Exhibit 21.1
 SUBSIDIARIES OF THE REGISTRANT
 State or Country ofName
    
    IncorporationAckerman International Holland B.V.
    
    NetherlandsAdvanced Wirecloth, Inc.
    
    LouisianaAG Holding UK Unlimited
    
    United KingdomAmclyde UK Limited
    
    United KingdomAndergauge Limited
    
    United KingdomAndergauge Redback, LLC
    
    TexasAndergauge USA, Inc.
    
    TexasAnderson Group Limited
    
    United KingdomBlack Max Argentina S.A.
    
    ArgentinaBowen Downhole LLC
    
    DelawareBowen Downhole, Inc.
    
    DelawareBrandt Energy Environmental, L.P.
    
    TexasBrandt Interests, Inc.
    
    DelawareBrandt Norge
    
    NorwayBrandt Oilfield Services (M) Sdn. Bhd.
    
    MalaysiaBrandt Servicios Petroleros S.A.
    
    PeruC.M.A. Canavera S.r.l.
    
    ItalyCamco Drilling Group Limited
    
    United KingdomChurch Oil Tools, Inc.
    
    TexasCJSC Novmash
    
    BelarusCoil Services (North Sea) Limited
    
    United KingdomCoil Services ME LLC
    
    United Arab EmiratesCorlac Equipment Corp
    
    BarbadosCTES Limited
    
    United KingdomDiamond Products Interantional Venezolana, C.A.
    
    VenezuelaDreco DHT, Inc.
    
    DelawareDreco Eastern Europe Ltd.
    
    AlbertaDreco Energy Services Ltd.
    
    AlbertaDreco Europe Limited
    
    United KingdomDreco International Finance (Barbados) Ltd.
    
    BarbadosDreco International Holdings Ltd.
    
    AlbertaDreco Limited
    
    United KingdomDreco LLC
    
    DelawareElmar Far East Pty Ltd
    
    AustraliaElmar Services (Middle East) Limited
    
    United KingdomElmar Services Pty Ltd
    
    AustraliaEnerpro de Mexico, S.A. de C.V.
    
    MexicoEnvironmental Procedures Inc.
    
    DelawareFiber Glass System (Suzhou) Co. Ltd.
    
    ChinaFiber Glass Systems (Harbin) Co., Ltd.
    
    ChinaFiber Glass Systems Holdings, LLC
    
    DelawareFiber Glass Systems, L.P.
    
    TexasGP USA Holding, LLC
    
    DelawareGPEX, L.P.
    
    TexasGrant Prdieco (Singapore) Pte Ltd
    
    SingaporeGrant Prideco (Jiangsu) Drilling Products Co., Ltd
    
    ChinaGrant Prideco AB TCA Holding LLC
    
    DelawareGrant Prideco Asia (Singapore) Pte Ltd
    
    SingaporeGrant Prideco Canada Ltd.
    
    AlbertaGrant Prideco de Venezulea, S.A.
    
    VenezuelaGrant Prideco Equipmentos para Petrolea Ltda.
    
    BrazilGrant Prideco European Holding, LLC
    
    Delaware




---



##### 



State or Country ofName
    
    IncorporationGrant Prideco Finance, LLC
    
    DelawareGrant Prideco Holding, LLC
    
    DelawareGrant Prideco III C V
    
    NetherlandsGrant Prideco Jersey Limited
    
    Jersey Island and DelawareGrant Prideco Limited
    
    United KingdomGrant Prideco Mauritius Limited
    
    MauritiusGrant Prideco Netherlands B.V.
    
    NetherlandsGrant Prideco PC Composites Holdings, LLC
    
    DelawareGrant Prideco Tube-Alloy Holding LLC
    
    DelawareGrant Prideco USA, LLC
    
    DelawareGrant Prideco, Inc.
    
    DelawareGrant Prideco, L.P.
    
    DelawareGrant Prideco, S.A. de C.V.
    
    MexicoGriffith Downhole Products GmbH
    
    GermanyHarbin Star Fiberglass Ltd.
    
