Welding Procedure Specifications
Welding Procedure Specification Example
A WPS is a document that describes how welding is to be carried out in
production. They are recommended for all welding operations and many
application codes and standards make them mandatory
What information should they include?
Sufficient details to enable any competent person to apply the information and
produce a weld of acceptable quality. The amount of detail and level of controls
specified on a WPS is dependant on the application and criticality of the joint to
be welded.
For most applications the information required is generally similar to that
recorded on a Procedure Qualification Record (PQR) or Welding Procedure
Approval Record (WPAR), except that ranges are usually permitted on
thicknesses, diameters, welding current, materials, joint types etc.
If a WPS is used in conjunction with approved welding procedures then the
ranges stated should be in accordance with the approval ranges permitted by the
welding procedure.
However careful consideration should be given to the ranges specified to ensure
they are achievable, as the ranges given by welding procedure standards do not
always represent good welding practice. For example welding positions
permitted by the welding procedure standard may not be achievable or practical
for certain welding processes or consumables.
EN ISO 15609-1 (formally EN 288 Part 2) European Standard For Welding
Procedure Specifications
EN ISO 15609 Defines the contents of a Welding Procedure Specification in the
form of a list of information that should be recorded. For some applications it
may be necessary to supplement or reduce the list. For example only in the case
of a procedure requiring heat input control would there be a necessity to quote
travel speed or run-out length for manual processes.
ASME IX American Boiler and Pressure Vessel Code
QW 250 Lists the variables for each welding process, all the variables stated
should be addressed. The range permitted by the WPS is dictated by the PQR or
PQR’s used to qualify it.
Typical Items That Should Be Recorded On W.P.S:-
Common to all Processes .
Procedure number
Process type
Consumable Size, Type and full Codification.
Consumable Baking Requirement if applicable
Parent material grade and spec.
Thickness range.
Plate or Pipe, Diameter range
Welding Position
Joint Fit Up, Preparation, Cleaning, Dimensions etc.
Backing Strip, Back Gouging information.
Pre-Heat (Min Temp and Method)
Interpass If Required (Maximum Temperature recorded )
Post Weld Heat Treatment. If Required (Time and Temp)
Welding Technique (weaving,max run width etc.)
Arc Energy Limits should be stated if impact tests are required or if the
material being welded is sensitive to heat input.
MIG
SUB
Specific To Welding Processes MMA TIG MAG
ARC
FCAW
Welding current yes yes yes yes
Type of Welding current AC/DC Polarity yes yes yes yes
Arc voltage If Auto yes yes
Pulse parameters (Pulse time and peak &
If Used If Used
backgound current)
Welding Speed If Mechanised yes yes yes
Wire configuration yes
Shielding gas (comp,flow rate) yes yes
Purge gas (comp & flow rate) If Used If Used
Tungsten electode Diameter and type. yes
Nozzle diameter yes yes
Type of Flux Codification & Brand Name yes
Nozzle Stand Off Distance (Distance from
yes
tip of nozzle to workpiece).
Sketches
A sketch of the joint configuration is required which should include the basic
dimensions of the weld preparation. Some indication of the run sequence is also
beneficial, particularly if the correct sequence is essential to ensure the properties
of the weld are maintained.
Production Sequence
Whilst this is good practice it is not a requirement of either ASME 9 or EN288
Part 2; it could be issued as a separate QA procedure if preferred.
Non Destructive Testing
A WPS is primarily concerned with welding not N D T, this activity should be
covered by separate N D T procedures.
Welding Procedure Specification Example
Welding Qualifications Sub Menu
Page last updated 21 March2008
Welding Procedure Specification:- Example
Weld Procedure Number 30 P1 TIG 01 Issue A
Qualifying Welding Procedure (WPAR) WP T17/A
Method Of
Machine and
Preparation
Manufacturer: National Fabs Ltd Degrease
and Cleaning:
25 Lane End Parent Metal Grade 304L
Birkenshaw Specification: Stainless Steel
Leeds
Parent Metal
Location: Workshop 3 to 8mm Wall
Thickness
Welding Process: Manual TIG
Pipe Outside Diameter 25 to 100mm
Joint Type: Single Sided Butt Weld
Welding Position: All Positions
Welding Progression: Upwards
Joint Design Welding Sequences
Size Of Type Of Wire
Current Voltage Travel Heat
Run Process Filler Current/Polarit Feed
A V Speed Input
Metal y Speed
1
TIG 1.2mm 70 - 90 DC-
2 And N/A N/A N/A N/A
TIG 1.6mm 80 - 140 DC-
Subs
Welding Consumables:- Production Sequence
Type, Designation Trade Name: BS 2901 Part 2 : 308S92
Any Special Baking or Drying: No 1. Clean weld and 25mm
borders to bright metal
Gas Flux: Argon 99.99% Purity using approved solvent.
Gas Flow Rate - Shield: 8 - 12 LPM 2. Position items to be
- Backing: 5 LPM welded ensuring good fit
up and apply purge
Tungsten Electrode Type/ Size: 2% Thoriated 2.4mm Dia 3. Tack weld parts together
Details of Back Gas Backing using TIG, tacks to at
Gouging/Backing: least 5mm min length
5°C Min 4. Deposit root run
using 1.2mm dia. wire.
Preheat Temperature: 200°C Max 5. Inspect root run
Interpass temperature: internally
Not Required 6. Complete weld
Post Weld Heat Treatment using 1.6mm dia wire
Time, temperature, method: using stringer beads as
Heating and Cooling Rates*: required.
7. 100% Visual inspection
of completed weld
Revision History
Date Issue Changes Authorization
26/11/2000 A First Issue Jack Straw Jack Straw
Welding Procedure Specifications
Welding Qualifications Sub Menu
Page last updated 26 November 2000
