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Technical Discussions
Jairo Humberto Guzman
NDT Inspector, NDT researcher
Ecopetrol ICP, Colombia, Joined Nov 1998, 6

Jairo Humberto Guzman

NDT Inspector, NDT researcher
Ecopetrol ICP,
Colombia,
Joined Nov 1998
6
06:56 May-21-1999
tube inspection

Does anybody know the best ultrasonic technic to find the innicial Creep in radiation tubes of furnaces.

The materials of these tubes are HP40 and HK40

What frecuence is the best?
Longitudinal or Shear waves get better results?
Pulse-eco or throw transmition give better results?

I will apreciatte any information

Jairo Humberto Guzman


 
 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
06:36 May-27-1999
Re: tube inspection
: Does anybody know the best ultrasonic technic to find the innicial Creep in radiation tubes of furnaces.

: The materials of these tubes are HP40 and HK40

: What frecuence is the best?
: Longitudinal or Shear waves get better results?
: Pulse-eco or throw transmition give better results?

: I will apreciatte any information

: Jairo Humberto Guzman

---------------------------
Jairo,

Conventional NonDestructive Examination(NDE) inspection techniques such as Ultrasonics (UT) and Eddy Current (ET) currently applied to tubing in process plants are geared to finding creep damage in the form of internal cracking within or accross grain boundries. However, with the trend towards larger tube diameters and longer intervals between turnarounds, the detection of such defects may not allow for sufficient time for forward planning of tube replacements. Also, such ‘end of life’ techniques do not allow any differentiation between the ‘good’ tubes. Early detection of underutilized tube life can prevent the lost opportunity on both unrealized production through running them too cool and tube life ‘giveaway’ if good tubes are discarded prematurely.

Tubes in furnaces, reformers, etc. undergo creep strain, in the form of diametrical growth, from the first day that they are fired. The ability to accurately measure and record this growth means that the tubes’ condition can be monitored from day one. Therefore, not only can individual tubes be retired from service at an appropriate time, but also the component as a whole can be assessed for performance. The use of QUEST Integrated, Inc. internal laser mapping technique is not only useful in preventing tube failures but has huge potential in optimizing production from the whole tube set without sacrificing reliability. Of course, EXTERNAL diameter measurements can be used but they are limited as the automated devices only measure across one diameter and are often access restricted. Manual measurements are too time consuming to provide more than a few readings per tube. Furthermore, neither way can provide diametral growth data at or through the furnaces or reformers refractory. External measurements are inherently less precise as they are based on a crude surface rather than the internal surface and do not take into account the effects of oxide shedding. The most accurate growth measurements are obtained when ‘as new’ baseline data has been taken prior to the tube being fired for the first time..

Recently, the use of the laser mapping method referred to as “laser profilometry” has gained worldwide acceptance as a viable inspection method for the early detection and characterization of creep. Process plants in New Zealand, South America, Canada, and the United States have successfully used the laser profilometry method. Whenever furnace, reformer, etc. tubes are operating under pressure in their creep temperature range, their ID will increase over time.. Use of laser profilometry allows mapping and quantification of a tube’s ID as several hundred thousand diameter readings can be acquired down its length. Since small diameter increases on the tube’s interior (i.e.1% are indications of early stages of creep, it is essential to gather data with such accuracy).

QUEST Integrated, Inc. has developed a laser-based system which provides precise inner diameter dimension down the length of catalyst tubes in reformers. This process has been quite successful in providing data to 3D model reformers in several Methanol plants. The advantage is that scale, corrosion, etc. on the tubes exterior has no effect on the data quality. When Eddy Current or Ultrasonics is utilized scale, corrosion, etc. tend to create noise levels which can produce erroneous results. QUEST’s laser method could also be used in your situation as well. If you have interest in knowing more please contact Richard D. Roberts/QUEST at 1-253-872-1275.



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

Anthony J. Egan

Consultant,
USA,
Joined Nov 2001
5
07:28 May-27-1999
Re: tube inspection
Richard
With regard to your comments / observations on the limitations of the ultrasonic and eddy current methods now employed in the evaluation of heater / furnace tube remaining life, specifically the effects that oxidation / scaling has on the results. Is the laser profilometry method without limitation? How does this method handle, for example, coke / product build up along the ID surfaces of the tube.
We recently removed sections of furnace tubes which had shown a significant diametrical growth. The decision to remove these sections was based on external measurements of the tube diameters. When these tube sections were removed there was obvious grooving, along the ID surfaces, from previous decoking (pigging)! Would the laser profilometry return anomlous results if either grooving (from decoking) or product build up were present?
Regards
Anthony



 
 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
09:02 May-27-1999
Re: tube inspection
: Richard
: With regard to your comments / observations on the limitations of the ultrasonic and eddy current methods now employed in the evaluation of heater / furnace tube remaining life, specifically the effects that oxidation / scaling has on the results. Is the laser profilometry method without limitation? How does this method handle, for example, coke / product build up along the ID surfaces of the tube.
: We recently removed sections of furnace tubes which had shown a significant diametrical growth. The decision to remove these sections was based on external measurements of the tube diameters. When these tube sections were removed there was obvious grooving, along the ID surfaces, from previous decoking (pigging)! Would the laser profilometry return anomlous results if either grooving (from decoking) or product build up were present?
: Regards
: Anthony
-----------------------------------
Anthony,

No, the laser mapping method is not without limitations. First off there must be access to the interior of the tube and the tubes surface must have been cleaned so that the coke is removed. QUEST has designed and built a remote inspection system referred to as the Furnace Tube Inspection System (FTIS). The FTIS is specifically designed for inspecting serpentine furnace tubing up to 3000’ in length with unlimited 1D return bends in approximately 17 minutes. The FTIS utilizes both a combination of LASER and ULTRASONICS. The FTIS system is run through the furnace right after the decoking (pigging) process has been completed. If coke is still remaining in the tube the FTIS will be capable of seeing and quantifying this. If grooving (from decoking) is present the FTIS will be capable of seeing and quantifying this as well.

Our partner with the FTIS technology is UCISCO (A division of Praxair). You may want to visit their web-site for further details or contact Mr. Steve Lalumandier in Houston, Texas at 1-281-478-1942.
Regards,
Richard D. Roberts





 
 Reply 
 
Johan van de Stadt
Johan van de Stadt
01:21 Jul-19-1999
Re: tube inspection
: Does anybody know the best ultrasonic technic to find the innicial Creep in radiation tubes of furnaces.

: The materials of these tubes are HP40 and HK40

: What frecuence is the best?
: Longitudinal or Shear waves get better results?
: Pulse-eco or throw transmition give better results?

: I will apreciatte any information

: Jairo Humberto Guzman

Hi,

When reviewing the forum I saw your questions regarding tube inspections. We (NUSON) are specialised in UT
tube inspections. We are capable in detecting cracks in tubing with an ID from 10 till 82 mm ID. Bends can
be negotiated till a certain amount. We use boreside pulse echo techniques. For crack detection normally 10 MHz
shear waves.

look also at WWW.NUSON.NL

Johan van de Stadt
NUSON Inspection Services


 
 Reply 
 

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