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VARCO BJROTARYEQUIPMENTCARE & MAINTENANCEHANDBOOK

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CARE AND MAINTENANCEHANDBOOK

TABLE OF CONTENTS

Section PageNumber NumberTopic

I. KELLYS AND KELLY BUSHINGSProper Handling of Kellys .......................... 7Care of Kellys ............................................. 12Description of Kelly Drive Bushings ........... 13Varco Kelly Bushings ................................. 15

Installation ............................................. 17Operation ............................................... 17Maintenance .......................................... 18Inspection .............................................. 19Indexing a Kelly...................................... 23Drive Pin Repair ..................................... 23Kelly Bushings with Drive Pin Locks ...... 24

II. MASTER BUSHINGS AND SLIPSProper Handling of Master Bushings and Slips .................................................... 25Varco Master Bushings .............................. 27

Installation ............................................. 28Casing Bushings .................................... 29Bit Breaker Adapter Plate ....................... 29Maintenance .......................................... 30Inspection .............................................. 30Drive Hole Bushing replacement ............ 37

Varco Slips................................................. 38Multipurpose Safety Clamp.................... 41Slip Inserts............................................. 41Operation ............................................... 42Maintenance .......................................... 43Spring Slips ........................................... 45Summary ............................................... 46

III. TECHNICAL DATAAppendix.............................................. TD-47

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Figure PageNumber NumberTitle

1. Kelly Sizes................................................... 72. Kelly and Rollers ......................................... 73. Kelly tolerances........................................... 84. Kelly Inspection........................................... 85. Maximum Kelly Wear .................................. 86. New Kelly Wear ........................................... 87. Kelly and Roller Wear Development ............ 98. Worn Kelly with New Rollers....................... 99. Maximum Kelly Wear .................................. 910. Deformed Kelly ........................................... 911. Kelly Measurement ..................................... 912. Driving Edge Wear ...................................... 1013. Kelly that Has Turned Thru Rollers.............. 1014. Driving Edge Inspection .............................. 1015. Roller Wear ................................................. 1016. Unusable Kelly ............................................ 1117. Common Kelly Fatique Locations................ 1118. Kelly Re-Milling........................................... 1119. Strength of Kellys........................................ 1120. Kelly in Scabbard ........................................ 1221. Improper Kelly Storage ............................... 1222. Kelly in Rathole ........................................... 1223. Heavy Duty Kelly Bushings ......................... 1324. 4KRS Kelly Bushing .................................... 1325. HDP/4KRP Size Comparison....................... 1326. Kelly Bushing Components ......................... 1427. Bolt/Stud Retaining Systems ...................... 1428. Roller Pin Development .............................. 1429. Thrust Washers and Seals .......................... 1530. HDP Kelly Bushing ...................................... 1531. HDS Kelly Bushing ...................................... 1532. MD Kelly Bushing........................................ 1633. 4KR Kelly Bushing ...................................... 1634. Kelly Bushing Installation............................ 1735. Kelly Bushing Assembly.............................. 1736. Kelly Bushing in Position ............................ 1737. Typical Kelly Bushing Roller Assy ............... 1838. Typical Pin Drive Kelly Bushing................... 1839. Typical Square Drive Kelly Bushing............. 1840. Kelly and Roller wear .................................. 19

Figure PageNumber NumberTitle

41. Hex Gauge on Kelly ..................................... 1942. Maximum Roller Wear ................................ 2043. Split Body Inspection .................................. 2044. Top Nut Inspection...................................... 2045. Roller Bearing Inspection............................ 2146. New Roller Assmebly .................................. 2147. Roller Pin Wear ........................................... 2148. Bearing Cage Inspection ............................. 2249. Journal Inspection ...................................... 2250. Outside Journal Measurement .................... 2251. Indexed Kelly............................................... 2352. Drive Pin Removal ...................................... 2353. Drive Pin With Lock .................................... 2454. Slips and Master Bushing Forces................ 2555. Results of Friction....................................... 2556. Distribution of Forces.................................. 2657. Square Drive Dimensions............................ 2658. Pin Drive Dimensions.................................. 2659. Long and Extra-Long Slips.......................... 2760. Square Drive Master Bushings.................... 2761. Lifting Slings............................................... 2862. Bowl Lock ................................................... 2863. MPCH Master Bushing................................ 2965. Casing Bushings ......................................... 2965. Bit Breaker Adapter Plate ............................ 2966. Rotary Equipment Wear Points ................... 3067. Slips Riding High in Master Bushing........... 3168. Slip Riding Low in Master Bushing ............. 3169. Wrapping Test Paper Around Kelly.............. 3170. Setting Slips................................................ 3171. Removing Slips........................................... 3272. Test Paper Full Contact................................ 3273. Test Paper Poor Contact.............................. 3274. Master Bushing Wear.................................. 3275. Rotary Table Wear....................................... 3376. New Bushing and Worn Rotary Table.......... 3377. Solid Body Master Bushing......................... 3378. Worn Slips in New Bushing......................... 3379. New and Worn Square Drive Bushings ....... 3480. Square Drive Bushing with Worn I.D........... 34

CARE AND MAINTENANCELIST OF ILLUSTRATIONS

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Figure PageNumber NumberTitle

81. Checking Master Bushing I.D...................... 3482. Checking Master Bushing Bowl Taper ......... 3483. Square Drive Bushing Wear ........................ 3584. New and Worn Pin Drive Bushings ............. 3585. Comparison of New and Worn MPCH ......... 3586. Pin Drive Bushing with Worn I.D................. 3687. Measuring Master Bushing ......................... 3688. Bowl Showing Maximum Wear ................... 3689. Pin Drive Bushing Wear .............................. 3690. Measuring Master Bushing Upper I.D ......... 3691. Measuring Wear in Hull Lower I.D .............. 3792. Worn Out Master Bushing........................... 3793. Drive Hole Bushing Removal....................... 3794. Drive Hole Bushing Replacement ................ 3795. SDS-Short Rotary Slips .............................. 3896. SDS-Grip Length......................................... 3897. SDML-Medium Rotary Slips ....................... 3898. SDML-Grip Length...................................... 3899. SDXL-Extra-Long Rotary Slips.................... 38100. SDXL Grip Length ....................................... 39101. Rotary Slip Set Parts................................... 39102. DCS-Multi-Segment Drill Collar Slips.......... 39103. DCS Parts ................................................... 39104. DCS Grip Lengths ....................................... 40105. CMS-XL Casing Slips .................................. 40106. CMS-XL Parts ............................................. 40107. CMS-XL Grip Length................................... 40108. CP-S- Conductor Pipe Slips ........................ 40109. Multipurpose Safety Clamp......................... 41110. Safety Clamp Assembly .............................. 41111. Safety Clamp Parts...................................... 41112. Rotary and Casing Slip Inserts.................... 41113. Stopping Pipe with Rotary Slips ................. 42114. Incorrect Use of Rotary Slips ...................... 42115. Drill Collar Slip Insert Damage .................... 42116. Setting Slips on Tool Joints......................... 43117. Rotary Slips in Position............................... 43118. Surfaces that Require Dressing................... 43119. Bent, Worn Slips ......................................... 44120. Checking Slip Segments ............................. 44

Figure PageNumber NumberTitle

121. Slip Segment Damage................................. 44122. Hinge Pin Removal...................................... 44123. Slip Segment............................................... 44124. Setting Slips................................................ 45125. Slips in Set Position.................................... 45126. PS-15 Assembly ......................................... 45

LIST OF ILLUSTRATIONS (Continued)

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INTRODUCTION

This handbook was devised to highlight theimportance of rotary equipment to the overalldrilling operation. The kelly is the direct linkbetween the power drive of the rotary and the drillbit. To keep turning to the right, the kelly andequipment that handless it must be taken care ofand kept in top working order.

It is Varco’s hope that this handbook will find itsway to every head and hand in the oil patch, that itwill be useful to them, and that it will be an aid tokeeping things running smoothly.

SO, USE IT, GET IT DIRTY, AND ASK FORANOTHER ONE!

HollandHoustonMontroseSingapore

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The care and maintenance of rotaryequipment

The search for energy continues at an ever-increasing rate. Wells are being drilled daily togreater depths than were thought possible only ageneration ago. These deep wells place greatdemands on both the rig’s rotary equipment andthe crews that operate and maintain it.

Th rotary equipment is the very heart of the drillingoperation. All drilling operations center around themaster bushing, slips, kelly and kelly bushing. Eventhough this equipment is designed for long servicelife and is able to absorb a certain amount ofmistreatment, it will eventually wear out.When a piece of rotary equipment fails in use, theresults are often dangerous and always expensive.

A planned program of regular inspection andmaintenance will save a great deal of rig time andmoney. The real problem seems to be that rotaryequipment on the rig may remain in service forseveral years without failure, and its performance istaken for granted. All too often, the only time aproblem appears is when a kelly turns through akelly bushing, or when pipe is inspected, andseveral joints must be discarded due tobottlenecking in the slip area.

The purpose of this handbook is to avoid expensivedamage to drill pipe, drill collars, and kellys due toimproper handling and equipment maintenance.

Although Varco BJ equipment is shown extensivelythroughout this handbook; inspection,maintenance, and operating principles areessentially the same for all manufacturers’products.

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SECTION IKELLYS AND KELLY BUSHINGS

Proper handling of kellys

The width of the driving surface on the kelly isdirectly proportional to the amount of clearancebetween the kelly and the kelly bushing rollers. Thetighter the clearance, the wider the driving surfacewill be.

A few facts about kellys and the causes of wear willgive better insight to the importance of kellybushing maintenance.

Kellys are manufactured either from bars with anas-forged drive section, or from bars with fullymachined drive sections . They may be hexagonalor square. When new, both kellys and kellybushings form perfect hexagons or squares. Figure1 shows the standard size kellys currently in use.

*SQUARE2-1/2 In.3.0 In.

3-1/2 In.4-1/4 In.5-1/4 In.

* HEX3.0 In.

3-1/2 In.4-1/4 In.5-1/4 In.6.0 In.

Kelly SizesFigure 1

For additional information on kellys of other sizes,refer to API Specification 7.

When the kelly and bushing are new, there is aperfect fit between the two hexagonal surfaces.

When the kelly is put into service, one small markstarts on the roller from kelly contact, the kellydeforms to provide driving surface on the kelly.

The 5-1/4 inch hex kelly is the most popular sizekelly in use today. Due to its strength, small OD

tool joint on the pin end and large bore for betterhydraulics, it is also one of the hardest kellys tomaintain. The kelly measures 5-1/4 inches (133mm) across the flats and only 6 inches (152 mm)across the corners. The kelly is almost round tostart with and must be run in a good kelly bushing (Figure 2).

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.013 to 0.06 In.(0,33 to 1,5 mm)WEDGE

5-1/4 In. + 1/32 -0)(133 mm + 0,8 -0)

1-1/4 In. (32mm)

MAX CONTACTANGLE

8° 37’

WIDE WEARPATTERN

FLATSURFACE

SMALLCONTACTANGLE

.187 In.(5 mm)

USESALMOSTALL THERADIUS

.013 to 0.06 In.(0,25 to 1,5 mm)

WEDGE

4-1/4 In. + 3/32 .0(108 mm + 2,4 .0)

Kelly TolerancesFigure 3

Figure 3 shows the API specifications for the twomost popular kellys, the 5-1/4 inch hex and the 4-1/4 inch square. Note the tolerances: 5-1/4 + 1/32, -0 inch hex and 4-1/4 + 3/32, -0 inch square.

Kelly InspectionFigure 4

A good indicator of the condition of the kelly andkelly drive bushing is the width and appearance ofthe wear pattern on the kelly flats (Figure 4).Recognizing wear patterns can give early warningof when the kelly drive bushing requires more thanroutine maintenance.

Wear pattern width is determined by:

1. Kelly size.2. Total clearance between kelly and rollers.3. Roller to kelly contact angle.

Maximum Kelly WearFigure 5

The maximum possible width of wear pattern on a5-1/4 inch hex kelly is 1-1/4 inches (32mm)(Figure 5). Notice that with this amount of drive, theradius on the corner is almost worn off but no metalhas started rolling over.

Figure 6

Figure 6 shows the wear pattern on a new kellywith a kelly bushing in new condition. The drivingedge is flat and there is a full 1-1/4 inches (32 mm)of driving edge.

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Kelly and Roller Wear DevelopmentFigure 7

Figure 7 shows the condition that exists with aworn kelly and worn parts in the kelly drivebushing. Due to roller wear, the driving edge is nolonger flat and the corners have begun to round off.

