DEFINITIONS

PWHT means “POST WELD HEAT TREATMENT” This is done to remove residual stress left in the joint which may cause brittle fracture

Strength:   Strength is defined as, “the ability of a material to withstand  an applied load.”

Ductility:  Ductility is a term which relates to the ability of a material  to deform, or stretch, under load                             

                      without failing.

Hardness: Hardness is the ability of a metal to resist penetration or indentation.

Toughness: Toughness is the ability of a material to absorb energy.

FATIGUE STRENGTH

                                 The relative ability of a metal to withstand cyclic loading, as in stress reversal

HAZ

             HEAT-AFFECTED ZONE ; the metal adjacent to a weld that does not melt but is affected by the heat              

             of welding.

NORMALIZING

                 A heat treatment whereby steel is heated into the austenite range and cooled in still air

QUENCHING

              In heat treatment, very rapid cooling from elevated temperatures.

TEMPERING

              A heat treatment which reduces the strength and hardness of as-quenched steels and restores ductility

              & toughness

DEFECT

              A discontinuity which exceeds the permissible limit of a code; a rejectable discontinuity requiring

              repair or replacement

DISCONTINUITY

             Any irregularity in the normal pattern of a material; any interruption of the uniform nature of an item.

DCEN

            Direct current, electrode negative. Referred to as straight polarity

DCEP

          Direct current, electrode positive. Referred to as reverse polarity.

CODE

          A body of laws, as of a nation, city, etc., arranged systematically for easy reference.

ESSENTIAL VARIABLES (Procedure)

             A change in a welding condition which will affect the mechanical properties (other than notch       

              toughness) of the weldment (e.g., change in P-Number, welding process, filler metal,

             electrode, preheat or postweld heat treatment).

ESSENTIAL VARIABLES (Performance)

                      A change in a welding condition which will affect the ability of a welder to deposit sound weld 

                       metal (such as a change in welding process, deletion of backing, electrode, F-Number,      

                       technique,etc.).

SUPPLEMENTARY ESSENTIAL VARIABLES

                          Supplementary essential variables are required for metals for which other Sections specify

                         notch-toughness tests and are in addition to the essential variables for each welding process.

NONESSENTIAL VARIABLES

                         Nonessential variables are those in which a change, as described in the  specific variables,                  

                        may be made in the WPS without requalification.

WELDING

                   A joining process that produces coalescence of materials by heating them to the welding temperature, with or without the application of pressure or by the application of pressure alone, and with or without the use of filler metal.

WELDABILITY

                The capacity of material to be welded under the imposed fabrication conditions into a specific,

                 suitably designed structure and to perform satisfactorily in the intended service.

PROCEDURE QUALIFICATION RECORD (PQR).

                A record of welding variables used to produce an acceptable test weldment and the results of tests conducted on the weldment to qualify a welding procedure specification.

                                                                                         (or)

Procedure Qualification Record (PQR). A PQR is a record of the welding data used to weld a test coupon.

The PQR is a record of variables recorded during the welding of the test coupons. It also contains the test results

of the tested specimens.

WELDING PROCEDURE SPECIFICATION (WPS).

                                A document providing the required welding variables for a specific application to assure repeatability by properly trained welders and welding operators.

                                                                             (or)

A WPS is a written qualified welding procedure prepared to provide direction for making production welds to Code requirements.