Basic Drill String Design

Basic Drill String Design

Sperry-SunHALLIBURTON


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1 Basic Drill String Design

1.1 Drill Pipe Characteristics

1.1.1 Introduction

Drill strings are subjected to forces of tension, torsion and bending when drilling a well. Designinga drill string to accommodate these forces requires knowledge of the physical characteristics of the pipeand the terminology used to identify these characteristics.

1.1.2 Objectives

After completing this section, you should be able to

� List the four basic functions of the drill string.

� Define the term "pipe grade" and list the four commonly used grades of drill pipe.

� Identify and define the three weight titles associated with drill pipe.

� Identify the eight API drill pipe sizes.

� Explain how drill pipe is classified by inspection and list the five drill pipe inspection classes.

1.1.3 Functions of th e Drill String

The Drill string must be designed to serve four basic functions

� Transmit and support axial loads.

� Transmit and support torsional loads.

� To withstand potential fatigue damage.

� To transmit hydraulics to clean the hole and cool the bit.

Applying sound engineering criteria to the selection of tubulars can help prevent failures as oilwells become deeper and environments more harsh.

The strength of tubulars, such as drill pipe is defined by a combination of pipe grade, weight, sizeand condition.

1.1.4 Pipe Grade

Grade indicates the yield strength of the drill pipe. There are four commonly used grades of drillpipe. These are:

� E-75

� X-95

� G-105

� S-135

There are four grades not in general use. These are:

� D-55

� N-80

� C-75

� V-150

The grade of drill pipe can be specified with or without the number following the letter. Forexample, either "Grade E" or "Grade E-75" is correct.


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The numbers in the pipe grade specifically refer to the yield strength of the pipe. For example,grade G-105 pipe has a minimum yield strength of 105,000 lb/in² (psi).

Yield strength Tensile StrengthMin Max MinGrade

psi Mpa psi Mpa psi MpaE-75 75,000 517 105,000 724 100,000 689X-95 95,000 655 125,000 862 105,000 724G105 105,000 724 135,000 931 115,000 793S-135 135,000 931 165,000 1138 145,000 1000

Figure 1 Drill Pipe Yield Strengths

1.1.5 Pipe Weight

The pipe weight must be considered, as it is part of the hook load on the derrick. This effects thedepth a rig is capable of drilling to safely. It is important that the specific weight of drill pipe is referred to.

Drill pipe is listed under three different weight titles. These are nominal weight, plain end weightand approximate weight.

Nominal Weight

Drill pipe is purchased and referred to by its nominal weight. The nominal weight is the pipes"given name" and refers to the wall thickness of the pipe it does not refer to its actual weight.

Plain End Weight

Plain end weight is the weight per foot of a non-upset, non-threaded and non tool-jointed piece ofpipe.

Approximate Weight

This is the average weight per foot of a joint of complete drill pipe. It includes the non-upsetsection, the upsets and both tool joints. The approximate weight depends upon the size and type of tooljoints on a piece of pipe. This is the value used in hook load calculations.

Weight Comparisons

The following table shows the weight comparisons for a 5" G-Grade drill pipe with a nominalweight of 19.5 lb/ft, a 0.362" wall thickness and H-90 connections

Size Wall Inches NominalWeight lb/ft

Plain EndWeight lb/ft

Approximateweight lb/ft

5" 0.362 19.5 17.93 22.32

Figure 2 Drill Pipe Weights

1.1.6 Pipe Size

API drill pipe is designated in terms of its outside diameter on the non-upset sections. There areeight different sizes. These are: 2 3/8", 2-7/8", 3-1/2", 4", 4 1/2", 5", 5-1/2" and 6-5/8"


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1.1.7 Pipe Class

Once drill pipe has been used, normal wear and other use related defects cause the pipe toloose some of its original strength. API has developed inspection criteria to determine the extent ofdamage. These criteria are used to assign the pipe to "classes" according to the extent of the damage.The inspection examines the following conditions with all the criteria having to be met for a drill pipe togain the specific class.

� OD wall wear

� Dents and mashes

� Slip area mechanical damage. Crushing, necking, cuts and gouges

� Stress induced diameter variations. Stretched or shot.

� Corrosion cuts and gouges, longitudinal and transverse.

� Fatigue cracks

� Internal corrosion and pitting

� Internal erosion and wear.