Worn Kelly with New RollersFigure 8

Figure 8 shows a kelly with considerable wear in akelly drive bushing with new roller assemblies. Theclearance between the kelly and the rollers hasincreased, resulting in reduced width of the drivingedge and an increased contact angle.

Maximum possible wear pattern widths vary withrespect to the size of the kelly (Figure 9). Notice the5-1/4 inch hex kelly has a 1-1/4 inch (32 mm) drivepattern. These measurements are only obtainablewith a new kelly in a new kelly bushing. Narrowerdrive patterns than those shown are due toadditional clearance between kelly and driverollers.

Maximum Kelly Wear Pattern Width (Inches)Figure 9

What causes kelly wear?

Deformed KellyFigure 10

The kelly in Figure 10 has been deformed by driveforces received from the rollers. The greater theclearance between the rollers and the kelly, thesmaller the available drive surface will be.

Kelly MeasurementFigure 11

INCREASEDCONTACT

ANGLE

NO FLATSURFACE

HIGHCONTACT

ANGLE

REDUCEDWIDTH

FLATSURFACTNOCURVATURE

10

Figure 11 shows the kelly driving edge beingmeasured. The older driving surface measured 1-1/4 inches (32 mm). Before this kelly was taken outof service, however, the area was reduced to 1/2inch (12,7 mm) due to excessive clearancebetween the kelly and the rollers.

Driving Edge WearFigure 12

Figure 12 shows the same kelly with an extremeroll-over of the kelly’s driving edge. A watchful eyeand the replacement or adjestment of worn parts inthe drive bushing would have extended the life ofthis kelly.

Kelly That Has Turned Through RollersFigure 13

Figure 13 shows a kelly in a drive bushing that wasstill in use. Observe the area of the kelly just abovethe drive bushing. The kelly has turned through therollers of the bushing at this point. A kelly will notturn through the rollers unless too much clearanceexists between the rollers and the kelly, reducingthe driving surface and increasing the contactangle. If the kelly is put in a high torque situationwith this much clearance, the kelly will turn throughthe bushing again and again.

Therefore, the kelly bushing must be taken out ofservice and thoroughly inspected for wear.

Driving Edge InspectionFigure 14

Figure 14 shows a kelly that has been in service foronly three months. The driving edge is not 1-1/4inches (32 mm) but only 1/2 inch (12,7 mm). If thekelly bushing or its parts are not replaced, the kellywill turn through the worn kelly bushing in as littleas three more months. The cost of replacing thiskelly can be avoided.

Roller WearFigure 15

Figure 15 shows a roller with a driving surfaceabout one inch (25,4 mm) wide, which is prettygood. The wear pattern, however, should be at thebottom on one side of the V and at the top of theother side. This shift in the placement of the drivingsurface on the rollers is due to wear in assemblyparts or in the body of the bushing.

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A kelly may be unusable for three reasons:

1. It is bent.2. Metal fatique.3. The corners of the drive surfaces are worn.

Unusable KellyFigure 16

1. Bent kellysIf a kelly has become bent (Figure 16), is

should be straighetened to avoid high bendingstresses and early fatique damage.

UPPER FILLET CENTER LOWER FILLET

Common Kelly Fatigue LocationsFigure 17

2. Kelly fatigueKelly fatigue is likely to occur in three places(Figure 17):

a. The upper filletb. The lower filletc. In the middle of the kelly body

The fillet is a transition area from the moreflexible body of the kelly to the very rigid tooljoint section. Even with the 37-degree taper,this transition area is susceptible to fatigue.

When the kelly is bored from both ends duringmanufacture, a misalignment of the two boresmay occur at the center due to the boringtools drifting slightly. this creates a possiblefatigue point.

3. Worn Kelly Drive Surfaces

If a 5-1/4 inch hex kelly has not turned throughthe bushing due to wear, it can be milled down1/8 inch (3,2 mm) on each flat and cleaned up.This kelly would then be referred to as a 5 inchspecial hex kelly.

If a kelly is re-milled it will be necessary toreplace the rollers with rollers for the nextsmaller size kelly.

Kelly Re-MillingFigure 18

Before a kelly is sent in to be milled, there areseveral checks that should be made to see if it willqualify:

a. It should be magnafluxed over its entire lengthto check for cracks.

b. Check the OD across the corners and acrossthe flats.

c. Check the ID.

d. The wall thickness should be checked byultrasonic measurement over its entire length.

e. Check the remaining tong area on the tolljoints.

Strength of Kellys (New vs. Re-Milled)Figure 19

The weakest section of a kelly is the lower pinconnection. As shown in the chart (Figure 19),a 5-1/4 inch hex kelly, bore will have an increased

diameter of 3-1/4 to 3-1/2 inches (82 to 89 mm).This weakens the pin section slightly

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Some dos and don’ts on Kellys:

Do’s:

Do inspect the kelly frequently.

Do keep the drive surfaces lubricated and use akelly wiper rubber.

Do use a saver sub to prevent wear of the lower pinconnection.

Do use new roller assemblies when a new kelly isput into service.

Don’ts:

Don’t weld on drive corners.

Don’t move or store a kelly without the use of ascabbard.

Don’t use a crooked kelly.

Care of kellys

Here are some tips on handling kellys to getmaximum life from them.

Kelly In ScabbardFigure 20

The drive section of a kelly is quite flexible. Due toits length and weight, a kelly should never behandled or moved without being in a scabbard(Figure 20). Always support the scabbard in twoplaces rather than one.

Shown in Figure 21 is an empty scabbard and anunprotected kelly on the bottom of the rack. Thisshould never be done.

Improper Kelly storageFigure 21

Kelly in RatholeFigure 22

The kelly should be tied back to prevent it frombeing bent (Figure 22). The weight of the swivelabove the kelly will bend it unless tie backprecautions are taken. This is especially importanton smaller size kellys.

When the kelly is picked up or set back, careshould be taken to ease the kelly fillet into the kellybushing. The shock loads from running the fillet intothe rollers of the kelly bushing can damagebearings in the bushing.

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Description of kelly drive bushings

The kelly drive bushing engages the masterbushing in the rotary (either square drive or pindrive). As the rotary turns, the kelly drive bushingturns with it, to drive the kelly. At the same time, asthe kelly worksdown, the rollers in the bushingallow the kelly free movement and keep it centeredin the rotary bore.

the earlier square kelly bushings worked fine in thesquare drive master bushings, but as wells becamedeeper, longer slips were needed, so the pin drivesystem was developed. While developing the pindrive kelly bushings, Varco also increased thecapability of both the pin drive and square drive,better enabling them to meet the challenges oftoday’s deeper wells. This development became theHeavy Duty, of HD series. The 4KR series ofsquare drive bushings is available for slim holedrilling or workover rig applications.

The Varco HDS and HDP (heavy duty square andheavy duty pin drive) kelly bushings (Figure 23)have been available since 1967, answering theneed for better, stronger kelly bushings for hightorque, high speed drilling operations.

HDS HDP

Heavy Duty Kelly BushingsFigure 23

HDS and HDP bushings are replacing the older4KRS and 4KRP bushings (Figure 24) that firstentered the market about 35 years ago.

4KRS Kelly BushingFigure 24

APPROX3 In.

(76 mm)

APPROX 3 In. (76mm)

150 lb(68 kg)

HEAVIERJOURNAL AREA

HDP 4KRP

HDP/4KRP Size ComparisonsFigure 25

The HD series kelly bushings, are 3 inches (76,2mm) shorter, 3 inches (76 mm) narrower, and 150pounds (68 kg) heavier, than the 4KR series kellybushings. The additional weight has been placed inthe journal area.

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Kelly Bushing ComponentsFigure 26

The same bearings and rollers are used in both the4KR series and the newer bushings. Majorchanges are in the bodu, the roller pins, and thethrust washers (Figure 26).

Bolt/Stud Retaining SystemsFigure 27

In the older 4KR series bushings, the hold-downnuts would often become frozen to the top of thestud (Figure 27). During disassembly, the studwould back out of the lower body rather than thenut coming off the stud.

All too often when this occurs, rig personnel will nottake the time to remove the nut from the stud andreplace the stud in the body with proper torque.Instead, the nut is left on the stud and assembledas a bolt. The stud becomes tight in the nut and thenut torques down a little more on the stud, causingthe stud to back out in even less time. As a resultthe top becomes loose, the viselike grip on theroller pins is no longer effective and the roller pinscan rotate a small amount in the hournal area,wearing pin and journal, creating slack in thebushing. In addition, the eccentric design of thepins allows the rollers to rotate away from the kelly,causing excessive clearance between kelly androllers.

The newer HD series bushing uses bolts pushedup into recesses in the lower body section andlocked in place with setscrews. The top nuts aretightened as before but is is impossible for the boltto back out in service.

The newer HDP bushing uses straight roller pinsthat lock against each other. Also, the hold-downbolts are outside the load to provide a vise-like gripon the pins (Figure 28). The 4KR had an eccentricroller pin held in position by a lock pin. If the topnuts became loose, the eccentric pin would tend tomove up and out when the kelly was raised, andwould tend to move down and out when the kellywas lowered. This movement caused excessivewear in the bushing’s journal area.NUT IS FROZEN TO

STUD AND STUDCOMES OUT WITH NUT

STUD

STUDRETAININGPIN

HDP 4KRP

ROLLER

THRUST WASHERHOLD DOWN

BOLTS

TOP VIEWS

ROLLER

HDPSTRAIGHTROLLER PIN

ECCENTRICROLLER PIN

4KRP

Roller Pin DevelopmentFigure 28

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HDP Kelly BushingFigure 30

A significant improvement to the thrust washer hasbeen the O-rings on both the OD and the ID thatprevent mud and grit from entering the bearingarea and also retain grease. Keeping the bearingsurfaces clean in this manner results in muchlonger bearing life.

LOCK PINTHRUST

WASHERS ROLLER PIN

BEARING

ROLLER

O-RINGSEALS

Thrust Washers and SealsFigure 29

Like the rest of the rotary equipment, the kelly drivebushing has a very long service life (approximately8 years). Due to this long life, maintenance is oftenneglected, and premature failure results.

Varco BJ kelly bushings

Varco HD Series Kelly Bushings

The Varco HDP pin drive roller kelly bushing(Figure 30) is designed for the most rugged, hightorque, high speed drilling conditions in the world.Its roller assembly provides an efficient drivingmechanism that maintains good driving edges onthe kelly and allows proper feed of the kelly withoutbinding.

By changing roller sizes, one bushing can handleseveral kelly sizes. Other features are aselfcentering stabbing skirt, roller bearings oroptional fibre sleeve bearings. The Varco HDPseries kelly bushing is widely recognized as thedrilling industry standard.

The Varco 27 HDP roller kelly bushing is used withVarco pin drive master bushings for 23, 26, 27-1/2,37-1/2, and 49-1/2 inch rotary tables. The 27 HDPhas 3-5/16 inch (84 mm) diameter drive pins on a25-3/4 inch (654 mm) diameter pin center and willaccommodate kelly sizes from 3 to 6 inches hex orsquare. This heavy duty kelly drive bushing isdesigned for high torque, high speed conditions.

HDS Kelly BushingFigure 31

the Varco 20 HDP roller kelly bushing is used withVarco pin drive master bushings for 20-1/2, 21, and22 inch rotary tables. The 20 HDP has 2-1/2 inch(63,5 mm) diameter drive pins on a 23 inch (584mm) diameter pin center. It uses the same rollers,roller assemblies and wiper assemblies as the 27HDP.

The Varco HDS (square drive) roller kelly bushing(Figure 31) is a heavy duty bushing designed forrugged, high torque applications. The HDS willaccommodate square or hex kellys from 3 to 6inches (76 to 152 mm).

The Varco HDS is used with master bushingshaving an inside drive square dimension of 13-9/16inches (344 mm). This bushing uses the samerollers, roller assemblies, and wiper assemblies asthe 27 HDP.

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Varco MD Series Kelly Bushings

Varco’s MD kelly drive bushing is used for shallowand medium depth drilling operations. Availableeither as pin drive (MDP) or square drive (MDS) itwill accommodate 3, 3-1/2, and 4-1/4 inch hexkellys and 2-1/2, 3-1/2, and 4-1/4 inch squarekellys.

MDP

MDS

4KRBM

4KRVS

MD Series Kelly BushingsFigure 32

A direct descendant of Varco’s heavy duty (HDPand HDS) kelly drive Bushing, this medium dutydrive bushing has the same rugged characteristicsbuilt into it. Installation, operation, and maintenanceare the same as for the larger bushings.

The MDP can be used on any drilling rig that hasthe Varco pin drive master bushing in either a 17-1/2 or 20-1/2 inch rotary table. The MDS has anAPI square to match the API squares in standardsquare drive master bushings.

