Engineering Glossary & Terms

Quick Reference

A-Z glossary of piping and engineering terminology. Use Ctrl+F (or Cmd+F on Mac) to search for specific terms. Terms with links point to detailed articles on this wiki.

A

Abbreviations

Abbreviation	Full Name
AGA	American Gas Association
AISI	American Iron & Steel Institute
ANSI	American National Standards Institute (formerly ASA)
API	American Petroleum Institute
ASA	American Standard Institute (now known as ANSI)
ASM	American Society for Metals
ASME	American Society of Mechanical Engineers
ASTM	American Society for Testing Materials
AWWA	American Water Works Association

Terms

Term	Definition
Alloy Surcharge	The producer’s selling price plus a surcharge added to offset the increasing costs of raw materials caused by increasing alloy prices, normally based on the LME, London Metal Exchange.
Annealing (Solution Annealing)	The controlled process of heating and cooling a tube to achieve a reduction in hardness. It relieves stresses that have built up during cold working and ensures maximum corrosion resistance. Annealing can produce scale on the surface that must be removed.
As-Drawn Tube	Any tube in any temper other than annealed or heat treated.
Austenitic Stainless Steel	Non-magnetic stainless steels (300 series) that contain chromium (18-30%) and nickel (6-20%) as their major alloying additions. Sufficient to develop and retain the austenitic phase at room temperature. Austenitic stainless steels are the most widely used category of stainless steel.

B

Abbreviations

Abbreviation	Full Name
BALES	Banded lifts of pipe
BAR MILL	Rolling mill where blooms are processed to form billets
BESS	Bessemer
BLK	Black, a term used when O.D. surface of the pipe is protected with a varnish-type oil. Also applies to bare pipe to denote not galvanized
B.O.F	Basic Oxygen Furnace
B.T.U.	British Thermal Unit
BLDS	Bundles practice of packaging pipe from 1/8 inch to 1 1/2 inch. Pieces per bundle vary with size
B.W.	Butt Weld Pipe - See Continuous Weld Pipe
B.W.G.	Birmingham Wire Gauge

Terms

Term	Definition
Bevel	The angle formed between the prepared edge of the end of the pipe and a plane perpendicular to the surface. Standard line pipe bevel is 30 degrees.
Billet	Round solid bar of steel which is pierced to form a seamless tube or pipe.
Bloom	A semifinished hot rolled product produced on a blooming mill.
Brigos Standard	A standard of thread dimensions. Same as American Standard.
Burst Test	A destructive hydraulic test to determine actual yield strength and ultimate strength of seamless and welded pipe.
Bend Tests	Tests used to assess the ductility and malleability of stainless steel tubes subjected to bending.
Bright Annealing	A heat treatment process performed in a carefully controlled furnace atmosphere filled with gases, such as hydrogen or nitrogen, resulting in a clean, scale-free metal surface.
Burst Pressure	The internal pressure that will cause a piece of tubing to fail by exceeding the plastic limit and tensile strength of the material from which the tube is fabricated.

C

Abbreviations

Abbreviation	Full Name
CASING	Pipe used as a structural retainer for the walls of a water, gas, or oil well
C.D.	Cold Drawn - Drawing pipe or tubing through a die to reduce diameter and wall, to obtain closer tolerances, a better finish or higher physical properties
CPLG	Coupling - threaded sleeve used to connect two lengths of pipe
CU	Copper
C.W.	Continuous Weld - method of producing pipe normally in sizes from 1/2 inch to 4 inches
C.W.T.	Per hundredweight

Terms

Term	Definition
Chamfer	A beveled surface to eliminate an otherwise sharp corner. A finishing operation prior to threading.
Chemical Properties	Normally associated with a limited number of chemical elements. Minimum or maximum limits are established in most ASTM and API Specifications.
Chemical Analysis	A report of the chemical composition of the elements, and their percentage that form a stainless steel tube, all is stated on the test certification.
Chloride Stress Corrosion Cracking	Cracking due to the combination of tensile stress and corrosion in the presence of water and chlorides.
Coils	A reel of stainless steel tubes that have been rolled into a coil to facilitate transportation and storage.
Cold Finished Tubes	Hot rolled stainless steel tubes that are annealed and cold worked to produce a higher surface quality and higher strength.
Cold Forming (Cold Working)	Any mechanical operation that creates permanent deformation, such as bending, rolling, drawing, etc. performed at room temperature that increases the hardness and strength of the stainless steel. This production method gives a better control of nominal dimensions, tolerances and surface finish without an additional process.
Concentricity	Used to describe tubing where the center of its inside diameter is consistent with the outside diameter resulting in no variation of wall thickness.
Conduit	Pipe serving as a duct for electrical wiring. Usually supplied in 10-foot lengths, threaded and coupled. Pipe used is normally galvanized, slightly lighter than standard weight with a smooth interior surface.
Corrosion	The attack upon metals by chemical agents converting them to non-metallic products. A film created by the presence of chromium (and often other alloying elements like nickel, molybdenum, titanium and niobium) resists this process.
Corrosion Fatigue	Cracking due to repeating and fluctuating stresses in a corrosive environment.
Corrosion Potential	The potential of a corroding surface in an electrolyte relative to a reference electrode under open-circuit conditions.
Corrosion Resistance	A metal’s ability to resist corrosion in a particular environment.
Cut Length	Pipe cut to a specific length as ordered.

