Hydrogen damage

  • Hydrogen damage

    Posted by arsal on 27/11/2021 at 2:06 pm

    I would like to know what Technics we can use to detect hydrogen damage and creep voices in steel pressure vessels

    lucas replied 5 months, 3 weeks ago 2 Members · 1 Reply
  • 1 Reply
  • Failure Mechanisms


    27/11/2021 at 10:18 pm
    2 Points

    There are a few methods used to inspect hydrogen damage. It is
    important to know which type of hydrogen damage you are looking for (ie.
    Wet Hydrogen Damage or High Temperature Hydrogen Damage).
    WET HYDROGEN DAMAGE: This is a fairly easy failure mechanism to detect
    and quantify if the proper testing equipment is utilized. I have used
    Automated Ultrasonic systems which tend to remove a lot of the human
    error, intern producing the best test results. There are several
    multi-channel automated ultrasonic systems on the market today which
    allow you to overlay the various shear wave angle (ie 45 degree) and
    compression wave (ie 0 degree) transducer data. With both 0 degree and
    45 degree data overlaid it is very easy to identify damaged areas and
    also identify linkage between the swelling planer inclusions.
    HIGH TEMPERATURE HYDROGEN DAMAGE: This one is a little more challenging
    to detect and quantify in the early stages of damage. One method taught
    by Chevron U.S.A. is a Velocity Ratio Comparison (VRC) and Shell Oil Co.
    also has their own method. The VRC method initially uses a 0 degree
    compression wave to locate noise ratio increase near the back 1/3 of the
    backwall. When noise of a predetermined ratio is exceeded, a
    oscilloscope is used in conjunction with a “0 degree shear” and “0
    degree compression” wave transducers to determine the velocity of each
    in the material at that point. The two velocities are then compared to
    determine if they exceed the determined attenuation differences.