Varco 4KR Series Kelly Bushings

The Varco 4KRVS and 4KRBM kelly bushings,(Figure 33), are square drive units used with VarcoMSS or API square drive master bushings. Both ofthese units will accomodat square and hexagonalkellys by changing roller sizes.

4KR Series Kelly BushingsFigure 33

The 4KRVS roller kelly bushing is applicable forshallow to medium depth drilling, and willaccomodate 2-1/2 thru 5-1/4 inch square or 3 thru4-1/2 inch hexagonal kellys. The 4 KRBM rollerkelly bushing is applicable for shallow, slim holedrilling and workover rigs. The 4KRBM willaccommodat 2-1/2 thru 4-1/4 inch square or 3 thru4-1/4 inch hexagonal kellys.

17

Kelly Bushing InstallationFigure 34

Installation of kelly bushings

a. Lift and set kelly bushing in master bushing.b. Remove four nuts and lockwashers.c. Lift top half of kelly bushing off studs and set

aside.d. Remove the four roller assemblies from lower

half of kelly bushing.e. Set top half of the kelly bushing loosely on

bottom half.

Note

Make sure that thrust washer lock pins (Figure35) are toward the center of bushing and lie inthe recessed areas of the lower body half.

All kelly bushing thrust washers come with O-rings on the inside and outside diameters.These )-rings help retain grease in the rollerbearing while keeping mud and water out.

f. Stab kelly through bushing.

g. Lift top half of bushing and reinstall rollerassemblies.

h. Lower the top half the kelly bushing, aligning itwith the locating pin.

i. Instal lockwashers and nuts, then tightenalternately until secure.

j. Apply multipurpose, water resistant grease tothe roller pin grease fitting before putting thekelly drive bushing into service

Kelly Bushing AssemblyFigure 35

Operation

a. Lower kelly bushing into the master bushing(Figure 36). The skirt will follow the taper downinto the throat of the master bushing. Thefloating ring (HDP and MDP bushing) will seat inthe upper portion of the master bushing,centering the kelly bushing.

Kelly Bushing in PositionFigure 36

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Operation (cont.)

b. It is recommended that the rotary table beturned slowly as the kelly bushing is beinglowered. The bushing will center and the drivepins* will stab into the drive holes of the masterbushing.

c. The skirt should be greased to allow the kellyfloating ring* to move up easily.

d. Care should be taken when lowering the kellyinto the rathole. Any sudden, jarring stop whenthe kelly upset strikes the rollers, can damagethe roller assembly.

e. the life of the kelly and drive bushing parts canbe increased at least 20 percent by using a kellywiper rubber. The wiper will keep dirt and othermaterial from getting between the kelly and therollers, resulting in less wear on all parts.

* HDP and MDP bushings.

Note

Applying grease to the kelly will increase the life ofthe wiper rubbers.

Maintenance

a. Tighten holddown nuts weekly (Figure 36).b. Grease roller assembly daily at four fittings.c. Grease stabbing skirt for ease of stabbing.*d. Replace drive pins when bottom taper is too

worn to aid in stabbing.e. Replace the drive hole bushing in master

bushing when worn to an egg shape.f. replace API drilling bowl when wear in throat

area exceeds 10-7/8 inches (276 mm). Properthroat size is necessary for good stabbin.

g. Between the top and bottom body halves thereshould be 1/8 inch (3,2 mm) clearance; if thereis none, worn journals are indicated and thekelly bushing should be replaced.

* HDP and MDP bushings.

SLEEVE BEARINGOPTIONAL

ROLLER BEARING

ROLLER PIN

V-ROLLER

FLAT ROLLER

THRUST WASHER

Typical Kelly Bushing Roller AssemblyFigure 37

Typical Pin drive Kelly BushingFigure 38

Typical Square Drive Kelly BushingFigure 39

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Kelly and Roller WearFigure 40

Inspection

The routine inspection of the kelly bushing isperformed as follows:

a. Check to see if top nuts are tight.b. Use a bar to check for body wear and roller

assembly wear.c. Check clearance between rollers and kelly.

5-1/4 in.KELLY

MAXIMUMDRIVINGSURFACE1-1/4 in(32 mm)

NEW KELLYNEW ROLLERS

REDUCED DRIVINGSURFACE1/2 in.(13 mm)

WORN KELLYWORN ROLLER

d. Check rollers and assemblies for wear.e. Check the body for wear.

The amount of driving suface on the kelly isinversely proportional to the amount of slackpresent between the roller and the face of the kelly.If, for example, there is only 1/16 inch (1,6 mm)clearance between the roller and the kelly, thedriving surface of the kelly will be wide and with thedriving forces spread over this wide area, wear willbe minimal. However, if this roller-to-kellydimension were 1/4 inch (6,3 mm), the drivingsurface would then be considerably reduced andthe concentrated force of the rotary would begin toroll the corners of the kelly over (see Figure 3).

Figure 41 shows a 5-1/4 inch hex gauge in a usedkelly bushing. The amount of clearance is greaterthan 1/8 inch (3,2 mm). If the gauge were a kellyand torque was applied, the corners of the kellywould be against the worn spots on the rollers.

Hex Gauge on KellyFigure 41

During a kelly bushing inspection, the rollerassemblies must be checked. The maximum wearsuggested by manufacturers is 1/16 inch (1,6 mm)for a hex kelly and 1/8 inch (3,2 mm) on rollers for asquare kelly. Only half the life of the roller assemblyin Figure 42 has been used. If the roller assemblyis turned 180 degrees in the body, however, acompletely new drive surface is exposed to thekelly (see page 17).

20

Maximum Roller WearFigure 42

1/16 in. (1,6 mm)

MAXIMUM ROLLERWEAR WITHHEX KELLY

1/8 in. (3,2 mm)

MAXIMUM ROLLERWEAR WITHSQUARE KELLY

ROLLER ASSY TOP NUTS ROLLER ASSY

UPPERBODYHALF

LOWER

BODY

HALF

PRY BAR

ROLLER PIN1/8 In. (3,2 mm)

CLEARANCE

BETWEEN TOP AND

BOTTOM BODY HALVES

Split Body InspectionFigure 43

Before inspecting a kelly bushing with a split bodyfor wear, make sure the top nuts are tight. Toprevent excessive wear, the nuts (Figure 43)should be checked weekly to make sure they aretight (Figure 44).

Top Nut InspectionFigure 44

21

Varco kelly bushings have 1/8 inch (3,2 mm)clearance between the top and bottom body halves(in new condition). When the top nuts are tight, thisprovides a vise-like grip on the roller pins. To checkwear in roller assemblies, place a bar under theroller and pry the rollers up. The assembly shouldnot move upward over 1/32 inch (0,79mm). Whilechecking for roller movement, be sure there is nomovement of the roller pin itself by watching theend of the pin. If there is m ovement of the rollerpin, the kelly bushing body has journal wear. Ifthere is more than 1/32 inch (0,79 mm) movementof rollers, but the pin itself does not move, then theroller bearings should be replaced and the pininspected for wear.

KELLY PRY BAR

ROLLER

1/8-in. CLEARANCE(3,2 mm) MAXIMUM

Roller Bearing InspectionFigure 45

With the kelly bushing on the kelly, the clearancebetween the drive rollers and the kelly should bechecked. Force a bar between the roller and thekelly flat surface (Figure 45). The clearance shouldnot be more than 1/8 inch (3,2 mm) clearance,there is wear in the roller assemblies and thebushing body.

Figure 46 shows a new roller assembly in positionin a new, lower body half. The thrust washer lockpins are retained in the recesses of the lower bodyhalf when the top is bolted in place.

New Roller AssemblyFigure 46

ROLLER PIN

THRUST WASHER

LOCK PIN

O-RING MISSING

O-RING

DEEP WEAR PATTERN

INNER SURFACE OF THRUST WASHER

SHOWS EXCESSIVE WEAR

LOCK PIN MISSING

NEW

WORN

Roller Pin WearFigure 47

Figure 47 shows the results of very little lubricationand a lock pin is missing on the outside of the rightthrust washer. The thrust washer must be locked inthe body by the lock pins so that it will not turn onthe roller pin. If the pin is missing, the thrustwasher will turn, and a deep wear pattern on theroller pin will result. In this case, the thrust washerwill no longer absorb the load it was designed totake. This will result in rapid bearing wear, allowingunacceptable clearance between the kelly andkelly bushing rollers.

22

Bearing Cage InspectionFigure 48

Check the bearing cage by taking one end in eachhand and trying to twist the ends in oppositedirections. If there is any movement, the bearingneeds to be replaced. If bearings are checkedevery three months or every rig move and replacedwhen the bearing cage has movement, beforefailure occurs, maximum life can be obtained fromthe kelly and kelly bushing.

Journal InspectionFigure 49

Here is a new roller pin in an old bushing. With useof a screwdriver, 1/8 inch (3,2 mm) wear in thejournal area is revealed. This wear was caused bynot keeping the top nuts tight on a split bodybushing, or by an accident where the kelly waseither drilled or dropped into the bushing.

Outside Journal MeasurementFigure 50

Here, the outside dimension of the body journals isbeing measured. The pencil points out where thenew measurement is and shows that there isapproximately 1/16 inch (1,6 mm) wear indicated.The exact original measurement is 16-15/16 inches(430 mm).

Figure 50 shows maximum allowable weardimensions across outside journal areas. This typeof inspection can be done to determine body wearor spread in the body. Spread in the body of thekelly bushing itself can occur if the total weight ofthe upper fillet of the kelly in the rollers of the kellybushing. This situation can occur if there is a breakin one of the tool joints above the body of the kelly.If such an accidental situation should arise, thekelly bushing body and assemblies must beinspected for damage as soon as possible.

Again, the routine inspection of the kelly bushing isas follows:

a. Check to see if top nuts are tight.b. Use a bar to check for body wear and roller

assembly wear.c. Check clearance between rollers and kellyd. Check rollers and assemblies for wear.e. Check the body for wear.

MAXIMUM ALLOWABLEMEASUREMENT

23

INCREASEDDRIVE ANGLE

REDUCEDDRIVESURFACE

ROLLEDOVEREDGE

REDUCEDDRIVEANGLE

INCREASEDDRIVESURFACE

ALL ROLLER ASSEMBLIES

ARE ROTATED 180° WITHIN

THE BUSHING TO PRESENT

NEW DRIVE SURFACES.

WITH KELLY

INDEXED 1/6

TURN ROLLED

OVER EDGE

WILL BE

DRESSED IN

’’VEE’’ OF

ROLLERIndexed KellyFigure 51

Indexing a kelly

Figure 51 shows the difference in the condition ofthe corners of the kelly. The corners that areagainst the flat rollers are rolled over more than thecorners that are in the V of the other two rollers.

What has happened is that the driving action of thebushing has forced the corner against both sides ofthe V-roller. This action has dressed the rolled overmetal back down.

If a procedure called indexing the kelly is followed,the maximum possible life of the kelly can beextended 30-40 percent if the kelly is indexed afterevery rig move when the kelly bushing is brokendown or once every three months, whichevercomes first.

To index the kelly, remove the top nuts on thebushing, lift the top and remove the rollerassemblies. Turn the kelly in the bushing 1/6 of aturn so that the two corners which were against theflat rollers are now in the V of the other rollers.Longer roller assembly life can be achieved byturning the roller assemblies 180 degrees in thebushing body, each time the kelly is indexed. Lowerthe top and tighten the nuts alternately until it issecure, using a hammer wrench.

WELDMENTDRIVE PIN WASHER

CHISEL

TAPERED AREA

DRIVE PIN

KELLY BUSHINGFLANGE

Drive Pin RemovalFigure 52

Drive pin repair

After several years of service, the lower taper of thedrive pins on the kelly bushing will be worn down tothe top of the taper. The following steps should befollowed to replace the drive pins:

a. Freeze new drive pins.b. Remove weld on top of the washer next to the

top of the drive pin in the bushing.c. Use a chisel to drive the washer up from the

flange of the kelly bushing.d. Drive the pin down and out with a sledge

hammer.e. After old pins are removed, clean the rust and

burrs from the inside of the taper in the bushing.f. Turn the kelly bushing upside down and preheat

the area around the hole 400-450° F (204.4-232.2° C).

g. Take the pins one at a time from the freezer anddrive them into the bushing until they seatcompletely.

h. Turn the kelly bushing over and place the drivepin washer over the extended end of the pin andweld it in place. Fill the recessed area of thewasher around the drive pin with weld.

