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GENERAL   Revised: 09/12/2014

Oilfield Glossary:
Terms and Definitions

To help visitors, many words below which name oilfield products manufactured by WOODCO USA have links to illustrations and additional information shown in WOODCO USA online catalogs or other sections of Web Site Tools.

Remember, "Whatever you say about a thing, or however you describe it, you have 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 

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(ABS) American Bureau of Shipping:
See also, Certifying Authority.

A well-known Certifying Authority organization that may be engaged to certify oilfield equipment components and systems. They can verify equipment designs, witness manufacturing processes, and review and stamp documents as in compliance with industry standards and regulations.

Acceptance Criteria: (General)

Defined limits placed on the characteristics of materials, products, or services. Visually stated in referenced industry specifications and standards

Acceptance Criteria: (NDT)

Reference documentation and/or illustrations that allow comparison of Indications or Discontinuities found during Nondestructive Testing to 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 a Double Studded Adapter (DSA), or a Single Studded Adapter (SSA).

Adapter Spool:

A unit of pressure control equipment with a body and two different end connections used to connect together other pieces of equipment that could otherwise not connect. Sometimes used instead of a Double Studded Adapter because at least one of the units to which it connects has a studded flange connection.

American Made:

See Made in U.S.A.

Annular:

Refers to the area of space between the inside diameter of a drilled or cased hole and a secondary string of pipe suspended inside this space.

ANSI  (ASA)

American National Standards Institute. An organization formerly known by the name American Standards Association (ASA). This organization sets standards for the ANSI B16.5 Blind, Weld Neck, and Threaded Flanges commonly used in refineries and process industries.

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

API

American Petroleum Institute. The organization that develops and publishes API specification documents.

API Flanges

The flanges specified in API Spec 6A and API Spec 17D. All of these flanges seal with Metal Ring Gaskets. For flange sizes and dimensions, see Flange Slide Rule Program.

API Monogram:
(Why you should
look for the API Monogram)

A registered trademark of the American Petroleum Institute (API). Qualified licensed manufacturers may apply the API Monogram along with their license number, as a mark onto product or equipment that serves to certify that the product or equipment meets the requirements of API published 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 and nuts used to connect flanges and clamps. Do not use compound made to this specification for rotary shoulder connections.

API Spec 6A:

Also, ISO 10423; The American Petroleum Institute publication that serves as the industry Specification for Wellhead and Christmas Tree Equipment. Those companies granted a license from API may apply an API Monogram mark, along with their license number, to products which they have made in compliance with this specification.

API Spec 16A:

Also, ISO 13533; The American Petroleum Institute publication that serves as the industry Specification for Drill Through Equipment. Those companies granted a license from API may apply an API Monogram mark, along with their license number, to products which they have made in compliance with this specification.

API Spec 16A Clamp:
Photo

A device, serving as a fastener, designed to mate with and Make-up to seal, API Spec 16A designated hubs.

API Spec 16A Clamp Hub:
Photo

An end connector specified in API Spec 16A that joins with a matching hub and secures with a Clamp.

API Spec 17D:

The American Petroleum Institute publication That serves as the industry Specification for Subsea Wellhead and Christmas Tree Equipment. Those companies granted a license from API may apply an API Monogram mark, along with their license number, to products which they have made in compliance with this specification.

ASME:

The American Society of Mechanical Engineers. This organization provides standards and specifications for pressure containing equipment and piping, at ambient and high temperatures.

ASTM:

American Society for Testing and Materials. An organization providing a vast array of specifications for test methods and materials, frequently referenced by other standards organizations.

Austenitic Stainless Steel:

300 series stainless steel with a chemical composition 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 out in API Spec 6A for standard service flange bolting. If B7M appears, it means B7 in a Modified condition with controlled hardness in the bolt (and a 2HM nut) for sour service exposed bolts.

Balance:

Also, Fluid Balance; That condition when the fluid Head in a well bore produces sufficient pressure inside the well bore to equal the pressure of the production zone and stop the outflow of fluid or gas from that zone.

Bell Nipple:

An upward pipe extension above the uppermost BOP, used to discharge returning drilling mud to the shakers, separators, and pits during drilling operations. The "Bell" term derives from the bell mouth usually fabricated on its upper end, See Flange, Bell Nipple.

BHN:
See all hardness
related definitions

An Abbreviation for Brinell Hardness Number. Now abbreviated HBW.

BHTA:

An Abbreviation for Bottom Hole Test Adapter. See Top Connector

Blast Joint:

For Choke Manifolds, see Blast Spool. For tubing strings in wells, the term Blast Joint applies to a piece of heavy walled tubing, run in the tubing string and positioned across from a perforated interval to resist erosion caused by high velocity production fluid coming from that zone, thus prolonging the life of the completion.

Blast Spool:

For Choke Manifolds, this term applies to a specially constructed Spacer Spool attached directly to the outlet connection of a Drilling Choke where high velocity fluid erosion may occur. Manifold designers build this spool with the maximum practical wall thickness and sometimes specify an erosion resistant liner for this spool.

Bleed Ring:

Another name for a Instrument Flange, a flange with bolt holes drilled through, or studded, with sealing surfaces on both sides and a tapped hole for sampling.

Blind Flange:

See Flange, Blind.

Blowout Preventer:
(BOP)

A unit of equipment, installed singularly or as a part of an assembly, attached to the Wellhead to control and/or contain well pressure occurring inside the Casing during Drilling, Workover, or Snubbing operations.

BOP:

An Abbreviation for Blowout Preventer.

Body:

The portion of a unit of pressure control equipment between separated end connections.

Bolt Circle:

The theoretical circle inscribed by the center point of a series of holes, drilled equally spaced, near the mid circumference of a flange.

Bolt Tension:

That energy achieved by applying Torque to nuts on bolts providing the compressive force necessary to hold connections in contact under pressure or load.

Bolt Torque :

That rotational force applied to nuts on stud bolts to tighten and apply Tension to the bolts in order to hold flanges or other connections in Make-up. This force 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 joined flanges or other Connectors.

