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- since 1996 -

Ultrasonic Sciences Ltd
We specialize in the design and manufacture of automated and semi-automated ultrasonic testing systems, including multi axis, multi channels systems and phased array electronics.
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Technical Discussions
Jairo Humberto Guzman
Jairo Humberto Guzman
02:34 Sep-10-1998
Hydrogen damage

I wuold like to know what technics we can use to detec hydrogen damage and creep voices in steel pressure vessels

Thanks


    
 
 Reply 
 
Richard D. Roberts
Engineering, Executive Managment
Quest Integrity Group, USA, Joined Nov 1998, 78

Richard D. Roberts

Engineering, Executive Managment
Quest Integrity Group,
USA,
Joined Nov 1998
78
00:23 Sep-11-1998
Re: Hydrogen damage
: I wuold like to know what technics we can use to detec hydrogen damage and creep voices in steel pressure vessels

: Thanks
--------------------------

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.

Richard D. Roberts
QUEST Integrated, Inc.
21414 - 68th Ave. S.
Kent, Washington 98032 USA
Tel: 1-253-872-1275
Fax: 1-253-872-8967
email: richardr@qi2.com

Web Site: http://www.qi2.com



    
 
 Reply 
 
Jan Verkooijen
Jan Verkooijen
05:38 Sep-11-1998
Re: Hydrogen damage
: I wuold like to know what technics we can use to detec hydrogen damage and creep voices in steel pressure vessels

: Thanks

As you may know, we as a company are involved in many aspects of NDT,
life assessment and materials testing. One of our topics is the detection
and monitoring of various forms of Hydrogen damage. We have, based upon
actual research and an experience of more than 10 years in this area, build
up procedures to assess and monitor these phenomena.
Our approach on High Temperature Hydrogen Damage is described in a paper,
presented at the ECNDT: "Hot Hydrogen Attack: A novel approach for reliable
reliable detection and monitoring". I can forward this article if you do not
have access to the ECNDT proceedings.
We have worldwide offices that can supply this service to you, such as our NDE
office in North Carolina.
Jan Verkooijen
AEA Sonomatic BV
Krombraak 15
4906 CR Oosterhout
The Netherlands
tel: +31 162 425588
fax: +31 162 424343
email: AEA.Sonomatic@aea-technology.nl
web site: http://www.aeat.co.uk/ndt



    
 
 Reply 
 
Rolf D.
Director,
NDT.net, Germany, Joined Nov 1998, 608

Rolf D.

Director,
NDT.net,
Germany,
Joined Nov 1998
608
08:02 Sep-11-1998
Re: Hydrogen damage
: : I wuold like to know what technics we can use to detec hydrogen damage and creep voices in steel pressure vessels

: : Thanks

: As you may know, we as a company are involved in many aspects of NDT,
: life assessment and materials testing. One of our topics is the detection
: and monitoring of various forms of Hydrogen damage. We have, based upon
: actual research and an experience of more than 10 years in this area, build
: up procedures to assess and monitor these phenomena.
: Our approach on High Temperature Hydrogen Damage is described in a paper,
: presented at the ECNDT: "Hot Hydrogen Attack: A novel approach for reliable
: reliable detection and monitoring". I can forward this article if you do not
: have access to the ECNDT proceedings.
: We have worldwide offices that can supply this service to you, such as our NDE
: office in North Carolina.
: Jan Verkooijen
: AEA Sonomatic BV
: Krombraak 15
: 4906 CR Oosterhout
: The Netherlands
: tel: +31 162 425588
: fax: +31 162 424343
: email: AEA.Sonomatic@aea-technology.nl
: web site: http://www.aeat.co.uk/ndt
-------------------------------------

Here is the abstract-URL of the mentioned ECNDT paper which was
presented within the Chemical, Petrochemical Industry session

http://www.ndt.net/abstract/ecndt98/105.htm

Next month NDT.net issue will publish the full-text article
of this and other sessions. The prospective URL will be

http://www.ndt.net/article/ecndt98/105/105.htm

Rolf



    
 
 Reply 
 
Silvio Elton KRUGER
Silvio Elton KRUGER
03:58 Sep-15-1998
Re: Hydrogen damage
: I wuold like to know what technics we can use to detec hydrogen damage and creep voices in steel pressure vessels

: Thanks

In principle, only ultrasonic techniques are used for hydrogen damage detection. Conventional ultrasonic techniques (pulse-echo)are only suitable for some types of hydrogen damage where there are macrocracks (>1mm).
Unfortunately often the hydrogen damage consists of distributed microcracks and only non conventional ultrasonic techniques can be applied.
These techniques are:
- Attenuation measurements (increase of the attenuation due to the hydrogen damage, sometimes evaluated in the frequency domain);
- Velocity change (the velocity of a damage region is higher than for a non attacked one). As transverse velocity is less sensitive it can be used to measure the thickness, method know as velocity ratio technique);
- Backscattering (increase of the backscattered signal due to hydrogen damage, also evaluated in the frequency domain);
You can e-mail me for references on this domain,

Silvio Kruger



    
 
 Reply 
 
Silvio Kruger
Silvio Kruger
07:35 Sep-15-1998
Re: Hydrogen damage



    
 
 Reply 
 
Anthony J. Egan
Consultant,
USA, Joined Nov 2001, 5

Anthony J. Egan

Consultant,
USA,
Joined Nov 2001
5
03:58 Oct-07-1998
Re: Hydrogen damage
The follow ups and answers submitted in reply to this question have covered, in name, probably all of the techniques currently available for the detection and quantification of High Temperature Hydrogen Attack and other forms of Hydrogen Attack.

