10 Sep 5 TOP TIPS, Shear Stud Welding
When shear stud welding on site, here are five of our top tips to make sure everything runs smoothly.
Ensure your top flanges are unpainted and have no contaminants.
The top flanges must be free from any type of paint, grease, loose rust or any other coating that could reduce the final weld strength. This check MUST be carried out before the metal floor deck is installed as it will be almost impossible to check after the deck has been laid. If the top flanges are painted or have a coating (and require studs), raise this with the steel contractor ASAP as you can imagine this will cause huge issues later down the line.
Power source and access.
Stud welding is typically undertaken using purpose-built mobile stud welding rigs, operating welding rectifiers and diesel generators. When using this kind of equipment, it’s essential to select the right one based on the size and scale of the project and for Health and Safety considerations, they must always be used in accordance to their instructions.
A stud welding rig with dimensions of 7m long, 2.5m wide and 4m high will require access and hardstanding to within 7.5m of the steel frame to ensure it can be safely earthed. If this isn’t possible due to site logistics or restrictions (the cable can only stretch 80m between the rig and stud welding tool), then an additional steel angle of around 50mm x 50mm is an option too.
The welding settings will differ for each site due to things like atmospheric conditions, weather, parent steel grade, cable distance and ambient temperature. Before you carry out the full installation of the area of studs, a test must be completed and the settings used should be recorded. The test involves 10. No test studs. They’ll need to be bent to an angle of 30° from their original axis using a bending bar over the stud and forcing the stud in the beam’s span direction towards the nearest column. Should this test fail, you must reset the equipment, adjust the settings and repeat the test with replacement welded studs until there’s a pass. A record of the WPQR location and settings should then be marked on a QA record drawing which is a requirement of BS EN 14555:2014.
You must Bend test!
Bend testing must be carried out in the same way as the pre-start WPQR check, but to 15° instead. This should be carried out to either 5% or at least two studs per beam, whichever is greater and if any fail, the three studs either side should also be tested. Any failing studs will need to be replaced and a note marked on the QA record drawing too.
Carry out a visual inspection and ring tests
Once stud welding has been carried out, the ferrules must be broken away from the base of the stud to allow for a visual inspection. Ring test every shear stud by tapping the head of each one with a hammer. Any that do not give a resonating ring sound will then need to be bend tested. If a high level of studs appear to fail, you will need to alter the stud welding settings to ensure a good weld is achieved.
When testing shear studs, you should refer to:
- The manufacturer’s instructions
- BS EN1994-1-1 BS5950: Part 3: Section 3.1
- BCSA Code of Practice for Metal Decking and Stud Welding
- National Structural Steelwork Specification
- BS EN ISO 14555:2014
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