Brinell Hardness:
See all hardness
related definitions

Now abbreviated HBW. A designation of hardness, usually of steel, performed by pressing a 10 mm spherical tungsten carbide ball against a clean prepared surface using a 3000 Kilogram force, producing an impression, measured and given a special numerical value. This numerical value relates to steel tensile strength. API Spec 6A specifies minimum Brinell Hardness requirements for different material designations. NACE Standard MR0175 references maximum hardness in determining steel’s suitability for use in H2S Service.

Buffer Chamber

Also, a Header; Typically, a fabricated pressure vessel with multiple inlets and outlets, used to contain and direct the discharge from Chokes in a Manifold system. An alternate method of buffer system construction allows the use of non-welded components.

Burn Through

A term used to describe an undesirable event during welding when the welding arc unintentionally burns trough a thin wall, or weld joint root, causing unacceptable irregularities on the reverse side (or the I.D.) of the weld. Excessive metal on the I.D. of a pipe butt weld joint may interfere with the passage 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 having specially prepared surfaces that makes a Full Penetration Weld possible, usually by leaving a small gap between the adjacent pieces that deposited weld metal will bridge, fill, and close.

BX:

See 6 BX

Carbon Steel

An iron based metal with only carbon and manganese deliberately added to specific limits. Other elements residual, except for small quantities added for deoxidization or to control the effects of sulfur.

Casing:

Pipe used to line the bore hole of a well.

Casing Head:

 

A single unit of well control equipment (usually flanged) attached to the upper end of surface casing, allowing the attachment of Blowout Preventers during drilling, and later suspending and sealing a secondary string of casing set inside.

Casing Spool:

A single unit of well control equipment attached above the Casing Head, used to suspend and seal a secondary casing string.

Cast Steel:

Steel formed by pouring molten steel  into a mold to produce 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.

Certifying Authority
(Oil Industry): 

An independent organization that can be engaged to provide certification indicating that identified equipment complies with industry requirements and specifications. The certifying authority shall be recognized by industry regulators and those engaging them as qualified to review designs, witness processes and tests, and review and approve documents verifying equipment compliance with applicable specifications and requirements. They shall not have involvement in manufacturing or producing oilfield products, or be affiliated by combined ownership with any organization involved with manufacturing, drilling or producing related to the oilfield. Currently (2014), the best known Certifying Authority organizations are Det Norske Veritas (DNV) and American Bureau of Shipping (ABS), many other organizations may also provide equipment certification.

Charpy V-Notch Test:
(CVN)

A test performed at a specified temperature by swinging a calibrated falling pendulum (hammer) fracturing (breaking) a specifically configured Specimen of Material and  measuring the force required, usually expressed in foot pounds.

Chemistry:

The chemical composition of Material. The expression of the elemental composition of material by percentage of weight for each measured chemical element.

Choke:

Also, Choke Valve; A unit of pressure control equipment used to restrict and regulate the flow of well fluids to maintain a desired pressure and flow rate. Chokes have hardened internal expendable parts specifically designed to resist erosion caused by high pressure, high velocity fluid. Often used as part of a Choke Manifold (also see Drilling Choke) or Christmas Tree.

Choke Manifold:

An assembly of valves, Fittings and Chokes arranged to regulate and control the flow of high pressure fluid from a well bore.

Christmas Tree:

An assembly of equipment topping off the Wellhead, including valves, Fittings, Chokes, Top Connectors, 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 friction between two bodies and the force pressing them together.

Coining:

The condition of bringing metal surfaces of differing hardness so tightly together that the softer surface deforms to match the harder surface exactly in shape and finish. See Intimate Contact.

Combination Adapter Ring Gasket:

A uniquely configured Ring Gasket that allows two flanges with ring grooves of different Pitch Diameters to join and seal when Made-up.

Combination Bolts:

Those special bolts made to join flanges of different Working Pressures, having a different diameter on each end to correspond with the bolt holes in each respective flange. See Cross Over Connections for a full explanation.

Combination Ring Gasket:

A specially configured Ring Gasket that allows two flanges with Ring Grooves of different width and depth 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 a smaller size on each end. The ends may have pipe threads 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 pressure containing / pressure controlling equipment that allows a mechanical joint that can provide a pressure seal: Flange, Hub, Union, etc., that does not seal on a thread.

Connector Axial Alignment:

Alignment to within specified tolerances of the connector centerline, to the centerline of the connector at the opposite end of the equipment unit.

Connector, Loose:

Any flange, hub, or Other End Connector, not integral to a body of an identified piece of equipment.

Connector Parallelism:

A measure of the connector face (or plane) with respect to the connector face at the opposite end of the equipment unit; e.g. do the connectors at opposite ends of a spool center on the same axis and do their faces lay parallel to one another? Operators may assume acceptable parallelism if assembled equipment will pass a drift test. See http://www.woodcousa.com/standoff.htm#Drift.

Corrosion Resistant Ring Grooves:
 

Ring Grooves lined with material resistant to Metal Loss Corrosion. This material is either an austenitic stainless steel or a corrosion resistant alloy, normally 316 SS or 625 Inconel. These groove inlays have nothing to do with H2S service, but serve only to provide protection from Metal Loss Corrosion (rust).

Corrosion Resistant Alloy:
(C.R.A)

Nonferrous alloys where any one or the sum of the specified amount of the following alloy elements exceeds 50%: titanium, nickel, cobalt, chromium, and molybdenum. A Material sometimes used in critical service applications for flanges, bodies, bonnets and other components. Also frequently used as a weld metal overlay for ring grooves to prevent Rust damage between connection make-ups. API requires CRA to appear in the connector marking when the connector  has UNS N06625 inlay in the ring groove.

Corrosion Resistant Material:
(C.R.M)

Generally refers to ferrous or nonferrous alloys which are more corrosion resistant than low alloy steels. This term includes CRA's, duplex, and stainless steels.