D

Abbreviations

Abbreviation	Full Name
DIA	Diameter
DRL	Double Random Length (35-foot minimum average)

Terms

Term	Definition
Deburring	Removing the subtle ridge from the edge of the tube that results from a cutting operation.
Die Stamping	Permanent marking placed on a pipe as required in some specifications.
Double Extra Heavy	Also known as double extra strong. Available from 1/2 inch to the 8-inch nominal pipe. Wall thickness is twice as heavy as an extra heavy pipe with the exception of 8 inch diameter.
Drifted	Attaining a certain minimum I.D. clearance by pushing a mandrel through pipe or tubing.
Drive Pipe	Pipe used for driving into the ground in water well applications. Supplied with drive coupling.
Ductility	The ability of a material to deform plastically without fracturing. Measured by elongation in a tensile test.
Duplex	Stainless steel comprised of austenitic and ferritic stainless steels that contain high amounts of chromium and nickel. This combination is stronger than both of the individual stainless steels. Duplex stainless steels are highly resistant to corrosion and cracking.

E

Abbreviations

Abbreviation	Full Name
ERW	Electric Resistance Weld Pipe - method of producing pipe normally in sizes from 2 3/8” O.D. through 22” O.D.
E.U.E.	External Upset Ends - used in API tubing and drill pipe

Terms

Term	Definition
Eddy Current Testing	The non-destructive test procedure that examines for outside diameter cracks and burrs.
Electropolishing	An electrochemical method of surface finish enhancement in which the metal to be polished is exposed to a suitable electrolyte, typically an acid solution, while carefully controlled current is passed between the object and a cathode. The object to be polished is the anode, and polishing is accomplished through the uniform removal of surface metal that goes into solution. Surface finish roughness of less than 0.000,010-inch (10 microinches) is attainable.
Elongation	A measurement of ductility expressed in terms of the stretch having occurred over a given length on a standard tensile specimen at the time of fracture, usually based upon an original length of 2 inches.
Erosion	The continuous depletion of a material due to mechanical interaction with a liquid, a multicomponent fluid, or solid particles carried with the fluid.
Expanded Pipe	Pipe which has been enlarged circumferentially by mechanical or hydraulic pressure.
Extra Heavy	Also known as extra strong - pipe with walls heavier than standard weight. Same as schedule 80 in sizes 1/8 inch to 8 inch diameter.
Extrusion	A shaped piece of stainless steel produced by forcing the pre-pipe, bar, or rod through a die of the appropriate shape.

F

Abbreviations

Abbreviation	Full Name
F.O.B.	Free on Board
FRI	Freight

Terms

Term	Definition
Ferritic	Magnetic stainless steels that have a low carbon content and contain chromium as the main alloying element, usually between 13% and 17%. It is the second most widely used stainless steel. Ferritic stainless steels are generally used in automotive trim and exhaust systems, hot water tanks, and interior architectural trim.

G

Abbreviations

Abbreviation	Full Name
GALV	Galvanizing - coating pipe with a protective coating of zinc
G.T.	Gross Ton - 2,240 pounds

Terms

Term	Definition
Grade A or B	Designations used to indicate minimum yield and tensile strengths of steel in seamless and welded pipe.
Grain (Grain Boundary)	The individual crystal units comprising the aggregate structure where the crystalline orientation does not change. The grain boundary is where these individual crystal units meet.

