API Related, Oilfield Pressure Control Equipment, Terms and Definitions, Glossary

7/24/2019 API Related, Oilfield Pressure Control Equipment, Terms and Definitions, Glossary

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3/7/2014 API Related, Oi lfield Pressure Control Equipment, Terms and Defini tions, Glossary, WOODCO USA

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GENERAL Revised: 11/12/2013

Oilfield Glossary:Terms and Definitions

To help visitors, many words below which name oilfield products manufacturedby WOODCO USA have links to illustrations and additional information shown in

WOODCO USA online catalogsor other sections of Web Site Tools.

Remember, "Whatever you say about a thing, or however you describe it, youhave not; for the words can never totally represent or equal the thing itself."

Find numerical entries by alphabetical spelling.A| B | C | D | E | F | G| H | I | J | K | L | M | N| O | P | Q | R | S | T

U | V | W | X | Y | Z

Provided links give access to illustrations and/or additional information. Toreturn to this page use your browser back button.

Acceptance Criteria:(General)

Defined limits placed on the characteristics ofmaterials, products, or services. Visually stated inreferencedindustry specifications and standards

Acceptance Criteria:

(NDT)

Reference documentation and/or illustrations that

allow comparison of Indications or Discontinuitiesfound during Nondestructive Testingto a standard,

for the purpose of acceptance or rejection.

Adapter Flange: Any flange that will connect between two other

flanges that would otherwise not connect. Usually aDouble Studded Adapter (DSA), or a SingleStudded Adapter (SSA).

Adapter Spool: A unit of pressure control equipment with a bodyand two different end connections used to connect

together other pieces of equipment that couldotherwise not connect. Sometimes used instead ofa Double Studded Adapterbecause at least one of

the units to which it connects has a studded flangeconnection.

American Made: See Made in U.S.A.

Annular: Refers to the area of space between the insidediameter of a drilled or cased hole and asecondary string of pipe suspended inside this

space.

ANSI (ASA) American National Standards Institute. An
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http://www.woodcousa.com/flgterms.htm#Rockwell_B_Hardness 2

organ za on ormer y nown y e name mer canStandards Association (ASA). This organizationsets standards for the ANSI B16.5 Blind, WeldNeck, and Threaded Flanges commonly used in

refineries and process industries.

For information comparing "ANSI" and "API"Flanges, seeA Brief History of Well Head Flanges.

API American Petroleum Institute. The organization thatdevelops and publishes API specificationdocuments.

API Flanges The flanges specified in API Spec 6A and APISpec 17D. All of these flanges seal with Metal RingGaskets. For flange sizes and dimensions, see

Flange Slide Rule Program.

API Monogram: A registered trademark of the American PetroleumInstitute (API). Qualified licensed manufacturers

may apply the API Monogram along with theirlicense number, as a mark onto product orequipment that serves to certify that the product orequipment meets the requirements of APIpublished specifications.

API RP 5A3

(ISO 13678):

A specification for a high-pressure thread

compound that works well to lubricate API casing,tubing and line pipe threads as well as bolts andnuts used to connect flanges and clamps. Do notuse compound made to this specification for rotaryshoulder connections.

API Spec 6A: Also, ISO10423; The American Petroleum Institutepublication that serves as the industry Specificationfor Wellhead and Christmas Tree Equipment.Those companies granted a license from API may

apply an API Monogram mark, along with theirlicense number, to products which they have made

in compliance with this specification.

API Spec 16A: Also, ISO13533; The American Petroleum Institutepublication that serves as the industry Specification

for Drill Through Equipment. Those companiesgranted a license from API may apply an APIMonogrammark, along with their license number,to products which they have made in compliancewith this specification.

API Spec 16A Clamp:Photo

A device, serving as a fastener, designed to matewith and Make-up to seal, API Spec 16Adesignated hubs.

API Spec 16A Clamp An end connector specified in API Spec 16A that
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Hub:Photo

joins with a matching hub and secures with aClamp.

API Spec 17D: The American Petroleum Institute publication Thatserves as the industry Specification for SubseaWellhead and Christmas Tree Equipment. Thosecompanies granted a license from API may applyanAPI Monogram mark, along with their license

number, to products which they have made incompliance with this specification.

ASTM: American Society for Testing and Materials. Anorganization providing a vast array of specificationsfor test methods and materials, frequently

referenced by other standards organizations.

Austenitic Stainless Steel: 300 series stainless steel with a chemicalcomposition of nickel, 8% minimum, chromium,16% minimum, and carbon, .08 maximum. All

elements measured in % mass fraction.

Axial Alignment: See Connector Axial Alignment

B7, B7M: A short form of expression for the ASTM

specification for bolting, A193 Grade B7, called outinAPISpec 6Afor standard service flange bolting.If B7M appears, it means B7 in a Modifiedcondition with controlled hardness in the bolt (and a2HMnut) for sour service exposed bolts.

Balance: Also, Fluid Balance; That condition when the fluid

Head in a well bore produces sufficient pressureinside the well bore to equal the pressure of theproduction zone and stop the outflow of fluid or gas

from that zone.

Bell Nipple: An upward pipe extension above the uppermostBOP, used to discharge returning drilling mud tothe shakers, separators, and pits during drillingoperations. The "Bell" term derives from the bell

mouth usually fabricated on its upper end, SeeFlange, Bell Nipple.

BHN:See all hardness

related definitions

An Abbreviation for Brinell Hardness Number. Nowabbreviated HBW.

BHTA: An Abbreviation for Bottom Hole Test Adapter. SeeTop Connector

Blast Joint: For Choke Manifolds, see Blast Spool. For tubingstrings in wells, the term Blast Joint applies to a

piece of heavy walled tubing, run in the tubing stringand positioned across from a perforated interval to
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fluid coming from that zone, thus prolonging the lifeof the completion.

Blast Spool: For Choke Manifolds, this term applies to a

specially constructed Spacer Spool attacheddirectly to the outlet connection of a Drilling Chokewhere high velocity fluid erosion may occur.Manifold designers build this spool with the

maximum practical wall thickness and sometimesspecify an erosion resistant liner for this spool.

Bleed Ring: Another name for a Instrument Flange, a flange withbolt holes drilled through, or studded, with sealingsurfaces on both sides and a tapped hole forsampling.

Blind Flange: See Flange, Blind.

Blowout Preventer:

(BOP)

A unit of equipment, installed singularly or as a part

of an assembly, attached to the Wellheadto controland/or contain well pressure occurring inside theCasing during Drilling, Workover, or Snubbingoperations.

BOP: An Abbreviation for Blowout Preventer.

Body: The portion of a unit of pressure control equipmentbetween separated end connections.

Bolt Circle: The theoretical circle inscribed by the center point

of a series of holes, drilled equally spaced, near themid circumference of a flange.

Bolt Tension: That energy achieved by applying Torqueto nuts onbolts providing the compressive force necessary tohold connections in contact under pressure or load.

Bolt Torque: That rotational force applied to nuts on stud bolts totighten and apply Tension to the bolts in order tohold flanges or other connections in Make-up. Thisforce is usually expressed in Foot Pounds

(FT/LBS). See Torque Wrench.

Bottom Hole Test Adapter(BHTA):

See Top Connector.

