WPS template. A filled-in example, ISO 15609-1 and ASME IX.

What a WPS is

A welding procedure specification (WPS) is the instruction for making a weld: process, joint preparation, filler, gas, current, voltage, travel speed, preheat and technique, run by run. It's written for the welder and the inspector, and everything in it has to sit inside what a qualified procedure covers.

The qualification is a separate record. Under ISO it's the WPQR, the welding procedure qualification record of a test to EN ISO 15614-1; under ASME IX it's the PQR. The test records what was welded and how it performed. The WPS gives the ranges production may use, within the limits the standard draws from that test. One WPQR can support several WPSs, and one WPS can rest on more than one WPQR.

What ISO 15609-1 asks a WPS to contain

EN ISO 15609-1 lists what an arc welding WPS has to state. The template groups it like this:

• Identification. Manufacturer, WPS number and revision, the supporting WPQR or other qualification route.
• Parent material. Designation, material group to ISO/TR 15608, thickness and outside diameter ranges.
• Process and joint. Process number to ISO 4063, joint type, a sketch of the preparation with its dimensions, the welding sequence, the position to ISO 6947.
• Filler and gas. Filler designation to its standard (EN ISO 14341-A for a MAG wire), size, any drying; shielding gas to ISO 14175 and its flow rate; backing gas.
• Electrical parameters, run by run. Current type and polarity, current, voltage, wire feed speed, travel speed, and heat input where it's limited.
• Temperatures. Minimum preheat, maximum interpass temperature, post-weld heat treatment.
• Technique. Weaving, torch angle, contact tube distance, cleaning, back gouging and backing.

Next to each item the template has an ASME IX column: where the same item goes on an ASME WPS (the QW-482 form) and which variables paragraph governs it. For GMAW, process 135, the variables are listed in QW-255.

Where the ranges come from

Every range in a WPS has to fall inside what its qualification covers: thickness, diameter, positions, current, heat input, preheat. Under EN ISO 15614-1 the WPQR states the range of qualification, worked out from the test piece by the rules of the standard. Under ASME IX the essential variables listed for the process decide. This template doesn't calculate ranges: copy them from your WPQR or PQR, then narrow them to what production needs. A WPS wider than its qualification is the error auditors find most often.

A procedure test isn't the only route. ISO 15607 also allows tested welding consumables (ISO 15610), previous welding experience (ISO 15611), a standard welding procedure (ISO 15612) and a pre-production test (ISO 15613). The application standard says which you may use: EN 1090-2, for instance, limits them by execution class.

Reading the example

The file comes filled in for a 10 mm single-V butt weld in S355J2+N (EN 10025-2, material group 1.2), welded with process 135, MAG with solid wire, in the flat position from both sides.

• Filler. EN ISO 14341-A G 42 4 M21 3Si1, 1.2 mm. The ASME column gives its usual counterpart, SFA-5.18 ER70S-6.
• Gas. ISO 14175 M21 ArC 18: argon with 18% carbon dioxide.
• Runs. DC with the wire positive. The root goes in at 120–160 A in short arc, fill and cap at higher current in spray. The back is gouged to sound metal and a back run closes it.
• Heat input. Worked out for each run from the lowest and highest settings with k = 0.8 (EN 1011-1): about 0.5 to 1.5 kJ/mm here. Check a run of your own with the heat input calculator.
• Temperatures. Minimum preheat 20 °C and maximum interpass 250 °C, as qualified. Check the preheat against EN 1011-2 for your carbon equivalent and thickness with the preheat calculator.
• Thickness range. 3 to 20 mm, shown as taken from the WPQR, not computed in the sheet.

How to fill it in

• Start from the WPQR, not from an old WPS. Copy the qualified ranges first, then narrow them.
• One row per run or group of runs in the parameter table: root, fill, cap, back run. Give a minimum and a maximum for current, voltage and travel speed, so the welder has a window and the inspector has something to check against. The heat input columns follow.
• Draw the joint with its tolerances: groove angle, root face, root gap, and the run sequence with numbers.
• Revision and approval. Every change gets a new revision, approved by the welding coordinator. Keep the current WPS where the welder works.

Common mistakes

• Ranges wider than the WPQR covers, or copied from another WPS with a different qualification behind it.
• The opposite: the test values copied as single figures, so every production weld is technically outside the WPS.
• No heat input limit where the WPQR had impact tests and the standard limits it.
• Filler and gas by trade name only, with no standard designation.
• A WPS revised without checking that it's still inside its WPQR.
• Approved WPSs that never reach the shop floor.

Where a spreadsheet stops

A spreadsheet WPS prints well. What it can't do is know its own qualification. It doesn't check its ranges against the WPQR, doesn't warn you when a joint is thicker than it covers, and doesn't know which welders are qualified to use it. With dozens of WPSs and their revisions, finding the one that covers a joint becomes a search through folders.

In Worgify the WPS is tied to the PQR or WPQR that qualifies it, the qualified ranges are worked out from the code, and the procedures that cover a joint are the ones the system offers when the joint is assigned.

Terms and standards on this page: WPS, PQR, essential variable, filler metal, ISO 15614-1, ASME IX, ISO 3834.