mr 017600

StandardMaterial Requirements

Metallic Materials for Sucker-Rod Pumpsfor Corrosive Oilfield Environments

This NACE International standard represents a consensus of those individual members who havereviewed this document, its scope, and provisions. Its acceptance does not in any respect precludeanyone, whether he has adopted the standard or not, from manufacturing, marketing, purchasing, orusing products, processes, or procedures not in conformance with this standard. Nothing containedin this NACE International standard is to be construed as granting any right, by implication orotherwise, to manufacture, sell, or use in connection with any method, apparatus, or product coveredby Letters Patent, or as indemnifying or protecting anyone against liability for infringement of LettersPatent. This standard represents minimum requirements and should in no way be interpreted as arestriction on the use of better procedures or materials. Neither is this standard intended to apply inall cases relating to the subject. Unpredictable circumstances may negate the usefulness of thisstandard in specific instances. NACE International assumes no responsibility for the interpretation oruse of this standard by other parties and accepts responsibility for only those official NACEInternational interpretations issued by NACE International in accordance with its governingprocedures and policies which preclude the issuance of interpretations by individual volunteers

Users of this NACE International standard are responsible for reviewing appropriate health, safety,environmental, and regulatory documents and for determining their applicability in relation to thisstandard prior to its use. This NACE International standard may not necessarily address all potentialhealth and safety problems or environmental hazards associated with the use of materials,equipment, and/or operations detailed or referred to within this standard. Users of this NACEInternational standard are also responsible for establishing appropriate health, safety, andenvironmental protection practices, in consultation with appropriate regulatory authorities if necessary,to achieve compliance with any existing applicable regulatory requirements prior to the use of thisstandard.

CAUTIONARY NOTICE: NACE International standards are subject to periodic review, and may berevised or withdrawn at any time without prior notice. NACE International requires that action betaken to reaffirm, revise, or withdraw this standard no later than five years from the date of initialpublication. The user is cautioned to obtain the latest edition. Purchasers of NACE Internationalstandards may receive current information on all standards and other NACE International publicationsby contacting the NACE International Membership Services Department, P.O. Box 218340, Houston,Texas 77218-8340 (telephone +1 281/228-6200).

Reaffirmed 03-28-2000Approved January 1976Revised October 1994

NACE InternationalP.O. Box 218340

Houston, TX 77218-8340+1 218/228-6200

ISBN 1-57590-099-8© 2000, NACE International

NACE Standard MR0176-2000Item No. 21303

MR0176-2000

NACE International i

Foreword

This standard specifies metallic material requirements for the construction of sucker-rod pumps forservice in corrosive oilfield environments. API(1) Spec 11AX1 provides dimension requirements thatensure the interchangeability of component parts. However, that document does not provide materialspecifications or guidelines for the proper application of various API pumps. API RP 11AR2 does listthe general advantages and disadvantages of the various pump types and lists the acceptablematerials for barrels and plungers; and API RP 11BR3 supplements API Spec 11AX by providingcorrosion control methods using chemical treatment. This NACE standard should supplement the useof the aforementioned API publications.

This standard was originally published in 1976 and was revised in 1994 by NACE Task Group T-1F-15 on Sucker-Rod Pumps for Corrosive Environments, a component of Unit Committee T-1F onMetallurgy of Oilfield Equipment. It was reviewed by Task Group T-1F-28 and reaffirmed by T-1F in2000. This standard is issued by NACE International under the auspices of Group Committee T-1 onCorrosion Control in Petroleum Production.

In NACE standards, the terms shall, must, should, and may are used in accordance with the definitionsof these terms in the NACE Publications Style Manual, 3rd ed., Paragraph 8.4.1.8. Shall and must areused to state mandatory requirements. Should is used to state that which is considered good and isrecommended but is not absolutely mandatory. May is used to state that which is considered optional.

___________________________(1) American Petroleum Institute (API), 1220 L St. NW, Washington, DC 20005.

MR0176-2000

ii NACE International

NACE InternationalStandard

Material Requirements

Metallic Materials for Sucker-Rod Pumpsfor Corrosive Oilfield Environments

Contents

1. General ...................................................................................................................... 12. Description of Tables .................................................................................................. 13. Barrel Selection .......................................................................................................... 24. Pump Selection .......................................................................................................... 25. Maintenance Record System ...................................................................................... 3Table 1........................................................................................................................... 3Table 2........................................................................................................................... 4Table 3........................................................................................................................... 5Table 4........................................................................................................................... 6Table 5........................................................................................................................... 7Table 6......................................................................................................................... 10Table 7......................................................................................................................... 12Table 8......................................................................................................................... 12Table 9......................................................................................................................... 12Table 10....................................................................................................................... 13References................................................................................................................... 13Appendix A................................................................................................................... 13Appendix B................................................................................................................... 14Appendix C................................................................................................................... 15

MR0176-2000

Section 1: General

1.1 An adequate chemical treatment program utilizingselection of proper corrosion inhibitors and applicationtechniques is necessary for optimum performance of sucker-rod pumping equipment in a corrosive environment.However, control of direct attack on pump materials may beaccomplished by materials selection alone or by materialsselection in combination with chemical treatment.