    ChinaHebei Huayouyiji Tuboscope Coating Co., Ltd.
    
    ChinaHITEC AS
    
    NorwayHydra-Rig, Inc.
    
    DelawareHydralift Amclyde, Inc.
    
    DelawareHydralift AS
    
    NorwayHydralift BLM SA
    
    FranceHydralift France SAS
    
    FranceHydralift Holding UK Ltd.
    
    United KingdomInmobiliaria Industrial de Veracruz, S.A. de C.V.
    
    MexicoInspecciones y Pruebas No Destructivs, S.A. de C.V.
    
    MexicoIntellipipe, Inc.
    
    DelawareIntelliserv International Holding, Ltd
    
    Cayman IslandsIntelliServ Norway AS
    
    NorwayIntelliserv, Inc.
    
    DelawareIstok Business Services LLC
    
    Russian FederationJiangsu Grant Prideco Oil and Gas Equipment Co., Ltd.
    
    ChinaJiangyin Tuboscope Tubular Development Co., Ltd
    
    ChinaJV FIDMASH
    
    BelarusLanzhou LS-National Oilwell Petroleum Engineering Co. Ltd.
    
    ChinaLLTT, Ltd.
    
    Trinidad And TobagoLSI Asia Pacific Pte. Ltd.
    
    SingaporeMid-South Machine, Inc.
    
    LouisianaMono Group
    
    United KingdomMono Group Pension Trustees Limited
    
    United KingdomMono Pumps (Australia) Proprietary Limited
    
    AustraliaMono Pumps Ltd.
    
    United KingdomMono Pumps New Zealand Limited
    
    New ZealandMonoflo NOV S.A.I.C.
    
    ArgentinaNational Oilwell Algerie
    
    AlgeriaNational Oilwell de Mexico S.A. de C.V.
    
    MexicoNational Oilwell de Venezuela, C.A.
    
    VenezuelaNational Oilwell DHT, LP
    
    DelawareNational Oilwell Middle East Company
    
    Nova ScotiaNational Oilwell Norway AS
    
    NorwayNational Oilwell Nova Scotia Company
    
    Nova ScotiaNational Oilwell Ontario, LLC
    
    DelawareNational Oilwell Poland S.p.z.o.o.
    
    PolandNational Oilwell Services de Mexico, S.A. de C.V.
    
    MexicoNational Oilwell Sogne AS
    
    Norway




---



##### 



State or Country ofName
    
    IncorporationNational Oilwell Varco (Thailand) Ltd.
    
    ThailandNational Oilwell Varco do Brasil LTDA
    
    BrazilNational Oilwell Varco Hjelset AS
    
    NorwayNational
Oilwell Varco Petroleum Equipment (Shanghai) Co., Ltd.
    
    ChinaNational Oilwell Varco Pte Ltd.
    
    SingaporeNational
Oilwell Varco Rig Equipment Trading (Shanghai) Co., Ltd.
    
    ChinaNational Oilwell Varco Solutions S.A. de C.V.
    
    MexicoNational Oilwell Varco UK Limited
    
    United KingdomNational Oilwell Varco, Inc.
    
    DelawareNational Oilwell Varco, L.P.
    
    DelawareNational Oilwell-Netherlands B.V.
    
    NetherlandsNational-Oilwell Canada Ltd.
    
    AlbertaNational-Oilwell Pte. Ltd.
    
    SingaporeNational-Oilwell Pty. Ltd.
    
    AustraliaNatoil LLC
    
    DelawareNatoil, Inc.
    
    DelawareNBJ Manufacturas Petroleras (Bolivia) S.A.
    
    BoliviaNOV (Caymans), Ltd.
    
    Cayman IslandsNOV (Malaysia) Sdn. Bhd.
    
    MalaysiaNOV Brandt Europe France
    
    FranceNOV Brandt Oilfield Services Middle East LLC
    
    United Arab EmiratesNOV de Argentina S.A.
    
    ArgentinaNOV DH de Mexico S.A. de C.V.
    
    MexicoNOV Expatriate Services, Inc.
    
    DelawareNOV India Private Limited
    
    IndiaNOV Rigstore, Inc.
    