Break-out: Also Break Apart; The act of disconnecting joinedflanges or other Connectors.
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Brinell Hardness:See all hardness

related definitions

Now abbreviated HBW. A designation of hardness,usually of steel, performed by pressing a 10 mmspherical tungsten carbide ball against a cleanprepared surface using a 3000 Kilogram force,

producing an impression, measured and given aspecial numerical value. This numerical valuerelates to steel tensile strength. API Spec 6Aspecifies minimum Brinell Hardness requirements

for different material designations. NACEStandardMR0175 references maximum hardness in

determining steels suitability for use in H2SService.

Buffer Chamber Also, a Header; Typically, a fabricated pressurevessel with multiple inlets and outlets, used to

contain and direct the discharge from Chokesin aManifold system. An alternate method of buffersystem construction allows the use of non-welded

components.

Burn Through A term used to describe an undesirable event

during welding when the welding arc unintentionallyburns trough a thin wall, or weld joint root, causingunacceptable irregularities on the reverse side (orthe I.D.) of the weld. Excessive metal on the I.D. ofa pipe butt weld joint may interfere with thepassage of tools, or in extreme cases the flow of

fluid.

Butt Weld The completed weld made in a Butt Weld Joint.

Butt Weld Joint This term describes a form of weld joint havingspecially prepared surfaces that makes a FullPenetration Weld possible, usually by leaving asmall gap between the adjacent pieces thatdeposited weld metal will bridge, fill, and close.

BX: See 6 BX

Carbon Steel An iron based metal with only carbon andmanganese deliberately added to specific limits.Other elements residual, except for small quantities

added for deoxidization or to control the effects ofsulfur.

Casing: Pipe used to line the bore hole of a well.

Casing Head:

A single unit of well control equipment (usuallyflanged) attached to the upper end of surfacecasing, allowing the attachment of BlowoutPreventersduring drilling, and later suspending andsealing a secondary string of casing set inside.

Casing Spool: A single unit of well control equipment attached
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,a secondary casing string.

Cast Steel: Steel formed by pouring molten steel into a mold toproduce a desired near finished shape after

solidification and cooling.

Casting: A shape made from cast steel. The term casting

may also apply to the process of pouring liquid

steel into a mold.

Certified Welder: See Qualified Welder.

Charpy V-Notch Test:(CVN)

A test performed at a specified temperature byswinging a calibrated falling pendulum (hammer)fracturing (breaking) a specifically configuredSpecimen of Material and measuring the forcerequired, usually expressed in foot pounds.

Chemistry: The chemical composition of Material. Theexpression of the elemental composition ofmaterial by percentage of weight for eachmeasured chemical element.

Choke: Also, Choke Valve; A unit of pressure controlequipment used to restrict and regulate the flow ofwell fluids to maintain a desired pressure and flowrate. Chokes have hardened internal expendableparts specifically designed to resist erosion caused

by high pressure, high velocity fluid. Often used aspart of a Choke Manifold(also see Drilling Choke)or Christmas Tree.

Choke Manifold: An assembly of valves, Fittings and Chokesarranged to regulate and control the flow of high

pressure fluid from a well bore.

Christmas Tree: An assembly of equipment topping off theWellhead, including valves, Fittings, Chokes, TopConnectors, etc. used to regulate and control the

flow of oil or gas during normal well production.

Clamp: See API Spec 16A Clamp.

Clamp Hub: See API Spec 16A Clamp Hub.

Coefficient of Friction (f): Term to describe the ratio of the force of frictionbetween two bodies and the force pressing themtogether.

Coining: The condition of bringing metal surfaces of differinghardness so tightly together that the softer surfacedeforms to match the harder surface exactly inshape and finish. See Intimate Contact.
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Combination AdapterRing Gasket:

A uniquely configured Ring Gasketthat allows twoflanges with ring grooves of different PitchDiametersto join and seal when Made-up.

Combination Bolts: Those special bolts made to join flanges of differentWorking Pressures, having a different diameter oneach end to correspond with the bolt holes in each

respective flange. See Cross Over Connectionsfora full explanation.

Combination RingGasket:

A specially configured Ring Gasketthat allows twoflanges with Ring Grooves of different width anddepth but the same pitch diameter to join and seal

when Made-up.

Companion Flange: See Flange, Companion.

Concentric Reducer: A pipe fitting that transforms from a larger to asmaller size on each end. The ends may have pipethreads or have butt weld preparations, with the

ends concentric about a common axis.

Threaded Concentric Reducer(Often called a Swage Nipple)

Butt Weld Concentric Reducer(Sometimes called a Transition Piece)

Connector: For Wellhead application, the part of pressurecontaining / pressure controlling equipment thatallows a mechanical joint that can provide apressure seal: Flange, Hub, Union, etc., that does

not seal on a thread.

Connector Axial Alignment to within specified tolerances of the
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,connector at the opposite end of the equipmentunit.

Connector, Loose: Any flange, hub, or Other End Connector, not

integral to a body of an identified piece ofequipment.

Connector Parallelism: A measure of the connector face (or plane) with

respect to the connector face at the opposite end ofthe equipment unit; e.g. do the connectors atopposite ends of a spool center on the same axisand do their faces lay parallel to one another?Operators may assume acceptable parallelism ifassembled equipment will pass a drift test. Seehttp://www.woodcousa.com/standoff.htm#Drift.

Corrosion Resistant RingGrooves:

Ring Grooves lined with material resistant to MetalLoss Corrosion. This material is either an austeniticstainless steel or a corrosion resistant alloy,normally 316 SS or 625 Inconel. These groove

inlays have nothing to do with H2S service, butserve only to provide protection from Metal LossCorrosion (rust).

Corrosion Resistant Alloy:

(C.R.A)

Nonferrous alloys where any one or the sum of the

specified amount of the following alloy elementsexceeds 50%: titanium, nickel, cobalt, chromium,and molybdenum. A Material sometimes used incritical service applications for flanges, bodies,bonnets and other components. Also frequentlyused as a weld metal overlay for ring grooves to

prevent Rust damage between connection make-ups. API requires CRA to appear in the connectormarking when the connector has UNS N06625inlay in the ring groove.

Corrosion ResistantMaterial:(C.R.M)

Generally refers to ferrous or nonferrous alloyswhich are more corrosion resistant than low alloysteels. This term includes CRA's, duplex, and

stainless steels.

Cross: AnyFittingwith four connections in the same planewith two of these connections forming an in-line

Run. Crosses may have more than fourconnections.

Cross-over Fitting: Any pipe fitting, or similarly configured part, having

two different end connection types, e.g. line pipe X8R Tubing Threads, male or female either way, andvarious sizes and combinations of unionconnectors, female end and male end with nut, etc.

"Cross StandardAdapter:

AnyAdapter Flange,Adapter Spool,or Cross-overFitting with connections specified in two different
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reference to one another. Typically, Cross Standardadapters may have API X ASME flangeconnections (studded adapter or flanged adapterspool), API flange X union (female end or male end

with nut), or ASME flange X union (female end ormale end with nut)

Country of Origin: That country within which 75% or more of the

manufacturing costs of a product item incur. Seealso Made in U.S.A.

Deep Ring Grooves: Now obsolete or withdrawn ring groovespecifications that allowed face to face contact onMade-up hubs or flanges when using RX ringgaskets. See SRring grooves.