1.2 The recommended materials in this standard arepresented in tables and listed in order of preferred usage insix different environments with varying degrees ofcorrosiveness and with and without possible abrasion. Thelisted materials have performed satisfactorily when used in

the specified environments. These material recommen-dations are based on field experience.

1.3 This standard is not intended to preclude thedevelopment and testing of new materials that might improvesucker-rod pump performance. It is the responsibility of theuser to fully evaluate the performance of any new materialprior to its use.

1.4 The designations and mechanical properties of thematerials covered by this standard are listed in selectedtables.

NACE International 1

Section 2: Description of Tables

2.1 The specific quantities of water, hydrogen sulfide (H2S),and carbon dioxide (CO2) that are used to classify thecorrosiveness of a fluid as mild, moderate, or severe aredetailed in Table 1.

2.1.1 Explanations of the mild, moderate, and severemetal-loss corrosion classifications given in Table 1 areintended to be a guide for the user. Currently, there isno clear consensus on which combination of producedfluids constitutes mild, moderate, or severe corrosiveenvironments for subsurface pumps. There can beamounts of H2S, CO2, and water that do not clearly fallinto one of the three combinations. The user’s operationexperiences coupled with analysis of failures should beused to develop the appropriate classification.

2.1.2 The three corrosion classifications are identifiedby amounts of water, H2S, and CO2 in the producedfluids. There are other constituents in the fluid that caninfluence corrosion. General comments on theseconstituents follow:

2.1.2.1 Oxygen—Oxygen can be very destructiveto the system. If oxygen is discovered, everyattempt should be made to free the system ofoxygen, or at least bring it to below 50 ppbdissolved oxygen. Severe corrosion can beexpected above 50 ppb dissolved oxygen.

2.1.2.2 Chlorides—High chlorides can lead topitting corrosion. High-chloride service conditionsshould be assumed to exist when the total dissolvedsolids exceed 10,000 mg/L and/or total chloridesexceed 6,000 mg/L.

2.1.2.3 H2S (Sour Service)—Sour serviceconditions should be assumed to exist when H2S ispresent in the system at partial pressures equal toor greater than 0.35 kPa (0.050 psi). Whenoperating in sour service, the material forsubsurface pump fittings (connectors, bushings,etc.) should conform to the requirements of NACEStandard MR0175.4

2.1.2.4 Water Content—Generally, if the watercontent is greater than 20%, the fluid exists as awater phase with oil droplets. If the water content isless than 20%, an oil phase with water droplets canexist. Inhibitors should be used if the water contentis greater than 20%.

2.1.2.5 Temperature—The higher the temperaturethe greater the rate of corrosion. Temperaturebelow the crystallization point of paraffin results indeposition of a film of paraffin that may act as acorrosion barrier.

2.1.2.6 pH—The pH at bottomhole conditions isfrequently lower (more acidic) than that measured atthe surface. After acidizing, the pH should bemonitored to ensure that the fluid does not attackchrome plate if chrome plate is used in the pump.

2.1.2.7 Pressure—Pressure does not have a directinfluence on the general corrosion rate. However,the system pressure influences the partial pressuresof H2S and CO2, which have an effect on thecorrosive nature of the fluids.

2.1.2.8 Velocity—Generally, the higher the velocityof produced fluids through the pump the greater themetal loss because of erosion-corrosion.

MR0176-2000

2.1.2.9 Abrasion—Abrasion results not only fromproduced fluids but also from corrosion by-products,e.g., iron sulfide. If the fluids contain greater than100 ppm solids, conditions are considered abrasive.

2.2 General definitions of mild, moderate, or severecorrosive environments follow:

2.2.1 Mild metal-loss corrosive environment: Corrosionattack on downhole equipment, rods, and tubing isevident but equipment may last several years (morethan three years) either with or without inhibitortreatment before corrosion-related failures occur.

2.2.2 Moderate metal-loss corrosive environment:Corrosion rates and time-to-failure are between mild andsevere.

2.2.3 Severe metal-loss corrosive environment:Corrosion rates are high and corrosion failures occur inless than one year unless effective inhibitor treatment isapplied.

2.3 Recommended materials for sucker-rod pumps to beused in mild, moderate, and severe metal-loss corrosiveenvironments are listed in Tables 2, 3, and 4, respectively.

The tables are each divided into two degrees of abrasion(i.e., “no abrasion” and “abrasion”) for each of the threecorrosive environments.

2.4 A determination of the correct environmentalclassification for the selection of the materials to be used in aparticular well should be made by an experienced corrosionor materials specialist.