What has not been covered is the absolute subjectivity of these techniques. No one or even two techniques combined is guaranteed to either detect or quantify this form of damage. The "norm", at least in my experience, has been to over call (Categorize inclusions, laminations etc as damage) findings.
It is important that the end user of the "Examination findings" be fully aware of the probabilities of incorrect calls. At this point in the technology of detection of HTHA it is imperative that the Examination Technician be fully versed in all of the techniques available to them and also the relationship between the different techniques.

A combination of Backscatter and Velocity Ratio may work very well in some circumstances but not in others. Depending on material, hydrogen partial pressures, product, temperature, thickness, pressure and history of equipment there may be a number of different combinations which will most accurately detect and quantify the extent of damage in pressurized equipment. An end user of these type inspection techniques should expect to see definitive inspection progress charts which will direct the examiner in which techniques to use to form their conclusions. The extent of damage and the location of the damage within the material have a significant bearing on the techniques which should be used.

It is possible to determine the through wall extent of damage, provided the damage is in fact damage. To suggest that Backscatter or Velocity Ratio give anomalous values for the extent of damage indicates a lack of understanding of the techniques used and where and when to apply them. In many cases if you have confirmed that your findings are indeed damage then an accurate through wall measurement to the damage can be made and this measurement can be compared to your minimum requirements.
In certain circumstances it will be prudent of the examiner and the owner / user to make the assumption that the damage extends from the inside diameter to the outer most indicator of damage.

ajegan@conaminsp.com



    
 
 Reply 
 
Mauricio Calva
Mauricio Calva
08:33 Oct-14-1999
Re: Hydrogen damage


ACOUSTIC EMISSION TECHNOLOGIES HAVE BEEN DETECTING HYDROGEN DAMAGE AND OTHER MATERIAL DEGRADATION FOR THE LAST 20 YEARS.

THE MATERIAL WILL PRODUCE ACOUSTIC EMISSION WHEN AN EXTERNAL STRESS IS APPLIED (PRESSURE, MECHANICAL, THERMAL) AND A DEFECT OR DAMAGE IS PRESENT. IT IS POSIBLE TO DETECT, LOACATE AND ESTIMATE THE GRADE OF DAMAGE.

PLEASE VISIT: PACNDT.COM OR MAIL ME.


    
 
 Reply 
 
Detkov Alexander
Detkov Alexander
01:52 Nov-15-1999
Re: Hydrogen damage

:
: ACOUSTIC EMISSION TECHNOLOGIES HAVE BEEN DETECTING HYDROGEN DAMAGE AND OTHER MATERIAL DEGRADATION FOR THE LAST 20 YEARS.

: THE MATERIAL WILL PRODUCE ACOUSTIC EMISSION WHEN AN EXTERNAL STRESS IS APPLIED (PRESSURE, MECHANICAL, THERMAL) AND A DEFECT OR DAMAGE IS PRESENT. IT IS POSIBLE TO DETECT, LOACATE AND ESTIMATE THE GRADE OF DAMAGE.

: PLEASE VISIT: PACNDT.COM OR MAIL ME.




    
 
 Reply 
 
Kevin
Kevin
06:37 Nov-19-1999
Re: Hydrogen damage
:
: :
: : ACOUSTIC EMISSION TECHNOLOGIES HAVE BEEN DETECTING HYDROGEN DAMAGE AND OTHER MATERIAL DEGRADATION FOR THE LAST 20 YEARS.

: : THE MATERIAL WILL PRODUCE ACOUSTIC EMISSION WHEN AN EXTERNAL STRESS IS APPLIED (PRESSURE, MECHANICAL, THERMAL) AND A DEFECT OR DAMAGE IS PRESENT. IT IS POSIBLE TO DETECT, LOACATE AND ESTIMATE THE GRADE OF DAMAGE.

: : PLEASE VISIT: PACNDT.COM OR MAIL ME.




    
 
 Reply 
 
Bjarne Larsen
Bjarne Larsen
00:03 Nov-23-1999
Re: Hydrogen damage
: The detection, classification and surveillance of hydrogen damages in pressure vessels and piping may be performed using automated ultrasonic examination. The examination is normally performed using one straight beam probe (for the detection of lamellar cracks) and 2 angle probes (for detection of cracks perpendicular to the surfaces). Hydrogen damages normally show as many small craks at the early stages, these cracks gradually grow together during the service untill the equipment fails.
The advantages of the automated ultrasonic examination are:
1.The examination may be performed with all 3 probes at a time reducing costs and time.
2.The condition at different stages e.g. examinations each year may be easily compared and the crack growth evaluated
3. The accuracy of the examination with regard to location and size of the damages is superior to other examination methods or manual ultrasonics.

For more information please contact me or visit our website: http://www.p-scan.com

BjarneLarsen
FORCE Institute
Oestre Gjesingvej 7
DK-6715 Esbjerg N
Denmark
Phone: +45 76 10 06 50
Fax: +45 75 45 00 86
E-mail: bjl@force.dk
WWW: http://www.force.dk
: :
: : ACOUSTIC EMISSION TECHNOLOGIES HAVE BEEN DETECTING HYDROGEN DAMAGE AND OTHER MATERIAL DEGRADATION FOR THE LAST 20 YEARS.

: : THE MATERIAL WILL PRODUCE ACOUSTIC EMISSION WHEN AN EXTERNAL STRESS IS APPLIED (PRESSURE, MECHANICAL, THERMAL) AND A DEFECT OR DAMAGE IS PRESENT. IT IS POSIBLE TO DETECT, LOACATE AND ESTIMATE THE GRADE OF DAMAGE.

: : PLEASE VISIT: PACNDT.COM OR MAIL ME.




    
 
 Reply 
 

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