Nondestructive Examination of Bolts/Studs for Corrosion Thinning 2

[Eddycurrentguy]

Greetings,

Bolts/studs (varying diameters and lengths, but generally 7/8” diameter B7) on flange connections for wellhead equipment [natural gas service] have been observed to be preferentially corroding within the flange area, most likely due to trapped moisture. Traditional in-situ NDE methods such as radiography, eddy current and standard ultrasonic testing techniques will not achieve the goal to qualify and quantify corrosion thinning in these areas. Hot bolting inspection methodology would not be our first choice either. Phased array ultrasonics might be an option, but this equipment does not appear to be readily available for this application

I would be interested in hearing from others in the industry to see how these inspections have been performed in the past. Any help would be appreciated.

Thanks…

 

[SJones]

The Energy Institute Guidelines For The Management Of The Integrity Of Bolted Joints For Pressurised Systems suggests that the use of cylindrically guided wave UT is appropriate for corrosion thinning assessment.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[vanmorrison]

http://www.eclipsescientific.com/Products/Scanning/BoltScanner/info.html

The above link is to the website of Eclipse Scientific in Waterloo, Ontario, Canada. They sell a phased array UT based inspection system for use on bolts and studs. The scanner has been used by several different large users including NASA for the inspection of bolts on the shuttle launch pads in Florida. Florida Light and Power uses this system to inspection the bolts on the high voltage transmission line towers for routine inspections and after hurricanes/server storms pass through.
Hope this information is of some help to you.

 

[Eddycurrentguy]

Thanks, Guys,

The information you provided is greatly appreciated!!