2.5 The recommended pump barrels and compatibleplungers are the first items shown under each environment.A plunger can be used with more than one barrel but thiscould alter the preferred order of usage.

2.6 The tables showing barrel/plunger combinations alsoshow the recommended material selections for valves,cages, pull tubes, valve rods, and fittings.

2.7 Materials for all parts are listed in preferred order basedon optimum operating costs as determined by fieldexperience rather than expected pump life or initial cost. Insome instances, performance of these recommendedmaterials can be similar. The total costs of pump repairs andproper material selection are discussed in Appendix A,Economic Benefits.

Section 3: Barrel Selection

3.1 Mechanical properties of the various pump barrel basematerials and available surface-conditioning requirements ofbarrels are given in Table 5.

3.2 There is no significant difference in corrosionperformance between the D1 and D4 nonhardened steelbarrels.

3.3 Generally, the corrosion performance of the four differentcase-hardened barrels is comparable. Case-hardeningprocesses recommended for steel pump barrels to be used inH2S environments are discussed in Appendix B.

2 NACE International

Section 4: Pump Selection

4.1 Interrelated factors, other than the corrosive andabrasive natures of the produced fluids, that shall beconsidered when selecting materials for a sucker-rod pumpinclude:

4.1.1 Type of pump.

4.1.2 Barrel length and diameter.

4.1.3 Seating depth and required material strength.

4.2 For a given pump size and seating depth, the strengthrequirement for a barrel in a top holddown pump is greaterthan that for a barrel of a bottom holddown pump. This is theresult of a top holddown pump having a greater pressuredifferential across the barrel.

4.3 Standards concerning the most practical pump assemblyfor various operating conditions are unavailable; however,guidelines for selecting the most suitable pump for aparticular application are given in Appendix C.

4.4 Materials should be selected from Tables 2 through 10to meet the strength and hardness requirements dictated bythe type of pump and anticipated operating conditions.

4.5 Information shown in Tables 5 through 8 lists many ofthe materials by specific alloy number.

4.5.1 When selecting pumps, the purchaser should beaware that common names, e.g., brass, are often usedto describe alloys of significantly different compositionsand properties.

MR0176-2000

4.5.2 Specific alloys should be designated as shown inthe tables to prevent substitution of trade name materials

with different composition, which has resulted inrepetitive failures in the past.


Section 5: Maintenance Record System

5.1 A maintenance record system should be initiated toassist in reducing expenses related to sucker-rod pumpfailures. API 11BR details a sucker-rod pump repair/newpump log that can initiate a database for pump performanceand aid in establishing a maintenance record system thatshould include the following factors:

5.1.1 A cross-reference file that lists the well numberand pump number.

5.1.2 All of the pertinent information on the pump,including pump type and description and the completemetallurgy of the individual parts.

5.1.3 Pumping conditions.

5.1.4 Length of run.

5.1.5 Volume of fluid lifted during the run.

5.1.6 Cost, description, frequency, and type of repairs,including the type of material used in the manufacture ofthe replaced part or parts.

5.1.7 A method of determining the point at whichreplacement of the pump becomes more economicallydesirable than continued repair.

5.2 Effectiveness of the maintenance record system isdependent on cooperation from the pump repair facility. Astudy of repair records should identify the principal causes ofrepeated failures and also indicate the corrective measuresrequired to solve these problems.

5.3 Record keeping should be used for tracking pump partmaterials and comparing the cost of repetitive failures andthe cost of upgrading with more expensive materials andparts. However, because many factors other than corrosionand abrasion can cause pump failures, upgrading themetallurgy of the entire pump assembly is seldom required.

TABLE 1CLASSIFICATION OF METAL-LOSS CORROSION FOR SUCKER-ROD PUMPS (A)

Mild Metal-Loss Corrosion (B)

Water Water cuts are less than 25%H2S is less than 10 ppmCO2 is less than 250 ppm.

Moderate Metal-Loss Corrosion (B)

Water Water cuts are between 25% and 75%and/or H2S is between 10 and 100 ppmand/or CO2 is between 250 and 1,500 ppm.(C)

Severe Metal-Loss Corrosion (B)

Water Water cuts are more than 75%and/or H2S is greater than 100 ppmand/or CO2 is greater than 1,500 ppm.(C)

(A) The classification of metal-loss corrosion is intended only as a guide for the user of subsurface pumps (see Paragraph 2.1.1).(B) For all three classifications, the higher number of the three constituents should be the guide.(C) High concentrations of CO2 at low pressures are not corrosive, i.e., in shallow-depth wells less than 300 m (1,000 ft).