Cross:

Any Fitting with four connections in the same plane with two of these connections forming an in-line Run.  Crosses may have more than four connections.

Cross-over Fitting:

Any pipe fitting, or similarly configured part, having two different end connection types, e.g. line pipe X 8R Tubing Threads, male or female either way, and various sizes and combinations of union connectors, female end and male end with nut, etc.

"Cross Standard” Adapter:

Any Adapter Flange, Adapter Spool, or Cross-over Fitting with connections specified in two different industry standards when those standards have no reference to one another. Typically, Cross Standard adapters may have API X ASME flange connections (studded adapter or flanged adapter spool), API flange X union (female end or male end with nut), or ASME flange X union (female end or male end with nut)

Country of Origin:

That country within which 75% or more of the manufacturing costs of a product item incur. See also Made in U.S.A.

Deep Ring Grooves:

Now obsolete or withdrawn ring groove specifications that allowed face to face contact on Made-up hubs or flanges when using RX ring gaskets. See SR ring grooves.

Discontinued:

Industry standard products or equipment that the issuing standards organization has announced it will no longer include in its published specifications.

Discontinuity:

A location, internal or external, where the structural nature of Material (or a weldment) has an interruption of its normal or continuous regularity. A place where metals exhibit some mechanical, physical, or metallurgical irregularity that requires evaluation by reference to Acceptance Criteria.

Diverter:

A specialized Annular Blowout Preventer used, in conjunction with large diameter flow valves, to close and divert shallow gas encountered during drilling operations.

Domestic Made:

See Made in U.S.A.

(DNV) Det Norske Veritas:
See also, Certifying Authority.

A well-known Certifying Authority organization that may be engaged to certify oilfield equipment components and systems. They can verify equipment designs, witness manufacturing processes, and review and stamp documents as in compliance with industry standards and regulations.

Double Extra Strong:
(XXS)
(XXH)

Also, Double Extra Heavy; A designation of pipe with a wall thickness twice that of Extra Strong Pipe. See Carbon Steel Pipe Dimensions and Weights for commonly available pipe sizes.

Double Studded Adapter:
(DSA)

Q & A

A flange with a through bore and a ring groove on each side, drilled and tapped bolt circles on both sides and Tap End Studs complete with nuts installed on both sides. Usually the two sides are different in size and/or pressure rating. Usually used to adapt between different flange end connections that would otherwise not connect.

 

Drift:

A gauge of special dimensions used to pass through the Run of pressure control equipment to demonstrate that the Run bore will pass working tools. Also, the act of passing this gauge through the bore.

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, used as part of a Choke Manifold.

Drilling Rig:

The entire collection of machinery and equipment brought together as a unit and used to drill and set Casing for an oil or gas well. An operating drilling rig includes Blowout Preventers and drill pipe.

Drilling Spool:

Also, Mud Cross; A unit of equipment used with Blowout Preventers to space pieces of equipment apart and provide outlets to attach lines extending to Choke and Kill Manifolds.

DSA:

An abbreviation for Double Studded Adapter.

Dual Flanges:

See Segmented Flanges.

Ductility:

A property of Material that allows it to yield or "bend before breaking."  Technically expressed by measurement records of Elongation and Reduction of Area determined 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 of temperatures.

Elongation:

That amount that a Material Specimen will stretch before fracture (separation). Usually expressed as a percentage of the original length.

End Connection:

That connection on either end of the Run (through the central bore) of pressure control equipment.

Extra Strong:
(XS)
(XH)

Also, Extra Heavy; A designation of pipe wall thickness specified  in API Spec 5L in addition to many other pipe  wall thicknesses. See Carbon Steel Pipe Dimensions and Weights for commonly available 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 fabricated equipment may contain pressure or provide structural support for pressure containing equipment. See One Piece Construction for comparison.

Figure 1502:

A term, preceded by an inch size, describing a specific union design widely used on flange by union adapters.

Figure 2202:

A term, preceded by an inch size, describing a specific union design widely used on flange by union adapters

Fitting:

A unit of pressure containing equipment designed to fit between other equipment for the purpose of adapting or arranging that other equipment to facilitate pressure control. See Tee or Cross.

"5 Bolt" Flanges:

See Segmented Flanges.

5 M:

An abbreviation for 5,000 pounds per square inch (psi) Maximum Service Pressure.

Flange:

A single disc or a protruding disc extension on a body with holes to accept bolts or with holes drilled and  tapped into its surface with Tap End Studs installed, with a sealing means, used to join pressure containing equipment.

Flange, ANSI:

A flange specified in American National Standards Institute published standards.

Flange, API:

A flange specified, now or in the past, in American Petroleum Institute published standards.

Flange, Adapter:

Any flange that will connect between two other flanges that would otherwise not connect. Usually a Double Studded Adapter (DSA), or a Single Studded Adapter (SSA).

Flange, Bell Nipple:

The Flange attached to the Bell Nipple used to secure 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 equally engaged on both ends of the bolts. Begin tightening with wrenches, choosing one bolt first, and then choosing the bolt 180° opposite second. Continue tightening the bolt at 90° and then the one 180° from that. Then step over one bolt from the first bolt tightened (decide for yourself clockwise or counter-clockwise) and continue the same pattern as with the first four. Proportion the tightening so that full tightening takes 4 to 5 passes around the full set of bolts. For sequence diagrams for most flanges, Click here.

Flange, Blind:

A flange with no center opening, designed to close off an outlet or end connection.

Flange, Companion:

A loose, Open Face Flange, usually threaded, but may have a Weld Neck or Blind configuration.

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 full surface flat face.

Flange, Gauge:

See Flange, Test

Flange, Instrument:

(1) An equipment piece usually made as a Spacer Flange with a ring groove on both sides to go between two other flanges, with special Tapped Connection Ports through its side (O.D.) into its bore, to facilitate the injection or sampling of fluid or the measurement of pressure.