    DelawareNOV Sara India Private Limited
    
    IndiaNOV Services Ltd.
    
    Cayman IslandsNOV Tuboscope Middle East LLC
    
    United Arab EmiratesNOV UK Finance Limited
    
    United KingdomNOV-Fabtech FZCO
    
    United Arab EmiratesNOW (Asia), Inc.
    
    MauritiusNOW (Barbados) SRL
    
    BarbadosNOW Canada, L.P.
    
    AlbertaNOW Downhole Tools, Inc.
    
    DelawareNOW International Nova Scotia Company
    
    Nova ScotiaNOW International, Inc.
    
    DelawareNOW Nova Scotia Holdings, Inc.
    
    DelawareNOW Oilfield Services, Inc.
    
    DelawareNQL (Illinois) Inc.
    
    IllinoisNQL (US) Inc.
    
    DelawareNQL Energy Services (Barbados) Ltd.
    
    BarbadosNQL Energy Services US, Inc.
    
    TexasNQL Finance, L.L.C.
    
    DelawareNQL Holland B.V.
    
    NetherlandsP&T Servicios Petroleros, C.A.
    
    VenezuelaPesaka Inspection Services SDN.BHD.
    
    MalaysiaPrescott Drilling Motors, Inc.
    
    LouisianaPretempca Servicios de Mexico, S.A. de C.V.
    
    MexicoPridecomex Holding, S.A. de C.V.
    
    MexicoProcon Engineering Ltd.
    
    United KingdomPT H-Tech Oilfield Equipment
    
    IndonesiaPT National Oilwell Varco
    
    IndonesiaReed Hycalog International Limited
    
    United Kingdom




---



##### 



State or Country ofName
    
    IncorporationReed-Hycalog de Mexico, S de R.L. de C.V.
    
    MexicoReed-Hycalog Investment Pte. Ltd.
    
    SingaporeReed-Hycalog Services de Mexico S. de R.L. de C.V.
    
    MexicoReed-Hycalog Singapore Partnership
    
    SingaporeReed-Hycalog UK Holdings, LLP
    
    United KingdomReedHycalog Angola, LLC
    
    DelawareReedHycalog Argentina, LLC
    
    DelawareReedHycalog Azerbaijan, LLC
    
    DelawareReedHycalog Cameroon, LLC
    
    DelawareReedHycalog CIS, LLC
    
    DelawareReedHycalog Colombia, LLC
    
    DelawareReedHycalog Congo, LLC
    
    DelawareReedHycalog Coring Services International, Inc.
    
    DelawareReedHycalog Del Ecuador S.A.
    
    EcuadorReedHycalog Eurasia Ltd
    
    United KingdomReedHycalog Europe B.V.
    
    NetherlandsReedHycalog Gabon, LLC
    
    DelawareReedHycalog International Holding, LLC
    
    DelawareReedHycalog Italia S.R.L.
    
    ItalyReedHycalog Kazakhstan, LLC
    
    DelawareReedHycalog Norway, LLC
    
    DelawareReedHycalog Oilfield Services, LLC
    
    Russian FederationReedHycalog Pty Ltd
    
    AustraliaReedHycalog Romania, LLC
    
    DelawareReedHycalog Thailand, LLC
    
    DelawareReedHycalog UK Ltd
    
    IrelandReedHycalog, L.P.
    
    DelawareReedHycalog, LLC
    
    DelawareSakhalin Outfitters LLC
    
    Russian FederationSampwell Testing Services Ltd.
    
    AlbertaScreen Manufacturing Co. Ltd.
    
    Trinidad And TobagoServicios Tubulares TT, S.A. de C.V.
    
    MexicoServizi Ispettivi s.r.l.
    
    ItalyShaffer India Private Limited
    
    IndiaSmart Screen Systems, Inc.
    
    MinnesotaSoil Recovery A/S
    
    DenmarkSTAR Sudamtex Tubulares S.A. (Joint Venture)
    
    VenezuelaSTS Products Inc.
    
    DelawareTA Industries, Inc.
    
