This is a USEFUL document for drilling engineers, inspectors and rig crew in order to help about recognizing their drill pipe common defects, their usual effects, probable causes and possible corrections, are listed and to do something about them in time. Thanks, TuboScope.

1. Drill Pipe Tips
These common defects, their usual effects, probable causes and possible corrections, are listed in this chart to help Tuboscope customers recognize their drill
pipe problems in time to do something about them.
© Copyright NOV Tuboscope 2011
Tube Body
PROBLEM:
WASHOUT
(Usually occurs near pin end
upset taper or in area from lower
part of slip area to box and upset
taper)
USUAL EFFECT:
Hole in pipe, drop in mud
pressure, string separation, lost
time
PROBABLE CAUSE:
Surface notching, cyclic stressing,
fatigue cracking
POSSIBLE CORRECTION:
Minimize surface notching,
reduce stress level, and avoid
critical rotary speed. Move
bottom-hole pipe up hole on trips,
taper transition zone, use shock
subs
PROBLEM:
TWIST OFF
(Usually occurs near pin end
upset taper or in area from lower
part of slip area to box end upset
taper)
USUAL EFFECT:
String separation, fishing job, lost
time
PROBABLE CAUSE:
Surface notching, cyclic stressing,
fatigue cracking
POSSIBLE CORRECTION:
Minimize surface notching,
reduce stress level, avoid critical
rotary speed. Move bottom-hole
pipe up taper transition zone, use
shock subs
PROBLEM:
FATIGUE CRACKING
(Predominately found near pin
end upset taper and in an area
from box end upset taper to lower
part of slip area)
USUAL EFFECT:
Washout, twist off, string
separation, lost time, pipe loss
PROBABLE CAUSE:
Cyclic stressing, surface notches
(corrosion, cuts, etc), hydrogen
embrittlement
POSSIBLE CORRECTION:
Dampen stress, avoid critical
rotary speeds, minimize surface
notching, move bottom-hole pipe
up hole on trips, use shock subs,
and prevent H2S in flow. Use
lowest strength pipe where
possible. Minimize rate of change
in hole deviation
PROBLEM:
Surface Notching
CORROSION PITTING
(General in location)
USUAL EFFECT:
Bodywall loss, localized surface
notch, stress concentration
PROBABLE CAUSE:
Water, oxygen, CO2, salt, H2S,
stress
POSSIBLE CORRECTION:
Maintain mud PH above 9.5, use
plastic coatings, inhibitors,
oxygen scavenger, clean pipe I.D.
& O.D., dampen stress, monitor
with corrosion test rings
PROBLEM:
Surface Notching
SLIP CUTS
(Located in slip area)
USUAL EFFECT:
Transverse surface notch, stress
concentrator
PROBABLE CAUSE:
Pipe turning in slips, defective
slips/bowl, improper slip handling
POSSIBLE CORRECTION:
Use back-up tong for makeup and
breakout, do not spin pipe with
rotary, improve slip/bowl
maintenance, use care while
setting slips.
PROBLEM:
Surface Notching
SLIP AREA MASH
(Located in slip area)
USUAL EFFECT:
Surface impression, stress
concentrator
PROBABLE CAUSE:
Defective slip component,
improper slip handling, excessive
connection make-up or breakout,
bending pipe in slips
POSSIBLE CORRECTION:
Improve slip/bowl maintenance,
use care while setting sips.