(2) A Special Flange Adapter, also known as a Transmitter Flange, having 2 sides, one side having a single flange face, either studded or open face, and the other side having 2 or more studded flange faces, all faces with bores interconnected. Usually used to connect pressure gauges and pressure transducers to a Choke Manifold assembly.

Flange, Integral:

A flange made as part of a Body or attached to a body 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 Diverters in 30" 500 and 30" 1000 psi working pressure.

Flange, Open Face:

A flange connection with through bolt holes. An open face flange will mate with another open face flange or with a Studded Face Flange.

Flange, Outlet Connection:

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

Flange Parallelism:

See Connector Parallelism.

Flange, RTJ:

A flange that utilizes a Ring Gasket has the designation "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 working pressure.

Flange, Spacer:

A flange, made with a ring joint connection on both sides, 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 and tapped into its face so as to accept Tap End Studs  (e.g. the connections on a Studded Cross). A studded face flange will mate only with an Open Face Flange.

Flange, Target:

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

Flange, Test:

A flange, similar to a Blind Flange, with a tapped port in its center or side to allow application of pressure or attachment of a gauge.

Flange, Threaded:

A flange with an internal (see Flange, Companion) or external  thread opposite its Ring Groove side to mate with standard threaded pipe.

Flange, Transmitter:

See Flange, Instrument

Flange, Weld Neck:

A flange with a butt weld neck for welding attachment to pipe or tubing. Material may vary from that required for Integral Flanges in order to facilitate field welding.

Flat Face Flange:

See Flange, Full Face.

Flowline:

Any line of  pipe, that contains and controls the flow of  fluid.

Fluoropolymer Coating:

A specialized coating that manufacturers may use on bolts, nuts, and other surfaces that need characteristics of low friction, wear resistance, and protection from corrosion; often described as Xylan or Teflon coating.

Foot Pounds:
(FT/LBS)

A term usually used to express the amount of rotational force (Torque) applied to nuts on stud bolts. "One Foot Pound" equals the force of one pound of pull on a wrench with a handle that extends 12 inches from the center axis of a bolt and nut upon which the force acts. See Bolt Torque and Torque Wrench.

Forged Steel:

Steel, plastically deformed and shaped, usually when hot, using compressive force to breakup and close any internal Discontinuities.

Forging:

See Forged Steel.  Also, the act of using compressive equipment (presses or hammers) to plastically deform steel into a desired shape.

4130:

A low alloy steel containing molybdenum and chromium as strengthening agents. The carbon content is nominally 0.30% and with this relatively low carbon content the alloy is excellent from the fusion weldability standpoint. The alloy can be hardened by heat treatment.

4140:

One of the chromium, molybdenum, manganese low alloy steels noted for toughness, good torsional strength and good fatigue strength after heat treatment. The carbon content of 0.40% makes this steel less easily 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 between adjacent pieces, the weld metal extending through the entire wall.

Gage:

Also, Gauge;  A preset device for determining the relative 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 to measure pressure within a pressure containing or controlling system.

Gauge:

See Gage.

H2S:

An abbreviation for the chemical Hydrogen Sulfide.

H2S Service:

Short for Hydrogen Sulfide Service (HSS). A term used to designate that equipment material specifications meet the requirements of NACE Standard MR0175, for use in controlling fluid containing partial pressure (some percentage) of Hydrogen Sulfide.

Hammer Unions:

Also, Wing Unions; Connectors that allow quick make-up and break-out of pipe and fittings used primarily in temporary flow-lines. Any connected Hammer 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 fits over the male connector and screws onto the female connector holding the two connectors together, achieving a seal.

Some Hammer Unions contain an elastomeric secondary 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 to tighten 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, as well as indicating Ultimate Strength. Most commonly expressed as Brinell Hardness and Rockwell Hardness. ASTM E140 provides a guide for comparing hardness determined by different methods and expressed on different scales.

Head:

The standing column of fluid in a well bore.  The measure of fluid pressure at the bottom of a column of fluid in a well bore or in any vertical fluid containing pipe or system.

Header:

See Buffer Chamber.

Heat Affected Zone
(HAZ)

That part of the base metal formed as a narrow band immediately adjacent to deposited weld metal, affected by welding heat input but not melted.

Heat Treatment:

Heating and cooling metallic Material in such a way as to produce selected and intended conditions and properties in the material. This process affects Tensile Strength, Yield Strength, Elongation, Reduction of Area, and toughness (usually measured as Impact Strength).

HBW:
See all hardness
related definitions

Abbreviation for Brinell Hardness, taken using a carbide ball indenter.

HRB:
See all hardness
related definitions

(Sometimes RB) An abbreviation for Rockwell Hardness measured on the B scale. The 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 Rockwell Hardness measured on the C scale. The abbreviation 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 another method of testing by indenting the test material under a specified load and measuring the size of the indention and comparing it to a number table. This method has gained greater use in testing of weld samples to meet NACE requirements.

Hydrotest:

Also, Hydrostatic Test; a pressure test conducted by pumping a fluid (usually water) into a closed vessel or equipment system until the pressure reaches a specific level. The test consists of holding this pressure for a specific period of time without observed leaks or pressure decline on the indicating 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 these steels exceeds a hardness of 22 Rockwell C.

I.D.

An abbreviation for Inside Diameter.

Impact Strength:

The amount of energy required to fracture (break) a Specimen of Material using an impact blow, usually performed 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 used to impress an indentation into the surface of steel (or other metal) parts in order to obtain a Hardness measurement of that part. See HBW, HRC, and HRB.

Indication:

A term used in magnetic particle testing to identify locations found that require evaluation by references 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. Frequently referring to Corrosion Resistant Alloy weld metal deposits in oversize grooves later machined to accept Ring Gaskets.

Intimate Contact:

The condition of bringing metal surfaces of matching shape and finish into contact with such force as to leave no space or gap. See Coining.

Integral:

Made as a single unit. Usually referring to connectors (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 for end and outlet connectors.

International Standards Organization

Abbreviated ISO, this standards organization has taken on a partnership with the American Petroleum Institute to establish equipment  and quality specifications. ISO now issues these specifications and the API adopts them back and further supports these specifications with the API Monogram program.