Discontinued: Industry standard products or equipment that theissuing standards organization has announced itwill no longer include in its published specifications.

Discontinuity: A location, internal or external, where the structuralnature of Material (or a weldment) has aninterruption of its normal or continuous regularity. Aplace where metals exhibit some mechanical,physical, or metallurgical irregularity that requires

evaluation by reference toAcceptance Criteria.

Diverter: A specializedAnnular Blowout Preventer used, inconjunction with large diameter flow valves, to closeand divert shallow gas encountered during drillingoperations.

Domestic Made: See Made in U.S.A.

Double Extra Strong:(XXS)(XXH)

Also, Double Extra Heavy; A designation of pipewith a wall thickness twice that of Extra StrongPipe. See Carbon Steel Pipe Dimensions andWeightsfor commonly available pipe sizes.

Double Studded Adapter:(DSA)

Q & A

A flange with a through bore and a ring groove oneach side, drilled and tapped bolt circles on both

sides and Tap End Studs complete with nutsinstalled on both sides. Usually the two sides aredifferent in size and/or pressure rating. Usually

used to adapt between different flange endconnections that would otherwise not connect.

Drift: A gauge of special dimensions used to passthrough the Run of pressure control equipment todemonstrate that the Run bore will pass working

tools. Also, the act of passing this gauge throughthe bore.
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Drilling: The process of making a bored well hole to test for and, if encountered in commercial quantities,produce oil and/or gas.

Drilling Choke:

A Choke specifically designated by its

manufacturer as suitable for drilling service, usedas part of a Choke Manifold.

Drilling Rig: The entire collection of machinery and equipmentbrought together as a unit and used to drill and set

Casingfor an oil or gas well. An operating drillingrig includes Blowout Preventersand drill pipe.

Drilling Spool: Also, Mud Cross; A unit of equipment used withBlowout Preventersto space pieces of equipment

apart and provide outlets to attach lines extendingto Chokeand KillManifolds.

DSA: An abbreviation for Double Studded Adapter.

Dual Flanges: See Segmented Flanges.

Ductility: A property of Materialthat allows it to yield or "bend

before breaking." Technically expressed bymeasurement records of Elongationand Reductionof Areadetermined as the result of a Tensile Test.

Elastomer: A flexible and elastic material used commonly for

molded seals, often referred to as rubber.Specialized elastomeric compound formulations

allow sealing various fluids over a broad range oftemperatures.

Elongation: That amount that a MaterialSpecimen will stretch

before fracture (separation). Usually expressed asa percentage of the original length.

End Connection: That connection on either end of the Run (throughthe central bore) of pressure control equipment.

Extra Strong:(XS)(XH)

Also, Extra Heavy; A designation of pipe wallthickness specified in API Spec 5L in addition tomany other pipe wall thicknesses. See CarbonSteel Pipe Dimensions and Weightsfor commonlyavailable pipe sizes.

15 M: An abbreviation for 15,000 pounds per square inch(psi) Maximum Service Pressure.

Fabricated Equipment: That equipment, made with 2 or more pieces of

steel joined together by welding. Such fabricatedequipment may contain pressure or provide
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equipment. See One Piece Construction forcomparison.

Figure 1502: A term, preceded by an inch size, describing a

specific union design widely used on flange byunion adapters.

Figure 2202: A term, preceded by an inch size, describing a

specific union design widely used on flange byunion adapters

Fitting: A unit of pressure containing equipment designedto fit between other equipment for the purpose ofadapting or arranging that other equipment tofacilitate pressure control. See Teeor Cross.

"5 Bolt" Flanges: See Segmented Flanges.


Flange: A single disc or a protruding disc extension on abody with holes to accept bolts or with holes drilledand tapped into its surface with Tap End Studsinstalled, with a sealing means, used to join

pressure containing equipment.

Flange, ANSI: A flange specified inAmerican National StandardsInstitutepublished standards.

Flange, API: A flange specified, now or in the past, inAmerican

Petroleum Institutepublished standards.

Flange, Adapter: Any flange that will connect between two otherflanges that would otherwise not connect. Usually aDouble Studded Adapter (DSA), or a Single

Studded Adapter (SSA).

Flange, Bell Nipple: The Flange attached to the Bell Nipple used tosecure it to the top of the uppermost BOP.

Flange Bolt Tightening

Sequence:

Begin tightening by hand by rotating nuts clockwise

until they touch the flange, with the nuts equallyengaged on both ends of the bolts. Begin tighteningwith wrenches, choosing one bolt first, and thenchoosing the bolt 180 opposite second. Continuetightening the bolt at 90 and then the one 180

from that. Then step over one bolt from the first bolttightened (decide for yourself clockwise or counter-clockwise) and continue the same pattern as withthe first four. Proportion the tightening so that fulltightening takes 4 to 5 passes around the full set of

bolts. For sequence diagrams for most flanges,Click here.
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Flange, Blind: A flange with no center opening, designed to closeoff an outlet or end connection.

Flange, Companion: A loose, Open Face Flange, usually threaded, but

may have a Weld Neckor Blindconfiguration.

Flange, Double Drilled: A flange with two Bolt Circles drilled through, or

tapped for studs, so that it may join another flange

of a lower working pressure.

Flange, End Connection: A flange integral with a body (e.g. spacer spool,etc.) with an opposite integral connection.

Flange, Full Face: A flange, with or without a ring groove, that has a fullsurface flat face.

Flange, Gauge: See Flange, Test

Flange, Instrument: (1) An equipment piece usually made as a SpacerFlange with a ring groove on both sides to gobetween two other flanges, with special TappedConnection Ports through its side (O.D.) into itsbore, to facilitate the injection or sampling of fluid orthe measurement of pressure.

(2) A Special Flange Adapter, also known as a

Transmitter Flange, having 2 sides, one sidehaving a single flange face, either studded or openface, and the other side having 2 or more studdedflange faces, all faces with bores interconnected.

Usually used to connect pressure gauges andpressure transducers to a Choke Manifoldassembly.

Flange, Integral: A flange made as part of a Bodyor attached to abody by welding.The flange Material conforms to

specification requirements for integral flanges.

Flange, Loose: See Connector, Loose

Flange, MSS: A flange specified in Manufacturing

Standardization Society, Standard Practice SP-44.Used by Manufacturers of Divertersin 30" 500 and30" 1000 psi working pressure.

Flange, Open Face: A flange connection with through bolt holes. An

open face flange will mate with another open faceflange or with a Studded Face Flange.

Flange, OutletConnection:

An integral flange connected to a Body(e.g. Tee,)usually at 90 degrees from the end connection.

Flange Parallelism: See Connector Parallelism.
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Flange, RTJ: A flange that utilizes a Ring Gasket has thedesignation "Ring Type Joint", abbreviated "RTJ"in flange standards other than API Spec. 6A. All

API Spec. 6A flanges have "Ring Type Joint"

sealing surfaces.

Flange, Segmented: See Segmented Flanges.

Flange Series: An out of date term, applied in the past to API

flanges now described in terms of workingpressure.

Flange, Spacer: A flange, made with a ring joint connection on bothsides, to go between two other flanges to space

them apart for some special purpose.

