we have beenasked to perform the following testing:
Vertical Heat Exchanger Tube Length 21 m Tube Diameter 3/4" Tube Material T11 Number of tubes 1885 The heat exchanger has been out of service for the last 5 years. Which is the best inspection to suggest the customer ? Is it OK Remote Field or MFL for flaw detection and IRIS for flaw carachterization ? Will the verticality of the item affect the performance of the inspection ?
Re: Inspection of a Platforming Plant Heat Exchanger st 5 years. : Which is the best inspection to suggest the customer ? : Is it OK Remote Field or MFL for flaw detection and IRIS for flaw carachterization ? : Will the verticality of the item affect the performance of the inspection ?
06:30 May-26-2000 Richard D. Roberts Engineering, Executive Managment Quest Integrity Group, USA, Joined Nov 1998 78
Re: Inspection of a Platforming Plant Heat Exchanger Dear Amedeo Marino,
Have you considered using LASER to inspect your tubes? QUEST designed a laser based tube inspection system for the US Navy in 1985 which has many advantages over other conventional NDT inspection methods. Of course there are also limitations such as any method. What type of defects or damage you are attempting to detect and quantify should be the deciding factor when selecting a testing method.
The advantages that the LASER method has are: a) Very High accuracy: +/-0.025mm (0.001) b) Inspection Speed: 77mm (3) per second c) Does NOT require water or any other type of couplant d) Set-up and calibration time takes less than 15 minutes e) Different material types have NO EFFECT on the data quality or accuracy f) Can inspect vertical or horizontal tubes with no problem
You may even want to consider this technology as a compliment to the Eddy Current (ET) or Magnetic Flux Leakage (MFL) technique. The very high resolution capabilities can generate highresolution pictures of any flaw located on the ID surface.
If you would like additional information please contact me at: Richard D. Roberts QUEST Integrated, Inc. Tel: (253) 872-1275 Fax: (253) 872-8967 http://www.qi2.com/field/fsddef.htm
07:08 May-26-2000 John O'Brien Consultant, - Chevron ETC , USA, Joined Jan 2000 278
Re: Inspection of a Platforming Plant Heat Exchanger This is a common problem. Obviously searching for areas of damage with RFEC or MFL is a good fast screening then proving up the most significant areas of damage with IRIS will give you the most detailed condition of the exchanger. Vertical exchangers do pose problems with IRIS. In the past when I have done these the best way is to plug the bottom of the tubes and then fill them so you have a static coloumn of water to work in with the IRIS. Some people use rubber bungs or corks. With the length and diameter of your tubes you will have a fair weight so I would use expanding sealing plugs. Most refinery maintenance shops should have these they are selectable based on diameter, rubber sealing rings with a central screw expander. These give a tight fit and will hold the water coloumn. Be aware it can be tricky and slow as it is not uncommon to lose the plugs at an inopportune moment. Depending on how many plugs are available you may find that you inspect as little as two tubes an hour. Sometimes as well it is difficult to obtain and maintain a good IRIS Sine Wave although in a 3/4" tube this should be OK. If this is a concern you may want to consider the Tubescan approach which does not depend upon a water driven turbine. You can find data on that technique at Scanning Systemms International.