03:50 Feb-26-2011 Nguyen Trong My Director, , Vietnam Inspection Solutions Co., Ltd, Vietnam, Joined May 2000 22
NDT of catalyst tubes of Primary reformer
I would appreciate experiences and comments from anybody who has worked with NDT of catalyst tubes of primary reformer used in fertilizer plant: Standards/Codes, methods and techniques, equipment, procedures for sutdown inspection.
The tube material: 25CR35NiNb.Ti; OD/ID: 152/132 mm; distance between the two agent tubes: 250 mm (clear space between the two agent tubes: 100 mm); Length: 12000 mm; working temp: 876 C degrees; working pressure: 34 Bar
This is a comment. Normally we (H2 Reformer Plant) have critical spare parts catalyst tubes stocked at plant's warehouse including spare catalyst itself. When pressure drop across the tubes go up abnormally then operators know that we need to arrange a scheduled (normal) plant shut down for inspection. Certainlay, we will have to replace the catalyst, but firstly we have to find out whether there is a crack in the tube or at its surface by the use of UT and PT. Particularly, if we can see a portion of tube looks like 'bulging'/'swollen'. Problem may arise when catalyst tube and its catalysts are not considered as critical plant spare part to be stocked at plant site.
13:16 Feb-26-2011 Nigel Armstrong Engineering, - Specialist services, United Kingdom, Joined Oct 2000 1029
For UT weld inspection you will need to train your technician(s) to use TR Longitudinal wave high angle probes specially designed for coarse-grained material such as stainless and Inconel. You will need to have a mock-up of the weld(s) you will be testing made with artificial flaws representative of what you may expect to find in reality as a performance demonstration. Then practice, practice, practice!
The shutdown planning will need to be carefully managed and will depend on what is to be achieved in what period of time. Manage every detail you can so that your technicians are fully supported and have nothing to concern them apart from the inspection schedule.
18:31 Feb-26-2011 Rich Roberts Engineering, Executive Managment, Quest Integrity Group, USA, Joined Nov 1998 78
Good Day Mr.
Testing of steam reformer tubes made of spun cast alloys is a very challenging exercise. The most prominent damage mechanism to be concerned with is Creep Stain. Creep strain can be detected very early in its life with the right NDE methodology. Micro and Macro cracking will occur, however closer to end of the tubeÂ’s life. WhatÂ’s important is that the NDE methodology being applied to detect early stage creep strain is that 100% of the tubes circumference is tested. NDE techniques which provide less than 100% circumference inspection (i.e. too few sensor and <100% surface coverage) have a high probability of missing the creep damage or underestimating the worst damage. We use combined Creep Stain and Crack Detection sensors in our LOTIS and MANTIS technologies to ensure 100% of the circumference is inspected.
Crack detection technologies such as Â“conventionalÂ” Eddy Current may produce erroneous results due to permeability variations within the spun cast tube material. We have developed a proprietary Â“cross cancelling permeabilityÂ” Eddy Current approach which is capable of distinguishing between permeability variations and cracking. This ensures good tubes are not retired early and severely damaged tubes are not left in service.
Please feel free to contact me directly if you would like additional information on either our LOTIS or MANTIS technologies.
Quest Integrity Group
Sir: In response to you inquiry on the assessment of Cast Reformer tubes,I have the following comments. The damage that occurs in these materials is such that no single technique will completely detect and quantify all said damage mechanisms,all the time.
For comprehensive assessment several techniques are employed ( H SCAN, a single scan deployment technology), each designed to measure a specific type and location of damage. The inspection needs to measure early (incepent) voids and micro-cracking,macro-cracking and both creep strain (growth) and remaining wall thickness. The inspection results can be directly used in a software program which uses operating conditions of the furnace (Stresses,tube temperature,cyclic operations) to predict remaining life on each individual tube or tube section.
The approach has been developed over several years research,and successfully deployed worldwide by Plant owners in the Ammonia, Hydrogen and Syngas industries. Please contact me directly for further information. Thank you. Brian Shannon
20:02 Feb-28-2011 S.Senthilkumar Engineering, QA/QC/NDT, NOV (National Oilwell Varco), Angola, Joined Mar 2006 36
2. What I use to test in same reformer tubes in 1996, UT bubbler and squriter method. using Tran and Recvr Seperate tranceducer Sound path 'W'. Use the fresh tube as a reference and set the gain range max acceptable and scanned in longitudinal scan (Tube divided in 5 segment)
3. Creep test using vernier caliper min/max dia in straight postion and bends.
4. Replica testing.
This was done in one of the fertilizer plant.
10:48 Mar-01-2011 LALIT MOHAN KOTHARI Consultant, -, On ..IOCL and BARC(Bhabha Atomic Research Centre).etc, India, Joined Jan 2003 128