24

Kelly bushings with drive pin locks

When using a motion compensator on a floatingoperation, the kelly bushing must be locked to themaster bushing to prevent the kelly bushing frombeing pulled out of the drive holes in adverseconditions. Kelly bushings ordered especially for

these conditions, have two drive pins equipped withspecial locks. These locks must be manuallyoperated to lock the drive pins into the masterbushing drive holes.

LOCKING HANDLE

DRIVE PIN

DRIVE HOLE WITHLOCKING POCKET

LOCK RECESS

KELLY BUSHING

LOCK 180Þ APART(2 PLACES)

MASTERBUSHING

BOWL

Drive Pin with LockFigure 53

25

SECTION IIMASTER BUSHINGS AND SLIPS

Proper handling of masterbushings and slips

One of the most expensive pieces of equipment onthe rig is the drill pipe. Not only is it expensive, butit is in very short supply. Typically, worn masterbushings and slips are discovered when inserts arewearing out much more rapidly than usual or whena drill pipe inspection reveals crushed orbottlenecked pipe. This is a needless waste ofvaluable material - a regular program of rotaryequipment inspection could have spotted theproblem in plenty of time to make corrections,without damaging the drill pipe.

AXIALFORCE

TRANSVERSE FORCE

Slips and Master Bushing ForcesFigure 54

In simple terms a comparison can be madebetween slips and a wedge driven into a log. Thewedge’s taper produces a side load or transverseforce which is transmitted into the log. Thistransverse force is much greater than the axialforce applied by the hammer to the wedge. If thewedge is clean and well lubricated, the coefficientof friction between the wedge and the wood is low.Thus, the ratio between the force applied by thehammer and the resulting splitting force on thewood is much greater. If the wedge is dry, dirty, orrusty with insufficient lubrication the coefficient offriction is high. When the coefficient of fricitionincreases, drag increases between the wood andthe wedge and it takes a much greater axial forceapplied by the hammer to split the log.

A related principle applies with slips and masterbushings that are suspending pipe in the rotary.The slip is the wedge. The hook load is the axialforce or vertical load. However, when splitting alog, the two halves of the log are not restrainedfrom outside forces as in the case of slips and pipein a master bushing. The slips’ job is not to actuallydo work - it simply supports a static load. Due tothe fact that the master bushing is restraining theoutward force, the weakest component becomesthe drill pipe.

Results of Friction BetweenSlips and master Bushing

Figure 55

Figure 55 shows the coefficient of friction betweenthe rotary slip and the master bushing, dependingon the condition of the mating surfaces. The lowerthe coefficient of friction between the slip and themaster bushing taper, the greater the amount oftransverse or crushing force per pound of axial orhook load. If, for example, a hook load of 100,000pounds (45,360 kg) is used, it can be seen fromthis chart what the resulting transverse load wouldbe. With dirty, dry, or rusty slips and masterbushing tapers, the ratio is 1.4 to 1. With new,clean, well lubricated slips and master bushingtapers, the ratio would be 4.4. to 1. The averageratio would be 3 to 1. This means that 100,000 Ibs(45,360 kg) results in 300,000 Ibs (136,079 kg) oftransverse load. This high transverse load is whythe master bushing and slips must be kept in goodcondition (or pipe may become bottlenecked.

26

One question is very important: How is this forcedistributed along the length of the slip inset contactarea? the hook load or axial force starts at zero atthe top and increases to a maximum at the toe ofthe slip. The transverse load or crushing forcebegins with a minimum at the top, increasing to amaximum in the center, then decreasing to aminimum again at the toe.

In practical application on a rig, these two forcesact upon each other, resulting in a concentration offorce slightly less than halfway above the throat ofthe master bushing.

Distribution of ForcesFigure 56

Heavy strings of drill pipe can be handled withoutany damage to pipe in the slip area, if the rotaryslip is supported so that the load is distributedequally on all of the inserts. If the slips are notsupported correctly, bottlenecking of drill pipe willoccur.

If slips and master bushings are kept in goodcondition, then the massive crushing force thatexists will be equally distributed. With this forcedistributed along the entire length of the slip, pipewill not be damaged. Wear in both the ID of themaster bushing and on the backs of the slips,however, reduces the length of load distribution toonly the area near the top of the slip, resulting inbottlenecking and of drill pipe.

The API standard master bushing is 10-1/8 inches(257 mm) in diameter at the throat, tapering at arate of 4 inches per foot, to a diameter of 13-1/16inches (332 mm) at the top. The tapered section is8-13/16 inches (224 mm) in length. Notice that theremaining 4 inches (102mm) of the master bushingis recessed to accept the square drive of the kellybushing.

API Standard Split Square DriveMaster Bushing Dimensions

Figure 57

The square drive bushing was approved by theAPI over 35 years ago when a 10,000 foot (3048m) well was considered deep. As hook loadsbecame heavier, drill pipe was being crushedmore frequently. Slip manufacturers increased theslip insert area from 12 to 18 inches (305 to 457mm) and more, without increasing the supportarea for the slips themselves. This did not solvethe probelm.

API Standard Slid Pin DriveMaster Bushing Dimensions

Figure 58

In the late 1950s, Varco realized the need foradditional support for the slip bodies. In an effort togain this needed support, the kelly drive was

HOOKLOAD

CRUSHINGPRESSURE

THE HOOK LOAD ISGREATEST AT THEBOTTOM OF THE SLIP

THE CRUSHING

PRESSURE DIMINISHES

TO ZERO AT TOP AND

BOTTOM OF SLIPAXIALLOAD

F

27

transferred tot he top of the master bushing by theuse of pins. The taper was then brought to the topof the master bushing, providing an additional 4inches (102 mm), or almost 50 percent increase inslip support (Figure 60). This increased the taperlength to 12-3/4 inches (324 mm) as opposed to 8-13/16 inches (224 mm) in the standard squaredrive master bushing.

Long and Extra Long SlipsFigure 59

Both long and extra-long rotary slips have thesame amount of insert contact. The majordifference between the two slips is the length of thetapered area. This longer bowl backup results inlower overall cost, longer life, and increasedprotection for the drill pipe.

Varco BJ master bushings

Varco 17-1/2 thru 27-1/2 Solid Body SquareDrive Master Bushing (MSS)

The Varco MSS Solid Body Square Drive MasterBusing is available for all sizes of rotary tables from17-1/2 thru 27-1/2 inches and is designed for alldrilling operations. A 4 inch (102 mm) deep recessallows a square drive kelly bushing to sit within themaster bushing. Developed for use when a 10,000foot (3048 m) well was considered deep, the MSSstill serves a useful purpose where a large slipbackup area is not required. The MSS will handledrill pipe, tubing, and casing from 2-3/8

thru 13-3/8 inches. The solid outer body takes alltransverse loads and provides proper backing forthe split insert bowls, allowing the rotary table torotate freely, unimpaired by transverse loads. Aswith all Varco master bushings, the MSS has a 500ton rated load capacity.

With the use of Varco extended bowls and theVarco SDXL extra long slip, maximum protection isattained for proper and safe handling of drill pipe

Square Drive BushingsFigure 60

Varco 20-1/2 thru 27-1/2 Solid Body Pin DriveMaster Bushing (MSPC)

the Varco MSPC Solid Body Pin Drive MasterBushing is designed for all drilling operations. Thepin drive allows the kelly bushing to ride on top ofthe roatary table and permits extended bowls to beused for better slip backup. Better slip backupmeans heavier strings can be run without thedanger of bottlenecking. With the extended APIinsert bowl No. 3, the MSPC will handle 2-3/8 thru8-5/8 inch OD drill pipe, drill collars, tubing, andcasing. Insert bowl No. 2 can handle tubular goods9-5/8 and 10-3/4 inches OD; while insert bowl No. 1is good for 11-3/4 and 13-3/8 inches OD. TheMSPC, with proper insert bowls to accommadate agiven diameter string, has a maximum capacity of500 tons. The MSPC has locks that hold the bowlssecurely in the bushing. The solid outer body takesall transverse loads and provides proper backingfor the split insert bowls, allowing the roatary tableto rotate freely, unimpaired by transverse stress.

CONVENTIONAL LONGROTARY SLIPS EXTRA LONG

ROTARY SLIPS

STANDARD APISPLIT MASTER

BUSHING

PIN DRIVE BUSHINGWITH EXTENDED APIINSERT BOWL

28

Master bushing installation

a. Inspect the top side of the rotary table masterbushing bore and the drive square or drive lugslots for peened-over edges. Chamfer asrequired to allow master bushing to enter therotary table freely. Clean and grease the insidesurface of the square of the rotary table.

b. Remove the insert bowls by lifting them out onehalf at a time with the lifting sling provided. Notethat the hooks engage both bowl halves fromthe inside.

Note

The MPCH Master Bushing is equipped with a four-hook sling. Do not use a two-hook sling to handlethis heavy unit.

c. When removing either one or both bowl halves,retract the locks first (except on the 27-1/2 MSSModel).

d. After the insert bowls are removed, pick up themain body with the lifting sling and lower it intothe rotary table.

e. Lower insert bowls into body one half at a timeto complete the installation.

f. Retract the two locks before lowering the insertbowl halves. This is done by lifting and turningthe two pins 180 degrees, then dropping themback into the recesses. After inserting lockbowls in place.

Note

In all instances, the insert bowl to be used shouldfit flush with top of the master bushing body. Whenchanging from one size range to another, replacethe bowl in use with one that corresponds to thenew pipe size.

g. The eccentric pins and locks must be washedfrequently to remove mud and then lubricatedwith oil.

Note

Steps f and G do not apply to 27-1/2 MSS Model

Varco 17-1/2 and 20-1/2 Split PinDive Master Bushing (MDSP)

The MDSP Split, Pin Drive Master Bushings givesuperior load handling capability because theyprovede 50% more slip support than square drive

bushings. MDSP bushings are available for 17-1/2and 20-1/2 inch rotary tables. If the rotary tablebore has over 3/16 in. (5 mm) wear, however, itmust be re-built or a solid bushing must be used.

Bowl LockFigure 62

4-Way Lifting SlingP/n 6699

2-Way Lifting SlingP/n 1021

29

Varco 37-1/2 and 49-1/2 Hinged Pin DriveMaster Bushing (MPCH)

The MPCH Pin Drive Hinged Master Bushing isspecially designed for floating andsemisubmersible drilling operations. With insertbowl No. 3 and optional insert bowls 1 and 2, theMPCH will handle 2-3/8 to 13-3/8 inch OD drillpipe, drill collars, tubing and casing (with a designcapacity of 500 tons). The MPCH has all theperformance features of a solid master bushing yetwith a hinged design, the MPCH can be removedfrom the drill string to pass large bit and pipeconnections directly through the rotary table.

The MPCH incorporates locking latches that lockthe bowls into the bushing. Bowls are alsoequipped with retainer pins to prevent them fromfalling out when the master bushing is hinged open.The MPCH can also be equipped with latches thatlock into the rotary table.

Pin Drive Hinged Master BushingFigure 63

Varco BJ casing bushings

CU, CUL, and CB Casin Bushing are inserteddirectly into the rotary table and insure that thecasing being run is perfectly aligned with the centerof the hole. Models CU and CUL are solid bushingsand Model CB is a split bushing. All of thesebushings accept bowls of different sizes toaccommodate a wide range of casing. Used withVarco’s CMS-XL Slips, these bushings can handlethe longest casing strings currently being set. Also,since these bushings fit into the rotary table, thecasing string can be rotated during cementtingoperations.

Casing BushingsFigure 64

Bit breaker adapter plate

A bit breaker adapter plate, Figure 65, is furnishedwith every Varco pin drive master bushing toconvert the round opening of a pin drive masterbushing to a 13-9/16 inch standard, API squaredrive opening. All rock bit companies furnish bitbreak-out boxes which fit into this opening. Theadapter plate is held in place with four pins which fitinto the four drive pin holes of the bushing.

When using bits in excess of 12-1/4 inches, suchas the 15-1/2 inch bit, it is suggested that a 15-1/2inch box (394 mm) be welded on top of a standardsize box which will, in turn, fit into the Varco bitbreaker adapter plate.

Bit Breaker Adapter PlateFigure 65

MPCH

CU

CUL

CB

30

Maintenance

1. When changing insert bowls, check topdiameter of bushing bore and insert bowl seatfor burrs and peened-over edges; file or grindflush as required. This procedure will ensureeasy installation and proper fit.

2. Clean the inside taper of the drilling bowls ofany abrasive material. This will cut down therapid wear on both slip backs and taper. It willalso provide easy handling of slips and keepthem from sticking in the bushing.

3. Lubricate the inside taper of the drilling bowls(when tripping) to prevent slips from sticking inthe bowls.

4. Lubricate the back of the drilling bowl each timeit is removed from the hull. This will prevent thebowls and slips from sticking and reduce masterbushing ID wear.

