Core Barrel System

Racks with three sizes [color coded] of core barrels onboard Knorr, September 07 during seatrials.

Barrel Array

Composed of sections with three wall thicknesses that share a common inside diameter.

Material cold drawn 4140 [chrome-moly]

Specifications
- Heavy wall [1.125”] 7.25” OD x 5” ID 20’ long @ 1500 pounds each. Code = dark red
- Medium wall [.75”] 6.5” OD x 5” ID 10’ long @ 460 pounds each. Code = orange
- Thin wall [.375”] 5.75” OD x 5” ID 10’ long @ 215 pounds each. Code = yellow

Corrosion prevention coatings
- Primer = Whitford Corp. Xylar aluminum filled ceramic (CERMET)
- Topcoat = Whitford Corp. Xylan resin bonded PTFE based dry film lubricant

Couplings. The lower insert shows the step-tapered couplings and their respective barrel type transitions.

Couplings

5 types of sleeve-type couplings are employed: 3 ‘straight’ and 2 ‘step-tapered’ to transition the core barrels from one wall thickness to another.

- Material cold drawn 4140 [chrome-moly] - Corrosion prevention coating = xylar/xylan system

Midsection of the long core showing barrel and coupling connections.

Maximum core barrel length

[current] = 46 meters [150 feet]

Core barrel crane delivers mid-barrel section to waiting truck. The truck travels fore and aft pneumatically on channel rails visible on the right.

Barrel handling and assembly

Purpose built pneumatic jib crane delivers barrels to barrel ‘truck’.The pneumatic truck is equipped with a tractor drive to move barrels fore and aft plus air jacks and a vibration system to assist assembly.

Detail of the barrel truck. Air jacks at either end elevate the barrel to the proper height for assembly at each coupling. The four blue casters in the middle transfer powerful vibration from device below to ease insertion and retraction at the barrel/coupling joint.

Premarked pvc core liner awaits insertion into the core barrels. Threaded joints are visable in the foreground.

Core Liner

Custom extruded pvc 4.875” od x 4.375” id. Ten foot lengths coupled during assembly via threaded joints at each end.

Robust core catcher acts as a ?valve?, opening curing penetration to allow sediment to enter the liner, then closing during pullout to prevent any sample loss.

Core cutter/catcher

Adjustable [via bushings] id core cutters and variable strength core catchers cut and retain the sample.

Material
- catchers - 316L and 17-4PH stainless steel
- cutters - 4140 cdom and 316L
- cutter bushings - AL 6061 and 316 SS

Located at the very bottom of the core assembly, the sharp-edged cutter acts as its name implies. It cuts and sizes [via variable id bushings] the sample as the core penetrates the stratified sediment.

The hydraulic extruder being installed during the final stages of core recovery.

Hydraulic extruder

A powerful hydraulic cylinder pushes 3 inch diameter plastic [HDPE] rods to incrementally extrude the liner at the lower end of the core.

The extruder is operated from an articulating platform well aft of the Knorr's stern. The white plastic pushrods are loaded into the extruder breech and when hydraulic force is applied, extrude the core liner at the base of the core.

At the bottom of the core, the liner is cut into 1.5 meter long sections as extrusion proceeds. The sections are capped and carefully stored onboard for future analysis.