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,