Consult API RP 7G for maximum
height setting of tool joints above
slips
PROBLEM:
Surface Notching
TONG CUTS
(Usually located near pin and box
end upsets)
USUAL EFFECT:
Multiple surface notches, stress
concentrators
PROBABLE CAUSE:
Tongs placed on pipe, worn tool
joints, improper tong jaws, poor
handling
POSSIBLE CORRECTION:
Place tongs only on tool joint,
maintain tool joint diameter, use
only correct long jaws, use sharp
tong dies
PROBLEM:
CHAIN CUTS
(Usually found in an area over
and just above pin end upset)
USUAL EFFECT:
Circumferential grooves (notch) at
pin end upset area, stress
concentrators, cold worked metal
PROBABLE CAUSE:
Excessive spinning; chain slip
POSSIBLE CORRECTION:
Power change tension, consider
use of power pipe spinner
PROBLEM:
Surface Notching
RUBBER CUT EXTERNAL RING
CORROSION
(Usually found in an area
approximately 2’ above pin end
tool joint)
USUAL EFFECT:
Circumferential groove, stress
concentrator
PROBABLE CAUSE:
Corrosion / erosion at ends of drill
pipe/ casing protectors– poor mud
drain/ cleaning at protector end
POSSIBLE CORRECTION:
Periodically move or remove
protector, clean pipe at ends and
under protector
PROBLEM:
Surface Notching
HAMMER MARKS
(Usually found on tube in areas
near the pin and box end tool
joints)
USUAL EFFECT:
Localized surface notch, cold
worked metal
PROBABLE CAUSE:
Tapping pipe to check fluid level
on trip out
POSSIBLE CORRECTION:
Use brass tipped hammer, tap
pipe lightly
PROBLEM:
SLIP AREA CRUSHING
(Located in slip area)
USUAL EFFECT:
Slip area O.D/ I.D. reduction,
longitudinal splits in slip area,
body wall thinning
PROBABLE CAUSE:
Abrupt setting of slips, defective
slip/ bowl maintenance, improper
slips size
POSSIBLE CORRECTION:
Stop pipe movement before
setting slips, check slip-to-pipe fit,
improve maintenance, and use
only correct slip size
PROBLEM:
NECKING
(Usually located near either or
both upsets)
USUAL EFFECT:
Reduced pipe O.D. / I.D., body
wall thinning
PROBABLE CAUSE:
Stuck pipe, over-pull (stretch),
excessive hook load
POSSIBLE CORRECTION:
Avoid sticking pipe, avoid over-
pull, consult API RP 7G for load
limits per pipe class
PROBLEM:
EXPANSION
(Usually located above the pin
and below the box which had
been backed off)
USUAL EFFECT:
Expanded O.D. /I.D. split pipe or
tool joint
PROBABLE CAUSE:
Stuck pipe, internal explosion for
back off
POSSIBLE CORRECTION:
Avoid sticking pipe, minimize
explosive force. Be sure explosive
is placed in tool joint area,
carefully inspect pipe before re-
use
PROBLEM:
COLLAPSE
(Usually begins near tube center,
often travels toward both ends)
USUAL EFFECT:
Flattens tube, circulation block,
string separation
PROBABLE CAUSE:
Excessive O.D. pressures, drill
stem test, O.D. wear, I.D. erosion
POSSIBLE CORRECTION:
Consult API RP 7G or drill pipe
manufacturers collapse charts per
pipe class, minimize O.D. wear,
keep pipe straight, and prevent
I.D. erosion with plastic coating
PROBLEM:
O.D. WEAR
(Usually appears in center third of
pipe body)
USUAL EFFECT:
Body wall thinning, reduced
tensile capacity, reduced cross
section, reduced collapse
resistance
PROBABLE CAUSE:
Abrasive formations, bent pipe,
deviated hole, high rotary speeds
POSSIBLE CORRECTION:
Straighten pipe, minimize ole
deviation/rate of change, and
avoid critical rotary speeds
PROBLEM:
ID. EROSION
(General location but often
appears near upset areas)
USUAL EFFECT:
Body-wall thinning, reduced
cross-section, reduced tensile
capacity, reduced collapse
resistance
PROBABLE CAUSE:
High velocity abrasion, sharp
sand (solids), drilling, fluid
turbulence, general corrosion
POSSIBLE CORRECTION:
Plastic coating, minimize drilling
fluid abrasives, inhibitors,
minimize exposure to treating
acids
Far East Inspection Locations-
Indonesia Inspection:
+62 (0)21 780 6265
Papua New Guinea Inspection:
+62 (0)21 780 6265
Singapore Inspection:
+65 6861 2688
Malaysia (Labuan) Inspection:
+60 8 741 3020
Malaysia (Kemaman)
Inspection:
+60 9 863 1885
China (Shekou) Inspection:
+86 755 2669 1915
PROBLEM:
BENT PIPE
(Most often found in the slip area
and center third of pipe body)
USUAL EFFECT:
Accelerated O.D. wear in pipe
body and tool joints, vibration,
high stress level, advanced
fatigue
PROBABLE CAUSE:
Bending in slips, setting tool joint
too high above slips, improper
tong/line geometry, no back up
tong on makeup or breakout, poor
transportation handling, dropping
pipe on racks, critical rotary
speeds, picking up pipe with
winch line in center, improper drill
collar weight
POSSIBLE CORRECTION:
Consult API RP 7G for maximum
height setting of tool joints above
slips, use both tongs, placed 90°
apart, consult API RP 7G or the
tool joint manufacturers
recommendations for proper
make-up torque per tool joint
class, minimize breakout torques,
minimize down-hole torques, use
properly spaced stripping
between pipe layers to minimize
bending in storage or transit,
avoid tough rough handling when
moving pipe, use slings to winch
pipe, avoid critical rotary speeds,
avoid dropping string
Tool Joint
PROBLEM:
WASHOUT
USUAL EFFECT:
Erosion of shoulder (face) seal
and threads, mud pressure loss,
string separation, lost time
PROBABLE CAUSE:
Leaking shoulder (face) seals,
damaged shoulder (face) seals,
insufficient make up torque,
galled threads producing
excessive shoulder standoff,
shoulder fins rolled between
seals, high spots on shoulder-
(false make-up torque), excessive
shoulder removal by refacing,
stretched pin threads, dirty
threads and shoulders, mis-
stabbing connection, improper
jacking of stands in stand back
area
POSSIBLE CORRECTION:
Consult API RP 7G charts for
proper make up torque per tool
joint class, or tool joint
manufacturer recommendations,
remove shoulder damage by
refacing. If possible, recut
connection; remove shoulder fins
by beveling shoulder; consult API-
RP 7G, or tool joint manufacturers
recommendations for maximum
shoulder removal by refacing;
keep thread protectors installed
while picking up, laying down,
handling, transporting, or storing
pipe; clean threads and shoulder
before make-up; use care when
tripping pipe; use use only pipe
jack tool with wide area contact.
PROBLEM:
DRY OR MUDDY CONNECTION
USUAL EFFECT:
Leaking shoulder (face) seals
PROBABLE CAUSE:
Insufficient make-up torque,
damaged shoulders (face)
POSSIBLE CORRECTION:
Consult API-RP 7G or tool joint
manufacturer recommendations
for proper make-up torque per
tool joint class, or, remove
shoulder damage by refacing. If
possible, recut connection;
remove shoulder fins by beveling
shoulder; consult API RP 7G, or
tool joint manufacturer for
maximum shoulder removal by
refacing; keep thread protectors
installed while picking up, laying
down, handing, transporting, or
storing pipe; clean threads and
shoulder before make-up; use
care when tripping pipe;
use stabbing guide
PROBLEM:
GALLED SHOULDERS
USUAL EFFECT:
Loss of shoulder seal, excessive
shoulder to shoulder standoff,
false make-up torque, unstable
connection (wobble)
PROBABLE CAUSE:
Insufficient lubrication on
shoulders, insufficient make-up
torque, shoulder fins, high spots
on shoulder
POSSIBLE CORRECTION:
Apply rotary tool joint compound
to shoulders when doping
connection, remove shoulder fins
by beveling shoulder, remove
high spots by refacing, consult
API-RP 7G or the tool joint
manufacturers charts for proper
make-up torques per tool joint
class, use stabbing guide
PROBLEM:
PIN BREAK
(Cup type failure)
USUAL EFFECT:
String separation, fishing job, lost
time
PROBABLE CAUSE:
Improper trip make-up torque,
additional downhole make-up,
improper type of lubricant
producing excessive tension vs.
