Glossary of Terms & Useful Codes

Codes - We work with the Following Codes:

AISC - (American Institute of Steel Construction)

ANSI - (American National Standards Institute)

API - (American Petroleum Institute)

ASME - (American Society of Mechanical Engineers)

AWS - (American Welding Society)

AWWA - (American Water Works Association)

NBIC - (National Board Inspection Code)

TEMA - (Tubular Exchanger Manufacturers Association)

UL - (Underwriters' Laboratories, Inc.)

Glossary

Alloy

Material having metallic properties with two or more elements.

API

American Petroleum Institute.

Arc Welding

A group of welding processes wherein coalescence is produced by heating with an electric arc.

ASME

American Society of Mechanical Engineers.

As-Welded

The condition of weld metal prior to any mechanical treatment.

Automatic Welding

Welding with equipment which performs the welding operation without adjustment of the controls by a welding operator.

AWWA

American Water Works Association.

Back Gouging

The removal of weld metal by arc gouging or grinding from the other side of a partially welded joint to assure complete penetration upon subsequent welding from that side.

Base Metal

The material to be welded.

Butt Weld

A weld joining two members laying in the same plane.

Cladding

A relatively thick layer of (> 0.04" ) of material applied by surfacing for the purpose of improving corrosion resistance.

Coating

A relatively thin layer of (< 0.04" ) of material applied by surfacing for the purpose of corrosion prevention.

Clad Vessel

A vessel made from plate having a corrosion resistant material bonded to a base of less resistant material.

Complete Penetration

Joint penetration in which the weld metal completely fills the groove and is fused to the base metal throughout its thickness.

Corrosion Allowance

Vessels subject to thinning by corrosion, erosion or mechanical abrasion shall provide for an increase in thickness which is added to the design thickness.

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.

Fillet Weld

A weld of approximately triangular cross section joining two surfaces at right angles to each other.

Filler Metal

Material added in making a weld.

FCAW

Flux Cored Arc Welding.

GMAC

Gas Metal Arc Cutting. (Air Arc)

GMAW

Gas Metal Arc Welding (MIG).

GTAW

Gas Tungsten Arc Welding (TIG).

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

The complete vessel filled with water shall be subject 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

Poisonous gas or liquid of such a nature that a small amount of the gas or of the vapor of the liquid is dangerous to life when inhaled. It is the responsibility of the user of the vessel to determine that the gas or liquid is lethal.

Liquid Penetrant Examination (PT)

A method of nondestructive examination. Typical discontinuities found with this method are cracks and laminations.

NBIC

National Board Inspection Code.

Magnetic Particle Examination (MT)

A method of detecting cracks at or near the surface in magnetic alloys.

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 lap joint.

Porosity

A cavity formed by gas entrapment during welding.

Postweld Heat Treatment

Heating a vessel 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

The demonstration that welds made by a specific procedure can meet code standards.

Radio graphing

The process of passing radiation through a weld joint obtaining a record of its soundness upon a readable film.

Seal Weld

Weld used primarily to obtain tightness.

SMAW

Shielded Metal Arc Welding.

Stud Welding

Joining a metal stud to a work piece by welding with a suitable process.

SAW

Submerged Arc Welding.

Tack Weld

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

Undercut

A groove melted into the base metal adjacent to the toe or root of a weld and left unfilled by weld metal.

WPS

Weld Procedure Specification.