� Internal fatigue cracks.

Any evidence of fatigue cracks or washouts and the pipe is designated as scrap.

(See figure 3 for the inspection criteria)

There are five classes of drill pipe indicating the amount of wear a joint of pipe has sustainedduring its lifetime.

� New

� Premium or class 1

� Class 2

� Class3

� Scrap

All new drill pipe becomes premium class as soon as it is used. New drill pipe indicates it isdirectly from the manufacturer and has never been used. As soon as a joint of new pipe is picked up foruse on a rig it is re classified as premium or class 1 pipe. Interestingly this allows the manufacturers abroader set of tolerances with the pipe having to conform to the requirements for Premium grade ratherthan the new specification.


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Figure 3 Class Inspection Criteria


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Pipe Tool Joint

Class OD ID WallTorsionalYield ftlbs

TensileYield lbs OD ID

M/U TRQft.lbs

New 5.000" 4.276" 0.362" 57633 553833 6.5000" 3.250" 25724

Premium 4.8552" 4.276" 0.290" 45199 436150 5.9062" 3.250" 21914

Class 2 4.7828" 4.276" 0.253" 39166 378605 5.8125" 3.250" 19244

Figure 4 Dimensional and Strength Variation with Class

Figure 4 illustrates the changes in dimensions and mechanical properties of 5" G-105 pipe withH-90 connections according to the different class specifications.


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2.2 Mechanical Limits of the Drill String

2.2.1 Introduction

This section covers the theory of the mechanical limits of drill pipe.

2.2.2 Objectives

After completing this section, you should be able to:

� Define the terms limit of elasticity, limit of plasticity, and yield strength, tensile strength and torsional

strength as they relate to drill pipe.

� Explain the effect tensile load has on torsional yield strength.

� Explain the causes of drill pipe fatigue failure.

� Define the term endurance limit as it relates to drill pipe fatigue.

� Explain the effect of yield strength, surface finish, environment and tension have on the endurance

limit of the drill pipe.

2.2.3 Tension

Drill pipe is designed to lower, support and raise large loads. The application of a load, whichmust be supported causes tensile stresses in the pipe.

2.2.4 Elasticity

One important property of steel is that, under certain conditions of loading it is elastic in natureand can be stretched and once the load is removed it will return to it's original size and shape.

The elastic nature of steel is difficult to measure without the aid of instruments.

The elastic behaviour of steel is extremely important when designing and load bearing steelstructure or part.

If a bar of steel L cm long and A square cm in cross sectional area is fixed at one end and a loadP applied to the free end the bar will stretch or elongate a small amount, e. If the load P is removed, thebar will return to its original length.

This type of non-permanent deformation is called elastic deformation and elasticity is theproperty which permits a material to deform under a load and return to it's original shape once the loadis removed.

Within the elastic range of a material, if a load P is applied to the bar the bar will elongate a smallamount. If more weight is added to the load P, the increase in elongation will be proportional to theweight added. For any successive increase in load, there will be a corresponding proportional increasein elongation (Hookes Law).

So, for each increase in stress, there will be a corresponding proportional increase in strain, andwhen the stress is removed the strain disappears and the bar returns to its original length.

The maximum stress that the bar can take without becoming permanently deformed is known asthe elastic limit .

2.2.5 Plasticity

The elastic condition has a limit and at some point of loading when the load is removed the barwill not return to its original length but will be longer than it was originally. The bar is then permanentlydeformed or plastically deformed . The amount of deformation is referred to as the permanent set.

Basic Dri lll String Design

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Plasticity is the ability of the material to assume permanent deformation without breaking.

The plastic limit is the point of highest stress the material can withstand before failure occursthis is also the tensile strength of the material.

L

Elastic Deformation

e

P

A

P

e

PermanentSet

Plastic Deformation

Figure 5 Elastic and Plastic Limits

2.2.6 Proportional Limit

The proportional limit is the greatest stress a material is capable of sustaining without deviatingfrom the law of proportionality of stress to strain (Hookes Law). In metals, the elastic limit and theproportional limit practically coincide.

2.2.7 Yield Point

The yield point is the stress at which a material exhibits a specified limiting elongation. For Oilfield tubulars this elongation is 0.2%. This is the value referred to in the drill pipe grade G-105 pipe has aminimum yield strength of 105,000 psi. It is also referred to as the yield strength .