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 to bring a well into Balance and stop the outflow from the well.

ksi:

Abbreviation for one thousand pounds per square inch 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 out in API Spec 6A for low temperature bolting. If L7M appears, it means L7 in a Modified condition with controlled hardness in the bolt (and a 2HM nut) for sour service exposed bolts.

Lack of Full Penetration:

This term describes a condition observed in a weld joint when the weld metal does not uniformly continue from the root of the weld to the final cover pass, most often observed at the root of a butt weld.

Line Pipe:
(LP)

Pipe generally intended for use in the oil and gas industry for the conveyance of oil and gas under pressure, or for a variety of industrial applications. API Spec 5L and 5LX specify this pipe. For commonly available sizes of line pipe, see Carbon Steel Pipe Dimensions and Weights on this web site.

Liquid Penetrant Test:

A method of surface inspection to detect indications not visible to the unaided eye on non-magnetic Materials, or to prove or disprove questionable Magnetic Particle indications.

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 have entered surface discontinuities.

  • Allowing time for the developer to draw out any penetrant to stain the developer coating.

  • Observing any colored surface stains and comparison of any indications seen to Acceptance Criteria for acceptance or rejection of the inspected part.

Loop, Pressure Controlling:

Any assembly of valves and fittings connected to a Blowout Preventer stack to allow pressure equalization and/or bleed down before opening rams. Most commonly used during Snubbing operations.

Loose Connector

See Connector, Loose.

Loose Flange

See Connector, Loose.

Low Alloy Steel:

An iron based metal alloy with small amounts of other elements added in specifically measured amounts to produce a desired response to Heat Treatment cycles and achieve intended mechanical properties..

LP:

An abbreviation for Line Pipe.

Lubricator Adapter:

See Top Connector.

M:

An abbreviation for "000 psi" in designating working pressure in equipment marking.

Manufacturers apply much of the marking on pressure control equipment by striking hand stamps, with a hammer, to apply individual numbers and letters. The Roman numeral for one thousand (1,000), M, provides a simple symbol to use and save the space used by 3 zeros and 3 letters when hand stamping parts, e.g. 10M, rather than 10,000 psi. This same term of abbreviation has 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 material melted in the U.S. as Made in U.S.A., and any product made from that steel and sold by WOODCO USA as Made in U.S.A.

or

2. WOODCO USA will make an unqualified Made in U.S.A. claim (U.S. origin claim) if, at the time it makes the claim, it possesses credible evidence that: (1) U.S. manufacturing costs constitute 75% of the total manufacturing costs for the product; and (2) the product was last substantially transformed in the United States. 75% of total manufacturing costs shall include all costs paid by WOODCO USA to all USA vendors, for material made in USA or outside services performed in USA, and best estimates of internal manufacturing costs, but not including calculated mark-up.

Made-up:

Refers to a completed connection after joining flanges or other connectors to achieve a seal.

Magnetic Particle Inspection:

A non-destructive surface inspection process for ferromagnetic materials (materials that will attract a magnet) performed by magnetizing the material, applying a fine iron powder, either dry or in liquid suspension, to the magnetized surface, and observing the collection of this powder along any breaks in the magnetic field that might represent fractures or other irregularities in the surface. See Indication.

Make-up:

The act of joining flanges or other connectors to achieve a seal.

Manifold:

An assembly of valves and Fittings arranged to regulate 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 documents for pressure control equipment, that identifies the Steel or Corrosion Resistant Alloy used for flanges, bodies, bonnets and other components specified.

Mechanical Properties:
See all hardness
related definitions

Measured aspects of Material used to describe its elastic and inelastic reaction to applied force; These may include Tensile Strength, Yield Strength, Elongation, Reduction of Area, Impact Strength and Hardness.

MegaPascal
(MPa)

A basic unit of pressure or tension measurement in the 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 converts the metal to an oxide or otherwise gradually consumes the exposed surface of the metal. Localized metal loss corrosion may appear as "pitting."

Microstructure (Steel):

The existing described order and arrangement of constituents of steel Material, as observed on a prepared sample through a microscope. For more on 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 Association of Corrosion Engineers defining the specific limits of chemistry, hardness and microstructure of Materials used to make equipment to contain or control well production fluids that include hydrogen sulfide.

NC:

National Coarse, See UN and 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 a designation only, not the actual measurement. (e.g. 2 inch nominal pipe measures 2-3/8 inches outside diameter and no standard Schedule of the 2 inch pipe has a 2" inside diameter).

Nondestructive Evaluation :
(NDE)

Also, Nondestructive Examination or Nondestructive Testing; these terms identify a group of activities using various methods to find, locate, measure, or determine something, without damage, about Material or equipment, that allows an investigator to decide if any identified characteristics or conditions constitute rejectable flaws.

O:

See Zero.

Obsolete:

Industry standardized products or equipment that the issuing standards organization has replaced with  updated products or equipment. Manufactured goods the manufacturer has replaced with updated goods.

O.D.

An abbreviation for Outside Diameter.

O.E.C.:

An abbreviation for Other End Connector.

O.E.M.

Original Equipment Manufacturer. Refers to the company which first designed and built equipment or 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 (or assembly) welding performed. Equipment manufactured from one piece may often have weld Inlay or Overlay to prevent corrosion damage to Well Wetted surfaces.

Other End Connector:
(O.E.C)

Any type  of end (or outlet) connector designed to contain pressure, other than those specified in API Spec 6A. An O.E.C. may have any configuration so long as it meets the design and performance requirements of API Spec 6A. Examples include Union and proprietary Lubricator connectors.

Outlet Connection:

Any connection other than an End Connection on a Run. Used to flow fluid or gas into a Manifold or Choke, or used to pump into, for the purpose of injecting fluid or to Kill a well.

Overlay:

Used to describe a form of weld metal deposit where the weld deposit entirely covers a base metal surface.  Frequently referring to Corrosion Resistant Alloy weld metal deposits over Well Wetted surfaces of pressure control equipment to prevent severe corrosion caused by well fluids.