H

Term	Definition
Hardness Test	Hardness testing consists of pressing an indenter into a flat surface under a perfectly controlled load, then measuring the dimension of the resulting indentation. The three methods most commonly used for stainless steel are the Rockwell B, Rockwell C, and Vickers tests. The higher the number, the harder the material.
Heat	A term referring to a batch of refined stainless steel tube; a charged oxygen or electric furnace full of stainless steel. A heat of stainless steel can be used to cast several slabs, billets, or blooms.
Heat-Affected Zone (HAZ)	The part of a metal that is not melted during cutting, brazing, or welding, but whose microstructure and physical properties are altered by these processes.
Heat Number	An identifying number assigned to the product of one melting (e.g.: 721299).
Heat Treatment	Altering the properties of stainless steel by subjecting it to a series of temperature changes. To increase the hardness, strength, or ductility of stainless steel so that it is suitable for additional applications.
Hollow	Seamless raw material supplied for tube processing. This may be in the form of an extrusion or tube reduced product.
Hot Forming	Hot forming operations are used widely in the fabrication of stainless steel to take advantage of their lower resistance to shape change. High temperature reduces their yield strengths, and this results in a marked lowering of the force that is required to bring about plastic movement or flow from one shape to another (hot rolling, hot stretching, etc.).
Hydrogen Stress Cracking	Cracking of a metal resulting from the combination of hydrogen and tensile stress.
Hydrostatic Testing	High pressure water test to predetermine pressures as required by specifications.

I

Abbreviations

Abbreviation	Full Name
I.D.	Inside Diameter - The O.D. measurement less double the wall thickness is the I.D. measurement of a pipe or tube
I.P.S.	Iron Pipe Size - Same as nominal size from 1/8 inch to 12 Inch
ISO	International Organization for Standardization - Prepares specifications. Both Canada and the U.S.A. are ISO members and participate in the ISO specification development

Terms

Term	Definition
Impact Test	Impact testing is used to measure the toughness of a material, corresponding to the energy necessary to cause fracture under shock loading. Low toughness is generally associated with brittle shear fracture and high toughness with ductile plastic tearing.
Ingot	Usually first solid form of steel, suitable for reworking or remelting.
Intergranular Corrosion	Corrosion that occurs at the grain boundaries in austenitic stainless steels that have been heated to and held at temperatures between 850 degrees F and 1450 degrees F. Slow cooling through this range can also result in sensitization to intergranular corrosion. Usually caused by precipitation of chrome carbides.

J

Term	Definition
Joint	A term used to refer to one length of pipe.

L

Abbreviations

Abbreviation	Full Name
LGTH	Length
L.T.C.	Long threads and coupling (OCTG)
L.W.	Lap Weld - an old method of producing pipe 5-inch diameter and over

Terms

Term	Definition
Large O.D. Pipe	Pipe 14 inch O.D. and larger.

M

Abbreviations

Abbreviation	Full Name
MN	Manganese

Terms

Term	Definition
Martensitic	A small category of magnetic stainless steels typically containing 12% chromium, a moderate level of carbon, and a very low level of nickel.
Mechanical Properties	Tensile strength, elongation, hardness, and fatigue limit of steel.
Mechanical Properties (Physical Properties)	Properties determined by mechanical testing, such as yield strength, ductility, ultimate tensile strength, hardness, bendability, impact strength, etc.
Mid-Welds	Two or more joints welded to form one long joint.
Minimum Wall	Minimum thickness permissible calculated by subtracting minus tolerance from the nominal wall.
Molybdenum (Mo)	An alloying element that enhances corrosion resistance along with chromium in stainless steels.

N

Abbreviations

Abbreviation	Full Name
N.A.S.P.D.	The National Association of Steel Pipe Distributors
N.B.S.	National Bureau of Standards
NOM	Nominal - the name given to standard pipe designations 1/8 inch through 12 inches. Does not indicate actual I.D. measurements. Wall thickness is also expressed as nominal
N.T.	Net Ton - 2,000 pounds

Terms

Term	Definition
Nickel (Ni)	An alloying element used in stainless steels to enhance ductility and corrosion resistance.
Nickel-Based Super Alloys	Alloy metal produced for high-performance, high-temperature applications such as nickel-iron-chrome alloys and nickel-chrome-iron alloys.
Nipple	Short length of pipe 12 inches and under normally threaded both ends.

O

Abbreviations

Abbreviation	Full Name
O.D.	Outside Diameter
O.H.	Open Hearth

Terms

Term	Definition
Orbital Weld	A circumferential, full fusion butt or girth weld used to join together two lengths of tubing. It is a GTAW welding process similar in nature to the longitudinal weld seam of a welded tubular product.
Ovality	A quantitative measurement of how round a tube is by comparing width to height. Limits are specified on the appropriate ASTM specification of a product.
Oxidation	Rust or corrosion due to exposure to oxygen.