0.2% elongation or permanent set is established to allow a standard to measure deformation.The only way of proving a material has reached its elastic limit is to deform it beyond the elastic limit.

2.2.8 Tensile Strength

As a material enters the plastic range, exceeding the elastic limit , the material becomesstronger from work hardening. This means a higher stress is required to further deform the material.This continues until the maximum stress the material can withstand is reached. This is referred to as theTensile strength . Once the tensile strength of a material is exceeded the material will rupture.

2.2.9 Maximum Allowable Hook Load

When drilling a well the main concern is how much can we pull on a string of drill pipe. The yieldstrength and tensile strength then become very important. From the previous discussion it is obviousthat the stress must be kept below the materials tensile yield point. This point is referred to as the tensileyield strength or maximum allowable hook load for the drill pipe.


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STRESS

STRAIN

A

B

C

A - Proportional Limit or Elastic Limit

B - Yield Point or Yield Strength

C - Tensile Strength

D - Elastic Range

E - Plastic Range

D E

0.2% Permanent Set

Figure 6 Stress / Strain Diagram for Drill Pipe Elongation

2.2.10 Calculating the Tensile Yield Strength

The Following formula is used to calculate the tensile yield strength, the yield point for a purelytensional load on the drill pipe.

Pt = YmA

Where:Pt = minimum tensile yield strength - poundsYm = Minimum unit yield strength - psiA = Pipe cross sectional area - in²

For API 5", G-Grade 19.5 lb/ft, premium grade drill pipe.

Then:

Ym = 105,000 psi for grade GOD = 4.8552 inID = 4.276 in

Solution:

P = 105,000 ( � /4) (4.8552² - 4.276²)

P = 436,150 lb.


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2.2.11 Torsion

One of the functions of the drill pipe in addition to supporting load is to rotate the bit and BHA.Rotation causes torsional stress to be imparted to the drill string. Wall friction, stabiliser hang up andother down hole conditions will increase the torque required to rotate the tube. If the torque becomes toogreat, the tube may fail.

2.2.12 Torsional Yield Strength

The torsional yield strength of a drill pipe is defined as the resistance of the tubular to failure by atwisting torque or force. The torsional yield strength is based upon the shear strength equal to 57.7% ofthe minimum yield strength (figure 1).

For Pure Torsion:

When the drill string is not under any tensile load the following formula is applied.

0.096167 J YmQ = D

Where:

Q = Minimum Torsional yield strength, ft/lb

Ym = minimum yield strength, psiJ = Polar moment of inertia = ( � /32)(OD4- ID4)D = Outside diameter, in

For API 5", G-Grade 19.5 lb/ft, premium grade drill pipe.

Then:

Ym = 105,000J = ( � / 32) (4.85524 - 4.2764 )

Solution:

(0.096167) (( � / 32) (4.85524 - 4.2764 )) (105,000)Q = 4.8552

= 45199 ft/lb

2.2.13 Combined Torsional and Tensional Yield

When a joint of drill pipe is subjected to a combined load of torque and tension, its ability to resisttorsional failure is reduced, as part of the strength of the drill pipe must go to supporting the tensionalload. In this case, as would be seen during normal drilling operations the following formula is used.

(0.096167 J) Ym² - (P²)Qt = D (A²)

Where:

Qt = Minimum torsional yield strength under tension - ft/lb.J = Polar moment of Inertia = ( � / 32) (4.85524 - 4.2764 )D = Outside diameter - inYm = Minimum yield strength - psiP = Total load in tension - poundsA = Cross sectional area - in²

For API 5", G-Grade 19.5 lb/ft, premium grade drill pipe supporting a tensile load of 100,000 lbs.


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Then:

J = ( � / 32) (4.85524 - 4.2764 )D = 4.8552Ym = 105,000P = 100,000A = ( � /4) (4.8552² - 4.276²)

Solution:

Qt = (0.096167) ( � / 32) (4.85524 - 4.2764) x 105,000² - 100,000²4.8552 (( � /4) (4.8552² - 4.276²))²

= 0.4305 x 102202.88

= 43995 ft / lbs

For API 5", G-Grade 19.5 lb/ft, premium grade drill pipe supporting a tensile load of 200,000 lbs.