MR0176-2000


TABLE 2RECOMMENDED MATERIALS FOR MILD METAL-LOSS CORROSION ENVIRONMENTS

NO ABRASION ABRASION

BARREL PLUNGER BARREL PLUNGER

1. Nonhardened steel 1. Chrome plate on steel 1. Case hardened steel 1. Chrome plate on steel

2. Spray metal on steel 2. Chrome plate on steel

VALVES VALVES(C)

1. Ball: UNS(A)

S44002(B)

Seat: UNS S440041. Cobalt alloy 1. Spray metal on steel

2. Cobalt alloy 2. Cobalt alloy ball, sintered carbide seat

2. Cobalt alloy ball,sintered carbide seat

CAGES CAGES

1. Steel 1. Steel

PULL TUBE, VALVE ROD,AND FITTINGS

PULL TUBE, VALVE ROD,AND FITTINGS

1. Steel 1. Steel

(A) Metals and Alloys in the Unified Numbering System (latest revision), a joint publication of the American Society for Testing and Materials(ASTM) and the American Society of Automotive Engineers Inc. (SAE), Warrendale, PA.(B) Pits in the presence of chlorides.(C) The type of valve and cage is also dependent on how hard the well is being pumped, the amount of free gas, and the pressure differentialacross the valve.

MR0176-2000


TABLE 3RECOMMENDED MATERIALS FOR MODERATE METAL-LOSS CORROSION ENVIRONMENTS



1. Brass, nonhardened 1. Spray metal with nickel-copper alloy pin ends

1. Chrome plate on brass 1. Spray metal with nickel-copper alloy pin ends

2. Spray metal withelectroless nickel pin ends


3. Heavy chrome plate onsteel

2. Heavy chrome plate onsteel

Same plungers as above

2. UNS N04400(A) Same plungers as above 3. Chrome plate on steel Same plungers as above

VALVES(A) VALVES(A)

1. Cobalt alloy 1. Sintered carbides

2. Cobalt alloy

CAGES(A) CAGES(A)

1. Nickel-copper alloy 1. Nickel-copper alloy, insertor lined

2. Brass 2. Stainless steel, insert orlined

3. Stainless steel 3. Brass, insert

PULL TUBE, VALVE ROD,AND FITTINGS(B)


1. Steel 1. Steel

2. Stainless steel 2. Stainless steel

3. Brass 3. Brass

(A) The type of valve and cage is also dependent on how hard the well is being pumped, the amount of free gas, and the pressure differentialacross the valve.(B) See Table 8 for materials within each component.

MR0176-2000


TABLE 4RECOMMENDED MATERIALS FOR SEVERE METAL-LOSS CORROSION ENVIRONMENTS



1. Nickel-copper alloy 1. Spray metal with nickel-copper alloy pin ends

1. Chrome plate on nickel-copper alloy

1. Spray metal with nickel-copper alloy pin ends



2. Brass, nonhardened Same plungers as above 2. Chrome plated on brass Same plungers as above

3. Electroless nickel coatingon steel

Same plungers as above 3. Electroless nickel coatingon brass

Same plungers as above

VALVES(A) VALVES(A)

1. Cobalt alloy 1. Sintered carbides

CAGES(A) CAGES(A)

1. Nickel-copper alloy 1. Nickel-copper alloy, insertor lined

2. Brass 2. Stainless steel, insert orlined

3. Stainless steel 3. Brass, insert

PULL TUBE, VALVE ROD,AND FITTINGS(A)


1. Nickel-copper alloy 1. Nickel-copper alloy

2. Stainless steel 2. Stainless steel

3. Brass 3. Brass

(A) The type of valve and cage is also dependent on how hard the well is being pumped, the amount of free gas, and the pressure differentialacross the valve.(B) See Table 8 for materials within each component.

MR0176-2000


TABLE 5

TYPICAL MECHANICAL PROPERTIES OF PUMP BARREL MATERIALS

IdentificationSymbol

Product Description Surface Condition (A) Base CoreHardness

Base Material TypicalYield

Strength,MPa (1,000

psi)

PLATING

A1 Chrome plate on 0.08 mm (0.003 in.) Base material Low-carbon 410 (60)steel min. plate thickness. hardness 95 steel. Ex.:

Chrome plate hardness HRB to 23 HRC UNS67 to 71 HRC G10200

A2 Chrome plate on 0.08 mm (0.003 in.) Base material Inhibited 380 (55)brass min. plate thickness. hardness 83 admiralty

Chrome plate hardness HRB to 23 HRC brass UNS67 to 71 HRC C44300

A3 Chrome plate on 0.08 mm (0.003 in.) Base material Red brass 240 (35)red brass min. plate thickness. hardness 83 UNS

Chrome plate hardness HRB to 23 HRC C2300067 to 71 HRC

A4 Chrome plate on 0.08 mm (0.003 in.) Base material 5% 480 (70)5% chromium min. plate thickness. hardness 94 chromiumsteel Chrome plate hardness HRB to 23 HRC steel

67 to 71 HRC UNSS50100

A5 Chrome plate on 0.08 mm (0.003 in.) Base material Nickel- 380 (55)nickel-copper min. plate thickness. hardness 85 copper UNSalloy Chrome plate hardness HRB to 20 HRC N04400