Pack-Off Adapter:

A single unit of equipment used in a wellhead assembly below the Tubing Head to adapt between flange sizes or pressure ratings and provide a seal around a secondary Casing String.

Parallelism:

See Connector Parallelism.

Pitch Diameter:

Specifically of a Ring Groove; The theoretical diameter of the ideal mid point (imaginary circular center line) of a ring groove. Most easily determined by measuring carefully from the inside of the ring groove on one side to the outside of the ring groove on the other side (same as measuring from the  centerline on one side to the centerline of the other side). See Measuring Ring Groove Pitch Diameter.

Port, Test:

A drilled and tapped port in pressure control equipment, or a flange, that penetrates through to the fluid containing bore. For more information, Click Here.

Post Weld Heat Treatment:

See Stress Relief.

Pressure Cut:

The erosion damage caused by high pressure fluid during an extended leak past a sealing surface.

Pressure, Maximum Service:

Also, Working Pressure; the maximum pressure that specific units of equipment should experience in use. API specifies that the manufacturer clearly mark the Maximum Service Pressure (MSP) on each unit of equipment; the equipment pressure rating limited by the lowest pressure connector on the equipment, or the manufacturers design.  For Test Pressure and Working Pressure tests explained, click here.

Pressure, Test:

The hydrostatic pressure applied to equipment to demonstrate the equipment's capacity to hold pressure. A pressure test on existing equipment in the field should equal but not exceed Maximum Service Pressure. The Test Pressure and procedures for new manufactured equipment, or remanufactured equipment, shall comply with that specified by API. For Test Pressure and Working Pressure tests explained, click here.

Pressure Test:

The act of applying fluid or gas pressure inside equipment bodies, or upstream of equipment closure mechanisms, to demonstrate equipment pressure containment integrity or pressure controlling reliability. The term may apply to any application of pressure intended to demonstrate equipment fitness for service. Pressure applied during a pressure test should never exceed specific equipment rated working pressure except in a controlled environment. See the definitions of the terms, Test Pressure and Working Pressure.

Pressure, Working:

See Pressure, Maximum Service.

Procedure Qualification Record:
(PQR)

A written document recording all of the testing utilized to prove the validity of the Welding Procedure Specification (WPS) which references it. The PQR contains actual records of the performance of all variable factors called out in the WPS, as well as, the results of all mechanical, volumetric, and surface tests made on samples of the test welds performed to demonstrate that production welds carried out in conformance with the WPS shall meet the specified requirements.

Qualification of a WPS necessarily requires calibrated welding equipment instruments and meters, a record of the calibration and the reference standard, and the date of calibration and frequency performed. Reference ASME SEC. IX QW-200.2. Also see Qualified Welder.

psi:

An abbreviation for pounds per square inch to indicate 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 requirements for materials and equipment. Other API Specifications include these PSL requirements by reference to API Spec 6A. For more complete information, CLICK HERE.

PSL 1:

Product Specification Level 1, references the minimum level of testing and inspection required for material and equipment as specified in API Spec 6A. For more complete information, CLICK HERE.

PSL 2:

Product Specification Level 2, references a level of testing and inspection requirements for material and equipment alternate to and in addition to PSL 1 requirements 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 material and equipment alternate to and in addition to PSL 1 and 2 requirements as specified in API Spec 6A. For more complete information, CLICK HERE.

PSL 3G:

Product Specification Level 3G, references a level of testing and inspection requirements for material and equipment specified in API Spec 6A as PSL 3, adding the requirement of gas testing of completed equipment units. For more complete information, CLICK HERE.

PSL 4:

Product Specification Level 4, includes all the testing and inspection requirements described in API Spec 6A for PSL 3G, plus additional restrictions on the material qualification and heat treating, and the prohibition of welding except for overlay/inlay of corrosion resistant material. For more complete information, CLICK HERE.

Qualified Welder:

A person who performs welding in accordance with a Welding Procedure Specification and a sample resulting weld has passed all required visual, mechanical and/or volumetric examinations necessary for acceptance. Maintenance of welder qualification requires that the welder performs welding, using the procedure methods and equipment within specified time periods, and maintains records of this performance. A welder so qualified has qualification to use the same and other WPS's utilizing the same welding process, depositing similar metal, using similar calibrated equipment; with the exception of Corrosion Resistant Alloy inlay, which requires separate specific qualification. Reference ASME SEC. IX ART. III QW-304 and QW-305

Qualified Welding Procedure:

A Welding Procedure Specification (WPS) containing a reference to the Procedure Qualification Record (PQR) which demonstrates that the procedure results in the desired properties in 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, use and retain a product, with continued satisfaction. Quality will draw the customer to return again to the provider to get more of the same.

Quality Assurance:

The predicate of quality outcome.

The planning, creation of specifications, choice of inputs, choice of processes (and machines), choice of personnel and training, and continuity of maintenance and management necessary  to produce predictable and desirable product outcomes.

Quality Control:

The examination of quality outcome.

The measurement and inspection activities performed 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 or hexagonal Ring Gasket.  A term used to refer to any ring groove that will accept an R ring gasket.

Raised Face:

Sometimes abbreviated RF. That portion of the face of a flange near the I.D. raised above the remaining face of the flange, providing a sealing surface for a flat gasket or containing a ring groove to affect a seal with a Ring Gasket. API Spec. 6A flanges do not utilize flat gaskets. Only Open Face Flanges sealed with BX ring gaskets must have a raised face, 1/8" minimum height. API Spec. 6A permits the omission of raised faces on all other flange connectors.

Raised Ring Groove:

Identifies flange facing that has a seal groove cut into a raised portion of the flange face closely surrounding the flange bore, required on 6BX and 17D SS Open Face flanges, optional and usually omitted on 6BX Studded Flanges and all API 6B flanges.