= 40167 ft / lbs

For API 5", G-Grade 19.5 lb/ft, premium grade drill pipe supporting a tensile load of 300,000 lbs

= 32808 ft / lbs


= 18017 ft / lbs


= 7563 ft / lb

For API 5", G-Grade 19.5 lb/ft, premium grade drill pipe supporting a tensile load of 436149 lbs

= 81 ft / lbs

Figure 7 Torsional / Tensile Load Cross Plot


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Figure 8 Effect of Class on the Torsional / Tensile cross plot

2.2.14 Fatigue

Usually a drill string is designed for its capability to withstand tensile loads under staticconditions. This takes into account yield strength, tensile strength and maximum hook load.

Most failures occur not through tension failure but through fatigue failure.

Fatigue is failure resulting from the progressive growth of irregularities to major cracks caused bythe repetitive cycling of stresses.

In many industries where fatigue failures limit the life of equipment, industry standards have beenestablished which permit the design of equipment to operate at stress levels, which assure indefinite lifefree from fatigue failure. Additionally equipment can be designed to operate at certain stress levels for afinite period before failure occurs. These designs will incorporate various periods of peak loading abovethe average stress level.

2.2.15 Nature of Failures

Very little statistical data concerning the nature of failures in drill pipe has been accumulated andpublished. Reports made to the AAODC confirm the consensus of personal observations from many inthe industry that failures occur in the following manner:

1) Most failures in drill pipe occur while rotating or when picking the pipe up off bottom immediatelyafter drilling rather than when pulling on stuck pipe.

2) Most failures occur within 4 ft of the tool joint at either end of the pipe.

3) Failures are frequently associated with severe pitting on the inside of the pipe, and these cracksappear to have started from the inside. Multiple cracks are frequently observed in severely pittedpipe failures. Progressive crack growth is indicated.

4) Failures that appear to originate from the outside of the pipe are usually associated with slip marksor surface damage. Progressive crack growth is indicated

5) Even when failure occurs as a result of pulling on stuck pipe failure frequently occurs in a locationwhere fatigue cracks have developed but not progressed to failure.


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2.2.16 Fatigue Failure

Any metal part subjected to a cyclic variation is stress will fail through the progressive growth ofsmall irregularities to larger cracks and fractures even when the average stress is less than the yieldstrength of the material. This type of failure is a high-cycle, low-stress fatigue failure. Characteristicallythe fatigue failure shows concentric semicircular marks illustrating periodic growth in the crack.

If we look at a round bar that is held in a bend when it is rotated, we find that every fibre of thebar is stretched in tension and then compressed. If there are any irregularities when they reach thetensile side of the bend it is opened up and forced to grow. If the stress level at the base of theirregularity is large enough the irregularity will enlarge progressively until the remaining solid material istoo weak to support the total load and a failure occurs. This failure will be instantaneous.

Figure 9 Effect of Bending on Fatigue

In the oil industry, a great deal of testing has been performed on full size drill pipe and tool jointspecimens. The results are plotted as stress vs. the number of cycles.

Figure 10 Loading Method for R.R.Moore Test Specimens


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From these plots, the stress level below which failures do not occur is called the endurancelimit . At stress levels above the endurance limit failure will occur at a predictable period in the life ofpart.

Figure 11 Endurance Limit for D and E grade pipe in Air

Tests with notched specimens show a sharp decrease in the endurance limit when compared tothe same material that was tested without notches.

2.2.17 Effect of Tensile Strength on Endurance Limit

In drill pipe steels, increases in yield strength are obtained without relative increases in ultimatestrength from published data the following properties can be seen.

Grade ElongationMinimum Yieldstrength, psi.

Rupture minimumTensile strength,

psi.

Ratio Minimumyield to minimumtensile strength

D-55 55,000 95,000 58%E-75 75,000 100,000 75%S-135 135,000 147,000 91%

Figure 12 Relative Increase in Tensile Strength with Grade

Comparing the endurance limits for these materials there is even less improvement from gradeE-75 to S-135. The endurance limit for grade E-75 specimens was 26,000 psi, 89% of the 29,000 psivalue obtained for S-135 specimens.

2.2.18 Effect of Surface Finish

The type of surface finish effects the endurance limit of drill pipe. Improvements in the endurancelimit can be seen from an "as forged" state to "hard rolled" to "machined" to "ground".