67 to 71 HRC

A6 Chrome plate on 0.08 mm (0.003 in.) Base material Low-alloy 550 (80)low-alloy steel min. plate thickness. hardness 82 steel. Ex.:


A7 Heavy chrome 0.15 mm (0.0060 in.) Base material Low-carbon 410 (60)on steel min. plate thickness. hardness 95 steel. Ex.:


A8 Electroless nickel 0.033 mm (0.0013 in.) Base material Low-carbon 410 (60)coating on steel min. plate thickness. hardness 95 steel. Ex.:

Plate hardness 45 to HRB to 23 HRC UNS70 HRC G10200

A9 Electroless nickel 0.033 mm (0.0013 in.) Base material Low-alloy 550 (80)coating on low- min. plate thickness. hardness 83 steel. Ex.:alloy steel Plate hardness 45 to HRB to 23 HRC UNS

70 HRC G41300

MR0176-2000





Strength,MPa (1,000

psi)

A10 Electroless nickelcoating on brass

0.033 mm (0.0013 in.) min.plate thickness. Platehardness 45 to 70 HRC

Base materialhardness 83 HRB to23 HRC

Inhibitedadmiralty brassUNS C44300

280 (40)

CASE HARDENING

B1 Carbonitrided 0.25 mm (0.010 in.) min.carburized case with 45HRC min. hardness 0.25mm (0.010 in.) from thesurface. Surface hardnessto be 58 HRC min., 63 HRCmax.

95 HRB to 23 HRC Low-carbonsteel. Ex.: UNSG10200

450 (65)

B2 Carburized 0.25 mm (0.010 in.) min.carburized case with 45HRC min. hardness 0.25mm (0.010 in.) from thesurface. Surface hardnessto be 58 HRC min., 63 HRCmax.

95 HRB to 23 HRC Low-carbonsteel. Ex.: UNSG10200

450 (65)

B3 Carbonitrided 5%chromium steel

0.25 mm (0.010 in.) min.carburized case with 45HRC min. hardness 0.25mm (0.010 in.) from thesurface. Surface hardnessto be 58 HRC min., 63 HRCmax.

98 HRB to 27 HRC(C) 5% chromiumsteel. UNSS50100

480 (70)

B4 Nitrided 4130 0.13 mm (0.0050 in.) min.nitrided case with 45 HRCmin. hardness 0.13 mm(0.0050 in.). Surfacehardness to be 58 HRCmin., 63 HRC max.

82 HRB to 23 HRC UNS G41300 550 (80)

NONHARDENED

D1 Nonhardened steel Surface is treated with anonmetallic-type phosphatecoating or other equallyeffective antigallingtreatment.


Low-carbonsteel. Ex.: UNSG10200

410 (60)

D2 Nonhardened brass Surface is oiled. Base materialhardness 83 HRB to23 HRC

Inhibited ad-miralty brassUNS C44300

280 (40)

D3 Nickel-copper alloy Surface is oiled. Base materialhardness 85 HRB to20 HRC

Nickel-copperalloy UNSN04400

380 (55)

MR0176-2000





Strength,MPa (1,000

psi)

D4 Nonhardened steel Surface is treated with anonmetallic-type phosphatecoating or other equallyeffective antigallingtreatment


Low-alloy steel.Ex.: UNSG41300

550 (80)

(A) Hardness readings are converted from Rockwell superficial hardness readings.(B) Regarding the thread base material condition, the hardness is the same as the core hardness.(C) 98 HRB to 29 HRC thread base material condition.

MR0176-2000


TABLE 6

TYPICAL MECHANICAL PROPERTIES OF PLUNGER MATERIALS


ProductDescription

Surface Condition Thread BaseMaterialHardness (C)

Base Material Typical YieldStrength, MPa(1,000 psi)

A1 Chrome plate 0.15 mm (0.0060 in.) min.plate thickness. Chromeplate hardness 67 to 71HRC(A)

Hardness 95HRB to 23 HRC

Carbon steel. Ex.UNS G10200

410 (60)

A2 Chrome plate 0.30 mm (0.012 in.) min.plate thickness. Chromeplate hardness 67 to 71HRC(A)

Hardness 95 HRBto 23 HRC

Carbon steel. Ex.:UNS G10250/G10350/G10450

410 (60)

SPRAY METAL

B1 Spray metal(B) 0.25 mm (0.010 in.) min.

coating thickness.Hardness 78.5 HRA (55HRC) min.


Carbon steel. Ex.:UNS G10260

410 (60)


coating thickness.Hardness 78.5 HRA (55HRC min.



410 (60)

B3 Spray metal(B) with

nickel-copper alloypin ends

0.25 mm (0.010 in.) min.coating thickness.Hardness 78.5 HRA (55HRC) min.

