The piping dictionary collects typical abbreviations, terms, and definitions as appearing in piping classes, specifications, and other technical and commercial documentation related to pipelines, process piping, and piping systems.

Piping Glossary



  • BALES: Banded lifts of pipe
  • BAR MILL: Roiling mill where blooms are processed to form billets
  • BESS: Bessemer
  • 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.
  • 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.
  • BLOOM: A semifinished hot rolled product produced on a blooming mill.
  • B.O.F: Basic Oxygen Furnace
  • BRIGOS STANDARD: A standard of thread dimensions. Same as American Standard
  • 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.
  • BURST TEST: A destructive hydraulic test to determine actual yield strength and ultimate strength of seamless and welded pipe.
  • B.W.: Butt Weld Pipe — See Continuous Weld Pipe
  • B.W.G.: Birmingham Wire Gauge


  • 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.
  • 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.
  • CUT LENGTH: Pipe out to a specific length as ordered.
  • 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.
  • CPLG: Coupling — threaded sleeve used to connect two lengths of pipe.
  • C.W.: Continuous Weld — method of producing pipe normally in sizes from ½ inch to 4 inches.
  • CU–Copper
  • C.W.T.: per hundredweight


  • DIA: Diameter
  • DIE STAMPING– Permanent marking placed on a pipe as required in some specifications.
  • DOUBLE EXTRA HEAVY–  Also known as double extra strong. Available from ½ 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.
  • DRL– Double Random Length (35-foot minimum average)
  • 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.


  • 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.
  • 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.



  • GALV– Galvanizing — coating pipe with a protective coating of zinc.
  • GRADE A OR B–  Designations used to indicate minimum yield and tensile strengths of steel in seamless and welded pipe.
  • G.T.– Gross Ton– 2,240 pounds


HYDROSTATIC TESTING–  High pressure, water test to predetermine pressures as required by specifications.


  • l.D.– Inside Diameter — The O.D. measurement less double the wall thickness is the I.D. measurement of a pipe or tube.INGOT– a Usually first solid form of steel, Suitable for reworking or remelting.
  • I.P.S.– Iron Pipe Size– Same as nominal size from 1/8 inch to 12 Inch.


JOINT–Term used to refer to one length of pipe.


  • LGTH–    Length
  • L.T.C.–Long threads and coupling (OCTG)
  • LARGE O.D. PIPE–  Pipe 14 inch O.D. and larger
  • L.W.– Lap Weld– an Old method of producing pipe 5-inch diameter and over.


  • MECHANICAL PROPERTIES– Tensile strength, elongation, hardness, and fatigue limit of steel.
  • 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.
  • MN–  Manganese


  • N.A.S.P.D.– The National Association of Steel Pipe Distributors
  • N.B.S.: National Bureau of Standards
  • Ni– Nickel
  • NIPPLE: Short length of pipe 12 inches and under normally threaded both ends.
  • 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


  • O-D. Outside diameter
  • O.H. Open heart


  • PCS–Pieces
  • P.E.–Plain ends
  • PERC–Plain end roller cut
  • PESC– Plain end square cut or saw cut or machine cut
  • PICKLING–Pipe immersed in the acid bath to remove scale, oil. dirt, etc.
  • PROTECTOR– Sleeve with threads to protect threads
  • PSI– Pounds per square inch.


  • RANGE– Allowable lengths in oilfield casing and tubing. Expressed as Range 1 (20 foot R/L). Range 2 (30-foot RIL) and Range 3 (40 foot R/L).
  • R/L–Random Length. Varying lengths of pipe.
  • R&D–Reamed and Drifted — commonly used in water wells to guarantee I.D. clearance


  • SAW–  Submerged Arc Weld — a method of producing very large OD pipe.
  • SCALE–       An oxide of Iron which forms on the surface of the steel.
  • SCHEDULE NUMBERS–  ANSI numbers assigned to pipe to designate wall thickness.
  • SMLS—Seamless– pipe without a seam or weld in the circumference.
  • SPEC–  Specification
  • SKELP–  Long narrow strip of a plate of correct thickness and width to produce CW or ERW pipe.
  • SRL–       Single Random Lengths — usually 18 foot to 22 foot. Minimum average of 17’6”.
  • S.T. & C.–    Short Thread & Coupled (OCTG).
  • STENCIL– identification painted on a pipe. Specification, size, wall, grade, test pressure, a method of manufacture and mill identification are usually indicated.
  • STO: Standard — Same as Sch. 40 1/8”-1.0”
  • STRETCH REDUCE: A technique employed in the manufacture of OW 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.


  • TBE: Thread Both Ends
  • T & C: Threaded and Coupled
  • TOE: Thread One End
  • TENSILE STRENGTH: Ultimate bursting strength to resist being pulled apart. Expressed in P.S.I.
  • TUBE ROUND–Billett


VICTAULIC JOINT: Pipe is grooved near ends to accommodate a Victaulic coupling.