Flange, Studded Face: A flange connection with the bolt circle drilled andtapped into its face so as to accept Tap End Studs

(e.g. the connections on a Studded Cross). Astudded face flange will mate only with an OpenFace Flange.

Flange, Target: A Blind Flange, usually with a lead filled cavity,used to cushion and minimize the erosion of highvelocity abrasive fluid.

Flange, Test: A flange, similar to a Blind Flange, with a tappedport in its center or side to allow application ofpressure or attachment of a gauge.

Flange, Threaded: A flange with an internal (see Flange, Companion)or external thread opposite itsRing Grooveside tomate with standard threaded pipe.

Flange, Transmitter: See Flange, Instrument

Flange, Weld Neck: A flange with a butt weld neck for weldingattachment to pipe or tubing. Material may varyfrom that required for Integral Flanges in order tofacilitate field welding.

Flowline: Any line of pipe, that contains and controls the flowof fluid.

Fluoropolymer Coating: A specialized coating that manufacturers may useon bolts, nuts, and other surfaces that needcharacteristics of low friction, wear resistance, andprotection from corrosion; often described as Xylan

or Teflon coating.

Foot Pounds:(FT/LBS)

A term usually used to express the amount ofrotational force (Torque) applied to nuts on stud
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bolts. "One Foot Pound" equals the force of onepound of pull on a wrench with a handle thatextends 12 inches from the center axis of a bolt and

nut upon which the force acts. See Bolt TorqueandTorque Wrench.

Forged Steel: Steel, plastically deformed and shaped, usuallywhen hot, using compressive force to breakup andclose any internal Discontinuities.

Forging: See Forged Steel. Also, the act of usingcompressive equipment (presses or hammers) toplastically deform steel into a desired shape.

4130: A low alloy steel containing molybdenum andchromium as strengthening agents. The carbon

content is nominally 0.30% and with this relativelylow carbon content the alloy is excellent from thefusion weldability standpoint. The alloy can behardened by heat treatment.

4140: One of the chromium, molybdenum, manganeselow alloy steels noted for toughness, good torsionalstrength and good fatigue strength after heattreatment. The carbon content of 0.40% makes thissteel less easi ly welded than 4130.

45K: An API Spec 6A abbreviation for 45,000 psi,minimum yield strength Material.

Full Face Flange: See Flange, Full Face.

Full Penetration Weld: A weld performed on a prepared joint betweenadjacent pieces, the weld metal extending throughthe entire wall.

Gage: Also, Gauge; A preset device for determining therelative size or shape of an object compared to a

standard (e.g. a Drift). The act of using a gage to

compare or confirm a size or shape. A device tomeasure pressure within a pressure containing orcontrolling system.

Gauge: See Gage.

H2S: An abbreviation for the chemical Hydrogen Sulfide.

H2S Service: Short for Hydrogen Sulfide Service (HSS). A termused to designate that equipment materialspecifications meet the requirements of NACE

Standard MR0175, for use in controlling fluidcontaining partial pressure (some percentage) ofHydrogen Sulfide.
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3/7/2014 API Related, Oil field Pressure Control Equipment, Terms and Definitions, Glossary, WOODCO USA


Hammer Unions: Also, Wing Unions; Connectors that allow quickmake-up and break-out of pipe and fittings usedprimarily in temporary flow-lines. Any connectedHammer Union consists of 3 pieces.

1) A male connector with a spherical sealing

surface.

2) A female connector with a tapered sealing

surface and external Acme threads.

3) A wing nut with internal Acme threads that fitsover the male connector and screws onto the

female connector holding the two connectorstogether, achieving a seal.

Some Hammer Unions contain an elastomericsecondary seal.

Hammer Wrench: A box end wrench with a shortened heavy handle

having an elongated square shaped end. Designed

to withstand heavy striking with a sledge hammer totighten or loosen nuts on stud bolts.

Hardness:See all hardness

related definitions

A measured factor that reasonably predicts the

amount metal will resist abrasion and bending, aswell as indicating Ultimate Strength. Mostcommonly expressed as Brinell Hardness andRockwell Hardness. ASTM E140 provides a guidefor comparing hardness determined by differentmethods and expressed on different scales.

Head: The standing column of fluid in a well bore. Themeasure of fluid pressure at the bottom of a columnof fluid in a well bore or in any vertical fluidcontaining pipe or system.

Header: See Buffer Chamber.

Heat Affected Zone(HAZ)

That part of the base metal formed as a narrowband immediately adjacent to deposited weld

metal, affected by welding heat input but notmelted.

Heat Treatment: Heating and cooling metallic Materialin such a wayas to produce selected and intended conditions

and properties in the material. This process affectsTensile Strength, Yield Strength, Elongation,Reduction of Area, and toughness (usuallymeasured as Impact Strength).

HBW:See all hardness

related definitions

Abbreviation for Brinell Hardness.

HRB:

(Sometimes RB) An abbreviation for Rockwell
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ee a ar ness

related definitionsar ness measure on e sca e. e

abbreviation usually appears after a number, e.g.83 HRB. See: Rockwell B Hardness.

HRC:See all hardness

related definitions

(Sometimes RC) An abbreviation for RockwellHardness measured on the C scale. Theabbreviation usually appears after a number, e.g.22 HRC. See: Rockwell C Hardness.

Hub: See API Spec 16A Clamp Hub.

Hub Parallelism: See Connector Parallelism.

HV:See all hardness

related definitions

Abbreviation for Hardness Vickers. The Vickers

hardness testing method represents anothermethod of testing by indenting the test materialunder a specified load and measuring the size ofthe indention and comparing it to a number table.This method has gained greater use in testing of

weld samples to meet NACErequirements.

Hydrotest: Also, Hydrostatic Test; a pressure test conductedby pumping a fluid (usually water) into a closed

vessel or equipment system until the pressure

reaches a specific level. The test consists ofholding this pressure for a specific period of timewithout observed leaks or pressure decline on theindicating instrument.

Hydrogen Sulfide:See all hardness

related definitions

The chemical commonly abbreviated H2S. This

deadly poison also has a destructive effect on high

strength low alloy steels when the hardness of thesesteels exceeds a hardness of 22 Rockwell C.

I.D. An abbreviation for Inside Diameter.

Impact Strength: The amount of energy required to fracture (break) aSpecimenof Materialusing an impact blow, usuallyperformed at a specified temperature, by means of

a Charpy V-Notch Test.

Indenter:See all hardness

related definitions

A hardened pointed or rounded contact object usedto impress an indentation into the surface of steel

(or other metal) parts in order to obtain a Hardnessmeasurement of that part. See HBW, HRC, andHRB.

Indication: A term used in magnetic particle testing to identifylocations found that require evaluation byreferences to Acceptance Criteria. See Magnetic

Particle Inspection.

Inlay: Used to describe a form of weld metal deposit,where the weld deposit fills a groove or cavity.

Fre uentl referrin to Corrosion Resistant Allo
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weld metal deposits in oversize grooves later

machined to accept Ring Gaskets.

Intimate Contact: The condition of bringing metal surfaces ofmatching shape and finish into contact with suchforce as to leave no space or gap. See Coining.

Integral: Made as a single unit. Usually referring toconnectors(Flanges, Hubs, and/or O.E.C.'s) made

as part of a body, or joined to a body by welding;the connectors meeting the API specifications forend and outlet connectors.