5. Replace lock assembly when it ceases tofunction.

6. Replace the API drilling bowls when throatmeasurement exceeds 10-7/8 inches (276 mm)on extended API bowls.

7. Replace API drilling bowls when a straight edgeheld against taper indicates wear from the tooljoint in the tapered section of the bowls

8. When the backs of the rotary slips and the taperof the bowls become rough, both of thesesurfaces must be polished by using emery clothon the backs of the slips or a flexible, finesandpaper disk. Keeping these surfacespolished will help prevent sticking.

9. Hinge Pins (MPCH Only)

a. The stationary hinge pin (without bail) has onelube fitting located at top center. This pin shouldbe greased daily.

b. The removable hinge pin (with bail) should becleaned up and greased each time it is takenout. It has a lube fitting located at top center.

InspectionInspection is the most important aspect ofpreventive maintenance. Inspection consists ofobserving, measuring, and testing.

Rotary Equipment Wear PointsFigure 66

Figure 66 shows typical conditions that can affectslip support:

a. There is wear in the ID of the rotary table whichgives insufficient support for the master bushingitself.

b. The OD of the master bushing is worn.

c. There is excessive wear in the taper and thethroat ID.

These wear conditions affect the function of theslips themselves:

a. The reduced backup area for the slip causeswear and crushing in the backs of the slips.

b. The gripping area of the slips on the pipe isgreatly reduced.

c. Slips used under these conditions are easilydeformed. Drill pipe damage is likely to occur.

WORN

MASTER

BUSHING

REDUCED BACKUP

AREA CAUSES WEAR

AND CRUSHING IN

BACKS OF SLIPS.

GRIPPING AREA

OF SLIPS

ISGREATLY REDUCED

PIPE IS

BOTTLENECKED

WORN

TAPER

IN BOWL

WORN

ROTARY

TABLE

SLIPS UNDER THESE

CONDITIONS ARE

READILY DEFORMED

31

Slips Riding High in Master BushingFigure 67

Observing the height of set slips in the masterbushing is an easy means of checking for wear.The slips ride high in the master bushing when therotary equipment is in good condition.

Slips Riding Low in Master BushingFigure 68

As the system wears, slips ride lower in the masterbushing.

Slip Test Procedure

A slip test is the best way to determine the degreeof rotary equipment wear. This test should beperformed every three months and each time anew master bushing or slip set is put into service.

For accurate results, use a hook load of at least100,000 pounds (45,360 kg):

a. Clean an area of pipe where there are no insertmarks. Clean slip inserts with a wire brush.

Wrapping Test Paper Around KellyFigure 69

b. Wrap a layer of test paper around the cleanedsection of pipe. Varco can supply test paper or alayer of mud sack paper will serve the purpose.Use friction tape to hold the paper to the pipe.

Setting SlipsFigure 70

c. Place the slips around the pipe and hold themwhile the pipe is lowered at normal speed.

32

Removing SlipsFigure 71

d. After the slips have been set, hold them firmlyaround the pipe as it is raised. they should beremoved carefully to prevent damage to thepaper.

Slip Test Paper(Full Contact)

Figure 72

Evaluation should be done using the secont layerof the paper because the outside layer will havemisleading slip impressions. If full insert contact isindicated, the master bushing and slips are in goodcondition and no further analysis is necessary.

Slip Test Paper Poor Contact (Top only)Figure 73

If there is not full contact, the test should be runagain with new slips. If the second test results infull contact, discard the slips because they areworn, crushed or otherwise distorted. Cut off thetoes of discarded slips so they cannot berefurbished and used again. If the results of thesecond test indicate top contact only, the masterbrushing and/or bowls are worn and should beinspected for replacement.

Master Bushing WearFigure 74

This is a worn split master bushing in a rotary. Thespace at the top, approximately 1/4 inch (6,5-mm)between these two bushing halves. The space atthe bottom however, has increased to more than3/4 inch (19 mm). This reduces support for the slipsand causes drill pipe damage. The white line (seearrow) indicates where the throat of the masterbushing was when new.

33

Worn Rotary Table BoreNew Standard API Split Master Bushing

Rotary Table WearFigure 75

The increased gap at the bottom, between themaster bushing halves, and the lack of slip supportshown in Figure 75, is not caused by wear in themaster bushing, but by wear in the ID of the rotarytable.

New Bushing and Worn Rotary TableFigure 76

Placing a new split master bushing in the wornrotary will not solve this problem. It can becorrected by removing the rotary and having it builtup to original specifications. Repairing the bore of atable is expensive and time consuming, requiringthat the complete rotary table be taken out ofservice, disassembled and repaired.

Solid Body Master BushingsFigure 77

A second and less expensive solution would be toreplace the split master bushing with a solidmaster bushing which does not depend on therotary bore for support. The solid master bushingwill contain the complete load of the string (and hasa capacity of 500 tons).

Worn, Deformed Slips in a New BushingFigure 78

When a master bushing is replaced, the rotary slipsmust be checked. Figure 78 shows a new masterbushing with worn rotary slips. A set of slipsconforms or wears in relation to the condition of themaster bushing. If a master bushing is worn andmust be replaces; it is probable that the slips arealso worn, due to improper support from the oldbushing. If worn and deformed slips do not receiveproper support from the new master bushing, theywill cause continued damage to the drill pipe. Aworn or bent slip will bend back in a new bushing,causing cracks in the slip body.

WORN TOTARYTABLE BORE

NEW STANDARD APISPLIT MASTER BUSHING

WORN ROTARYTABLE BORE

34

New and Worn Square Drive BushingsFigure 79

Square Drive Solid Master Bushing Inspection

Here is a comparison of new and worn conditionsfor a square drive master bushing and their effectson slip support: the API specification for the throatmeasurement is 10-1/8 inches (257 mm).The master bushing should be replaced when themeasurement reaches 10-5/8 inches (270 mm).

Due to reduced support in the critical area of aworn master bushing, the slip body will beconcentrated in the upper portion of the slip bodyonly, causing bottlenecking of the drill pipe. Asimilar condition can occur when the ID of therotary itself is worn beyond the 3/16 inch (4,8-mm)recommended limit.

Square Drive Master Bushing with Worn IDFigure 80

Figure 80 shows a solid master bushing that hasbeen sent in for repair. The first thing that can benoticed is that the bowls are together at the top andopen at the bottom. This condition means there iswear on the back of the bowls and inside of theouter hull.

Checking Master Bushing IDFigure 81

While the ID of the top of this hull is correct,inspection shows that the ID at the bottom is worn3/16 inch (4,8 mm), enough to cause theseparation between the bowls.

Checking Master Bushing Bowl TaperFigure 82

In Figure 82 the inspector is checking the taper.The length of the original taper was 8-13/16 inches(224 mm). this is now reduced to approximately 7inches (178 mm) which amounts to 2 inches (50,8mm) less support for the rotary slip. Notice thecircular line at the end of the rule. This markindicates tool joint wear.

NEW WORN

10-1/8 in.(257 mm)

NEW

10-5/8 in(270 mm)

MAX.

22 in. (559 mm) NEW

22-3/16 in. (563 mm) WORN

35

Square Drive Bushing Worn By Tool JointFigure 83

Figure 83 shows the start of the new taper that hasbeen cut by the wear of tool joints which passthrough the rotary. The effective backup for therotary slip has now been reduced to 5 inches (127mm). When using a long rotary slip, the total lengthof the slip is 20 inches (508 mm) with 16-1/2 inches(419 mm) of inserts. Working in a bushing in thiscondition with only 5 inches (127 mm) of taperedarea for backup will cause the backs of the slips tocrush.

New and Worn Pin Drive BushingsFigure 84

Pin-Drive Solid Master Bushing Inspection

Figure 84 compares new and worn conditions for apin drive master bushing and the effects on slipsupport. The API specification for the throatmeasurement is 10-1/8 inches (257 mm). However,the maximum allowable wear has increased to 10-7/8 inch (276 mm) limit is to avoid damage to drillcollar slips which were designed for the shortertaper of the square drive master bushing. Noticethat the toe of the slip has pulled aqay from the drillpipe. This is due to the combination of wear in thethroat area and the outer hull. If the

ID of the outer hull were in good condition, the slipswould still have good support and proper contactwith the drill pipe. Even though there would not bedamage to drill pipe, deformities in the drill collarwould still occur.

Comparisonof New and Worn Hinged Master Bushing

Figure 85

In recent years, due to the introduction of largerrotaries, a new hinged 37-1/2 inch master bushinghas come into the market. The throat and outer hullwear measurements are the same as for theextended bowl. A new wear zone must beconsidered - the hinge pin. Maximum suggestedwear is .032 inch (0,8 mm). Beyond this point,conditions similar to wear in the ID of the rotary ona split square drive master bushing will exist,allowing the bushing halves to separate and reduceslip back-up area. Use bar at the hinged section tomove the bushing back and forth, to determinewear. maximum movement should not exceed 1/16inch (1,6 mm).

INCORRECTTAPER CUT BY

TOOL JOINT

HARDBANDING

10-5/8 in.(270 mm) WORN

NEW WORN

NEW WORN12-3/4 in.(324 mm)

NEW

REDUCEDBACK UP

WEARDUE

TO PIPEDRAGGING

THRU BUSHING

10-7/8 in.(276 mm)

WORN

10-1/8 in.(257 mm)

NEW19 in. (482 mm)

NEW

19-3/16 in. (487 mm)WORN

WORN HINGE PIN

(MAX. WEAR OCCURSAT BOTTOM OF PIN)

0.032 in.(0.81 mm)

MAX

36

Pin Drive Master Bushing with Worn I.D.Figure 86

Figure 86 shows a pin drive master bushing thathas been sent in for repair. As With the squaredrive bushing, the obvious problem is that thebowls are together at the top and open at thebottom.

Measuring Master Bushing ThroatFigure 87

To measure a bushing, first make sure the bowlsare pushed back against the hull. measure thethroat or the bottom of the taper with calipers asshown here. The manufactured dimension is 10-1/8inches (257 mm). The recommended maximumwear dimension is 10-7/8 inches (276). Themeasurement of this bushing is 11-1/16 inches(281 mm) or 3/16 inch (5 mm) over the allowablemaximum.

Where does all this wear occur?

The inspector in Figure 88, is measuring the throatof one insert bowl. The measurement is 10-7/8inches (276 mm) across the throat. This bowl isworn to the maximum allowable dimension.

Measuring Master Bushing Upper IDFigure 90

Bowl with Maximum Throat WearFigure 88

Pin Drive Bushing Worn by Tool JointFigure 89

Halfway down the tapered area is a line where thetool joints of the drill pipe have hit the taper andworn a recess in the slip backup area. This wearalone has reduced the area of slip support by 4inches (101,6 mm).

REDUCED SLIP BACKUP

9 in.(229 mm)

WORN12-3/4 in.(324 mm)NEW

INCORRECTTAPER CUTBY TOOL JOINT

HARDBANDING

10 7/8 in. # 3 Bowl12 7/8 in. # 2 Bowl15 5/8 in. # 1 BowlMAX THROAT WEAR

37

Inspecting the hull shows there is no measurablewear in the ID of the upper portion. However, wearcan easily be seen at the point where the hullextends below the bowls.

With the drill pipe tight against one side of thetable, the hard band area of the box will hit thetaper 4 inches (101,6 mm) above the throat. thehard band will grind the bowl and cut a secondtaper.

Measuring Wear in Hull lower IDFigure 91

In Figure 91 lower ID wear is being measured, andthe reruslt is 19-3/16 inches (487 mm) or 3/16 inch(5 mm) of wear, which is the recommendedmaximum allowable wear.

Worn Out Master BushingFigure 92

The combination of wear in the bowls and wear inthe ID of the hull have reduced the effective slipsupport area by almost 50 percent. There is nolonger proper support in the critical area of the slip

Drive hole bushing replacement

After a period of time, the drive holes in the MSPCand MPCH master bushing will become deformedand the bushings in these holes will needreplacement.

a. Place new drive hole bushings in a freezer.

b. Cut the worn bushing top to bottom with a torchin two places about 180° apart. Drive out thepieces from the mud drain hole.

Drive HoleBushing Removal

Figure 93

c. Clean out the drive holes, remove any rust anddeburr the top edge.

d. Preheat the master bushing body around thedrive hole bushing area to 400-450° F(204.4-232.2° C).

Drive HoleBushing Replacement

Figure 94

e. Remove drive hole bushings one at a time fromfreezer when ready to install.

f. Make sure master bushing drive hole area is atthe proper temperature. Drive the bushing in,using a wooden block on top of it to preventdamage to the bushing. Drive the bushing intothe hole as fast as possible with a sledgehammer. If too much time is taken, the bushingwill expand in the drive hole and prevent fullseating.