RB:

See HRB

RC: See HRC
Reduction of Area:

The amount that a Material Specimen necks down (or becomes smaller in section) as it experiences stretching under a load sufficient to cause fracture (separation). Usually expressed in percentage of the 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 machined into the face of flanges and/or other connectors and provide a seal after Make-Up.

Ring Groove:

A closely dimensioned groove machined into the face of a Connector, designed to accept a Ring Gasket and 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 or position. See Spacer Spool.

Rockwell B Hardness:
See all hardness
related definitions

A designation of hardness of metallic materials measured by pressing a small rounded indenter against a clean prepared surface with a specific force. The machine making the indention also measures the depth of the indention and provides a numerical value for that depth. The Rockwell B scale expresses more accuracy in the hardness measurement of metallic materials softer than HRC 20. To convert hardness numbers between measuring methods and scales, see Hardness Number Conversion Chart.

Rockwell C Hardness:
See all hardness
related definitions

A designation of hardness, usually of steel or Corrosion Resistant Alloys, measured by pressing a specially shaped indenter against a clean prepared surface with a specific force. The machine making the indention also measures the depth of the indention and provides a numerical value for that depth. This numerical value relates to steel Tensile Strength and NACE Standard MR0175 references hardness in determining steel’s suitability for use in H2S Service. To convert hardness numbers between measuring methods and scales, see Hardness Number Conversion Chart.

RTJ:

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

Run:

That passage through a Body, between End Connections, that will pass fluid and working tools.

Rust:

The Metal Loss Corrosion product, iron oxide. The most common form of metal loss corrosion associated 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 R ring grooves in 6B flanges and only RX ring gaskets fit SR ring grooves in API Spec. 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 Pipe has a 4.500 inches outside diameter with a .337 inch wall). See Carbon Steel Pipe Dimensions and Weights.

Seal Contact Area:

Those areas that gaskets seal against in joined connections.

Segmented Flanges:

Sometimes called "5 Bolt" or "Dual" flanges. These flanges connect valves and tubing head adapters on Christmas Trees where 2 producing tubing strings hang inside a single cased well bore. They have a special "one sided" configuration that allows the producing tubing to have a small center to center distance.

Series

A now obsolete term adopted originally by API to distinguish API well head flanges that matched dimensions with ASA flanges. The ASA identified flanges with a number followed by the term "Lb" and API designated flanges of the same dimensions by the term "Series". "Series" flanges having a higher standard working pressure and made of higher strength steel than the standard ASA (now ANSI) flanges.

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

Service:

A term used to denote the suitability of equipment for 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 on each side, with a drilled through bolt circle the same as an Open Face Flange on it's larger side and a drilled and tapped bolt circle on it's smaller side, with Tap End Studs installed.

 

6 B:

A term applied to API Spec 6A flanges which have ring grooves dimensioned to accept R or RX ring gaskets.  API originally specified these flanges in API STD. 6 B. R or RX appears in the prefix of the numbered ring gaskets which fit 6 B flanges.

6 BX :
(or BX)

A term applied to API Spec 6A flanges which have ring grooves dimensioned to accept BX ring gaskets.  API originally specified these flanges in API STD. 6 BX.  BX appears in the prefix of the numbered ring gaskets which fit 6 BX flanges.

60K:

An API Spec 6A abbreviation for 60,000 psi, minimum yield strength for Material, or an abbreviation adopted on this Web Site for 60,000 psi, 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 Blowout Preventers in 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 Blowout Preventers or to connect a Choke Manifold to the well control system.

Specimen :

A sample, usually of Material, shaped and processed 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 of the hub connections which utilize RX ring gaskets. Take special care not to confuse connections with SR ring grooves with those connections that have Deep Ring Grooves previously used in now obsolete or withdrawn flanges or hubs.

SRX:

A Ring Gasket based on RX gasket design but drilled with a special vent hole for underwater (subsea) Make-up.
  

SS Flanges:

API Spec 17D specifies these 2-1/16" through 11" flanges in 5,000 psi working pressure with BX ring grooves, otherwise dimensioned the same as API 6B flanges, manufactured from, or inlayed with Corrosion Resistant Material. For more information, see About API Spec 17D SS and SV Flanges.

SST:

Required by API to appear in the connector marking when the connector has 300 series stainless steel inlay in the ring groove.

Stainless Steel:

An iron based metal alloy with a high chromium content sufficient to reduce or prevent Metal Loss Corrosion.

Standard:
(STD)

A designation of pipe wall thickness intended for ordinary use with water, air, steam and gas as well as plumbing and heating applications. See Carbon Steel Pipe Dimensions and Weights for commonly available pipe sizes.

Standards:

An alternate term used to describe specifications published by an industry organization, a certifying authority, or a government agency.

Stand-off:

The distance between Made-up connection faces utilizing R or RX ring gaskets, measured near the ring groove.

STD:

See Standard.

Steel:

An iron based metal, combined with carbon, manganese, and other constituents as required, to obtain response to heat treat and/or to secure desired mechanical properties.

Stress Relief:

A heat treating process usually used after welding. It involves heating the weld deposit and base metal affected to a suitable temperature and holding this temperature long enough to reduce residual stress. This process, when performed in accordance with a Qualified Welding Procedure, then termed Post Weld Heat Treatment, may also serve to satisfy NACE MR0175 requirements for equipment used in H2S Service.

String:

A term used to refer to a vertical arrangement of pipe suspended in a well bore as Casing, Tubing or drill pipe.

Stud Bolts:
(See Catalog)

Stud bolts for Open Face Flanges that have threads over their full length or may have an unthreaded portion on the central area of the body diameter. (See PDF file AWHEM document TR9601 for 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 land based 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 equipment intended for use on land or above the waterline in offshore applications.

SV Flanges:

API Spec 17D refers to Swivel Flanges (flanges that swivel around a hub) as  "SV Flanges". API specifies these flanges in a limited range of sizes in 5,000 psi and 10,000 psi working pressures. For more information, see About API Spec 17D SS and SV Flanges.

Swage Nipple:

See Concentric Reducer.