    DelawareTAI Holding, Inc.
    
    DelawareTexas Oil Tools, Inc.
    
    NevadaThe Brandt Company de Argentina S.A.
    
    ArgentinaTianjin Grant Prideco TPCO Oilfield Products Co., Ltd.
    
    ChinaTianjin Grant TPCO Drilling Tools Company Limited
    
    ChinaTS&M Supply
    
    AlbertaTS&M Supply  Ontario
    
    OntarioTS&M Technical Sales & Maintenance Company
    
    Nova ScotiaTube-Alloy Capital Corporation
    
    TexasTube-Kote, Inc.
    
    TexasTubo-FGS, L.L.C.
    
    DelawareTuboscope & Co. LLC
    
    OmanTuboscope (Holding U.S.) Inc.
    
    DelawareTuboscope Brandt de Colombia
    
    ColombiaTuboscope Brandt de Venezuela S.A.
    
    Venezuela




---



##### 



State or Country ofName
    
    IncorporationTuboscope Holdings Limited
    
    United KingdomTuboscope Norge AS
    
    NorwayTuboscope Pipeline Services Inc.
    
    TexasTuboscope Pipeline Services Limited
    
    United KingdomTuboscope Services, L.L.C.
    
    DelawareTuboscope Servicios de Bolivia S.A.
    
    BoliviaTuboscope Vetco (Deutschland) GmbH
    
    GermanyTuboscope Vetco (France) S.A.
    
    FranceTuboscope Vetco (Osterreich) GmbH
    
    AustriaTuboscope Vetco Canada Inc.
    
    AlbertaTuboscope Vetco Capital Limited
    
    United KingdomTuboscope Vetco de Argentina S.A.
    
    ArgentinaTuboscope Vetco Mexico, S.A. de C.V.
    
    MexicoTuboscope Vetco Moscow
    
    Russian FederationTuboscope Vetco Nigeria Limited
    
    NigeriaTulsa Equipment Manufacturing Company
    
    OklahomaTVI Holdings, L.L.C.
    
    DelawareV.O.F. National Oilwell Varco
    
    NetherlandsVarco Al Mansoori Services Company LLC
    
    United Arab EmiratesVarco BJ BV
    
    NetherlandsVarco BJ FSC Inc
    
    BarbadosVarco Canada Limited
    
    AlbertaVarco CIS
    
    Russian FederationVarco do Brasil Ltda.
    
    BrazilVarco Drilling Equipment do Brasil Ltda.
    
    BrazilVarco I/P, Inc.
    
    DelawareVarco International de Venezuela, C.A.
    
    VenezuelaVarco International do Brasil Equipamentos e Servicos Ltda.
    
    BrazilVarco Sara (India) Private Limited
    
    IndiaVarco U.S. Holdings, Inc.
    
    DelawareVarco UK Acquisitions Limited
    
    United KingdomVarco US Finance, Inc.
    
    DelawareVarco, L.P.
    
    DelawareVCR Panama Inc.
    
    PanamaVector Oil Tool Ltd.
    
    AlbertaVenwell International Inc. (Trinidad Branch)
    
    TexasVetco Coating GmbH
    
    GermanyVetco Enterprise AG
    
    SwitzerlandVetco Pipeline Services Ltd.
    
    AlbertaVetco Pipeline Services, Inc.
    
    TexasVetco Saudi Arabia Ltd.
    
    Saudi ArabiaVetco Services Sendirian Berhad
    
    Brunei DarussalamVetco Technology GmbH
    
    GermanyVoest Alpine Middle East Free Zone Establishment
    
    AustriaVoest Alpine Tubulars Gmbh
    
    AustriaVoest Alpine Tubulars GmbH & Co KG
    
    AustriaWelch Power Source, L.L.C.
    
    LouisianaWoolley, Inc.
    
    TexasXL Systems Antilles, N.V.
    
    NetherlandsXL Systems Europe B.V.
    
    NetherlandsXL Systems International, Inc.
    
    DelawareXL Systems, L.P.
    
    TexasXST Holdings, Inc.
    
    Texas