TO REPLACEDRIVE HOLE BUSHING:TORCH CUT 2 PLACES180° APART AND DRIVEOUT FROM DRAIN HOLE

DRIVE IN BUSHINGUNTIL FIRMLY SEATED

38

Varco BJ slips

SDS, SDML, and SDXL Rotary Slips

These models are for use in API standard insertbowls. These slips feature improved contact on drillpipe through a superior wrap around configurationand unique insert design that helps to preventbottlenecking and gouging damage. The buttressdesign of the body segments provides greatstrength while minimizing weight for ease ofhandling.

Varco rotary slips provide long and troublefreeservice under the most severe conditions. Insertsare held securely in dovetail slots and are easilychanged by removing the nuts, bolts, and retainerat the top of the slots.

SDS Slips are designed for shallow hole drilling

SDML Slips are the perfect choice for all mediumdepth drilling. With the proper drill string designthey can handle depths beyond 20,000 feet.

Varco SDXL Slips are designed for deep drilling.

SDS Grip LengthFigure 96

SQUAREDRIVEMASTERBUSHING

11 in.(279 mm)

API BOWL

SDS

SDS-Short Rotary SlipsFigure 95

SDXL- Extra Long Rotary SlipsFigure 99

SDML

SDML-Medium Rotary SlipsFigure 97

VARCONO. 3 BOWL API BOWL

VARCO PIN DRIVEMASTER BUSHING

ANY API STANDARDSQUARE DRIVE

MASTER BUSHING

SDML Grip Length and Insert Bowl ContactFigure 98

SDXL

39

Varco DCS Drill Collar Slips

Varco DCS slips provide superior holding powerunder all conditions. Each segment, manufacturedfrom a rugged drop forging, has an extra long backto give maximum support to the circular buttongripping elements. Full wrap-around designcompensates for irregularities in wear. Circularbuttons hold against load from all directions toassure positive holding and slip setting. Drill collarslips are flat on top to accommodate the MPClamp.

Rotary Slip Set PartsFigure 101

RETAINING RING

HANDLELEFT

HANDLE PINW/COTTER PIN

& WASHER

SLIP SEGMENTLEFT

HINGE PINW/COTTER PIN

SDXL

SLIPSEGMENTRIGHT

HANDLERIGHT

HANDLECENTER

SLIP SEGMENT CENTER

VARCO NO. 3 BOWL

16-1/2 in.(419 mm)

VARCO PIN DRIVEMASTER BUSHING

SDXL Grip LengthFigure 100 DCS

DCS-Multi-Segment Drill Collar SlipsFigure 102

DCS-Multi-Segment Drill Collar Slips PartsFigure 103

BODYSEGMENT

HANDLE-L & R

CIRCULARBUTTONS

HINGE PIN

HANDLEPIN

HANDLE-INTERMEDIATE

RETAININGCOTTER

RETAININGSCREW

40

DCS-Drill Collar Slip Grip LengthsFigure 104

CMS-XL Casing Slips

CMS-XL Slips will handle the longest casing stringscurrently being set. Manufactured from dropforgings, their reindorced design will stand up tothe most severe service. The self-centering, fullwrap-around grip holds positively while preventingdamage - even to thin wall casing. By varying thecircular button size and adding or removing bodysegments, casing from 6-5/8 to 30 inches OD caneasily be accommodated. Light and easy to handle,Varco CMS-XL casing Slips are unexcelled.

CMS-XL- Casing Slip Grip LengthFigure 107

CP-S Conductor Pipe Slips

CP-S Slips are used in offshore or marshylocations when conductor pipe is used. These slipsare available in three models to handle conductorpipe with OD’s of 24, 26 or 30 inches (610, 660 or

CP-S-Conductor Pipe SlipsFigure 108

CMS-XL-Casing SlipsFigure 105

CMS-XL

7-1/8 in.(181 mm)

7-7/8 in.(200 mm)

9 in.(229 mm)

DCS-SRANGE3-4-7/8

DCS-RRANGE4-1/2-7

DCS-LRANGE5-1/2-14

CP-S

13-1/2 in.(343 mm)

CMS-XL-Casing Slips PartsFigure 106

HANDLE-L & R

BODYSEGMENT

HANDLEINTERMEDIATE

HANDLEPIN

RETAININGSCREW

HINGE PINCIRCULARBUTTONS

41

Multipurpose safety clampThe MP Multipurpose Safety Clamp provides safehandling of all typesof flush joint pipe, liners anddrill collars during makeup, breakout and settingthrough the rotary table. The MP Clamp can beadapted to act as an elevator shoulder wheneverthe necessity arises, or fitted with lifting eyes tohandle large diameter pipe. This provides aconvenient and safe method of handling surfacepipe, drilling risers and other types of largediameter tubular products during installation. TheMP Clamp can also be inverted and fitted withholddown lugs for use in all types of snubbingoperations. Interchangeable handles, lifting eyes,and holddown lugs are forged and heat-treatedsteel for maximum durability and long life.See also page 87.

Slip inserts

Varco rotary slips, drill collar and casing slips areuniquely designed to provide even distribution ofload on pipe. Varco inserts fall midway between thetwo extremes of high ratio and low ratio in poundsper linear inch of contact. The rotary slip insertgripping dies have a 0.01 inch (.25 mm) wide flaton the top of each tooth. This flat will peen, ratherthan cut, the metal of the pipe, which reducespotential stress risers.

Varco Gripping Dies Last Longer. After machining,the gripping dies must pass a rigorous inspection,then they are heat treated and brought to ahardness of 58062 Rockwell C., to ensurelongevity.

Rotary and Casing Slip InsertsFigure 112

Resistant to Fracture and Chipping - Varco casingand drill collar slips use circular button grippingdies, which do not create stress risers. This isespecially important on thin wall casing where aheavy pull is exerted due to the casing length.Circular buttons have no exposed edges that canfracture and chip.

Specify Varco gripping dies as replacements forworn of damaged gripping dies to ensure thatVarco’s high standards of quality will be on yourside when handling all tubulars.

Safety Clamp AssemblyFigure 110

Carrier With GrippingDie Parts Disassembled

ROLLPIN

SPRINGLINK ASSEMBLY

HAMMERWRENCH

Multi-Purpose Safety ClampFigure 109

CASE

MP Complete WithCase and Wrench

DIE CARRIER

GRIP DIE

HANDLE SCREW PIN BUSHING

SCREW PIN

SIDEBARS

LINK

LINK PIN

THRUSTWASHER

MAKEUPNUT

LATCH LINK

SCREW

Safety Clamp partsFigure 111

42

The industry has had many accidents caused byslips being set on moving pipe. The drill pipe mustbe stopped completely before the slips are set onthe pipe. The driller should look at the weightindicator to see that he is holding the full load. If thebit should hit a ledge which supports part of theweight of the string, when the elevator is removedthe pipe could be jarred free and the full shock loaddumped on the slips. When the shock load hits theslips, the drill string acts like a rubber band. A15,000 foot (4572 m) string of 4-1/2 inch drill pipecan stretch approximately 38 feet (11 m). Thestring will start to bounce and could cause the slipsto be thrown out of the rotary table; then the pipewill be dropped in the hole. If the pipe does not goin the hole and the slips do hold, another problemcould occur; the drill pipe is could be permanentlydeformed and cracked just below the slips,resulting in wash-outs.

Stopping Pipe With Rotary SlipsFigure 113

Operation

Do not set slips on larger size pipe than they weredesigned to hold. Figure 114 shows the effects ofusing slips on the wrong size pipe. When 5 inchslips for example, are used on 5 inch pipe, theinserts have the proper contour. If the slip is usedon larger pipe or on tool joints, the stress is placedon the outside corners of each segment. Thiscauses the slip bodies to spread and crack. Afterthe slip has been used on larger pipe and thenplaced on the pipe size for which it was designed,the slip bodies will conform to their original contour.This could cause the slips to break and allowpieces to fall into the hole.

Results of Improperly set Drill Collar SlipsFigure 115

If drill collar slips are used on collars with recessedareas, care should be taken in setting. If setpartially on the upset area, the insert and insertslot will be damaged, making it difficult, if notimpossible, to change inserts. The retaining screwor cotter pin area, could be damaged so that it willbe difficult to remove.

OVERSTRESSED OR’’STRETCHED’’PIPE

Proper use of Rotary Slips

EXCESSIVE

STRESS

PLACES

ON SLIP

BODY AND

INSERTS

Pipe too large

RIBSCRACKED

DEFORMED

Pipe too small

RIBSCRACKED

Incorrect Use of Rotary SlipsFigure 114

DRILLCOLLARSLIPSEGMENT

INSERT SLOT DAMAGED

RETAINING SCREWHEX HEAD CRUSHED

INSERTS CRUSHED

43

Setting Slips on Tool JointFigure 116

One final word of caution: There are times whensetting the slips that the driller does not pick upenough to get the rotary slips around the pipe. Inthis case the top of the rotary slips is on the tooljoint. When the drill pipe is lowered, the slip’s bodyis bridged between the master bushing and thepipe. This causes the back of the slips to bend. Thenormal reaction is to raise the string and let the slipsegment settle around the pipe. The slip segmentshave been bent and when placed in the masterbushing around the pipe, they will bend back totheir original form, however, cracks may havedeveloped in the slip bodies. As a result of this, thetoe of the slip could break and fall into the hole. Ifthe driller runs into a slip, inspect it or use a newset until the damaged slip can be inspectedproperly.

Maintenance

Rotary Slips in PositionFigure 117

Cleaning and Lubrication

Clean the inside taper of the drilling bowls of anyabrasive material. Lubricate the inside taper of thedrilling bowls frequently with grease to prevent slipsfrom sticking in the bowls. It is suggested that theoutside surface of the bowl and the inside diameterof the hull be cleaned and well lubricated. This willallow the bowls to move up slightly when the drillpipe is picked up. At this time, either the rotary slipwill release between the backs and the taper of thebowl, or the rotary slip together with bowl, will moveup a short distance until the bowl hits the lock,whick will then free the slips. If this area betweenthe bowls and the master bushing is kept clean andwell lubricated, the slips will not stick in the masterbushing.Warning: Never use pipe dope to grease the backof the slips.

Surfaces that Require DressingFigure 118

Dressing Slips and Insert Bowls

The slips and bowl ID should be dressed as well ascleaned to prevent sticking of the slips. Abrasivematerials in the drilling mud can cause horizontallines of wear in the mating surfaces of the slips andbowls.

Dressing these surfaces, using an up and downmotion with emery cloth will result in the grain ofthe two parts running with each other tosignificantly reduce friction.

CRUSHEDINSERTS

SLIPBACKSWILLBEND

LOCK ASSY

RETAING PIN

LOCK

ECCENTRIC PIN

CLEAN AND LUBRICATETHESE SURFACES

44

Bent, Worn, SlipsFigure 119

Slip Inspection

Periodic inspections should be performed on drillpipe and drill collar slips as a preventive measure.Areas of particular concern are slip segmenthinges and the hinge pins.

Checking Slip SegmentsFigure 120

Placing a straight edge against the backs andinside face of the slips will indicate if they are bentor worn. A good slip back is straight, smooth, andwell greased.

Slip Segment DamageFigure 121

Webs and toes of slips can develop cracks fromexcessive wear or from use in a badly wornbushing. If cracks are present, destroy the slips andremove them from the site. If cracked slips are keptin service, parts could break off and fall into thehole.

Hinge Pin RemovalFigure 122

Slip segment hinges should be inspected regularyto see that the hinge pin is locked into position withthe cotter pin and not worn or cracked. Slips thatsag or flop over when standing alone on the rigfloor, are extremely worn in the hinge area. Pullthee hinge pins and check for straightness. A benthinge pin will indicate oversize hinge pin holes.Oversize hinge pin holes are cause for replacint theslips. If not replaced, wear will increase at anaccelerated rate until the slips do not set correctlyin the master bushing. This could damage drill pipe.

Slip Segment (shown without retaining ring)Figure 123

Check inserts and insert slots for damage ar wear.When the insert slots are badly worn, danger oflosing an insert down the hole exists. Replace theslips before a costly failure occurs. Slips should bereplaced when there is over 1/8 inch to 3/16 inch(3.2 to 4.8 mm) clearence between the back of theinserts and the insert slot.

