Micrometer

[MacGruber22]

Has anyone found or use a micrometer that is large enough to reach around a 6 or 8 inch wide flange to measure web thickness?

 

[TehMightyEngineer]

Nope, I use an ultrasonic thickness gauge for those few times I can't figure out what the wide flange section is based on flange dimensions and depth.

Maine EIT, Civil/Structural.

 

[MacGruber22]

I was waiting for that. So..expensive. Do you own yours or is it your firm's?

Determining the original section isn't usually a problem, as you suggested. But, when the web is chewed up, it is nice to be able to map out the section loss.

 

[TehMightyEngineer]

The firms; cost about $900 if I recall correctly. Paid itself back after a year of thickness testing industrial oil tanks.

For section loss I've typically just found a rough, average loss of thickness (admittedly with the thickness gauge but you could get a rough idea from the flanges) and use that to find the typical section properties assuming a uniform loss of thickness on the corroded surfaces. Any errors or thicknesses below the assumed, average thickness will likely be reinforced by areas which are above the average thickness.

Alternatively, this is a great time to justify the purchase of a thickness tester.

Maine EIT, Civil/Structural.

 

[Compositepro]

http://www.starrett.com/metrology/p...s-and-Tram/111301-Calipers-and-Dividers/36-12

Transfer calipers

Transfer calipers are used for measuring chamfered grooves or flanges. A screw attaches a small auxiliary leaf to one of the caliper legs. The measurement is made as with ordinary calipers. The leaf is locked to the leg. The legs may be opened or closed as needed to clear the obstruction. The legs are then brought back and locked to the leaf, restoring them to the original setting.

 

[XR250]

Straight edge up each side - measure to the web. Then measure flange and do the math.

 

[EngineeringEric]

Just find the end, its a lot easier that way I've always done the math way, good for plus or minus 1/8".

 

[JStephen]

Something like this might be workable, I'm not sure how the extra pieces fit in there. It looks like it might be easiest to slip it over the end of the beam and slide it down to the point in question:

http://www.mcmaster.com/#outside-micrometers/=uk07u4

This is an awfully expensive way to say, "Yup, it's rusty". The ultrasonic doohickeys would be more all-around useful, I would think.
Labs that do steel inspection should have the ultrasonic testers and people that know how to use them.

 

[JStephen]

Corrected link:

http://www.mcmaster.com/#8597a34/=uk09yj

 

[TehMightyEngineer]

Nice but that's the same cost as the ultrasonic thickness tester I use.

Maine EIT, Civil/Structural.

 

[azcats]

I've used a Phase II brand ultrasonic thickness gauge for several years. We use it on large diameter pipe where we can't get to an end.

I have noticed some much-less-expensive (sub $200) models on Amazon lately. Not sure of your certification/documentation requirements however, which I believe these less expensive models lack.

For example: Link

I do not vouch for this unit - just an example.

 

[Archie264]

Are you sure you need the web thickness to identify the member? Web thickness tends to vary less from shape to shape than flange thickness does. Usually if depth, flange width and flange thickness are known the beam can be identified. That's been my experience, at least.

 

[MacGruber22]

If you are asking me, Archie, no I don't worry about it for identifying the section. I agree, it isn't *too* difficult not having the web thickness. I intend on utilizing it for web deterioration.

 

[Archie264]

Ah, that makes sense.