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UNDERWATER
VIBROCORING
 
SELECTING A VIBROCORER
 
CORETUBES,
LINERS, & CORE
RETENSION
 
BUOYANT-FRAME
vs RIGID FRAME
 
SPECIFICATIONS
 
OPERATIONS
FURTHER NOTES
 
 

CORETUBES & LINERS

Our vibrocorers can be operated with steel or aluminum coretubes with or without liners.

If the metal coretube is intended to be used with a plastic liner, it is often difficult to find the matching tubes and liners off the shelf, i.e. a plastic liner with an OD smaller than the ID of the coretube (generally by some 0.060-0.080" or 1.5-2mm). In this case the best solution is to first select the coretube and to have the liner custom-made to match it. Most common liners are made of polycabrbonate or CAB (cellulose-acetate butyrate). Note that in non-abrasive sediments a soft polyethylene tube (usually purchased in 6" wide x 1000 ft rolls) with a thickness of 6 mils for the P-3, can be an effective, easy-to-find alternate to a rigid plastic liner.

As a rule of thumb, optimum penetration is generally achieved with steel coretubes in the 3.5" to 4" (8.9 to 10.2cm) diameter and 0.083 to 0.120" (2 -3 in) wall thickness. However, in similar diameter, expendable linerless thin-wall aluminum coretubes, e.g. 0.062 - 0.080" (1.5 - 2 mm) wall thickness, often are the most practical candidates for a vibrocoring project that requires a hard case to ship samples to a lab. Please Note: Aluminum core tubes can not be used with the P-5. Also, some of our clients have obtained excellent results with bare, stiff plastic Lexan coretubes, e.g. 4.0" OD. 0.125" wall, up to 20 ft long, without any metal coretubes or conrnoses, provided with a plastic core-catcher (orange-peel type) simply glued inside the tube.

RETENTION OF THE CORE :

In order to maximize the core recovery, the retention of the core is a factor as important as the penetration achieved. To this effect, our vibrocoring systems incorporate a tight-sealing water-escape valve mounted within the vibrohead. Reusable plug-valve to fit the top of the coretube itself and also stainless-steel thinwall corenose with fingered (orange-peel) core-catcher can be delivered upon request for the diameters to be exactly specified by the client. The corenoses can be fabricated with a stepped shoulder for the seating of a hard internal liner.
 
PO Box 1030,
Poway CA 92074-1030
Phone: 858-679-7361