Principles and Working of
Automated Reformer Tube Inspection System
ARTiS
TCR Advanced Engineering Pvt Ltd,
Vadodara India
TCR Engineering Services Pvt. Ltd.,
Mumbai India
Background on Reformer Tubes
The primary reformers are used in various industries
like fertilizers, petrochemical and refineries, for
cracking of hydrocarbons in presence of nickel based
catalyst in reformer tubes.
The reformer tubes are operational at 800+ C
temperature and are internally pressurized.
Over long operational life, the material undergoes
high temperature creep damage, which is often
reflected as increase in tube diameter and with or
without formation of internal creep fissures.
The extent of damage is quantified through various
non-destructive such as diameter measurement,
apparent bowing and increase in diameter along
with Ultrasonic Inspection.
Principles of reformer tube inspection
The ultrasonic inspection of reformer tubes is done in T-R (TransmitReceive) mode where ultrasound energy is transmitted from one
sensor, passed through middle of the wall section and received at other
sensor (Figure 1). The energy transmitted is the sum of energy received
and the energy lost in beam scatter.
Principles of reformer tube inspection
In as-cast condition, ultrasound scattering occurs at dendrite boundaries from
primary carbides.
After prolonged exposure to high temperature, precipitation of secondary
carbides and creep void formation additionally scatters the ultrasound.
The additive effect of beam scatter becomes the measure of energy lost.
Principle of Ultrasonic Test in reformer tubes
Increase in diameter:
Internal or external tube diameter growth is also a material degradation
indicator. Whenever catalytic tubes are operating under pressure in their
creep temperature range, their diameters will increase in time. Generally,
diameter increases in the range of 1-6% are potential indicators of certain
stages of creep.
Tube bowing:
Sometimes, tubes exhibit bending or bowing after being in service. Tube
bowing could potentially be harmful when it touches to the other tube or
excessively bowed. Generally, bowing beyond 1x tube diameter is considered
as replacement planning.
Tube inspection by ARTiS
ARTiS is a proprietarily developed method referred as the Automated
Ultrasonic test System used to override the manual ultrasonic scanning.
TCR has developed the technology and necessary instrumentation for ARTiS.
This is a robotic crawler that aids ultrasonic testing of reformer tubes in more
systematic manner and provide tabular output.
The sensors fitted on the crawler measures the tube diameter. During
crawling, the diameter is measured at fixed interval of distance.
The gyro-sensors fitted on the crawler aids for angular measurements. Post
analysis of angles would give quantitative figure of bowing.
Microstructural degradation v/s Ultrasound attenuation
The microstructure of unused tubes is
shown in Figure left, having dendritic
columnar austenite grains oriented
perpendicularly to tube walls.
Attenuation level: 35 55 dB
Upon aging, the structure degrades. The
original morphology of eutectic carbides
gets modified after exposure at
elevated temperatures.
Attenuation level: 55 62 dB
At life fraction near to 80 - 95%, the
microstructure is coarsened secondary
carbides with presence of inter
dendritic micro cracks.
Attenuation level: 62 72 dB
Microstructural interpretation capability of TCR
TCR has expert metallographers with high skills.
TCR has database of microstructure of nearly 1000 spots. This includes the
tube condition having virgin condition, tubes after normal aging and tubes
that have failed in service.
TCR has microstructure interpretation expertise for evaluation of the tube
condition based on surface replication method to identify creep stage
classification.
TCR has provided services on in-situ microstructural replication and
condition assessment of tubes to more than 50 different customers in
India and outside conurty.
Comparison between Manual v/s ARTiS
Parameter
Manual method
ARTiS
Ultrasound test
Manual scanning
Automated tube crawler
Requirement of scaffolding
Needed
Not needed
Time of test inclusive of
construction of scaffolding
4 to 5 days for 100 tubes
2 days for 100 tubes
Resolution of test result
Reported in 6 feet
segments
As low as 100mm distance.
Outer diameter
measurement
One or two locations
manually
Every 100 mm distance
Tube bowing
Apparent assessment
Quantitative figure
5 to 200mm
Tube inspection by ARTiS
The crawler is powered by 4 metal gear motors, with
total capacity of 200 watts.
Rubber padded shoe assembly carries
ultrasound sensors for T-R mode inspection.
IR Sensors provide diameter measurements.
the
Crawling demonstration
Water tank
for coupling
Water
pump
Motors
Adjustable
arm
UT Probes
ARTiS Technical specifications
Parameter
Value
Scanning speed
2 to 5 minutes per 10 meters adjustable
Scanning resolution
100 mm
Fixing time of Crawler
3 minutes
Flexible UT probe adjustment
Tube OD:
Tube thickness:
Adoptability (tube outer diameter)
Minimum 125mm
Maximum 195mm
Climbing height
Maximum 15000 mm
DM Water consumption
500 ml per 10 meters
Outer diameter measurements
IR Distance sensors resolution 0.5% of OD
Tube bowing
Gyros sensors minimum detection 5mm.
UT Probe
Diameter: 25mm
Frequency:
1 MHz
Range / resolution
30 to 100 dB
/ 0.1 dB
Operating conditions
Max. temperature
Max humidity
10 to 40C
20 to 80 RH
130 to 180 mm
8 to 20 mm
List of the clients
Condition Assessment with Automated UT
GNFC Bharuch Through: Spic India.( ARTiS)
BPCL, refinery, Through: Radiant engineers ( ARTiS)
Godrej industries Valia ( Manual)
RLA & Failure Investigation :
CFCL Kota, Indo Gulf Jagdish Pur, GNFC Bharuch, Godrej Ltd. Valia.
Althuriya, kuwait , Maden , Saudi Arabia.
In situ metallography
GNFC Bharuch, GSFC Vadodara, CFCL Kota, IOCL Vadodara, BPCL Cochin,
BPCL Mumbai, RIL Jamngar, RIL Vadodara, RIL Hazira, Deepak Fertilizers,
RCF Thal, VVF Ltd. Mumbai, Nirma Ltd. Vadodara, NPL Kalyan, Welspun
Maxsteel Ltd. Alibaug, Maden , Saudi Arabia
Contac us :
testing@tcradvanced.com
sales@tcreng.com
www.tcradvanced.com
www.tcreng.com
