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RE: Radiographic inspection

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The instructions for the pachometer I used once indicated that the 
instrument will tell you one of two things: size or depth/cover.    
If you know the depth to the bar, it will tell you the approximate 
size.  If you know the size, it will indicate depth.   The Hilti reps 
claim their instrument can give you both.

Dave Evans, P.E.
TNH, Inc.

> From:          "Dennis S. Wish" <wish(--nospam--at)cwia.com>
> To:            <seaoc(--nospam--at)seaoc.org>
> Subject:       RE: Radiographic inspection
> Date:          Mon, 30 Mar 1998 11:45:52 -0800
> Importance:    Normal
> Reply-to:      seaoc(--nospam--at)seaoc.org

> Most testing labs use Pachometer's. A pachometer is actually nothing more
> than a metal detector. In fact, Fisher is one of the companies that supplies
> Pachometers for testing. Mel Fisher is also the treasure hunter that
> discovered millions off the Florida coast a few years ago. Fish Metal
> Detectors have been popular for years and serve a purpose for professionals
> and hobbyists.
> The depth of the detection is questionable. Certainly a couple of inches is
> expected. In coin detection, it can be up to a foot or more depending upon
> the mineralization of the soil (from my hobby days). I would caution,
> though. I recently had a Pachometer study done on an infill in an
> Unreinforced Masonry building and the results showed no steel rebar or
> dowels. When the work began to remove the infill, rebar was uncovered less
> than 4 or 5 inches from the surface. The lab that performed the Pachometer
> study returned to the site with the equipment and did not detect the steel.
> We still don't know why, but I do know that the testing tech was also the
> owner of the Company and someone I've known for over twelve years and
> trusted (also an engineer).
> On a similar note, I was a Cross-Complainant in a law suit that arose from
> the work done on a Unreinforced Masonry building owned by the Girl Scouts of
> America. I was supplied a Pachometer survey which showed the building to be
> Unreinforced. The lab was one that I did not respect, but who had been in
> business specializing in Unreinforced masonry testing for years.
> The roof was stripped and the contractor started to core the walls (this was
> a blockwall building where the client wanted to Center-core the URM wall
> rather than anchor through the face of the wall. The contractor hit vertical
> and horizontal steel almost immediately.
> I was notified, stopped the job and contacted the testing agency
> immediately. They returned to the site and performed another study - to find
> it reinforced to the hilt. They claimed that either the equipment was faulty
> at the time of the original test or that their technician did not know
> enough to check the batteries.
> I was dropped from the suite (no liability insurance) and the Testing Lab,
> Contractor and Roofer (the contractor and Roofer were Cross complainants
> with insurance) were found liable and had to compensate the GSA for all
> damages to the building.
> IMHO, the Lab should have been the only one liable.
> 
> I've had Pachometers used on hundreds of buildings for veneer tie testing as
> well as other needs without a problem. Generally the Pachometer can detect
> the depth below surface, the spacing horizontally and vertically as well as
> the size of rebar (I'm not sure how they do this).
> 
> Dennis Wish
> 
> Dennis Wish PE
> La Quinta, California
> wish(--nospam--at)cwia.com
> ICQ# 6110557
> http://wwp.mirabilis.com/6110557
> 
> "Silence is the virtue of fools."
> Francis Bacon
> 
> |-----Original Message-----
> |From: Powers, Tony [mailto:tpowers(--nospam--at)hdrinc.com]
> |Sent: Monday, March 30, 1998 9:19 AM
> |To: seaoc(--nospam--at)seaoc.org
> |Subject: RE: Radiographic inspection
> |
> |
> |Tom Harris wrote:
> |>       When walls or slabs above grade are too thick to use pachometer,
> |> i have
> |> used x-ray successfully.
> |	[Powers, Tony]
> |	How thick is too thick for a pachometer?  Where can I get more
> |general information on pachometers and their use?  Thanks,
> |
> |	Tony Powers, PE
> |	HDR Engineering, Inc.
> |
> |
> |
> |
> |
> 
> 
> 
>