YIELD STRENGTH: The tensile stress required to produce a total elongation of .5 percent of the gauge length as determined by an extensometer. Expressed in P.S I.


  • XHY: Extra Heavy (Extra Strong)
  • XXHY: Double Extra Heavy (Double Extra Strong)

Please contact us in case you have other terms to add to our piping dictionary 


Piping Glossary

ASME (American Society of Mechanical Engineers)
An organization of engineers dedicated to the preparation of design code requirements, and material and testing standards.


ASTM (American Society for Testing and Materials)
A body of industry professionals involved in writing universally accepted steel material and test specifications and standards.


As-drawn tube
Any tube in any temper other than annealed or heat treated.

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.

Austenitic Stainless Steel
Non-magnetic stainless steels ( 300 series ) that contain chromium (18-30%) & 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.

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.

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.

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 on nominal dimensions, tolerances and surface finish without an additional process.

Used to describe tubing where the center of its inside diameter is consistent with the outside diameter resulting in no variation of wall thickness.

The attack upon metals by chemical agents converting them to non-metallic products film created by the presence of chromium (and often other alloying elements like; nickel, molybdenum, titanium & niobium) that 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.

Removing the subtle ridge from the edge of the tube that results from cutting operation.

A measurement of the malleability of stainless steel in terms of the amount of deformation it will withstand before failure

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.

Eddy Current Testing
The non-destructive test procedure that examines for outside diameter cracks and burrs.

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 microinch) is attainable.

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.

The continuous depletion of a material due to mechanical interaction with a liquid, a multicomponent fluid, or solid particles carried with the fluid.

A shaped piece of stainless steel produced tube by forcing the pre-pipe, bar, or rod through a die of the appropriate shape

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.

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.

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.

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.

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
A non-destructive test procedure that checks for holes, cracks or porosity. Tubing is pressurized internally with water to a high pressure but does not exceed material yield strength.

Inside diameter of a tubular product. It is also known as the opening or bore of a tube or pipe.

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.

Intergranular Corrosion
Corrosion that occurs at the grain boundaries in austenitic stainless steels that have been heated to and held at temperatures between 850° F and 1450° F. Slow cooling through this range can also result in sensitization to intergranular corrosion. Usually caused by precipitation of chrome carbides.

ISO (International Organization for Standardization)
Prepares specifications. Both Canada and the U.S.A. are ISO members and participate in the ISO specification development.

Line Pipe
A pipe extending over long distances that transports oil, natural gas, and other fluids.

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 (Physical Properties)
Properties determined by mechanical testing, such as yield strength, ductility, ultimate tensile strength, hardness, bendability, impact strength, etc.

Molybdenum (Mo)
An alloying element that enhances corrosion resistance along with chromium in stainless steels.

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.

Outside diameter of a tubular product.

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.

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.

Rust or corrosion due to exposure to oxygen.

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.

A process that removes surface scale and oxidation products by immersion in a chemically active solution, such as sulphuric or hydrochloric acid

Localized corrosion (in the form of pits) of a metal surface that is confined to a small area.

Common engineering abbreviation for pounds per square inch. A measurement of stress in a material.

Outside some capillary tubes, all our tubes are printed with information needed to verify such as; heat number, dimensions, material, smls ( seamless ), mill’s reference.This is printed along the length of all tubes dispatched.

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.

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.

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 degree F. This change destroys the passivity in these locations.

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.

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 its strength at high temperatures.

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.

Tensile Strength
A short form of “ultimate tensile strength”. The maximum load per unit area that a material is capable of withstanding before it fails (pulls apart). Units are in psi.

Tubing Dimensions
OD = Outside Diameter
ID = Inside Diameter
Wall thickness or gauge
All tube dimensions are specific; pipe dimensions are nominal.
Specific – actual measurement in inches
Nominal – theoretical or stated value of a dimension

Yield Strength
The stress beyond which stainless steel undergoes important permanent flow – commonly specified as that stress producing a 0.2% or 1.0%  offset from the linear portion of the stress-strain curve.


General information about steel pipes: Seamless pipe | Welded pipe ERW and LSAW | Pipe vs tube, key differences | OCTG casing and tubing pipe | Steel pipe manufacturers, stockists, and distributors | Piping materials chart | Pipe color coding ASME A13.1 and PFI ES-22

Pipes dimensions and weights: Pipe size chart ASME B36.10 and ASME B36.19 | Pipe size chart EN 10220 | Pipe size chart API 5CT | Pipe length and pipe ends

Carbon and alloy steel pipes: ASTM A53 black and galvanized pipe | ASTM A106 high-temperature carbon steel pipe | API 5L line pipe | Difference ASTM A106 and A53 pipe | ASTM A333 pipe for low-temperature service | ASTM A335 Chrome Moly Alloy pipe | API 5CT casing and tubing pipe materials 

Stainless steel pipes: ASTM A312 stainless steel pipe | ASTM A790 Duplex and Super Duplex pipe

Pipeline coating and lining materialsCoating and lining materials for pipes