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ANNEALING
The controlled process of heating and cooling a metal to, among other ends, achieve a
reduction in hardness, remove stress, and to refine the grain microstructure.
ASME
American Society of Mechanical Engineers.
ASTM
American Society for Testing Materials.
ASTM A213/ASME SA213
Standard specification for seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes.
ASTM A249/ASME SA249
Specification entitled "Welded Austenitic Steel Boiler, Superheater, Heat
Exchanger and Condenser Tubes". This specification covers pressure tubes made from a variety of
austenitic steels.
ASTM A269
Specification titled "Seamless and Welded Austenitic Stainless Steel Tubing for General
Service". This specification covers a variety of grades of austenitic stainless steel tubing.
ASTM A270
Standard Specification for Seamless and Welded Austenitic Stainless Steel Sanitary tubing.
ASTM A312/ASME SA312
Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes
ASTM A450*
Specification titled "General Requirements for Carbon, Ferritic and Austenitic Alloy Steel
Tubes". This covers common requirements for ASTM tubular product specifications.
ASTM A511
Standard Specification for Seamless Stainless Steel Mechanical tubing
ASTM A554
Standard Specification for Welded Stainless Steel Mechanical tubing
ASTM A632
Specification titled "Seamless and Welded Austenitic Stainless Steel Tubing (Small
Diameter) for General Service". This specification covers a variety of grades of austenitic stainless steel
tubing in sizes under 1/2" down to .050" outer diameter wall thickness less than .065" down to .005".
ASTM A688
Specification titled "Welded Austenitic Stainless Steel Feedwater Heater Tubes". This
specification covers welded austenitic stainless steel tubes used in feedwater applications. Size range is
5/8" to 1" outside diameter inclusive and walls of .028" and heavier. Specification also covers U-bends.
ASTM A789
This specification covers grades of normal wall thickness stainless steel tubing for services
requiring general corrosion resistance, with particular emphasis on resistance to stress corrosion
cracking. These steels are susceptible to embrittlement if used for prolonged periods at elevated
temperatures.
ASTM A790/ASME SA790
Standard Specification for Seamless and Welded Ferritic/Austenitic Stainless Steel Pipe
ASTM A1016/ASME SA1016
Standard Specification for General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and
Stainless Steel Tubes.
ASTM B161/ASME SB161
Standard Specification for Nickel Seamless Pipe and Tube
ASTM B163/ASME SB163
Standard Specification for Nickel Seamless Pipe and Tube
ASTM B165/ASME SB165
Standard Specification for Nickel-Copper Alloy (UNS N04400) Seamless Pipe and Tube
ASTM B167/ASME SB167
Standard Specification for Nickel-Chromium-Iron Alloys (UNS N06600, N06601, N06603, N06690,
N06693, N06025, N06045, and N06696) and Nickel-Chromium-Cobalt-Molybdenum Alloy (UNS N06617)
Seamless Pipe and Tube
ASTM B407/ASME SB407
Standard Specification for Nickel-Iron-Chromium Alloy Seamless Pipe and Tube
ASTM B423/ASME SB423
Standard Specification for Nickel-Iron-Chromium-Molybdenum-Copper Alloy (UNS N08825 and N08221)
Seamless Pipe and Tube
ASTM B444/ASME SB444
Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloys (UNS N06625 and UNS
N06852) and Nickel-Chromium-Molybdenum-Silicon Alloy (UNS N06219) Pipe and Tube
ASTM B514/ASME SB514
Standard Specification for Welded Nickel-Iron-Chromium Alloy Pipe for general corrosive service and heat-resisting applications.
ASTM B515/ASME SB515
Standard Specification for Welded UNS N08120, UNS N08800, UNS N08810, and UNS N08811 Alloy
Tubes for use in boilers, heat exchangers, and condensers for general corrosion resisting and low or
high-temperature service.
ASTM B626/ASME SB626
Standard Specification for Welded Nickel and Nickel-Cobalt Alloy Tube intended for heat exchanger and
condenser tubes and tubes for general corrosive service for heat-resisting applications.
ASTM B675/ASME SB675
Standard Specification for UNS N08367 Welded Pipe for general corrosion applications.
ASTM B676/ASME SB676
Standard Specification for UNS N08367 Welded Tube of limited diameter and thickness for general
corrosion applications.
ASTM B688/ASME SB688
Standard Specification for Chromium-Nickel-Molybdenum-Iron (UNS N08366 and UNS N08367) Plate,
Sheet, and Strip for use in corrosive service and heat-resisting applications.
ASTM B704/ASME SB704
Standard Specification for Welded UNS N06625, UNS N06219 and UNS N08825 Alloy Tubes for use in
boilers, heat exchangers and condensers for general corrosion prevention in either low or
high-temperature environments.
