Hydrogen Induced Cracking (HIC) is a common form of wet H2S cracking caused by the blistering of a metal due to a high concentration of hydrogen. The blistering damage tends to form parallel to the surface and to the direction of hoop stress.
HIC usually occurs due to the effects of aqueous hydrogen charging of steel in wet H2S refinery process environments. It can occur at relatively low temperatures, largely as a result of atomic hydrogen from wet H2S corrosion reactions which enter the steel and collect at inclusions or impurities within the steel. The H2S prevents the hydrogen recombination reaction that would normally occur so, rather than bubbling off from the corroding surface, the hydrogen atoms are forced into the metal structure causing corrosion and weakness.
The damage occurs when the hydrogen collects at inclusions or impurities in the steel. It tends primarily occur in steels that have a hardness of 22 or more on the Rockwell C scale.
As far as damage mechanisms go HIC is usually, but not always, fairly innocuous. It usually isn’t damaging until it becomes extensive and begins to affect the material properties. Once the ductility of the metal has reduced to a significant amount, the metal will form stepwise internal cracks connecting adjacent hydrogen blisters. These can become dangerous should they propagate into a weld.
On the surface, HIC is often horseshoe shaped and no bigger than the cuticle of your small finger. Regular inspection and testing should be performed in order to eliminate the chances of hydrogen corrosion. The conventional method for detecting wet H2S cracking is Wet Fluorescent Magnetic Particle Inspection (WFMPI) which is able to detect sub-surface cracks in the steel caused by HIC. When it comes to cracked piping and other components which cannot be inspected using WFMPI, Phased Array Ultrasonic Testing (PAUT) is the most convenient and reliable non-destructive method available.
Is this definition incomplete? You can help by contributing to it.
|
January/February 2017 Inspectioneering Journal
By Abdelmounam Sherik at Saudi Aramco Research and Development Center, Mark Rosa, PE at Harvard Business School, and Abderrazak Traidia at Saudi Aramco Research and Development Center
This article summarizes a comprehensive survey conducted by the Research & Development Center (R&DC) of Saudi Aramco to understand top corrosion damage mechanisms experienced by its operating onshore surface facilities. |
|
November/December 2015 Inspectioneering Journal
By Rick Eckert at DNV GL - North America Oil & Gas
Understanding the common factors that promote corrosion threats in the oil and gas value chain helps operators create effective inspection strategies. |
|
Blog
May 5, 2014 By Greg Alvarado at Inspectioneering Journal
AE monitoring has been done for HIC affected vessels, with limited success. The limitation, which greatly affects the confidence level of results, is that traditional AE testing stresses, i.e. Kaiser affect overpressure and felicity effect types of re-stressing do not generate the types of stress necessary to generate elastic strain waves at the HIC laminar crack tips. |
|
Blog
March 17, 2014 By Greg Alvarado at Inspectioneering Journal
A question was posed to me regarding guidelines for routine external inspection of spheres, including procedural approaches along with any nondestructive examination (NDE). Here are two approaches to inspection of spheres, and a mixture of the two, as a third. |
|
May/June 2013 Inspectioneering Journal
By Marc McConnell, P.E. at Pro-Surve Technical Services
With 30 years of refinery experience, I have been through many turnarounds and been involved with a lot of repairs. When I started in the business, we would have inspectors that “owned” their specific pieces of equipment. |
|
May/June 2006 Inspectioneering Journal
By John Reynolds at Intertek
As noted in the discussion on delayed cracking, when the steel contains hydrogen as a result of service exposure (or corrosion, or high temperature - high pressure hydrogen processing) then a hydrogen bake out may be needed to avoid cracking problems during or after welding. |
|
November/December 2003 Inspectioneering Journal
By John Reynolds at Intertek
There are a variety of forms of wet H2S cracking. In this short article I will focus on two of the most common forms: hydrogen induced cracking and stress-oriented hydrogen induced cracking (HIC/ SOHIC). HIC is often fairly innocuous (but not always), while SOHIC is a type of cracking that can easily lead to failure and needs to be mitigated. HIC is a form of tiny blistering damage that is mostly parallel to the surface and to the direction of hoop stress, hence is usually not damaging until it is extensive and affects material properties or gives rise to step-wise cracking that propagates into a weld or begins to go step-wise through the wall. |
|
September/October 2001 Inspectioneering Journal
By W. David Wang at Shell Global Solutions
Hydrogen-induced cracking is a damage mechanism commonly observed in the petroleum refining industry [1, 2]. The damage appears as laminar cracks and blisters, which can link up in the through-wall direction to form stepwise cracking. |
|
May/June 1995 Inspectioneering Journal
By Dr. Russell D. Kane at CLI International Inc., and Dr. Michael S. Cayard at Flint Hills Resources
Exposure of carbon steel equipment to wet H2S service environments can lead to various forms of attack, e.g. hydrogen blistering and hydrogen induced cracking (HIC), stress oriented hydrogen induced cracking (SOHIC) and sulfide stress cracking (SSC). Documented cases of leaks and failures of pressure containing equipment have been attributed to these forms of corrosive damage. |
