All Member Open Forum

H everyone, 

i have some issues about inspection of a 45 years old line of bunker. 
i only have 1 line.
i know it was corrode and i dont want to remove all isolate to inspect.

My staff done thermographic inspection but with the reflectibility of the aluminium coating over isolation, i'm spectical of the result

any feedback about how can i do that to by effective and in operation?

thanks

Patrick

------------------------------
patrick girard
maintenance manager Port and Handling
Arcelormittal
Port-Cartier QC
------------------------------

Hi Patrick,

One option might be to undertake Ultrasonic Thickness gauging. There might be professionals in your area - those associated with ship repair are familiar with it. It is not expensive. The only concern is, if the pipe is heavily corroded internally, you may not get accurate readings of the thickness.
As a former ship's engineer, we used to pressure test these fuel pipes once a year to about 2 times the working pressure.
In your case, it might be a good idea to open a few flanges and remove a section of piping for an internal inspection. You can pull out 2-3 such short pipes at various locations of the overall length and make a sample visual assessment of how strong ( or weak the pipe is). You can choose bends because that's where the pipe is most likely to be eroded . And then, based on your findings, you can inform your management to set aside a budget for the phased renewal of these pipes if the condition is really bad as found from your inspection.

All the best.

------------------------------
MATHEWS VADAKKAKARA
MSPL Diamond PTE Ltd
SINGAPORE
------------------------------

I checked with a colleague, and she suggested Moisture Detection Imaging (MDI) as a way to check the condition of the insulation. Moisture in the insulation means corroded pipes, while dry insulation means there is a lower risk. You are correct, thermal images of aluminum sheathing are basically just reflections and you can't trust them.

The rest of her response:

Possible options depending on the pipe design and diameter can be found in API 583 Recommended practice, it has information of advantages and disadvantage:

 

1. Guided Wave
1. It is an ultrasonic test
2. It requires removal to place the transducer and it is limited to the flange to flange distance, since the signal will not pass those points.
3. It can detect inside an outside metal loss

 

1. Radiography
1. For pipe < 8in
2. Do not detect external chloride stress corrosion cracking on austenitic and duplex materials
3. Not removal of insulation required
4. Recommended to specific areas suspected to have CUI
5. Different technologies available

1. Film profile radiography
2. Computed and digital detector array (DDA) profile radiography

• DDA

1. Linear diode array
2. Film density radiography complementary to profile radiography
3. Flash radiography

• Radiometric profiling
• Real time radiography examination method (RTR)

 

1. Pulse Eddy current (PEC) We have used this method on Glycol vessels
1. Detect average wall loss outside and inside
2. No removal of insulation
3. Electromagnetic examination

 

1. Neutron Backscatter
1. Moisture detection\
2. No removal of insulation

 

1. Thermal imaging (thermography)
1. Detection of wet spots in the insulation
2. No removal of insulation

 

1. Moisture Detection Imaging (MDI)
1. Detect fluids on insulation (organic compounds detection)
2. No removal of insulation

------------------------------
Dale Nicholson, PE, CMRP, CRL
Reliability Engineer
Evonik Corp
Lafayette IN
------------------------------

I see a lot of good suggestions. Another suggestion is called a smart pig that is used for pipeline inspections. Please let us how you decide to do the inspections?

Best regards,
Owe Forsberg
Certified Competency as Chief Engineer in Motor Ships

------------------------------
Owe Forsberg
Senior Consultant
IDCON, Inc.
Raleigh NC
------------------------------

Patrick:
You could still use thermography to check line.  Inside a building make sure room is dark.  Outdoors take a look at night after in the dark.   There is a emissivity number for aluminum.  



------------------------------
Wayne Offermann
Maintenance Manager
Lawrenceville GA
------------------------------