International StandardsOrganization

Abbreviated ISO, this standards organization hastaken on a partnership with the American

Petroleum Institute to establish equipment andquality specifications. ISO now issues thesespecifications and the API adopts them back andfurther supports these specifications with the API

Monogramprogram.

ISO: See:International Standards Organization

k: Also, kip; A load of 1000 pounds. See ksi.

Kill: The act of pumping heaver fluid into a well bore tobring a well into Balanceand stop the outflow fromthe well.

ksi: Abbreviation for one thousand pounds per squareinch usually used to indicate material (e.g. steel)strength, sometimes shortened to a suffix K.

L7, L7M: A short form of expression for the ASTM

specification for bolting, A320 Grade L7, called outinAPISpec 6Afor low temperature bolting. If L7Mappears, it means L7 in a Modified condition withcontrolled hardness in the bolt (and a 2HMnut) forsour service exposed bolts.

Lack of Full Penetration: This term describes a condition observed in a weld

joint when the weld metal does not uniformlycontinue from the root of the weldto the final coverpass, most often observed at the root of a buttweld.

Line Pipe:(LP)

Pipe generally intended for use in the oil and gasindustry for the conveyance of oil and gas underpressure, or for a variety of industrial applications.

API Spec 5L and 5LX specify this pipe. For

commonly available sizes of line pipe, see CarbonSteel Pipe Dimensions and Weights on this website.
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Liquid Penetrant Test: A method of surface inspection to detectindicationsnot visible to the unaided eye on non-magnetic Materials, or to prove or disprove

questionable Magnetic Particleindications.

A liquid penetrant inspection consists of:

Applying a liquid penetrant colored dye to a

clean material surface.

Allowing time for penetrant to enter any

Discontinuities.

Drying this surface of all liquid visible on the

surface.

Applying a developer coating to the surface

to draw out any penetrant that may haveentered surface discontinuities.

Allowing time for the developer to draw outany penetrant to stain the developer coating.

Observing any colored surface stains and

comparison of any indications seen toAcceptance Criteria for acceptance orrejection of the inspected part.

Loop, PressureControlling:

Any assembly of valves and fittings connected to aBlowout Preventer stack to allow pressureequalization and/or bleed down before opening

rams. Most commonly used during Snubbingoperations.

Loose Connector See Connector, Loose.

Loose Flange See Connector, Loose.

Low Alloy Steel: An iron based metal alloy with small amounts ofother elements added in specifically measuredamounts to produce a desired response to HeatTreatmentcycles and achieve intended mechanical

properties..

LP: An abbreviation for Line Pipe.

Lubricator Adapter: See Top Connector.

M: An abbreviation for "000 psi" in designatingworking pressure in equipment marking.

Manufacturers apply much of the marking on

pressure control equipment by striking handstamps, with a hammer, to apply individual


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numbers and letters. The Roman numeral for onethousand (1,000), M, provides a simple symbol touse and save the space used by 3 zeros and 3letters when hand stamping parts, e.g. 10M, rather

than 10,000 psi. This same term of abbreviationhas become commonplace now in the literature.

Made as one piece: See One Piece Construction

Made in U.S.A.: 1. WOODCO USA shall consider steel materialmelted in the U.S. as Made in U.S.A., and anyproduct made from that steel and sold byWOODCO USA as Made in U.S.A.

or

2. WOODCO USA will make an unqualified Madein U.S.A. claim (U.S. origin claim) if, at the time itmakes the claim, it possesses credible evidencethat: (1) U.S. manufacturing costs constitute 75% ofthe total manufacturing costs for the product; and

(2) the product was last substantially transformed inthe United States. 75% of total manufacturing costsshall include all costs paid by WOODCO USA to allUSA vendors, for material made in USA or outsideservices performed in USA, and best estimates ofinternal manufacturing costs, but not includingcalculated mark-up.

Made-up: Refers to a completed connection after joiningflanges or other connectors to achieve a seal.

Magnetic ParticleInspection:

A non-destructive surface inspection process forferromagnetic materials (materials that will attract amagnet) performed by magnetizing the material,applying a fine iron powder, either dry or in liquidsuspension, to the magnetized surface, andobserving the collection of this powder along anybreaks in the magnetic field that might represent

fractures or other irregularities in the surface. SeeIndication.

Make-up: The act of joining flanges or other connectors toachieve a seal.

Manifold: An assembly of valves and Fittings arranged toregulate and control the flow of high pressure fluid

from a well bore. Also see Choke Manifold.

Material: A term used on this web site, and in API documentsfor pressure control equipment, that identifies the

Steelor Corrosion Resistant Alloyused for flanges,bodies, bonnets and other components specified.

Mechanical Properties:

Measured aspects of Materialused to describe its
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See all hardness

related definitionselastic and inelastic reaction to applied force;These may include Tensile Strength, Yield Strength,Elongation, Reduction of Area, Impact Strengthand

Hardness.

MegaPascal(MPa)

A basic unit of pressure or tension measurement inthe International System of Weights and Measures.1 MPa - 145 psi,

1 MPa = 1 N/mm2.

(For converter, click here)

Metal Loss Corrosion: That corrosion on the surface of metal that convertsthe metal to an oxide or otherwise graduallyconsumes the exposed surface of the metal.

Localized metal loss corrosion may appear as"pitting."

Microstructure (Steel): The existing described order and arrangement ofconstituents of steel Material, as observed on a

prepared sample through a microscope. For moreon Microstructure, click here.

M.S.P.: An abbreviation for Maximum Service Pressure.

Mud Cross: See Drilling Spool.

NACE MR 01 75:See all hardness

related definitions

A document published by the National Associationof Corrosion Engineersdefining the specific limits

of chemistry, hardness and microstructure ofMaterials used to make equipment to contain orcontrol well production fluids that include hydrogensulfide.

NC: National Coarse, See UNand UNC.

Nipple, Swage: See Concentric Reducer.

Nipple-Up: Usually refers to assembling BOP Stacks and

Choke Manifolds. See Make-up.

Nominal: A term related to "size" or "dimension", indicating adesignation only, not the actual measurement. (e.g.

2 inch nominal pipe measures 2-3/8 inches outsidediameter and no standard Scheduleof the 2 inchpipe has a 2" inside diameter).

Nondestructive Evaluation:(NDE)

Also, Nondestructive Examination orNondestructive Testing; these terms identify agroup of activities using various methods to find,locate, measure, or determine something, without

damage, about Materialor equipment, that allowsan investigator to decide if any identifiedcharacteristics or conditions constitute rejectableflaws.
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O: See Zero.

Obsolete: Industry standardized products or equipment thatthe issuing standards organization has replacedwith updated products or equipment. Manufacturedgoods the manufacturer has replaced with updatedgoods.

O.D. An abbreviation for Outside Diameter.

O.E.C.: An abbreviation for Other End Connector.

O.E.M. Original Equipment Manufacturer. Refers to thecompany which first designed and built equipmentor parts.

One Piece Construction: This term refers to flanged or hub connection

equipment made from a single steel forging.

Equipment made this way has no Fabrication (orassembly) welding performed. Equipmentmanufactured from one piece may often have weldInlay or Overlay to prevent corrosion damage toWell Wettedsurfaces.