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Figure 13 Effect Of Surface Finish on Endurance Limit

2.2.19 Effect of Corrosive Environment

The continuous immersion in a corrosive fluid while undergoing cyclic stressing is extremelydamaging to steel. Conducted tests indicate a severe reduction in the ability of S-135 pipe to withstandbending fatigue when immersed in seawater. No endurance limit is indicated for specimens run inseawater.

Figure 14 Effect of Corrosive Environment on Endurance Limit

2.2.20 Combined Stresses of Tension and Bending

Referring to the earlier example of a bending drill pipe Figure 9 we noted each fibre is alternatelyin tension and compression. If a high tensile load is added to the pipe the stresses can vary frommaximum tension to minimum tension without the pipe ever becoming compressed. The addition of thistensile stress reduces the ability of the pipe to withstand cyclic stresses.


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Additional factors are the sharpness of the bend the pipe is rotating in and the amount of tensileload on the specific area of the drill pipe. The sharper the angle and the greater the tension the fasterthe drill pipe fatigues.

Figure 15 Effect Of Gradual Dogleg on Drill Pipe Life

Figure 16 Effect of Sharp Doglegs on Drill Pipe Life

It is worth noting that all fatigue experienced by a piece of drill pipe is cumulative. If exposed tohigh stress bending in a sharp dogleg the joints are damaged by this although it may be of shortduration, shortening their effective life. The life of the pipe depends upon its cumulative history atvarious stress levels, a short period of stress can significantly shorten the life of a joint of pipe. Thisdamage cannot be detected by any current field method until cracks develop.

Tensile Requirements and Properties

Pipe Grade Sigma Sigma Min Minimum Fatigue Stress M. Elasticity Density Poisson'sSteel Ultimate (psi) Tensile Yield (psi) Endurance Limit (psi) (psi) lb/gal Ratio

E 100000 75000 22000 30 x 10^6 65.4 0.3G 130000 105000 25000 30 x 10^6 65.4 0.3

S135 160000 135000 31000 30 x 10^6 65.4 0.3S165 175000 165000 33000 30 x 10^6 65.4 0.3

Aluminum 64000 58000 18000 10.6 x 10^6 27 @ 29 0.33Al 2014-T6 for 2.0 x 10^6 revolutions with TJ steel

Titanium 130000 120000 40000 17 x 10^6 33 @ 35 0.35Ti-641-AV with TJ steel

HW 1340 MOD 95000 55000 20000 30 x 10^6 65.4 0.3HW 4145H MOD 140000 110000 20000 30 x 10^6 65.4 0.3

DC 4145H MOD 100000 15000 30 x 10^6 65.4 0.3DC 15-15LC MOD 110000 15000 27.7 x 10^6 65.4 0.3

API Recommended Practice 7G Variation with Class

5" Drill Pipe nominal weight 19.5 lb/ft Class OD ID WallNew 5.000" 4.276" 0.362"

80% Premium 4.855" 4.276" 0.290"70% Class 2 4.783" 4.276" 0.253"

4 1/2" Drill Pipe nominal weight 16.6 lb/ft Class OD ID WallNew 4.500" 3.826" 0.337"

80% Premium 4.366" 3.826" 0.270"70% Class 2 4.298" 3.826" 0.236"

3 1/2" Drill Pipe nominal weight 13.3 lb/ft Class OD ID WallNew 3.500" 2.764" 0.368"

80% Premium 3.352" 2.764" 0.294"70% Class 2 3.280" 2.764" 0.258"

2 7/8" Drill Pipe nominal weight 10.4 lb/ft Class OD ID WallNew 2.875 2.151" 0.362"

80% Premium 2.731" 2.151" 0.290"70% Class 2 2.657" 2.151" 0.253"

Appendix


Sperry-Sun / Brazil

* Drill Pipe Data Tube Size OD Tube Size ID Nom Weight Tool Joint

inches mm inches mm lbs/ft OD range ID range

2 3/8 60.3 1.995 50.7 4.85 3 1/8 - 3 3/8 1 3/4 -21.815 46.1 6.65 # 2 7/8 - 3 3/8 1 3/8 -2

2 7/8 73.0 2.441 62 6.85 3 3/4 - 4 1/8 2 1/8 - 2 7/162.151 54.6 10.40 # 3 1/8 - 4 1/4 1 1/2 - 2 5/32

