Welding Procedure Specification WPS
WPS per Section IX
What is a WPS?
WPS is an abbreviation for Welding Procedure Specification. The WPS is a written welding document that provides the ranges of variables for welding process parameters which the welders shall comply with in production.
Welding procedures are based on one or more PQR’s (Procedure Qualification Record). The WPS has a qualified range of variables under which the material joining process must be performed. The range of conditions permitted on the WPS are based on the actual values of the PQR and what the code permits as a result.
The WPS is limited by the code to ensure that the same mechanical properties established on the PQR will be maintained with the WPS in production.
Reference ASME Section IX QG-102 and QW-200.1for more details.
What is Included on a WPS?
A WPS shall include as a minimum the essential, and non-essential variables as listed in Table QW-252 through QW-267. In addition when referencing codes, standards, or specifications require supplementary essential variables they shall be addressed as well.
The sections of the WPS are as follows on the list below.
QW-401 General
QW-402 Joints
QW-403 Base Metals
QW-404 Filler Metals
QW-405 Positions
QW-406 Preheat
QW-407 PWHT
QW-409 Electrical Characteristics
QW-410 Technique
What Are WPS Variables?
Essential Variables
Variables for which a change is considered to affect the mechanical properties (other than notch toughness) of the joint. Essential variable changes that fall outside their qualified range requires re-qualification.
See Section IX QG-105.1, and QW-251.2 as well as Table QW-252 through QW-267.
Supplementary Essential Variables
Variables for which a change is considered to affect the toughness properties of the joint, heat-affected zone (HAZ), or base material. Supplementary essential variables become additional essential variables in situations where toughness testing is required. When toughness testing is not required supplementary essential variables are not applicable.
See Section IX QG-105.3, and QW-251.2 as well as Table QW-252 through QW-267.
Nonessential Variables
Variables for which a change is considered to not affect the mechanical properties of the joint. This allows for editorial revisions to procedures within that permitted by Section IX without the need to requalify the procedure. Nonessential variables shall be documented on the procedure.
See Section IX QG-105.4, and QW-251.3 as well as Table QW-252 through QW-267.
How Does the PQR and WPS Work Together?
The PQR supports the WPS and is the foundation upon which all of the qualified range of variables are established.
When submitting a WPS for review as required by some contracts, the PQR(s) should always be attached to the WPS, so the reviewer can properly evaluate the PQR and confirm the variables on the WPS are within the established ranges permitted by the governing welding code(s).
It should be noted that a single PQR can support one or multiple WPS’, and multiple PQR’s can support one WPS.
Reference Code vs Construction Code
ASME Section IX works as a reference code or standard in support of the ASME Construction standards.
Construction Standards:
Section I - Power Boilers
Section VIII - Pressure Vessels
B31.1 - Steam Piping
B31.3 - Process Piping
Reference Standards:
Section V - Nondestructive Examination (NDE)
Section IX - Qualifying Procedures & Personnel
The fabrication or construction standards of BPVC (Boiler & Pressure Vessel Codes) such as Section I, Section VIII, B31.1, and B31.3 all reference Section IX for how to qualify the procedures and personnel (welders) for performing any work within the BPVC.
The construction standards each apply to specific industries and types of welded products, and as such will apply additional requirements or restrictions to the foundational requirements of Section IX.
As a reference standard Section IX does not provide specific production joining requirements. Section IX provides the rules on how to qualify the procedures and personnel, and nothing more.
To address production joining requirements the applicable details of the construction standards and engineering specifications need to be incorporated into the welding procedure.
What Form Should I Use for a WPS?
The information required to be in the WPS may be in any format, written or tabular, to fit the needs of each organization, as long as every essential, nonessential, and, when required, supplementary essential variables outlined in QW-250 is included or referenced.