Other End Connector:(O.E.C)

Any type of end (or outlet) connector designed tocontain pressure, other than those specified in APISpec 6A. An O.E.C. may have any configuration solong as it meets the design and performance

requirements of API Spec 6A. Examples include

Union and proprietary Lubricatorconnectors.

Outlet Connection: Any connection other than an End Connectionon aRun. Used to flow fluid or gas into a Manifold orChoke, or used to pump into, for the purpose ofinjecting fluid or to Killa well.

Overlay: Used to describe a form of weld metal deposit

where the weld deposit entirely covers a basemetal surface. Frequently referring to CorrosionResistant Alloy weld metal deposits over WellWetted surfaces of pressure control equipment to

prevent severe corrosion caused by well fluids.

Pack-Off Adapter: A single unit of equipment used in a wellheadassembly below the Tubing Headto adapt betweenflange sizes or pressure ratings and provide a sealaround a secondary CasingString.

Parallelism: See Connector Parallelism.

Pitch Diameter: Specifically of a Ring Groove; The theoreticaldiameter of the ideal mid point (imaginary circular
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.determined by measuring carefully from the insideof the ring groove on one side to the outside of thering groove on the other side (same as measuringfrom the centerline on one side to the centerline of

the other side). See Measuring Ring Groove PitchDiameter.

Port, Test: A drilled and tapped port in pressure control

equipment, or a flange, that penetrates through tothe fluid containing bore. For more information,

Click Here.

Post Weld HeatTreatment:

See Stress Relief.

Pressure Cut: The erosion damage caused by high pressure fluidduring an extended leak past a sealing surface.

Pressure, MaximumService:

Also, Working Pressure; the maximum pressurethat specific units of equipment should experience

in use. API specifies that the manufacturer clearlymark the Maximum Service Pressure (MSP) oneach unit of equipment; the equipment pressure

rating limited by the lowest pressure connector on

the equipment, or the manufacturers design. ForTest Pressure and Working Pressure testsexplained, click here.

Pressure, Test: The hydrostatic pressure applied to equipment todemonstrate the equipment's capacity to hold

pressure. A pressure teston existing equipment in

the field should equal but not exceed MaximumService Pressure. The Test Pressure andprocedures for new manufactured equipment, orremanufactured equipment, shall comply with that

specified by API. For Test Pressure and WorkingPressure tests explained, click here.

Pressure Test: The act of applying fluid or gas pressure insideequipment bodies, or upstream of equipmentclosure mechanisms, to demonstrate equipment

pressure containment integrity or pressurecontrolling reliability. The term may apply to any

application of pressure intended to demonstrateequipment fitness for service. Pressure appliedduring a pressure test should never exceed specific

equipment rated working pressure except in acontrolled environment. See the definitions of theterms, Test Pressureand Working Pressure.

Pressure, Working: See Pressure, Maximum Service.

Procedure QualificationRecord:

(PQR)

A written document recording all of the testingutilized to prove the validity of the Welding

Procedure Specification (WPS) which references
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it. The PQR contains actual records of theperformance of all variable factors called out in the

WPS, as well as, the results of all mechanical,volumetric, and surface tests made on samples ofthe test welds performed to demonstrate thatproduction welds carried out in conformance withthe WPS shall meet the specified requirements.

Qualification of a WPS necessarily requires

calibrated welding equipment instruments andmeters, a record of the calibration and thereference standard, and the date of calibration andfrequency performed. Reference ASME SEC. IXQW-200.2. Also see Qualified Welder.

psi: An abbreviation for pounds per square inch toindicate pressure or load.

PSL: Product Specification Level, as described in API

Spec 6A. The term applies to a tiered progression

of increasing testing and inspection requirementsfor materials and equipment. Other APISpecifications include these PSL requirements byreference to API Spec 6A. For more complete

information, CLICK HERE.

PSL 1: Product Specification Level 1, references theminimum level of testing and inspection required formaterial and equipment as specified in API Spec6A. For more complete information, CLICK HERE.

PSL 2: Product Specification Level 2, references a level of testing and inspection requirements for materialand equipment alternate to and in addition to PSL1requirements as specified in API Spec 6A. For

more complete information, CLICK HERE.

PSL 3: Product Specification Level 3, references a level of

testing and inspection requirements for materialand equipment alternate to and in addition to PSL1and 2requirements as specified inAPI Spec 6A.For more complete information, CLICK HERE.

PSL 3G: Product Specification Level 3G, references a levelof testing and inspection requirements for materialand equipment specified inAPI Spec 6Aas PSL 3,adding the requirement of gas testing of completedequipment units. For more complete information,CLICK HERE.

PSL 4: Product Specification Level 4, includes all thetesting and inspection requirements described in

API Spec 6A for PSL 3G, plus additionalrestrictions on the material qualification and heat

treatin and the rohibition of weldin exce t for
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overlay/inlay of corrosion resistant material. For

more complete information, CLICK HERE.

Qualified Welder: A person who performs welding in accordance witha Welding Procedure Specificationand a sampleresulting weld has passed all required visual,

mechanical and/or volumetric examinations

necessary for acceptance. Maintenance of welder

qualification requires that the welder performswelding, using the procedure methods andequipment within specified time periods, andmaintains records of this performance. A welder soqualified has qualification to use the same andother WPS's utilizing the same welding process,

depositing similar metal, using similar calibratedequipment; with the exception of CorrosionResistant Alloy inlay, which requires separatespecific qualification. Reference ASME SEC. IX

ART. III QW-304 and QW-305

Qualified WeldingProcedure:

A Welding Procedure Specification (WPS)containing a reference to the ProcedureQualification Record (PQR) which demonstratesthat the procedure results in the desired propertiesin the weld metal, heat affected zone and base

metal after any post weld heat treatment.

Quality: (As perceived in the business market)

That which makes a customer choose, buy, useand retain a product, with continued satisfaction.

Quality will draw the customer to return again to theprovider to get more of the same.

Quality Assurance: The predicate of quality outcome.

The planning, creation of specifications, choice ofinputs, choice of processes (and machines), choiceof personnel and training, and continuity ofmaintenance and management necessary toproduce predictable and desirable product

outcomes.

Quality Control: The examination of quality outcome.

The measurement and inspection activitiesperformed at various times during the making of

product(s) to ensure that the product(s) meet(s)specified standards.

R: A prefix designation, always followed by a number,(e.g. R-24) designating a standard oval orhexagonal Ring Gasket. A term used to refer to

any ring groove that will accept an R ring gasket.
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a se ace: ome mes a rev a e . a por on o eface of a flange near the I.D. raised above theremaining face of the flange, providing a sealingsurface for a flat gasket or containing a ring groove

to affect a seal with a Ring Gasket. API Spec. 6Aflanges do not utilize flat gaskets. Only Open Face

Flangessealed with BXring gaskets musthave araised face, 1/8" minimum height. API Spec. 6Apermits the omission of raised faces on all other

flange connectors.

Raised Ring Groove: Identifies flange facing that has a seal groove cutinto a raised portion of the flange face closelysurrounding the flange bore, required on 6BXand

17D SS Open Face flanges, optional and usuallyomitted on 6BX Studded Flanges and all API 6Bflanges.