3 1/2 88.9 2.992 76.0 9.5 4 5/8 - 4 3/4 2 11/16 - 32.764 70.2 13.3 # 4 1/8 - 5 1/4 2 1/8 - 2 3/42.602 66.1 15.5 5 - 5 1/2 2 1/4 - 2 9/16

4 1/2 114.3 3.958 100.5 13.75 5 3/4 - 6 3/8 3 1/4 - 3 7/83.826 97.2 16.60 # 5 7/8 - 6 3/8 2 3/4 - 3 3/43.640 92.5 20.00 6 - 6 5/8 2 1/2 - 3 5/8

5 127.0 4.276 108.6 19.50 # 6 3/8 - 7 1/4 2 3/4 - 3 1/24.000 101.6 25.60 6 3/8 - 71/4 2 3/4 - 3 1/2

5 1/2 139.7 4.778 121.4 21.90 # 7 - 7 1/2 3 - 44.670 118.6 24.70 7 - 7 1/2 3 - 4

6 5/8 5.965 25.20 # 8 - 8 1/2 4 1/4 - 5

Appendix


Sperry-Sun / Brazil

New Drill Pipe Data and Tool Joint Range

Drill Pipe Data Tool Joint DataNominal Nominal Approx Type Upset Connection

Size Weight Weight and Grade Type OD IDinches lbs/ft lbs/ft inches inches

2 3/8 6.65 7.11 EU-G105 NC26(IF) 3 3/8 1 3/46.99 EU-G105 SLH90 3 1/4 1 13/16

2 7/8 10.40 11.09 EU-G105 NC31(IF) 4 1/8 210.95 EU-G105 SLH90 4 211.55 EU-S135 NC31(IF) 4 3/8 1 5/811.26 EU-S135 SLH90 4 1/8 1 5/8

3 1/2 13.3 14.71 EU-G105 NC38(IF) 5 2 7/1614.06 EU-G105 SLH90 4 3/4 2 9/1614.92 EU-S135 NC38(IF) 5 2 1/814.65 EU-S135 SLH90 5 2 1/8

4 1/2 16.6 18.36 EU-G105 NC50(IF) 6 5/8 3 3/418.79 IEU-G105 NC46(XH) 6 1/4 318.62 EU-S135 NC50(IF) 6 5/8 3 1/219.00 IEU-S135 NC46(XH) 6 1/4 2 3/4

5 19.50 22.62 IEU-G105 5 1/2(FH) 7 3 3/421.93 IEU-G105 NC50(XH) 6 5/8 3 1/423.48 IEU-S135 5 1/2(FH) 7 1/4 3 1/222.61 IEU-S135 NC50(XH) 6 5/8 2 3/4

5 1/2 21.90 25.38 IEU-G105 FH 7 1/4 3 1/226.50 IEU-S135 FH 7 1/2 3

6 5/8 25.20 28.20 IEU-G105 FH 8 1/4 4 3/429.63 IEU-S135 FH 8 1/2 4 1/4

New Tool Joint and Type Upset

Appendix


Sperry-Sun / Brazil

# Mechanical Specifications 3 1/2" 13.3 lb/ft Drill Pipe NC38 Connections

Tensile Yield Data ( lbs ) Connection Make-Up Torque ( ft.lbs )

Grade New Premium Class 2 New Premium Class 2

E-75 271569 212150 183398 9054 7274 6268X-95 343988 268723 232304 10163 8822 7785

G-105 380197 297010 256757 11106 9879 8822S-135 488825 381870 330116 14965 12569 10768

# Mechanical Specifications 4 1/2" 16.6 lb/ft Drill Pipe NC46 Connections



E-75 330558 260165 225771 16997 12085 10647X-95 418707 329542 285977 17765 15035 12813

G-105 462781 364231 316080 19829 16546 14288S-135 595004 468297 406388 22436 21230 18083

# Mechanical Specifications 5" 19.5 lb/ft Drill Pipe NC50 Connections



E-75 395595 311535 270432 18838 15776 14083X-95 501087 394612 342548 22345 19919 17497

G-105 553833 436150 378605 25724 21914 19244S-135 712070 560764 468778 31703 28381 24645

Appendix


Sperry-Sun / Brazil

Alumimum Drill Pipe 2014-T6

Minimum Yield Strength 58000 psi Minimum Ultimate Strength 64000 psi

Maximum Tensile Load ( lbs )

