Inspection Methods For HF Modified Pipe 1

[gullygossner]

Good day,

We have a fair amount of HF modified pipe in our facility and are currently in the midst of revamp work where tie-ins and pipe rework is required. Prior to cutting pipe, the project management contractor is requiring a thickness reading to ensure adequate material is present for welding. In the past we have done ultrasonic thickness readings on the lines but have quit this practise because we feel the results are questionable due to the grain size of HF material. The pipe ranges from 4.00" to 14.00" and sch 40 to 160.

I am wondering what inspection methods others are using for corrosion monitoring and weld inspections.

Thank you in advance.

 

[Guest102023]

If you have doubts about adequate wall thickness for welding on pipes of the sizes you quote, then something is missing. If UT has been unreliable, you could try X-ray methods.

Another question that arises is the metallurgical condition of the pipes; there might be weldability concerns there.

 

[gullygossner]

The concern arises from the fact that there could be corrosion occurring causing inadequate material for welding. Cutting into the pipe and finding a thinned situation would not be ideal as HF Modified piping is not readily available. With this metallurgy there should not be an issue with corrosion but never say never as high turbulence zones have shown erosion in the past. X-ray is an option but due to the thickness, cobalt would have to be used which raises issues with closing off the area to a high number of personal not to mention requirements for engineered scaffold in order to support the cobalt source.

 

[unclesyd]

I would rethink using UT because I don't like Cobalt, having taken around 200 shots with a trap door camera.

I've talked to a level III and two experience level II's all said there should be not be a problem with UT if the proper gauge block is used. There might be some attenuation but neither said that would prevent getting a good thickness reading.

I'm a little curious as to the physical measurements of the pipe in question.
If as you post it is large and heavy wall you might want to contact Duraloy or Kubota about the lead time for same.

http://www.duraloy.com/

http://kubotametal.com/alloys/heat_resistant/index.html

 

[ndeguy]

Is there no available spare material out of which you can make a test piece to ascertain inspection reliability and repeatability and perfect your technique?

Due to the potentially large grain size, have you tried a large diameter (24mm/1")low frequency (1 to 2 MHz) probe?

The 4" sch 40 (6mm wall) will need a twin-crystal, but the 14" Sch 160 (35mm) will be better measured with a single crystal

For corrosion monitoring, UT is the most widely available and flexible option, from manual data loggers to fully-automated C-scan colour imaging systems. The equipment manufacturers will sort out your specific problems.

For weld inspection focussing on the root in particular , I would recommend trialling ToFD for wall thickness 8mm and more. You can get an idea of the general corrosion condition of the ID simultaneously. Approach an experienced ToFD service-provider.

Like all things you pays your money, you takes your choice.