RB: See HRB

RC: See HRC

Reduction of Area: The amount that a MaterialSpecimennecks down(or becomes smaller in section) as it experiencesstretching under a load sufficient to cause fracture

(separation). Usually expressed in percentage ofthe original cross sectional area.

Ring, Bleed: See Bleed Ring.

Ring Gasket:

A metal gasket shaped like a ring, with a number

designation, designed to fit into grooves machinedinto the face of flanges and/or other connectors andprovide a seal after Make-Up.

Ring Groove: A closely dimensioned groove machined into theface of a Connector, designed to accept a RingGasketand achieve a seal when Made-up.

Riser: A unit of pressure control equipment used to space

apart or raise other equipment to a useful height orposition. See Spacer Spool.

Rockwell B Hardness:See all hardness

related definitions

A designation of hardness of metallic materialsmeasured by pressing a small rounded indenter

against a clean prepared surface with a

specific force. The machine making the indentionalso measures the depth of the indention andprovides a numerical value for that depth. TheRockwell B scale expresses more accuracy in thehardness measurement of metallic materials softer

than HRC 20. To convert hardness numbersbetween measuring methods and scales, seeHardness Number Conversion Chart.
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Rockwell C Hardness:See all hardness

related definitions

A designation of hardness, usually of steel orCorrosion Resistant Alloys, measured by pressinga specially shaped indenter against a clean

prepared surface with a specific force. Themachine making the indention also measures thedepth of the indention and provides a numericalvalue for that depth. This numerical value relates tosteel Tensile Strength and NACE Standard

MR0175 references hardness in determiningsteels suitability for use in H2S Service. To converthardness numbers between measuring methodsand scales, see Hardness Number ConversionChart.

RTJ: An abbreviation for Ring Type Joint. See Flanges,RTJ.

Run: That passage through a Body, between EndConnections, that will pass fluid and working tools.

Rust: The Metal Loss Corrosionproduct, iron oxide. The

most common form of metal loss corrosionassociated with steel.

RX: A prefix designation, always followed by a number,for API Spec. 6A self energizing seal rings. RX

ring gaskets will fit all Rring grooves in 6Bflangesand only RX ring gaskets fit SRring grooves in APISpec. 16A hubs.

SBX: A Ring Gasket based on BX gasket design but

drilled with a special vent hole for underwater(subsea) Make-up.

Schedule: A term used to indicate the wall thickness of standard pipe sizes (e.g. 4 inch Schedule 80 Pipehas a 4.500 inches outside diameter with a .337inch wall). See Carbon Steel Pipe Dimensions andWeights.
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3/7/2014 API Related, Oilfield Pressure Control Equipment, Terms and Definitions, Glossary, WOODCO USA


connections.

Segmented Flanges: Sometimes called "5 Bolt" or "Dual" flanges. Theseflanges connect valves and tubing head adapterson Christmas Trees where 2 producing tubingstrings hang inside a single cased well bore. They

have a special "one sided" configuration that allowsthe producing tubing to have a small center tocenter distance.

Series A now obsolete term adopted originally by API todistinguish API well head flanges that matched

dimensions withASAflanges. The ASA identifiedflanges with a number followed by the term "Lb"and API designated flanges of the samedimensions by the term "Series". "Series" flangeshaving a higher standard working pressure andmade of higher strength steel than the standard

ASA (nowANSI) flanges.

For information comparing "ANSI" and "API"

Flanges, seeA Brief History of Well Head Flanges.

Service: A term used to denote the suitability of equipmentfor use in a particular environment e.g. H2S

service, High Temperature, Low Temperature, etc.

75K: An API Spec 6A abbreviation for 75,000 psi,minimum yield strength for Material.

Single Studded Adapter:Q & A

A flange with a through bore and a ring groove oneach side, with a drilled through bolt circle thesame as an Open Face Flangeon it's larger side

and a drilled and tapped bolt circle on it's smallerside, with Tap End Studsinstalled.

6 B: A term applied to API Spec 6A flanges which havering grooves dimensioned to accept R or RX ringgaskets. API originally specified these flanges in

API STD. 6 B. R or RX appears in the prefix of thenumbered ring gaskets which fit 6 B flanges.

6 BX :

A term applied toAPI Spec 6A flangeswhich have
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gaskets. API originally specified these flanges in

API STD. 6 BX. BX appears in the prefix of thenumbered ring gaskets which fit 6 BX flanges.

60K: An API Spec 6A abbreviation for 60,000 psi,

minimum yield strength for Material, or anabbreviation adopted on this Web Site for 60,000psi, minimum yield strength in relation to Line Pipe.

Snubbing: A term used to describe the process of removing or installing pipe into a pressurized well bore, using

specialized equipment including BlowoutPreventersin a special arrangement.

Sour: Crude oil or natural gas contaminated with sulfur or sulfur compounds, especially hydrogen sulfide. At

high concentrations, sulfur is odorless and deadly.

Spacer Flange: See Flange, Spacer.

Spacer Spool: A unit of pressure control equipment usually having

only end connections and an extended body, most

commonly used to raise or space apart BlowoutPreventersor to connect a ChokeManifold to the

well control system.

Specimen : A sample, usually of Material, shaped andprocessed according to a detailed specification,tested and used as a representation of the

properties of the lot of Material from which it came.

Spherical Washers: See Washers, Spherical.

SR : A term designating special ring grooves specified

in API Spec 16A that allow face-to-face make-up ofthe hub connections which utilize RX ring gaskets.Take special care not to confuse connections withSR ring grooves with those connections that haveDeep Ring Grooves previously used in now

obsolete or withdrawn flanges or hubs.

SRX: A Ring Gasket based on RX gasket design butdrilled with a special vent hole for underwater(subsea) Make-up.
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(See Catalog)

threads over their full length or may have anunthreaded portion on the central area of the bodydiameter. (See PDF file AWHEM documentTR9601for bolt dimension information).

Stud Face Flange: See Flange, Studded Face.

Substructure: That base of fabricated steel beams or columns

that supports the working floor and mast of a landbased Drilling Rig.

Subsea: A term used to identify oilfield wellhead equipment

used offshore and below the surface of the water.

Surface: A term used to identify oilfield wellhead equipmentintended for use on land or above the waterline inoffshore applications.

SV Flanges: API Spec 17D refers to Swivel Flanges (flangesthat swivel around a hub) as "SV Flanges". APIspecifies these flanges in a limited range of sizesin 5,000 psi and 10,000 psi working pressures. Formore information, see About API Spec 17D SS

and SV Flanges.

Swage Nipple: See Concentric Reducer.

Sweet: Crude oil or natural gas without appreciableamounts of sulfur or sulfur compounds.

Tap End Studs:Q & A 27

Q & A 51

Stud bolts threaded on each end, with anunthreaded portion on the body center diameter.The thread length dimension on one end controlsthe depth of engagement of that end into a tappedhole, and also controls the extension length of the

stud beyond a Studded Flange Face (See PDFfile AWHEM document TR9601 for tap end studdimension information).

Target Flange: See Flange, Target.

Tee: Any Fitting with three connections in the same

plane with two of these connections forming an in-line Run. A Tee may have a fourth outlet not in thesame plane as the run.

Teflon: Fluoropolymer Coating.


Tensile Strength: Also, Ultimate Strength; The breaking strength of aMaterialSpecimenwhen subjected to a stretching
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orce su c en o pu apar , usua y expresse nksi.