Nickel-copper alloypin ends. Hardness84 HRB to 23 HRC

Carbon steel. Ex.:UNS G10260/G10450

410 (60)


electroless nickelpin ends


Electroless nickelcoating 0.033 mm(0.0013 in.) on thepin ends. Basematerial hardness85 HRB to 23 HRC


410 (60)


electroless nickelpin ends




480 (70)



Hardness 82 to 23HRC

Low-alloy steel. Ex.:UNS G41300

550 (80)

MR0176-2000



ProductDescription

Surface Condition Thread BaseMaterialHardness (C)

Base Material Typical YieldStrength, MPa(1,000 psi)




Low-alloy steel. Ex.:UNS G41300

550 (80)

NONHARDENED

C1 Nonhardened Surface is not hardenedor plated.


Carbon steel. 23HRC. Ex.: UNSG10260/G10350/G10450

410 (60)

(A) Converted from Knoop or Vickers microhardness.(B) See Table 6.1 for typical chemical composition of spray metal.(C) Critical strength component or plunger.

TABLE 6.1TYPICAL CHEMICAL COMPOSITION OF SPRAY METAL

wt% wt% Minimum Maximum

Carbon 0.50 1.00Silicon 3.50 5.50

Phosphorus ------- 0.02Sulfur ------- 0.02

Chromium 12.00 18.00Boron 2.50 4.50Iron 3.00 5.50

Cobalt ------- 0.10Titanium ------- 0.05

Aluminum ------- 0.05Zirconium ------- 0.05

Nickel Remainder

MR0176-2000


TABLE 7TYPICAL MATERIALS FOR CAGES

Steel Carbon Steels UNS G10200 through G10450Low-Alloy Steels UNS G41300 through G41450UNS G86200 through G86450

Nickel-Copper Alloy UNS N04400

Brass UNS C46400

Stainless Steel UNS S30400, UNS S31600

TABLE 8TYPICAL MATERIALS FOR PULL TUBE, VALVE ROD, AND FITTINGS

Pull Tube Steels UNS G10200 through G10450Stainless Steels—UNS S30400, UNS S31600Brass UNS C46400Nickel-Copper Alloy UNS N04400

Valve Rod Steels G10200 through G10450Stainless Steels—UNS S30400, UNS S31600Nickel-Copper Alloy UNS N04400

Fittings SteelCarbon Steels UNS G10200 through G10450Low-Alloy Steels UNS G41300 through G41450Stainless Steel—UNS S30400, UNS S31600Nickel-Copper Alloy UNS N04400

TABLE 9TYPICAL COMPOSITION AND HARDNESS OF CAST COBALT ALLOYS USED FOR VALVE PARTS

wt% wt%Ball Seat

Cobalt 45.2 57.9Chromium 32.0 24.5Tungsten 18.0 12.0Carbon 2.3 2.1Other 2.5 3.5

HRC 58-63 51-55

MR0176-2000

TABLE 10TYPICAL COMPOSITION AND HARDNESS OF SINTERED CARBIDES USED FOR VALVE PARTS

wt% wt%Balls and Seats Balls

Tungsten Carbide 87 Titanium Carbide(A) 60Cobalt 13 Nickel/Cobalt 14

Trace Elements 1

HRA 88 HRA 90

(A) The lighter-weight titanium carbide ball reduces the impact of the ball in the valve. Titanium carbide is used in heavy pumping wells or gassywells to reduce the effects of impact.

References

1. API Spec 11AX (latest revision), “Specification forSubsurface Sucker Rod Pumps and Fittings” (Washington,DC: API).

2. API RP 11AR (latest revision), “Recommended Practicefor Care and Use of Subsurface Pumps” (Washington, DC:API).

3. API RP 11BR (latest revision), “Recommended Practicefor Care and Handling of Sucker Rods” (Washington, DC:API).

4. NACE Standard MR0175 (latest revision), “SulfideStress Cracking Resistant Metallic Materials for OilfieldEquipment” (Houston, TX: NACE International).

5. “A Data-Gathering System to Optimize ProductionOperations: A 14-Year Overview,” Journal of PetroleumTechnology 39, 4 (1987): pp. 457-462.

6. D.S. Clark, W.R. Varney, Physical Metallurgy forEngineers, 2nd ed. (Princeton, NJ: Van Nostrand, 1962).

7. “Heat Treatment of Steels,” Republic Alloy SteelsHandbook, Republic Steel Corporation, Cleveland, OH, 1961.

8. T. Baumeister, Mark’s Standard Handbook forMechanical Engineers (latest edition) (New York, NY:McGraw-Hill).

9. J. Zaba, Modern Oil-Well Pumping (Tulsa, OK:Petroleum Publishing Co., 1962).

10. T.C. Frick, ed., Petroleum Production Handbook (NewYork, NY: McGraw-Hill, 1962).

11. B.R. Bruton, “Selection of Metallic Materials forSubsurface Pumps for Various Corrosive Environments,”presented at University of Oklahoma Short Course,September 14-16, 1970.