CRACKS

CRACKS

BENT BACKS

GREATLYREDUCEDGRIPPINGAREA

SLIP BACKSWORN & BENT

CRACKS

SLIP BACKSWORN & BENT

CRACKEDWEBS

WORN BOWLRESULTS IN REDUCEDSLIP BACK UP

HINGE PINWITHCOTTER PIN

SLIP SEGMENT

SLIP SLOT

1/8 - 3/16 in. (3-5 mm)MAX. CREARANCE

SLIP INSERT

45

PS-15 and PS-16Spring Slip Assemblies

Another Varco Innovation to improve Efficiencyand Reduce Crew Fatigue.

Lifting and setting slips is one of the mostbackbreaking jobs on a rig. Varco’s spring slipseliminate this tough hand work. These models areset by foot pressure on the slipset ring, rather thansheer muscle power. The spring slips enable fasterand safer handling of pipe.

Setting Spring SlipsFigure 124

How Varco Spring Slips Operate

The PS-15 uses coll springs as a counterbalanceto offset the weight of the slips when in the upper,released position. Slips are set by standing on theslipset ring. The foot pedal is pressed to releasethe slips. Slips remain set until the driller picks upthe drill string.

The PS-16 is an air operated version of the PS-15.Varco’s spring slips provide even distribution ofload on the pipe. Model features slip segments andinserts designed to protect expensive drill pipe andtubing.

Spring Slips in Set PositionFigure 125

Varco Spring Slips fit directly into Varco MasterBushings. The PS-15 handles 3-1/2 to 5-1/2 inchO.D. drill pipe. The PS-15 can be used with Varco’’Big Foot’’ pipe handling system for maximumefficiency, safety and speed.For more information on the PS-16, please refer tothe PS-16 manual.

PS-15 Spring Slip AssemblyFigure 126

46

Summary

Properly maintained master bushing and rotaryslips can prevent premature damage to drill pipe.Normal maintenance is frequently forgottenbecause of the durability of Varco BJ. equipment.Many times the first inkling of a problem is when aninspection reveals damaged drill pipe. Knowing themaximum limits of master bushing wear and whatto look for when inspecting rotary slips can go along way toward preventing drill pipe damage in theslip area.

Points to keep in mind:

1. Replace worn or defective equipment.

2. Stop the drill pipe completely before the slipsare set on the pipe. The driller should look at hisweight indicator to see that he is holding the fullload.

3. Perform a slip test every three months.

In this handbook we have presented the properinspection and maintenance procedures requiredfor trouble-free operation and maximum service lifeof your rotary equipment. Become familiar withthese procedures, and put them into operation.

The Continuing Search for energy requires highlysophisticated equipment and crews trained tooperate and care for it properly.

As this information is put to use, the result will beless ’’downtime’’ and more productive hours spent’’turning to the right.’’

47

SECTION IIITECHNICAL DATA

4849

Technical DataTable of Contents

SubjectPageNumber

Metric Conversion Factors ................................... 49Abbreviations Commonly Used............................ 49Kellys ................................................................... 50Kelly Bushings ..................................................... 52Master Bushings.................................................. 64Rotary Slips ......................................................... 76

Drill Collar Slips ................................................... 81CMS-XL Casing Slips ........................................... 84CP-S Conductor Pipe Slips .................................. 85Multi-Purpose Safety Clamp ................................ 86PS-15 Spring Slip ................................................ 89Appendix.............................................................. 90

Technical DataList of Figures

Figure PageNumber Title Number

TD-1. Square Kelly............................................. 50TD-2. Hex Kelly.................................................. 51TD-3. 20 HDP Roller Kelly Bushing ................... 52TD-4. 27 HDP Roller Kelly Bushing ................... 53TD-5. HDS Roller Kelly Bushing ........................ 53TD-6. Roller Assembles and Part....................... 56TD-7. MDP Roller Kelly Bushing........................ 61TD-8. MDS Roller Kelly Bushing........................ 61TD-9. API Rotary Table Openings ...................... 64TD-10. API Insert Bowls ...................................... 64TD-11. Master Bushing Dimensions.................... 65TD-12. MSS Master Bushings ............................. 67TD-13. MSPC Master Bushings ........................... 69TD-14. MPCH Master Bushings........................... 71TD-15. SDS Rotary Slips ..................................... 76TD-16. SDML Rotary Slips .................................. 77TD-17. SDXL Rotary Slips ................................... 79TD-18. DCS Drill Collar Slips ............................... 81TD-19. CMS-XL Casing Slips............................... 84TD-20 CP-S Conductor Pipe Slips ...................... 85TD-21. MP Safety Clamp ..................................... 86TD-22. MP Safety Clamp Parts ............................ 87TD-23. MP Safety Clamp ..................................... 88TD-24. Spring Slip............................................... 89TD-25. Galling ..................................................... 91TD-26. Pipe Cup Failure....................................... 92TD-27. Pipe Flat Failure ....................................... 92

Technical DataTable of TablesTable PageNumber Title Number

TD-1. Measurement of a New Square Kelly ....... 50TD-2. Square Kelly end Connections ................. 50TD-3. Measurement of a New Hex Kelly ............ 51TD-4. Hex Kelly end Connections ...................... 51TD-5 HDP and HDS Kelly Bushing Parts........... 54TD-6. HDP and HDS Roller Assy ....................... 57TD-7. HDP and HDS Rollers Only ...................... 57TD-8. 4KRVS Roller Assy .................................. 57TD-9. 4KRVS Roller Only................................... 58TD-10. 4KRBM Roller Assy ................................. 58TD-11. 4KRS and 4KRP Kelly Bushing Parts ....... 59TD-12. 4KRVS and4KRP Roller Assy................... 60TD-13. MDS and MDP Kelly Bushing Parts ......... 62TD-14. Rotary Table Dimensions ......................... 64TD-15. Insert Bowl Dimensions........................... 64TD-16. Master Bushing Dimensions.................... 66TD-17. MSS Master Bushing Parts...................... 67TD-18. MSS Master Bushing

Ordering Information ............................... 68TD-19. MSPC Master Bushing Parts ................... 69TD-20. MSPC Ordering Information .................... 70TD-21. MPCH Master Bushing Parts ................... 72TD-22. MPCH Ordering Information .................... 72TD-23. Master Bushings and Insert Bowls .......... 73TD-24. Casing Bushings and Insert Bowls........... 75TD-25. Hinged Casing Spiders and Insert Bowls . 75TD-26. SDS Rotary Slips Ordering Information... 76TD-27. SDS Rotary Slips Parts............................ 76TD-28. SDML Rotary Slips Ordering Information 77TD-29. 3-1/2 and 4-1/2 Inch SDML Parts............ 78TD-30. 5 and 5-1/2 Inch SDML Parts .................. 78TD-31. SDXL Rotary Slips Ordering Information. 79TD-32. 3-1/2 and 4-1/2 Inch SDXL Parts............. 80TD-33. 5 and 5-1/2 Inch SDXL Parts ................... 80TD-34. DCS-S Drill Collar Slips Parts .................. 82TD-35. DCS-R Drill Collar Slips Parts .................. 82TD-36. DCS-L Drill Collar Slips Parts................... 82TD-37. DCS Ordering Information ....................... 83TD-38. Circular Buttons for Drill Collar Slips ....... 83TD-39. CMS-XL Casing Slips

Ordering Information ............................... 84TD-40. CMS-XL Casing Slips Parts ..................... 84TD-41. CP-S Ordering Information ...................... 85TD-42. Circular Buttons for Casing and

Conductor Pipe Slips ............................... 85TD-43. MP Safety Clamp Ordering Information ... 86TD-44. MP Safety Clamp Parts ............................ 87TD-45. PS-15 Ordering Information .................... 89

49

METRIC CONVERSIONS

Metric conversions thruout this handbook conformto the Systeme Internationale (SI) metricequivalents.

The formulas used are:

inches x 25.4 = millimetres (mm)feet x .3048 = metres (m)pounds x .4536 = kilograms (kg)ounces x .0283 = kilograms (kg)tons x .9078 = tonnes (t)

ABBREVIATIONS

°C - Celsius or Centigradedia. - diameter°F - Fahrenheitft - foot or feethex - hexagon or hexagonalID - inside diameterin. - inch(es)kg - kilogram(s)lb - pound(s)m - metre(s)mm - millimetre(s)no. - numberOD - outside diameteroz - ounce(s)P/N - part numberqty. - quantitysq - squarew/ - withwt - weight

50

Kellys

Kellys are manufactured with one of two basic configurations - square or hexagonal. The size of a kelly isdetermined by the distance across the drive flats (See Figure TD-1 and TD-2).API kellys are manufactured in two standard lengths: (1) 40 feet (12.2 metres) overall with a 37 foot (12metres) working space or (2) 54 feet (16.5 metres) overall with a 51 foot (15.5 metres) working space.

*6-inch square not API

Square Kelly

51

Hex Kelly

52

Roller kelly bushings

20-HDP Heavy duty pin drive roller kelly bushing.Figure TD-3

53

27-HDP Heavy duty pin drive roller kellybushing.

Figure TD-4

HDS Heavy duty square drive roller kellybushing.

Figure TD-5

Used for heavy duty drilling in 17-1/2- to 27-1/2-in.Rotary tables with square drive master bushings.Fits any standard 17-1/2- to 27-1/2-in. Split MasterBushing and Varco MSS

54

(Continued)

Table TD-5 Parts List for Varco Type 20 HDP, and 27 HDP, HDS, Roller Kelly Bushings

55

(Continued)

Table TD-5 Varco Tyype HDS and HDP Roller Kelly Bushings

56

Roller Assemblies and Parts for Heavy Duty Roller Kelly BushingsFigure TD-6

1605or 1505

150650924 1316

1313

1210 1208 13111312

V-ROLLERFLAT ROLLER

Replacement parts, roller kelly bushings20-4 KRP, 27-4KRP, 4 KRS (discontinued)

Roller assemblies and partsHDP & HDS

BEARING 1312

V-ROLLER

FLAT ROLLER

SLEEVE BEARING 1326OPTIONAL

THRUST WASHER 3618W/O-RINGS & LOCK PIN

ROLLER PIN 3609

BEARING 5218

4KRBM

V-ROLLER

FLATROLLER

THRUST WASHER 2912ROLLER PIN2910

4KRVSSLEEVEBEARING 1422OPTIONAL

V-ROLLER

FLAT ROLLER

BEARING 1412

THRUST WASHER1413

ROLLER PIN1411

57

58

59

60

Table TD-12 4 KRS 20-4KRP and 27-4KRP, Complete Roller Assemblies

* Note: Rollers, Bearings and Wipers for Varco HDP, HDS, 4KRS and 4 KRP Kelly Drive Bushings are interchangeable

61

17 and 20-MDP Medium DutyFigure TD-7

MDP-Dimensional data

MDS Medium Duty Square DriveFigure TD-8

Used for medium duty drilling in 17-1/2 to 27-1/2 in.Rotary tables with square drive master bushings.Fits any standard 17-1/2 to 27-1/2 in.Split Master Bushing and Varco MSS

62

Table TD-13 Varco Type MDS, 17 MDP, and 20 MDP Roller Kelly Bushings Parts List

(Continued)

63

(Continued)Table TD-13 Varco Type MDS, 17 MDP, and 20 MDP Roller Kelly Bushings Parts List

* Recommended Spares include two wiper rubbers for each size kelly for bushings with wiper assemblies.

64

Master bushings

API Insert BowlsFigure TD-10

Table TD-15 API Insert Bowls Dimensional Data

Table TD-14 API Rotary Table Dimensional Data

API Rotary Table OpeningFigure TD-9

65

MDSPPIN DRIVE

MSSSQUAREDRIVE

MSPCPIN

DRIVE

Figure TD-11 Master bushing Dimensions in inches (mm)(See Next Page for data)

66

Table TD-16 Varco Rotary Table Master Bushings

*API STANDARDVARCO SOLID**17-3/16 inch (437 mm)** 20-1/8 inch (511 mm)** 27-3/8 inch (695 mm)

67

Note: * No locking device is used for the insert bowl of these two sizes.When ordering or requesting quotation, please specify make, size and type of rotary table.

Note: ** Special API extended insert bowl for round trips only.

For 20-1/2 in. Tables For 27-1/2 in. Tables

17-1/2 thru 27-1/2 MSS Solid Body Square Drive Master BushingsFigure TD-12

Table TD-17 MSS Parts List

68

Table TD-18 17-1/2 thru 27-1/2 Solid Body Square Drive Master Bushing (MSS) Ordering Information

69

For 23, 26 and 27-1/2 In. tables -Shown with API extended insert bowl no. 3

Uses Varco 27 HDP or 27 KRP Kelly Bushings

For 20-1/2, 21, and 22-1/2 in. tables-Shown less insert bowls.

