat the solution within the cell to 50°C and maintain that temperature for the duration of the test. A switch activated relay stops the timer upon failure and records the time-to-failure (TTF) to the nearest 0.01 hours. Test samples are removed at failure, or after 100 hours if no failure occurs.
Background
The European Federation Internationale de la Precontrainte (FIP) developed a laboratory test during the late 1960's and early 1970's for evaluation of the hydrogen embrittlement (HE) sensitivity of PCCP prestressing wire. A recommended procedure for performing the test was published by the organization in 1980 that is most often referred to as the FIP ammonium thiocyanate test.
Lewis Engineering and Consulting, Inc. (LEC) constructed a dedicated test system in 1990 for performing the FIP test in accordance with the recommended procedure in support of forensic investigations of PCCP failures. Based upon test data acquired by LEC between 1990 and 2002 on prestressing wire manufactured between the mid-1950's to 2002, a presentation was made by LEC to the ASTM A01.05 Wire Products Task Group subcommittee proposing the development of an ASTM standard for the test.
The result was the ASTM A1032-04 test procedure published by ASTM in September 2004, "Standard Test Method for Hydrogen Embrittlement Resistance for Steel Wire Hard-Drawn Used for Prestressed Concrete Pipe".
Supplementary Requirements were added concurrently to ASTM A648-04a addressing the use of A1032-04 in purchase order specifications for contemporary pipe wrap wire. RJ Peterman & Associates, Inc. purchased the HE test apparatus from LEC in November 2019 and now conducts HE tests in accordance with the latest revision of the ASTM A1032 standard.
Sudden Brittle Failure of Prestressing Wire During ASTM A1032 Test (Click on Photo Below to Access video clip)