Nominal Premium Class 2Pipe New 80% Nom. Wall 70% Nom. Wall

3 1/2" 297660 230490 1983004" 313490 244640 211350

4 1/2" 373520 291570 2518905" 442420 345910 299160

Maximum Torsional Load ( ft-lbs )

3 1/2" 20160 15360 131304" 25480 19690 16930

4 1/2" 33310 25740 221505" 44750 34690 29890

3¹⁄₂ 2¹⁄₄ 0.625 5.645 4 3⁵⁄₈ 310,475 18,460 NC 38 (3¹⁄₂ IF) 4³⁄₄ 2³⁄₈ 675,045 17,575 10,000 30/27 31'-0"4 2⁹⁄₁₆ 0.719 7.410 4¹⁄₂ 4¹⁄₈ 407,550 27,635 NC 40 (4 FH) 5¹⁄₄ 2¹¹⁄₁₆ 711,475 23,525 13,300 30/27 31'-0"4¹⁄₂ 2³⁄₄ 0.875 9.965 5 4⁵⁄₈ 548,075 40,715 NC 46 (4 IF) 6¹⁄₄ 2⁷⁄₈ 1,024,500 38,800 21,800 30/27 31'-0"5 3 1.000 12.566 5¹⁄₂ 5¹⁄₈ 691,185 56,495 NC 50 (4¹⁄₂ IF) 6⁵⁄₈ 3¹₁₆ 1,266,000 51,375 29,200 30/27 31'-0"5¹⁄₂ 3³⁄₈ 1.063 14.812 6 5⁵⁄₈ 814,660814,660 74,14074,140 5¹⁄₂ FH 7 3¹⁄₂ 1,349,3651,349,365 53,08053,080 32,80032,800 30/27 31'-0"6⁵⁄₈ 4¹⁄₂ 1.063 18.567 7¹⁄₈ 6³⁄₄ 1,021,185 118,845 6⁵⁄₈ FH 8 4⁵⁄₈ 1,490,495 73,215 45,800 30/27 31'-0"

Nom. Size(in)

ID(in)

Wall Thickness

(in)Area(in)

Nominal Tube Dimensions

Center Upset

OD(in)

Elevator Upset

OD(in)

TensileYield(lb)

Torsional Yield(ft-lb)

Connection Size(in)

OD(in)

ID(in)

TensileYield(lb)

Torsional Yield(ft-lb)

Make-up Torque(ft-lb)

Approx Overall Length Pin/Box

Approx Overall Length

(ft)

TubeMechanical Properties

Tube Section Tool Joint

Drilco Hevi-Wate Drill Pipe Dimensions - Standard and Spiraled

Make-up

Appendix


Sperry-Sun / Brazil

Notes on drill pipe fatigue 1. Lubinski: grade E Se=20,000 at 2,000,000 cycles and S=53,000 at 10,000 cycles 2. S/N curves; N/N0=[S/S0]1/b

3. Eastman Teleco document: S=55,000 at 10,000 cycles and S=20,000 at 1,000,000 4. Maurer document S/N points Grade E Grade S cycles stresses (ksi) 75 135 1,000 53 80 10,000 33 45 100,000 21 30 1,000,000 19.5 21 10,000,000 18 20 100,000,000 Used Maurer points on S-N curve and solved for exponent b from Eq. 2 to approximate single equation curve for cycles between 100,000 and 1,000,000. 5. Practical Oilfield Metallurgy book page 96 grade S S=29,000 at 2,000,000 cycles grade E S=26,000 at 1,000,000 cycles 6. API RP7G: S-135, Sb=20,000 [1-St/145,000]; St = tensile stress 7. “Fatigue Testing of Drill Pipe”, G.Y.Grondin SPE 1994 from Lubinski Grade E ; LOG N=13.31 - 4.56 LOG(S/1000)

for corrosive fluids; LOG N=12.30 - 4.56 LOG(S/1000)


Sperry-Sun / Brazil

Appendix

10 10

σS

log N f6 8

e

Ferrous and Ti-based alloys

Non-ferrrous materials (e.g Al or Cu alloys) ( @ 10 cycles)

= fatigue limit or endurance limit ( @10 cycles)σe6

8σe

Schematic representation of S-N curves for ferrous and non ferrous materials.

Documents

Basic Drill String Design