AUSTENITIC
The family of chromium-nickel stainless steels often referred to as the 300 series of 18-8
group. These steels can only be hardened by cold working. In the annealed condition they are
nonmagnetic. In general, they have good corrosion resistance, good formability and are readily
weldable.
BRIGHT ANNEALING
An annealing process which employs a reducing gas atmosphere. Stainless steel
tubing annealed in this manner has a bright, clean appearance and is free from any oxides or scale. The
process eliminates the need for the old fashioned acid bath pickling operations.
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.
COLD DRAWING
The mechanical work process of pulling a tube through a carbide die to reduce the
diameter of the tube. Small tubes with very high thickness-to-diameter ratios are commonly produced
this way in long lengths. The drawing of the tube is done at room temperature, i.e., Cold.
CONCENTRICITY
Used to describe tubing where the center of its inside diameter is consistent with the
center of its outside diameter resulting in no variation of wall thickness. By virtue of the fact that welded
tubing is fabricated from precision rolled flat stock, concentricity is inherent with a roll-formed, welded
tube.
DESTRUCTIVE TESTING
Any of the mechanical tests performed on an expendable sample of tubing to
check physical properties. These tests include: tensile, yield, elongation, hardness, flare, flattening, bend
and burst.
ECCENTRICITY
Opposite of concentricity, resulting in variations of wall thickness. This is a problem
associated with seamless tubular products.
EDDY CURRENT TESTING
A nondestructive testing procedure which is a continuous process performed
on the tubular products during fabrication and in final inspection. It is by nature an electrical test which
checks tubing (against a calibrated standard) for possible defects such as holes, cracks, gouges, etc. on
both inside and outside surfaces of the tube. All eddy current testing at Gibson Tube is done in
accordance with ASTM-E 426.
GAS TUNGSTEN ARC WELDING (GTAW)
An arc welding process that uses an arc between a tungsten
electrode (nonconsumable) and the weld pool (base metal of strip). A high quality full fusion weld is
achieved using no filler metal (i.e., the weld is the same metal as the rest of the tube). The GTAW
process is also commonly referred to as Tungsten Inert Gas (TIG) welding.
HARDNESS
Hardness of tubular products is measured on samples of tubing using a standard Rockwell
Penetrator and recording the results on the Rockwell "B" scale. Hardness is the direct result of annealing
temperatures and material properties. In general, as the hardness number increases, both tensile and
yield strengths increase along with a corresponding decrease in elongation (ductility).
HYDROSTATIC TESTING
A nondestructive 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.
ID
Inside diameter of a tubular product.
LINE MARKING
A continuous strip of information that is printed with an inert ink along the longitudinal
surface of the tube after final inspection. This data includes ASTM spec number, material identification,
size and wall thickness, as well as a heat number identity. Full traceability is possible with any line
marked product.
MEAN COEFFICIENT OF THERMAL EXPANSION
This is the amount that a material will grow in size
when subjected to a temperature rise. It is measured in inches/inch/ °F. This number multiplied by the
length of the tubing (in inches) and by the temperature rise (in °F) indicates how much the tube length
will expand (in inches). If the temperature decreases, the tube will shrink by a similar amount.
MODULUS OF ELASTICITY
A ratio of stress to strain. Used in engineering calculations to determine
rigidity and deflections. The higher the number, the more rigid the item will be for a given load. The
units are in pounds per square inch (psi).
NONDESTRUCTIVE TESTING
See Eddy Current Testing or Hydrostatic Testing.
OD
Outside diameter of a tubular product.
ORBITAL WELD
A circumferential, full fusion 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.
PASSIVATION
A protective layer of oxides on the surface of a metal which resists corrosion. This
passive oxide layer is the chief reason why stainless steels have such good corrosion resistant properties.
It is a natural phenomenon, but can be accelerated by special passivating solutions that can be applied
to tubular products by an optional process.
psi
Common engineering abbreviation for pounds per square inch. A measurement of stress in a material.
TENSILE STRENGTH
The maximum load per unit area that a material is capable of withstanding before
it fails (pulls apart). Units are in psi.
WELDED TUBING
Tubular products which are roll formed and then joined continuously along a
longitudinal seam by a material fusion process. The process employed at Gibson Tube is Gas Tungsten
Arc Welding (GTAW). See Gas Tungsten Arc Welding.
YIELD STRENGTH
The load per unit area that a material can withstand before permanent deformation
(nonelastic) occurs. It is conventionally determined by a .2% offset from the modulus slope on a
stress/strain diagram. Units are in psi and referenced to .2% offset in most literature.