Acceptable Weld
A weld that meets all requirements and acceptance criteria of the designand welding specifications.
Actual Throat
The shortest distance between the weld root and face.
Alloy
Metal having different properties than the original base elements.
Arc Blow
The deflection or wandering of an electric welding arc from its normal path due to magnetism in the base metal.
Arc Welding
A group of welding processes wherein coalescence or complete fusion is produced by heating with an electric arc.
Arc Strike
A discontinuity on the surface of the base metal or weld consisting of pits, craters and/or re-melted metal.
As-Welded
The condition of weld metal after welding but prior to any thermal, mechanical, or chemical treatment.
Automatic Welding
Welding with equipment which performs the welding operation without adjustment of the controls by a welding operator.

Back Bead
A weld resulting from a back pass.
Back Gouging
The removal of weld and base metal by arc gouging or grinding from the other side of a partially welded joint to assure complete fusion and
penetration upon subsequent welding from that side.
Base Metal
The material to be formed, welded, brazed, soldered, or cut.
Butt Weld
A weld joining two members laying in approximately the same plane.
Cladding
A relatively thick layer of (> 0.04" ) of different material applied by surface welding for the purpose of improving corrosion or heat
resistance.
Complete Fusion
Fusion occurring over the entire base metal surfaces intended for welding and between all joining weld beads and layers.
Clad Vessel
A vessel made from plate having a corrosion resistant material bonded to a base of less resistant material.
Complete Joint Penetration
Joint penetration in which the weld metal completely fills the groove and is fused to the base metal throughout its thickness.
Concavity
A weld that falls below the intended perpendicular plane.
Convexity
A weld that exceeds the intended perpendicular plane.


Design Pressure
The pressure used in the design of a vessel. It is recommended to design a vessel and its parts for a pressure 10% above its operating
pressure.
Design Temperature
The maximum metal temperature expected under operating conditions.
Defect
A discontinuity or discontinuities that accumulate to render a weld or part unable to meet minimum acceptance standards or criteria of the
design specifications.


Fillet Weld
A weld of approximately triangular cross section joining two surfaces at right angles to each other.
Eddy Current Testing (ET)
A non-destuctive test method that induces an electrical current into a test piece by an alternating magnetic field. This is accomplished by the
use of different probes or coils and eddy current devices operating at frequencies that are appropriate for the material being tested.
Filler Metal
Metal added in making a welded, brazed, or soldered joint.
FCAW
Flux Cored Arc Welding. Welding process that uses a tubular weld wire with an internal flux with or without an externally supplied gas
shielding.


GMAC
Gas Metal Arc Cutting. Metals are cut by the heat of an arc between a continuous filler metal electrode and the work piece with externally
supplied shielding gas.
GMAW
Gas Metal Arc Welding. Metals are welded by the heat of an arc between a continuous filler metal electrode and the work piece with externally
supplied shielding gas. GMAW-P (pulse arc) and GMAW-S (short arc) are variations of this method.
GTAW
Gas Tungsten Arc Welding. A gas shielded welding method where the heating is produced using a non-consumable tungsten electrode to
transfer the arc to the work piece.
Groove Weld
A weld made in the groove between two plates to be joined.

Head
The end of a cylindrical shell. Types include flat, ellipsoidal, flanged and dished, conical and hemispherical.
Heat-Affected Zone
The portion of the base metal which has not been melted, but whose mechanical properties have been altered by the heat of welding or
cutting.
High-Alloy Steel
Steel containing large percentages of elements other than carbon.
Hydrostatic Test
A vessel, pipe spool or piping system is completely filled with water and subjected to a test pressure which is equal to 1.5 times the design
pressure.
Impact Test
Determination of the resistance of a material to breaking by impact. The test is measured by breaking the material by a single blow.
Joint Efficiency
The ratio of the strength of a joint to the strength of the base metal, expressed in percent.
Lap Joint
A welded joint in which two overlapping metal parts are joined by means of a fillet, plug or slot weld.
Lethal Substance
Substance that is of such a nature that a small amount of the substance is dangerous to life when absorbed by a human or animal.
Liquid Penetrant Examination (PT)
A method of non-destructive examination that uses three different chemicals to expose welding defects that are open to the surface. These
chemicals are applied using an inspection procedure.

Magnetic Particle Examination (MT)
A method of detecting cracks at or near the surface in magnetic alloys using a specially designed electro-magnet and a magnetic liquid or
powder.
Material Test Report (MTR)
A document on which the material manufacturer records the results of test examinations or treatments required by the material specification.


Operating Pressure
The pressure at the top of a pressure vessel at which it normally operates. It can not exceed the maximum allowable working pressure
(Stamped Pressure).

Plug Weld
A circular weld made through a hole in one member of a joint to fuse it to another member.
Porosity
A rounded or elongated cavity formed by gas entrapment during cool down or solidification.
Postweld Heat Treatment
Heating a weld or welded assembly to a sufficient temperature to relieve the residual stresses which are the result of welding and forming.
Preheating
Heat applied to base metal prior to welding.
Procedure Qualification Record (PQR)
The written demonstration record that welds made by a specific welding procedure can meet code standards.

Radiography
The process of passing radiation through a weld joint or base material to obtain a film record of its soundness.


Seal Weld
Weld used primarily to obtain complete tightness against leakage.
SMAW
Shielded Metal Arc Welding. Also known as stick welding. This process uses a powder coated welding rod placed in a holder that is arced
against the base metal.
Stud Welding
Joining a metal stud to a work piece by welding with arc, friction, resistance, or other process.
SAW
Submerged Arc Welding. A bare metal electrode(s) method of welding where the arc and molten metal are shielded by a granular fusible
blanket of material on the work piece.

Tack Weld
A weld made to hold parts of a weldment in proper alignment until final welds are made.

Ultrasonic Testing (UT)
A non-destructive inspection method using sound waves for surface or sub-surface welding or base material testing. Ultrasonics can also be
used for thickness testing.

Undercut
A jagged groove melted into the base metal adjacent to the toe or root of a weld and left unfilled by weld metal. Also known as edge melt.


WPS
Weld Procedure Specification. A written document providing in detail the required variables for specific application to assure repeatability by
properly qualified welders and welding operators.