Uses Varco 20 HDP and 20 4KRP Kelly

20-1/2 thru 27-1/2 MSPC Solid Body Pin Drive Master BushingsFigure TD-13

Table TD-19 MSPC- Parts List

(Continued)

70

(Continued)

Table TD-19 MSPC- Parts List

Note: Split Pin Drive Master Bushing for 27-1/2 In. Rotary Tablesavailable on Special order only... P/N 5429

Table TD-20 MSPC Ordering Information

(Continued)

CONTINALEMSCO

IDECO NATIONAL OILWELL

71

(Continued)

Table TD-20 MSPC Ordering Information

MPCH master bushings

MPCH Hinged Pin Drive Master BushingFigure TD-14

72

Table TD-21 MPCH Parts List

Note: When ordering or requesting quotation, please specify size, make and model of rotary table.

Table TD-22 MPCH-Ordering Information

73

Table TD-23 Master Bushings and Insert Bowls

Al Dimensions in Inches

(Continued)

74

(continued)

Table TD-23 Master Bushins and Insert Bowls

Al l Dimensions in Inches

75

Table TD-24 Casin Bushings and Insert Bowls

Table TD-25 Bowls used with HCS Spider

All Dimensions in Inches

76

Rotary slips

API BOWL

SQUAREDRIVEMASTERBUSHING

11 in.(279 mm)

SDS-Short Rotary SlipsFigure TD-15

Table TD-26 SDS Ordering Information

Table TD-27 SDS-Short Rotary Slips Parts List

* Kits contain bevelled inserts.

77

VARCONO. 3 BOWL API BOWL

VARCO PIN DRIVEMASTER BUSHING

ANY API STANDARDSQUARE DRIVE

MASTER BUSHING

SDML-Medium Rotary SlipsFigure TD-16

Table TD-28 SDML Ordering Information

* Kits contain bevelled inserts.

78

Table TD-29 3-1/2 and 4-1/2-in. SDML Parts List

**6 required for this one only

Table TD-30 5 and 5-1/2 in. SDML Parts List

79

VARCO NO. 3 BOWL

VARCO PIN DRIVEMASTER BUSHING

16-1/2 in.

(419 mm)

SDXL-Extra Long Rotary SlipsFigure TD-17

Table TD-31 SDXL Ordering Information

* Kits contain bevelled inserts.

80

Table TD-32 4-1/2 and 5 in. SDXL Parts List

Table TD-33 5 1/2 and 7 in. SDXL Parts List

81

DCS-Drill Collar SlipsFigure TD-18

DCS-Drill Collar Slip Grip Lengths

DCS-SRANGE3-4-7/8

DCS-RRANGE4-1/2-7

DCS-LRANGE5-1/2-14

7-1/8 in.

(181 mm)7-7/8 in.

(200 mm)

9 in.

(229 mm)

Drill collar slips

HANDLE-INTERMEDIATE RETAINING COTTER RETAINING SCREW

HANDLE PIN

HINGE PINCIRCULAR BUTTONS

HANDLE-L&R

BODY SEGMENT

DCS-Multi-Segment Drill Collar Slips DCS-Multi-Segment Drill Collar Slips Parts

82

Table TD-34 DCS-S Drill Collar Slip Parts List

Table TD-35 DCS-R Drill Collar Slip Parts List

Table TD-36 DCS-L Drill Collar Slip Part List

83

Table TD-37 DCS Ordering Information

Notes: * This size is furnished with 4 handlesAll Varco DCS Drill Collar Slips have an API taper of 4 in./ft on the diameter.

Tabele TD-38 Circular Buttons for DCS Drill Collar Slips

84

Casing slips

CMS-XL

HANDLE-INTERMADIATE

HANDLE-L & R

BODYSEGMENT

HANDLEPIN

RETAININGSCREW

HINGE PINCIRCULARBUTTONS

13-1/2 in.

(343 mm)

CMS-XL Casing SlipGrip Length

CMS-XL Casing Slips Parts

Figure TD- 19 CMS-XL Casing Slips

Table TD-39 CMS-XL Ordering Information

Notes: *Theses sizes are furnished with 4 handles.All Varco CMS-Extra Long Casing Slips havean API taper of 4 in./ft on the diameter.

Table TD-40 CMS-XL Parts List

85

CP-S Conductor Pipe SlipFigure TD-20

Table TD-41 CP-S Ordering Information

Table TD-42 Circular Buttons for CMS-XL & CP-S Slips

86

MultipurposeSafety Clamp

CASE

MP Complete WithCase and Wrench

DIE CARRIER

GRIP DIE

SPRINGROLLPIN

HAMMERWRENCH

Carrier With GrippingDie Parts Disassembled

LINK ASSEMBLYCarrier With Gripping

Die Assembled in LinkMP-Multipurpose Safety Clamp

Figure TD-21

Table TD-43 MP Ordering Information

87

SCREW PIN BUSHINGSCREW

SCREW PIN

SIDEBARS

LINK

LINK PIN

HANDLE

THRUSTWASHER

MAKEUPNUT

LATCH LINK

Safety Clamp PartsFigure TD-22

Table TD-44 MP Ordering Information

AR = As RequiredOpt = Optional

88

Handle

All gripping diesmust be makinggood even contactwith the pipe

Latch jaw

Remove the dowelpin of the latch jaw

Adjustment

Pipe

Link pin

All movementrestriction dowelpins must be clearof the locatingshoulders on theconnecting links

Multipurpose Safety ClampFigure TD-23

Wear data (inches)

Link

Link part number 3307Total clearance “A” 0.04Pin dia. New Max. 0.872Bore dia. New Max. 0.895Bore dia Worn max. 0,905

Handle

Handle part number 3305Total clearance “A” 0.04Pin dia. New pin 0.872Bore dia. New max. 0.895Bore dia. Worn max. 0,905

Latch

Link part number 3307Total clearance “A” 0.04Pin dia. New Max. 0.872Bore dia. New Max. 0.895Bore dia Worn max. 0,905

Insert carrier

Insert Maximum clearance “B”insert carrier/insert: 0.04”

89

Spring slip assemblies

*When fitted with specified slip set and guide ring

Table TD-45 PS-15 Ordering Information

PS-15 Spring Slip AssemblyFigure TD-24

PIN DRIVE SOLIDMASTER BUSHING

GUIDERING

BOWL

SLIP

GRIP

LENGTH

16-1/2 in.

(533 mm)

19 in.

(483 mm)

SLIPS RELEASED

33 in. (838 mm)

SLIPS SET

11 in.

(279 mm)

Appendix

Drill stem care and Maintenance

Handling the Drill Stem

Picking up and laying downThe Drill Stem

Use thread protectors when available. Whenthreads and shoulders are unprotected, doe notpermit the tool joints to strike steel surfaces suchas walks, stairs, or machinery. USE WOOD SURFACESIN PLACES WHERE THE TOOL JOINT MAY HIT.

Cleaning and Lubrication(thread Compounds)

Pin and box threads and shoulders should bethoroughly cleaned. Use solvent and wipe dry witha clean rag. Inspect carefully for any burrs or nickson the shoulders or threads. DAMAGEDCONNECTIONS SHOULD NEVER BE RUN INTHE HOLE.After cleaning, apply tool joint thread comound tothreads and shoulders with a round, stiff bristlebrush. Use thread compounds containing 40% to50% by weight of finely powdered metallic zinc.NEVER, UNDER ANY CIRCUMSTANCES, USECASING AND TUBING LUBRICANT. THREADCOMPOUND MUST BE APPLIED TO THE TOOLJOINT EVERY TIME IT IS MADE UP.

Stabbing and spinning The Drill Stem

DO NOT ALLOW THE ENDS OF THE PIN TOSTRIKE THE BOX SHOULDERS. THESHOULDER MUST NOT BE NICKED OROTHERWISE DAMAGED. Before spinning the pipe,make sure connections are in alignment. Do notrotate the pipe too fast, especially when wobblingor binding occurs.Extra care is necessary when a power-operatedspinner is used.

Making up The Drill Stem (Torque)

PROPER MAKEUP IS THE MOST IMPORTANTSINGLE FACTOR IN PREVENTION OF TOOLJOINT FAILURE. Observe the following steps:

1. Torque measuring equipment must be used

2. When using tongs, it is imortant that line pull be measured when the line is at right angles or 90° to the tong handle.

3. When applying line pull, do not jerk the tongs.

4. OVER-TORQUE CAN BE JUST AS DAMAGING AS UNDER-TORQUE.

5. Use both tongs (when tongs are used) when making up tool joints.

6. Do not make up pipe using spinners only.Torquing devices must be used.

Breaking-in New Connections

Initial makeup is most critical and extra care isessential for long trouble-free service. Follow thesesteps:

1. Inspect threads and shoulder for any damage.

2. Clean and Lubricate as indicated above.

3. Walk in or slowly rotate joints together.

4. Makeup to recommended torque.

5. Breakout and slowly spin out.

90

91

Breaking and Spinning-outThe Drill Stem

When breaking out the joint, use both tongs (whentongs are used).Always follow these steps:

1. Do not let the end of the pipe strike the box shoulder.

2. Come out of the hole on a different break each trip so that every connection con be periodically broken and its condition and torque checked.

3. When standing the pipe back, be sure the set back area is clean where the pin will rest.

Limitations on The Drill Stem

Cautions

1. Most drill pipe failures are a result of fatigue. Drill pipe should be routinely inspected for fatigue cracks.

2. Notches from stamps, grooves, tong marks, junk cuts, etc. on the drill pipe will accelerate fatigue and failure.

3. Remove damaged pipe from the drill string immediately.

4. Never guess at makeup torque, pipe grade,size, weight or tool joint type. LOOK IT UP!

Corrosion

Corrosion (rust, pitting and loss of metal) is causedby mud composition and pH, formation fluid inflow,and oxygen. THE MOST SEVERE CONDITIONUSUALLY ENCOUNTERED IS THE PRESENCEOF SOUR GAS (H2S). When H2S is present,obtain expert advice to prevent premature failure,especially when high strength drill pipe is beingused. WHEN USING WATER BASE DRILLINGFLUIDS, MAINTAIN A MINIMUM pH OF 9.5 (11 TO13 IS PREFERRED). Determine if corrosioninhibitors in the drilling mud will be effective andeconomical.

Hole Deviations

Directional wells or doglegs caused by hole angleor direction change, often contribute to drill pipefatigue. If doglegs are present, it is a good practiceto string ream the dogleg area. The portion of thestring immediately above the drill collars is mostlikely to suffer fatigue failure. These joints should bemarked, inspected more frequently, and moved upthe hole each trip. A shallow dogleg in a deep holecan cause as much damage as a severe dogleg,due to the high tension load at the top of the drillstring.

Drill Stem Tests

When emptying the pipe, the bottom joints aresubject to collapse from the pressure of the drillingfluid. Consult an expert or the API/ADC tables formaximum external pressures. When using plasticcoated pipe, limit testing to as brief a period aspossible to minimize errosion damage to thecoating. DO NOT TEST IN H2S ENVIRONMENTSWITHOUT EXPERT ADVICE.

Troubleshooting The Drill Stem

(Remember, damaged pins or boxes mean twojoints of pipe must be removed.)

A. DRY OR MUDDY CONNECTION-(no lubricant when broken out)- is positive indication of damaged shoulders which will result in a washout.

B. GALLED SHOULDER. Galls 180° apart areindications of insufficient makeup torque resulting in wobble and thread section failure.

GallingFigure TD-25

Flat failure (Fatigue)Figure TD-27

C. GRAY RING ON OUTSIDE OF SHOULDERS is indication of insufficient makeup torque.

D. ABNORMALLY HIGH BREAKOUT TORQUE is a sure sign of damaged connection. Remove from string for thread inspection.

E. CUP TYPE THREAD FAILURE is usually caused by excessive torque (tension failure).

Cup Failure (Tension)Figure TD-26

F. FLAT TYPE THREAD FRACTURE - is usually caused by insufficient makeup torque (fatigue failure) or by sour gas (hyrdogen embrittlement) accelerating fatigue (when makeup torque is known to be sufficient).

G. SHARP OR BROKEN THREADS are evidence of insufficient makeup torque.

H. THIN SHOULDERS caused by wear of tooljoint, either eccentrically or uniform, will result in twist-offs.

I. UNDERCUTS next to hardfacing (stepwear) will result in failure. Remove from string.

J. CORROSION GROOVES are sometimes found under rubber protectors, especially on high strength drill pipe. Remove from string.

K. PIPE FATIGUE FAILURE is accelerated by rotating in severe doglegs, or by bent pipe or kellys. Notches, grooves, etc. also accelerate fatigue failure.

92

93

Notes

94

Notes

95

Notes

96

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