Sweet:

Crude oil or natural gas without appreciable amounts of sulfur or sulfur compounds.

Tap End Studs:
Q & A 27
Q & A 51
Q & A 62

Stud bolts threaded on each end, with an unthreaded portion on the body center diameter. The thread length dimension on one end controls the depth of engagement of that end into a tapped hole, and also controls the extension length of the stud beyond  a Studded Flange Face (See PDF file AWHEM document TR9601 for tap end stud  dimension 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 the same plane as the run.

Teflon:

Fluoropolymer Coating.

10 M:

An abbreviation for 10,000 pounds per square inch (psi) Maximum Service Pressure.

Tensile Strength:

Also, Ultimate Strength; The breaking strength of a Material Specimen when subjected to a stretching force sufficient to pull it apart, usually expressed in ksi.

Tensile Test"

A test performed on a Material Specimen by pulling it to failure (separation) and measuring the results in 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), usually measured 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 of producing specified conditions and properties in the 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 to Line Pipe.

36K:

An API Spec 6A abbreviation for 36,000 psi, minimum Yield Strength for Material.

Thread Anchored Studs:

Studs screwed into tapped bolt circle holes in a flange face. See Tap End Studs.

Top Connector:

The Top Connector of a Christmas Tree that allows access to the full bore of the valves. Usually a flange bottom and union top configuration with a cap and Gage tap. Operators may also identify this unit of equipment as a Bottom Hole Test Adapter, a Tree Cap or a Tree Top.

Torque:

See Bolt Torque.

Torque Wrench:

A wrench for tightening nuts that incorporates a measuring means, usually expressed in Foot Pounds.  See Bolt Torque.

TPI:

Threads per Inch.

Transition Piece:

In the past, API Spec 6A specified weld end reducers that adapted the weld necks of 6BX flanges to standard pipe sizes and schedules. API no longer specifies transition pieces in API Spec 6A. See Concentric Reducer.

Tree Cap:

See Top Connector

Tree Top:

See Top Connector

Trim: A general term used to describe the metallurgy and other material considerations used when specifying pressure control equipment, including internal parts, for use in particularly corrosive environments. e.g. "H2S Trim."
Triple Extra Strong:
(XXXS)
(XXXH)

 

Also, Triple Extra Heavy; An uncommon designation of pipe with a wall thickness three times that of extra heavy pipe. This pipe does not appear on standard pipe dimension charts. See Carbon 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 the Casing Head and the smallest Casing String, used to suspend and seal the production Tubing string.

Tubing Head Adapter:

A single unit of equipment attached above the Tubing Head, used to join the tubing head to the Christmas Tree.

20 M:

An abbreviation for 20,000 pounds per square inch (psi) Maximum Service Pressure.

22 RC:
See all hardness
related definitions

22 RC, 99 RB, 237 HBW (read 235 in table), and 248 HV represent the important upper hardness limit for non austenitic steel for H2S service specified in NACE MRO175 and referenced in API Spec 6A. Some authorities may offer slightly different equivalent hardness numbers.

2H, 2HM:

A short term form of expression for ASTM specification for nuts, A194, used with API flange bolts. 2H nuts have standard service and low temperature application. When specifications require B7M or L7M studs, use 2HM nuts.

Ultimate Strength:

See Tensile Strength.

Ultrasonic Testing:

A method of non-destructive examination of solid metal bodies utilizing high-frequency sound waves that allows the discovery and identification of internal anomalies by measurement of the reflection of the sound waves. (Anomalies, in this case, defined as any interruption of regularity.) This method of inspection requires special calibration samples for the type of material and shape examined. Standards define anomalies discovered by this method as acceptable or unacceptable based on size and location.

UN:

National Coarse threads, in form and pitch, but outside the Unified System, e.g. 1" x 8 TPI threads fall within the UNC System, 1-1/8" x 8 TPI threads and all larger bolts threaded 8 TPI fall outside the Unified System, and carry the designation 8UN.

UNC:

Unified National Coarse. The most common standardized inch bolt thread for heavy duty fasteners 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 flow through 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 of detecting any internal Discontinuities that may require evaluation by references to Acceptance Criteria.

Washers, Spherical:

Washers, designed for use in pairs (2), one having a concave face on one side, and the other having a convex face. These washers, nested together with a nut, allow the nut bearing face to make a 100% flat contact against the load bearing surface under the nut, when the nut and equipment surfaces are not parallel.

Wear Bushing:

A removable insert used inside a Casing Head or Casing Spool during drilling operations to prevent damage to casing suspension and sealing surfaces.

Weld Inlay:

See Inlay.

Weld Neck:

An extended prolongation on a flange or other fitting with a bevel prepared for butt weld connection 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 or field welds meeting specified requirements. The WPS includes a reference to the Procedure Qualification Record (PQR). Welding procedure performance assumes welding by a Qualified Welder. Reference ASME SEC. IX ART. II

Wellhead:

All of the equipment attached above the Casing used to control a well. That portion of the completed well 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 well fluid.

Wing Unions:

See Hammer Unions.

Withdrawn:

Industry standardized products or equipment documented in once published specifications that the issuing Standards organization has declined to reaffirm.

WN:

When applied to flanges, this means: Weld Neck.

WNRF:

When applied to flanges, this means: Weld Neck Raised Face.

WNRTJ:

When applied to flanges, this means: Weld Neck Ring Type Joint.

Working Pressure:

See Maximum Service Pressure.

Workover:

The process of re-entering an existing well to perform a remedial action that will restore or improve the commercial production of oil and/or gas.

Workover Rig:

A specialized assembly of machinery, usually as a self propelled unit, that can perform re-entry of existing oil and/or gas wells. The unit has hoisting capability and can remove and reinstall the well production 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 Material elongates or stretches enough that after removal or release of this stress the material will not return to its original length or size, usually expressed in ksi.

0:

See Zero.

Zero:

Also, 0; Indicates the absence of any amount in measurement.  Designates the freezing temperature of water on the centigrade scale.

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