P

Abbreviations

Abbreviation	Full Name
PCS	Pieces
P.E.	Plain ends
PERC	Plain end roller cut
PESC	Plain end square cut or saw cut or machine cut
PSI	Pounds per square inch - a measurement of stress in a material

Terms

Term	Definition
Passivation	When exposed to air, stainless steels passivate naturally (due to the presence of chromium). But the time required can vary. In order to ensure that the passive layer reforms rapidly after pickling, a passivation treatment is performed using a solution of nitric acid and water.
Pickling	A process that removes surface scale and oxidation products by immersion in a chemically active solution, such as sulphuric or hydrochloric acid. Pipe is immersed in the acid bath to remove scale, oil, dirt, etc.
Pitting	Localized corrosion (in the form of pits) of a metal surface that is confined to a small area.
Printing	Outside some capillary tubes, all tubes are printed with information needed to verify such as heat number, dimensions, material, smls (seamless), and the mill’s reference. This is printed along the length of all tubes dispatched.
Protector	Sleeve with threads to protect threads.

R

Abbreviations

Abbreviation	Full Name
R/L	Random Length - Varying lengths of pipe
R&D	Reamed and Drifted - commonly used in water wells to guarantee I.D. clearance

Terms

Term	Definition
Range	Allowable lengths in oilfield casing and tubing. Expressed as Range 1 (20 foot R/L), Range 2 (30-foot R/L) and Range 3 (40 foot R/L).
Roughness Average (Ra)	An expression of measured surface roughness or texture, typically, of a polished or machined metal surface. The arithmetic average value of the departure (peaks and valleys) of a surface profile from the centerline throughout the sampling length, generally expressed in micro-inch (0.000,001-inch) or micrometer (or micron) (0.0003937-inch) units.

S

Abbreviations

Abbreviation	Full Name
SAW	Submerged Arc Weld - a method of producing very large OD pipe
SMLS	Seamless - pipe without a seam or weld in the circumference
SPEC	Specification
SRL	Single Random Lengths - usually 18 foot to 22 foot. Minimum average of 17’6”
S.T. & C.	Short Thread & Coupled (OCTG)
STO	Standard - Same as Sch. 40 1/8”-1.0”

Terms

Term	Definition
Scale	An oxide of iron which forms on the surface of the steel.
Schedule Numbers	ANSI numbers assigned to pipe to designate wall thickness.
Seamless Tube	Tube produced from a solid billet that is heated and rotated under pressure. This rotating pressure creates a hole in the middle of the billet, which is then formed into a tube by a mandrel.
Sensitization	The phenomenon in austenitic stainless steels that causes a change to occur in the grain boundaries when heated in the general range of 850 to 1475 degrees F. This change destroys the passivity in these locations.
Skelp	Long narrow strip of a plate of correct thickness and width to produce CW or ERW pipe.
Solution Heat Treatment	Heating a metal to a high temperature and maintaining it long enough for one or more constituents to enter the solid solution. The solution is then cooled rapidly to retain the constitutes within.
Stabilization	An addition of titanium or niobium, making stainless steels less sensitive to intergranular corrosion.
Stainless Steel	Group of corrosion resistant steels containing at least 10.5% chromium and may contain other alloying elements. These steels resist corrosion and maintain their strength at high temperatures.
Stencil	Identification painted on a pipe. Specification, size, wall, grade, test pressure, method of manufacture and mill identification are usually indicated.
Stress Corrosion Cracking (SCC)	Slowly developing cracks that form in stainless steel due to mechanical stress and exposure to a corrosive environment.
Stress Relieving	Heat treatment carried out in order to reduce internal stresses in steel.
Stretch Reduce	A technique employed in the manufacture of CW pipe in which one or several master sizes of pipe are produced, then stretched reduced through a number of rolls to achieve a variety of pipe diameters. Also used in certain instances in seamless and ERW manufacturing.

T

Abbreviations

Abbreviation	Full Name
TBE	Thread Both Ends
T & C	Threaded and Coupled
TOE	Thread One End

Terms

Term	Definition
Tensile Strength	Ultimate bursting strength to resist being pulled apart. Expressed in P.S.I.
Tube Round	Billet.

U

Term	Definition
Victaulic Joint	Pipe is grooved near ends to accommodate a Victaulic coupling.

Y

Term	Definition
Yield Strength	The tensile stress required to produce a total elongation of 0.5 percent of the gauge length as determined by an extensometer. Expressed in P.S.I.

X

Abbreviation	Full Name
XHY	Extra Heavy (Extra Strong)
XXHY	Double Extra Heavy (Double Extra Strong)