Form QW-482 (see Nonmandatory Appendix ) has been provided as a guide for the WPS. This Form includes the required data for the SMAW, SAW, GMAW, and GTAW processes. It is only a guide and does not list all required data for other processes. It also lists some variables that do not apply to all processes (e.g., listing shielding gas which is not required for SAW).
What is Required for Revisions of a Procedure?
Revisions of the WPS may be necessary as a result of typographical errors or for adjustments to meet project specifications or construction code requirements. Revisions to the variables of the WPS can be made to suit production requirements without requalification as long as they are still in compliance with the variables required in Table QW-252 through QW-267.
Amendments to the WPS can be used and are sometimes effective for applications where the WPS is compliant to Section IX and the applicable construction code, but where contract specifications make requirements above and beyond these codes.
Changes outside the permitted ranges of the stated essential or supplementary essential variables will require requalification.
Whenever revisions are made the WPS revision number should be updated for proper document control practices.
When Do I Have to Qualify a New Procedure?
When variables needed in production exceed the essential or when applicable supplementary essential variables of the procedure a new procedure will need to be qualified. Refer to Section IX Table QW-252 through QW-267 for a complete list of variables by joining process.
Who is Responsible for the WPS?
A WPS used by an organization that will be responsible for operational control of production welding shall be a WPS that has been qualified (PQR) by that organization in accordance with Article II of Section IX or be an AWS Standard WPS (SWPS) and be properly adopted by that organization in accordance with Article V of Section IX.
Section IX QW-103 and QW-201 further clarify that each organization shall conduct the required tests and maintain the proper records for work performed under their operational control.
Can a WPS be Shared by Two Companies?
As per Section IX QG-106.1, if the effective operational control of the welding program is shared by two or more companies of different names which exist under the same corporate ownership, the companies involved shall describe in their quality programs the operational control of procedure specifications. This means that separate procedures are not required, provided that the other requirements of QG-106 Organizational Responsibility are satisfied. It should be emphasized that the essential part of this paragraph is that the companies involved have shared corporate ownership.
See also QG-106.4 for simultaneous procedure qualifications that permit companies of different ownership to participate in procedure qualifications under specific conditions.
Can A WPS be Transferred to New Ownership?
When an organization or some part of it is acquired by a new owner, the PQRs, and WPSs may remain valid for use by the new owners provided the requirements of Section IX QG-107 are met.
Paragraph QG-107 addresses how welding documents can be transferred under new ownership. It is essential that the quality program of the organization shall describe the effective operational control and authority of the new owner in relationship to the original qualifying organization prior to use.
WPS Naming Strategies
WPS can be referenced on inspection forms where there isn’t a lot of room, so it is best to keep WPS titles as short as possible. It is also beneficial that the file name of the WPS provide some recognition to the user and cause similar file names to be sorted in recognizable groups.
Consider the following abbreviations when naming a WPS:
Weld process (GT for GTAW and FC for FCAW)
P-Number (1 or 1-1 for P-1 to P1 and 8-43 for P8 to P43)
Heat Treatment (H for Heat Treatment or PWHT)
Supplementary Testing (CVN or I for Impact testing)
Special Version of Weld Process (SC for Short Circuit, G for Globular, SP for Spray, P for Pulse, OL for Overlay, B for Buttering, A for Automatic, or M for Machine, V for Vickers, BR for Brinell, LTCS for Low Temperature Carbon Steel)
WPS Examples:
GT-SM-1-H : GTAW root, SMAW fill and cap, P1 material, Heat Treated
GM-FC-1-CVN : GMAW-SC root, FCAW fill and cap, P1 material, Charpy V-Notch or Impact Tested
GT-8-F43-OL : GTAW of P8 material, with F43 Overlay filler metal
GT-SAW-4-H-V : GTAW root, Submerged Arc fill and cap, P4 material, Heat Treated, Vickers Hardness Tested
In some cases it is desirable to create a document that contains the naming conventions to also include the descriptions of the abbreviations used in the WPS so the process can be standardized and understood by anyone using the program.