12. “Subsurface Pumps—Selection and Application,” UnitedStates Steel Corporation (Oilwell Supply Division), Pittsburgh,PA, 1967.


Appendix AEconomic Benefits

The selection of the proper materials for use in subsurfacepumps is paramount in establishing low costs per barrel offluid lifted. The differential cost of selecting a premiummaterial over a common material can be relativelyinsignificant when the total costs for a single pump failure areevaluated. The total costs for repairing a subsurface pumpinclude:

Pump Pulling Cost- Rig Travel Cost- Rig Operating Cost- Rig Waiting Cost

Pump Repair CostAdministrative Cost (Direct Overhead Cost)Electrical Cost Resulting from DecreasedVolumetric EfficiencyRod and Tubular Replacement CostLost Production Cost

MR0176-2000

The pump pulling, pump repair, electrical, and lostproduction costs are self-explanatory. Administrative costsare direct overhead costs that can be attributed directly to thefailure. For example, for each failure there is generally averification, data bank entry, establishment of failure cause,and development of a solution to prevent further failure.

Rod and tubular replacement costs are those costsassociated with rods and tubing that are damaged becauseof the failure. The more frequently rods and tubing arehandled or the connections broken and remade, the moreopportunity there is for error and subsequent failures.

One company reported an average pump repair cost of

$720.5 The average well-pulling cost, to pull the pump and

run it or another pump back in the well, was $1,620. Theaverage pump repair was 31% of the total of the pump repaircost and the well-pulling cost. It is difficult, however, toassign a dollar value to the other costs because these varyfrom well to well. From a conservative standpoint, thepercentage of total costs contributed by pump pulling andrepair can easily drop to 20% of the total repair cost.

The key to low cost per barrel of fluid lifted is generallyassociated with long pump life and keeping the pump in thewell. Proper material selection, along with pump design, is akey factor in achieving this goal.


Appendix BCase-Hardening Processes for Steel Pump Barrels for a Corrosive Environment

GENERALPump barrels intended for service in an abrasive,

corrosive environment must have a wear-resistant surfaceand body strength capable of resisting sulfide stress cracking(SSC). This combination can be achieved in steel barrels byeither plating or case hardening the wear surface.

The inner diameter (ID) surfaces of steel pump barrelsare commonly hardened by five case-hardening processesused individually or in combination: flame hardening,induction hardening, carburizing, carbonitriding, and nitriding.Although low-carbon steels can be properly cased byinduction hardening, the carburizing, carbonitriding, andnitriding processes are preferred for service in an H2Senvironment. Barrels through-hardened by flame hardeningor induction hardening are not recommended for H2Senvironments because of their susceptibility to SSC. Steelbarrels that have been cold worked are not recommendedbecause of residual stresses.

The surface hardness, obtained by carburizing andcarbonitriding, depends on heat treatment after thecomposition of the case has been altered. Nitriding alters thecomposition of the case in such a way that hard compoundsare formed without further heat treating.

A brief description of each of the three preferred case-hardening processes follows. 6,7,8,12

CARBURIZINGIn this process, the carbon content of the surface of a

low-carbon steel (0.15 to 0.25% carbon) is increased. Thereare two carburizing processes used to case harden pumpbarrels. The characteristics of the case produced by bothmethods are somewhat similar. Hardness values as high asHRC 62 can be obtained with both methods.

1. In gas carburizing, carbon is absorbed into thebarrel surface by heating in an atmosphere of methane.Carbon is dissolved and subsequently precipitated asiron carbide.

2. Liquid carburizing utilizes a fused bath of sodiumcyanide and alkaline earth salt. The salt reacts with the

cyanide to form a cyanide of the alkaline earth metal thatthen reacts with iron to form iron carbide. A smallamount of nitrogen is liberated and absorbed. Nitrogenincreases the hardenability of steel and increases thesolubility of carbon. Barrels treated by this process arehardened on both the outer diameter (OD) and ID.

The final characteristics of a carburized barrel dependon the heat treatments in general use. One method is adirect quench from the carburizing temperature into a suitablequenching medium. A second treatment is to cool slowlyfrom the carburizing temperature, reheat to above the criticaltemperature of the case, and quench.

CARBONITRIDINGThis is a modification of the gas carburizing process. A

low-carbon steel is normally used. Anhydrous ammonia isadded to the furnace atmosphere so that both carbon andnitrogen are absorbed by the steel surface. Carbonitriding isconducted at lower temperatures than gas carburizing toincrease the absorption of nitrogen. Nitrogen increases thehardenability of steel and the solubility of carbon. At highertemperatures, the process approaches gas carburizing with aminimum transfer of nitrogen. The final properties aredependent primarily on the rate of cooling following thecarbonitriding process. The increased hardenability madepossible by the alloying effect of nitrogen permits the oilquenching of carbonitrided low-carbon steels. Otherwise,this process requires drastic water quenching to developeffective hardening. Hardness values as high as HRC 62can be obtained by carbonitriding.

