Welding procedure specification
A Welding Procedure Specification or WPS is the legal and formal written document describing welding procedures. The WPS provides information and direction to the welders and welding operators to create the best quality production welds. All workers need to understand the content of WPS used during welding. WPS is like a recipe for welders and welding operators. Welding Procedure Specification contains the variables of the welding parameter created for the purpose of being used as a welder or welding operator to perform welding work (welding connections) in accordance with the provisions of the code (ASME, API, and AWS). A WPS is based on the allowable variables of the approved PQR.
Procedure Qualification Record (PQR)
A Procedure Qualification Record (PQR) is the document that records actual weld test parameters used during welding.
The welding process that is not in accordance with the procedure can cause work accidents that even cause fatalities or cause equipment to break faster. There are some cases of work accidents due to the bad welding process. ASME Boiler and Pressure Vessel Code are one of the standards used in the oil and gas industry, consisting of 12 sections. In this article, we discuss the qualifications of WPS that refer to the ASME Boiler and Pressure Vessel Code Section IX – Welding and Brazing Qualifications standards.
ASME Section IX QW-490 describes the definition of welding as a localized connection of metal (metal) or non-metal produced by heating the material to welding temperature, with or without using pressure (pressure), or only pressure, with or without the use of filler metal (filler metal). Most of the oil and gas industries use an arc welding process, namely SMAW, GMAW, GTAW and SAW.
welding procedure specification – 3 variables
Variables involved during welding are grouped into 3, namely essential variables, nonessential variables, and supplementary essential variables (if needed).
Essential variables are all variables that, if changed, will affect the mechanical properties of the weld results require re-qualification of WPS (QW-251.2). Nonessential variables are all variables that, if changed, can be made in WPS without requalification (QW-251.3). Whereas the Supplementary essential variable will be an essential variable if the welding process requires a notch-toughness test or an impact test. This impact test is often required by the Designer or Code for equipment used in low-temperature conditions that cause changes in material properties from ductile to brittle.
- base metals
- welding process
- joint design
- Arc Voltage
- welding Amperage
- travel speed
Each welding process has different variables. This variable data can be seen in full in ASME Section IX. For example, the SMAW welding process is regulated in QW-253. The test coupon used when qualifying WPS is considered an essential variable. If the test coupon uses a plate with T = 1.5mm thickness, then the WPS is only valid for use in welding production with a material thickness of 1.5 mm to 3.00 mm (according to QW-451.1). If production welding has a 4mm material thickness, it needs additional WPS.
You can download an example of the WPS full form in pdf document in the below link:
If you want to get more detail about how to make welding procedure specifications in pdf format, please download this Url: https://www.pdfdrive.com/welding-procedure-guide-d5583847.html
testing requirement for welding procedure specification
WPS needs to be tested to ensure that the procedures made can produce good production welds. The test method is divided into two, namely the Destructive Test and Non-Destructive Test. Following are the types of tests used:
1) Mechanical Tests (QW-141) are used for WPS qualifications and welder qualifications consisting of:
Tension tests. This test is a destructive test method to determine the ultimate strength of the groove-type welding joints on the test coupon.
Guided-bend tests or bending tests, to determine the degree of smoothness (soundness) and ductility of the groove-type welding connection.
Fillet-weld tests, to determine the size, contour, and degree of soundness of the fillet-type welding joints.
Notch-toughness tests, to determine the notches of welding. This method uses Charpy V-Notch and Drop Weight
2) Radiography Examination. This test can be used to replace the mechanical test in qualifying the performance of groove-type welding to prove the ability of welders to make sound welds (QW-142).
3) Visual examination. this test show complete joint penetration and complete fusion between weld metal and base metal