Tensile Test" A test performed on a MaterialSpecimenby pulling

it to failure (separation) and measuring the resultsin terms of Ultimate Strength, Yield Strength,Elongation, and Reduction of Area.

Tension: For bolts, the amount of stretching force placed into

a bolt by the tightening of the nut(s), usuallymeasured in pounds per square inch (psi).

Test Flange: See Flange, Test.

Test Port: See Port, Test

Test Pressure: See Pressure, Test

Thermal History: A record of the cycles of heating and cooling

performed on metal Material for the purpose ofproducing specified conditions and properties inthe material.

30 M: An abbreviation for 30,000 pounds per square inch

(psi) Maximum Service Pressure.

3M: An abbreviation for 3,000 pounds per square inch(psi) Maximum Service Pressure.

35K: An abbreviation adopted on this Web Site for 35,000 psi, minimum Yield Strength in relation toLine Pipe.

36K: An API Spec 6A abbreviation for 36,000 psi,minimum Yield Strengthfor Material.

Thread Anchored Studs: Studs screwed into tapped bolt circle holes in a

flange face. See Tap End Studs.

Top Connector: The Top Connectorof a Christmas Treethat allowsaccess to the full bore of the valves. Usually aflange bottom and union top configuration with a

cap and Gagetap. Operators may also identify this

unit of equipment as a Bottom Hole Test Adapter, aTree Cap or a Tree Top.

Torque: See Bolt Torque.

Torque Wrench: A wrench for tightening nuts that incorporates ameasuring means, usually expressed in FootPounds. See Bolt Torque.

TPI: Threads per Inch.

Transition Piece: In the past, API Spec 6A specified weld end
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re ucers a a ap e e we nec s oflanges to standard pipe sizes and schedules. APIno longer specifies transition pieces in API Spec6A. See Concentric Reducer.

Tree Cap: See Top Connector

Tree Top: See Top Connector

Trim: A general term used to describe the metallurgy andother material considerations used when specifyingpressure control equipment, including internal parts,for use in particularly corrosive environments. e.g."H2STrim."

Triple Extra Strong:(XXXS)(XXXH)

Also, Triple Extra Heavy; An uncommondesignation of pipe with a wall thickness threetimes that of extra heavy pipe. This pipe does notappear on standard pipe dimension charts. SeeCarbon Steel Pipe Dimensions and Weights for

commonly available sizes.

Tubing: Pipe suspended in a well bore, inside the casing,used to produce fluid or gas from the well.

Tubing Head: A single unit of equipment attached above theCasing Headand the smallest CasingString, usedto suspend and seal the production Tubingstring.

Tubing Head Adapter: A single unit of equipment attached above the

Tubing Head, used to join the tubing head to theChristmas Tree.


22 RC:See all hardness

related definitions

22 RC, 99 RB, 237 HBW (read 235 in table), and248 HV represent the important upper hardnesslimit for non austenitic steel for H2S service

specified in NACE MRO175 and referenced in APISpec 6A. Some authorities may offer slightlydifferent equivalent hardness numbers.

2H, 2HM: A short term form of expression for ASTMspecification for nuts, A194, used with API flangebolts. 2H nuts have standard service and lowtemperature application. When specifications

require B7Mor L7Mstuds, use 2HM nuts.

Ultimate Strength: See Tensile Strength.

Ultrasonic Testing: A method of non-destructive examination of solid

metal bodies utilizing high-frequency sound wavesthat allows the discovery and identification ofinternal anomalies by measurement of the reflection
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o e soun waves. noma es, n s case,defined as any interruption of regularity.) Thismethod of inspection requires special calibrationsamples for the type of material and shapeexamined. Standards define anomalies discovered

by this method as acceptable or unacceptablebased on size and location.

UN: National Coarse threads, in form and pitch, but

outside the Unified System, e.g. 1" x 8 TPIthreadsfall within the UNCSystem, 1-1/8" x 8 TPI threadsand all larger bolts threaded 8 TPI fall outside theUnified System, and carry the designation 8UN.

UNC: Unified National Coarse. The most common

standardized inch bolt thread for heavy dutyfasteners used for rapid assembly.

USA, Made in: See Made in U.S.A.

Valve: A unit of pressure controlling equipment with a bore( Run ) between End Connections containing a

closing mechanism to stop and seal any flowthrough the bore.

Velocity, Fluid: The speed, usually measured in feet per second,that fluid passes through the inside of a pipe or

tube.

Volumetric Examination: A nondestructive means of examining Material

throughout its volume (or section) for the purpose ofdetecting any internal Discontinuities that mayrequire evaluation by references to AcceptanceCriteria.

Washers, Spherical: Washers, designed for use in pairs (2), one havinga concave face on one side, and the other having aconvex face. These washers, nested together witha nut, allow the nut bearing face to make a 100%flat contact against the load bearing surface underthe nut, when the nut and equipment surfaces are

not parallel.


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Wear Bushing: A removable insert used inside a Casing HeadorCasing Spoolduring drilling operations to preventdamage to casing suspension and sealing

surfaces.

Weld Inlay: See Inlay.

Weld Neck: An extended prolongation on a flange or otherfitting with a bevel prepared for butt weldconnection to pipe or another fitting with a similar

beveled prolongation.

Weld Overlay: See Overlay.

Welding Procedure

Specification:(WPS)

A written document giving all necessary

parameters and directions to make production orfield welds meeting specified requirements. TheWPS includes a reference to the ProcedureQualification Record (PQR). Welding procedure

performance assumes welding by a QualifiedWelder. ReferenceASMESEC. IX ART. II

Wellhead: All of the equipment attached above the Casingused to control a well. That portion of the completedwell at, and above, the ground surface or sea floor.

Well Wetted: Any part of pressure control or pressure containing

equipment that has contact with pressurized wellfluid.

Wing Unions: See Hammer Unions.

Withdrawn: Industry standardized products or equipmentdocumented in once published specifications thatthe issuing Standardsorganization has declined toreaffirm.

WN: When applied to flanges, this means: Weld Neck.

WNRF: When applied to flanges, this means: Weld NeckRaised Face.

WNRTJ: When applied to flanges, this means: Weld NeckRing Type Joint.

Working Pressure: See Maximum Service Pressure.

Workover: The process of re-entering an existing well toperform a remedial action that will restore orimprove the commercial production of oil and/orgas.
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Workover Rig: A specialized assembly of machinery, usually as aself propelled unit, that can perform re-entry of

existing oil and/or gas wells. The unit has hoistingcapability and can remove and reinstall the wellproduction tubing and perform other services.

XH: See Extra Strong.

XXH: See Double Extra Strong.

XXXH: See Triple Extra Strong.

XS: See Extra Strong.

XXS: See Double Extra Strong.

XXXS: See Triple Extra Strong.

Xylan: See Fluoropolymer Coating.

Yield Strength: The stress (load) at which a Materialelongates orstretches enough that after removal or release ofthis stress the material will not return to its originallength or size, usually expressed in ksi.

0: See Zero.

Zero: Also, 0; Indicates the absence of any amount inmeasurement. Designates the freezing

temperature of water on the centigrade scale.

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CONTACT:

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API Related, Oilfield Pressure Control Equipment, Terms and Definitions, Glossary