NITRIDINGWhen using this process, the surface hardness of certain

alloy steels may be increased by heating, in contact withammonia, without the necessity of quenching. The processinvolves the formation of hard, wear-resistant nitrogencompounds on the surface of the steel by absorption ofnascent nitrogen.

Most of the steels that are commonly used for nitridingcontain combinations of aluminum, chromium, molybdenum,

MR0176-2000

vanadium, and in some instances, nickel. Steels in the UNSS40000 series also respond well to nitriding but do notdevelop as hard a surface. Hardenable stainless steels may

also be nitrided but their corrosion resistance is greatlyreduced by nitriding.


Appendix CSelection of Optimum-Type Pump

In selecting materials for a sucker-rod pump, the pump type,size, seating depth, and required material strength must beconsidered. There are several methods for determining thesize of pump required.9,10 Differing opinions concerning theproper application of various API pumps exist. However,there are some generally accepted recommendations thatare outlined below as a guide.9,10,11,12

TUBING PUMPThis pump is suitable for severe service. It is adaptable

for producing viscous fluids because of the large flow areas.A tubing pump has fewer working parts and is often lower incost than a rod pump of corresponding size. However, thesesavings can be offset by repair costs because the tubingmust be pulled to repair the barrel of a tubing pump. Tubingpumps are generally used when it is necessary to lift largevolumes of fluid and a pump of high displacement is required.The greater volume can result in a heavier fluid load on thesucker-rod string. A portion of the capacity advantage maybe lost in excessive rod and tubing stretch.

INSERT PUMPSStationary Barrel with Top Holddown . A top

holddown pump is designed for low-fluid-level wells becausethe standing valve can be submerged in the well fluids. Thispump is also capable of handling low-gravity crudes and isideally suited for fluids carrying sand. The top holddownprovides a seal just below the point where fluid is dischargedto the tubing; sand cannot settle around the barrel and causethe pump to stick in the tubing. Intermittent pumping mayallow sedimentation between the plunger and barrel; this canbe prevented by sealing off the pump body at the top with asand-check guide and drop. The barrel in this type of pumpis subject to tensile stresses that can lead to prematurefailure in a sulfide environment. This pump is not suitable fordeep pumping because of the pressure differential across thewall of the barrel. The inside of the barrel is exposed topressure of the full column of fluid and the outside only to thepressure of submergence. The resulting breathing of thebarrel during the pumping cycle tends to increase theclearance between the plunger and the barrel, therebyincreasing the slippage of fluid past the plunger. In extremecases, the barrel can burst.

Stationary Barrel with Bottom Holddown . This isbetter suited for deep-well pumping because both sides ofthe barrel are exposed to the pressure of the column of fluid.However, a long pump should not be used because it is notanchored at the top, and the action of the sucker-rod stringtends to weave it back and forth, which may cause premature

failure. This pump is not suited for handling fluid containingsand, because sand tends to settle between the barrel andthe tubing, causing the pump to stick. The outside of thebarrel tube of this type of pump is susceptible to corrosionbecause it is surrounded by stagnant fluid. To prevent this, apartial bottom discharge can be utilized to forceapproximately 25% of the pumped fluid through the pump-tubing annulus. Methods that permit sealing the top of thepump are available. This prevents settlement of sand in thepump-tubing annulus and corrosion of the barrel. Thisrepresents the ideal technique for deep wells producing sandwith the well fluids and it is also acceptable when a longpump is needed for a deep well.

Traveling Barrel Pump . The bottom-seated travelingbarrel pump is well suited for handling fluid with sandbecause the turbulence caused by the action of the barrelprevents the sand from settling. Also, the construction of thistype of pump is such that sand cannot settle into the pumpbarrel when the pump is shut down, because the largetraveling valve acts as a built-in sand check valve. However,in intermittent pumping, it is possible for sand to settle belowthe barrel, between the barrel and the holddown, and preventfull travel of the barrel on the downstroke. This type of pumpcan be used to pump deep wells because both sides of thebarrel are exposed to the full fluid column pressure.However, long traveling barrel pumps are seldom used topump deep wells because the compressive load on thestanding valve tends to buckle the pull tube. This pump isnot suited for pumping large volumes of heavy, viscous oil.Because of the long fluid passage, the smaller standingvalve, and the comparatively smaller compression ratio, thispump is not suited for pumping wells that tend to gas lock.

Special Pumps. In addition to the standard API pumps,specialty sucker-rod pumps have been designed to handleunusual downhole conditions. These include such pumps ascasing pumps, double-displacement pumps, three-tubepumps, and pumps having two compression chambers.Detailed discussion of these pumps is beyond the scope ofthis standard.

mr 017600

Documents