make-up/torque
POSSIBLE CORRECTION:
Consult API RP 7G charts or the
tool joint manufacturer
recommendations for proper
make-up torque per tool joint
class, minimize additional
downhole make-up, use
recommended rotary tool joint
compound
PROBLEM:
PIN BREAK
(Flat fracture type failure)
USUAL EFFECT:
String separation; fishing job, lost
time
PROBABLE CAUSE:
Pin wobble due to insufficient
make-up, shoulder fins, false
torque, fatigue cracking at thread
root, galled threads
POSSIBLE CORRECTION:
Consult API-RP 7G charts or the
tool joint manufacturer
recommendations for proper
make-up torque per tool joint
class, repair shoulder fins, use
stabbing guide, repair galled
threads
PROBLEM:
PIN BREAK
(Flat fracture type failure when
torque and make-up are known to
be satisfactory)
USUAL EFFECT:
String separation; fishing job, lost
time
PROBABLE CAUSE:
H2S, hydrogen embrittlement,
excessive pin tension
POSSIBLE CORRECTION:
Control H2S in flow, reduce stress
level if possible, remove string
from service for period of time,
inspect tool joint threads
PROBLEM:
WEAR
(Thin shoulders)
USUAL EFFECT:
Reduces torque capacity, belled
boxes, reduced shoulder seat
area
PROBABLE CAUSE:
Crooked pipe, high rotary speeds,
abrasive formations
POSSIBLE CORRECTION:
Straighten pipe, reduce rotary
speeds where possible, apply
hard facing to box and pin end
tool joints where possible
PROBLEM:
BELLED BOXES
USUAL EFFECT:
Distorted connection, loss of
shoulder seal, will not mate
properly with another connection,
split body
PROBABLE CAUSE:
Improper make up torque,
additional down-hole make up,
thin tool joints, improper thread
lubricants
POSSIBLE CORRECTION:
Maintain tool joint O.D., consult
API RP 7G charts or tool joint
manufacturer recommendations,
for proper make up torque per
tool joint class, minimize
additional down-hole make up,
use only recommended rotary tool
joint compound, use stabbing
guide, recut box
PROBLEM:
STRETCHED PINS
USUAL EFFECT:
Distorted connection, will not
mate properly with another
connection, possible pin break
PROBABLE CAUSE:
Improper make-up torques,
additional down-hole make-up,
improper thread lubricant
POSSIBLE CORRECTION:
Consult API RP 7G or tool joint
manufacturer recommendations
for proper make-up torques per
tool joint class, minimize
additional downhole make-up,
use only recommend compound,
use stabbing guide, recut pin
PROBLEM:
GALLED THREADS
USUAL EFFECT:
Damages mating threads, false
torque, improper make-up,
connection wobble, leaking
shoulder seal, washout, pin
break, drop string, lost time
PROBABLE CAUSE:
Thread damage, handling without
thread protectors, cross
threading, worn threads, improper
lubrication, dirty connection,
defective kelly saver sub
POSSIBLE CORRECTION:
Handle pipe only with thread
protector, use care in stabbing
and make-up, use stabbing guide,
recut worn threads, use only
recommended rotary tool joint
compound, clean connections
before use, repair or replace kelly
saver sub
PROBLEM:
SHOULDER FINS
USUAL EFFECT:
Prevents shoulder make-up, false
torque, leaking shoulder seal,
wash-out, connection wobble, pin
break, drop string, lost time
PROBABLE CAUSE:
Mating tool joint with different
O.D.’s, handling damage
POSSIBLE CORRECTION:
Maintain tool joint O.D‘s if
possible, remove fins by refacing
and beveling, use stabbing guide,
handle pipe only with thread
protectors
PROBLEM:
HEAT CHECKING
USUAL EFFECT:
Time joint body cracking,
washout, string separation lost
time
PROBABLE CAUSE:
Rapid heating due to friction
between tool joint and formation,
casing, whip stock, etc. high
rotary speeds, rapid cooling
POSSIBLE CORRECTION:
Reduce rotary speeds through
tight areas; minimize tool- joint-to-
formation contact
PROBLEM:
SHOULDER DAMAGE
USUAL EFFECT:
Leaking shoulder seal, washout.
String separation, lost time
PROBABLE CAUSE:
Miss-stabbing connection,
handling damage,, improper pipe
jacking
POSSIBLE CORRECTION:
Use care when tripping pipe,