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IADC DULL GRADING CHART

IADC Dull Bit Grading

Cutting Structure Dull Characteristic Outer 2 3

Inner 1 1 Inner cutting structure 2 Outer cutting structure In columns 1 and 2, a linear scale from 0 to 8 is used to describe the condition of the cutting structure according to the following: Steel tooth bits A measure of lost tooth height resulting from abrasion and/or damage. 0 - no loss of tooth height 8 - total loss of tooth height

Insert bits A measure of total cutting structure reduction resulting from lost, worn and/or broken inserts. 0 - no lost, worn and/or broken inserts 8 - all inserts lost, worn and/or broken Fixed cutter bits A measure of lost, worn and/or broken cutting structure. 0 - no lost, worn and/or broken cutters 8 - all of cutting structure lost, worn and/or broken

3

Dull characteristic

Roller Cone

Fixed Cutter (O) Outer Rows (I) Inner Rows (I) Inner 2/3 (O) Outer 1/3

4

(Use only cutting structure related codes) BC BF BT BU CC CD CI CR CT ER FC HC JD LC LN LT OC PB PN RG RO SD SS TR WO WT NO

- broken cone - bond failure - broken teeth/cutters - balled up bit - cracked cone - cone dragged - cone interference - cored - chipped teeth/cutters - erosion - flat crested wear - hear checking - junk damage - lost cone - lost nozzle - lost teeth/cutters - off-center wear - pinched bit - plugged nozzle - rounded gauge - ring out - shirttail damage - self-sharpening wear - tracking - washed out bit - worn teeth/cutters - no dull characteristic

Show cone number under location (O) Outer Rows (I) Inner Rows

Bearings & Seals 5

Location 4

Other Dull Characteristics 7

Gauge 6

Location

6

Roller Cone N - nose row M - middle row G - gauge row A - all rows Fixed Cutter C - cone N - nose T - taper

Reason Pulled 8

Gauge (measure in 1/16 of an inch)

Cone no. 1 2 3

I - in gauge 1 - 1/16 in / out of gauge 2 - 2/16 out of gauge

S - shoulder G - gauge A - all areas

7

Other dull characteristics Refer to number

3

codes

Location on Fixed Cutter Bits 8 Gauge Shoulder Cone Nose

Taper

Cone

Gauge Shoulder Taper Nose

Gauge Gauge

Shoulder Taper Cone Nose

5

Cone

Shoulder Nose

Bearings / seals Non-sealed bearings A linear scale estimating bearing life used. (0 - no life used, 8 - all life used, i.e., No bearing life remaining.) Sealed bearings E F N X

Reason pulled or run terminated BHA DMF DTF DSF DST LOG LIH RIG CM CP DP FM HP HR PP PR TD TQ TW WC

- change bottom hole assembly - downhole motor failure - downhole tool failure - downhole string failure - drill stem test - run logs - left in hole - rig repair - condition mud - core point - drill plug - formation change - hole problems - hours on bit - pump pressure - penetration rate - total depth/casing depth - torque - twist off - weather conditions

- seals effective - seals failed - not able to grade - fixed cutter bit (bearingless)

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