IBEX 2013

IBEX 2013 

IBEX is the International Boatbuilders Exhibition & Conference

This past year I had the honor to present a session with fellow marine surveyor Jack Allinson of Allinson & Associates on metal boat surveying.  We mostly covered how to apply Infrared Thermography or also know as Thermal Imaging to metal boat surveys. Jack has been involved in Infrared Thermography for ten years now and I have been building and repairing metal boats for over 20 years, so I think we are a good match for a talk like this.

Below is the description from the IBEX website:

Session Description

Infrared thermography gives metal-boat surveyors a whole new tool kit. This session will cover the equipment, the skills, and the training needed to correctly obtain and interpret thermal patterns.

• Surveying Metal Boats with Non-Destructive Testing (NDT)

When it comes to vessels and ancillary components constructed of composite materials—such as sailboat masts, booms, and rudders—most of us are familiar with the use of infrared thermography as an inspection tool. There is little in the literature, however, describing thermal images to evaluate boats constructed of a metal shell plating supported by internal frames.

Jack Allinson and Dylan Bailey will introduce you to what infrared thermography can do and how this “better set of eyes” can demonstrate your findings to your customers. This team will show you examples of thermal patterns and several types of instruments used to measure infrared radiant energy. They'll explain how the instruments work and describe the differences between a spot radiometer, a thermal imager, and a radiometric infrared imager. "We’ll also present visual examples with regards to some of the more common errors that surveyors can make when interpreting a thermal pattern."

These examples are extrapolated from the 2011 Edition of the published Standard for Infrared Inspection of Recreational Yachts & Small Craft Constructed of Fiberglass Reinforced Plastic and Composite Materials (co-authored by Allinson).

A skilled and trained infrared thermographer can help you locate areas of trapped moisture on the interior of a vessel, i.e. trapped behind foam insulation; minute pinhole corrosion on exterior shell plate; and the location of hidden and inaccessible internal framework structures used to support the shell plate.

The condition of hidden-side shell plate or internal frames commonly results in accurate Ultrasonic Thickness Measurement (UTM) readings (a.k.a. audio gauging) when a single-echo machine is used—readings unobtainable when using a multiple-echo machine. Errant or unmeasurable readings are likely a result of hidden, heavy scale and/or corrosion.

When scale or corrosion is located, the UTM technician resorts to destructive testing with a chipping hammer to remove the scale so a good UTM reading can be obtained. Proper interpretation of thermal patterns from infrared thermal Imaging can show where you may expect to have difficulties in getting an accurate UTM reading.

In our speakers’ opinion, being able to identify why good UTM readings are not obtainable is just as important as getting accurate readings that are used to compute the amount of metal wastage and the need for plating replacement.

Infrared thermal imaging and correct interpretations of surface thermal patterns can be a real boon to cost-conscious clients keen on the price point required to find metal wastage, trapped and hidden moisture, and to document the water routes (trails) created when dewatering a vessel. On most UTM jobs, as much as 60% of the work effort goes into planning and implementing where to take the random spot checks for plating thickness. With the right environmental conditions this work can be easily reduced by half by scanning the shell plate with an infrared thermal imager.

We'll also briefly review traditional methods for evaluating metal plating and corrosion. Among the non-destructive testing (NDT) methods are UTM, using a pit gauge, a coating-thickness gauge and, of course, a trained and experienced eye. Among the destructive testing (DT) methods are employing a wire brush, a grinder, a chipping hammer, and drilling holes.

Whether one employs NDT or DT, experience is of the greatest importance, followed closely by documentation through visual images such as photography and high-definition videography. Documentation is key to supporting a defensible opinion. It is important to note that conclusive proof of NDT findings requires destructive testing.

Below are some images of a steel boat using IR.