Field welding is a common construction practice to assemble structural steel elements. Most construction welding is done using ‘stick’ welding, or SMAW, Shielded Metal Arc Welding. SMAW uses an electrode (euphemistically called a ‘stick’) and electric current to create an electric ‘arc’ between the stick and the base material, which has a ground clip attached to it to complete the electric circuit. This arc creates a very high temperature between the electrode (stick) and the metal being joined or welded. The electrode is a solid metal selected to be compatible with the material being welded (base material) and is coated with compounds and metal powders (flux) that improve the weld quality. The flux generates a gas when heated by the arc which surrounds the point being welded and reduces contamination of the weld from the atmosphere. The electrode is ‘consumable’ in that the electrode core metal is used to fill the weld joint.
Stick Field Welding, like every process has pros and cons:
SMAW Field Welding Pros
- Equipment is readily available at low cost
- Does not require external shielding gas (in cylinders)
- Can work on rusty materials though most welding processes call for cleaning rust and paint before welding
SMAW Field Welding Cons
- While it can be performed when it’s rainy or windy, this presents safety hazards
- Electrodes must be properly stored per AWS standards and be readily available at site to avoid delays
- Operators need a high level of skill and experience
- Construction welds must be 100% inspected to demanding standards
Additionally, depending upon the location of the welding taking place:
- A generator or engine driven welding system might be needed if there’s no conventional power available
- There might be fire hazards to manage from splatters of molten metal or grinding sparks
- Fume extraction equipment for poorly ventilated areas might be needed, again possibly with their own power source
Challenges with Field Welding
Welding already isn’t easy. Field welding adds an even greater level of difficulty with wind, airborne contaminants, moisture and common site hazards such as being on ladders or standing in the rain. Field welding exposes welders to the elements but also exposes other workers to the hazards of being near welding operations including line-of-sight risks as well as weld splatter and burns. Onsite welding means that electrodes must have a controlled storage area for welds to be performed to code with ample supplies of the right electrodes onsite.
Per building codes, welds must be inspected, and sometimes require LPT, X-Ray or other advanced NDT inspection which are costly. Structural steel inspection is critical to the safety of structural steel buildings. Poorly welded steel joints or misaligned steel welded joints can adversely affect the structural integrity and safety of a building.
Building weld inspectors are required to be certified to AWS and/or ICC standards including visual inspection processes and also NDT weld testing such as LPT, ultrasonic, X-Ray and magnetic particle testing. Since these certifications require a high level of training and expertise, these skills can be hard to come by and expensive to retain for a project. Adding to the cost, during inspection, the welding inspector must measure the size and length of the structural welds. This means that the inspection of welds on components such as embedded plates, which are often quite high up, can be cumbersome and time consuming, and therefore costly.
Field welds that fail inspection must be redone, which means that the operator, gear and supplies must be brought back to the weld, the weld ground out, redone and reinspected. Inspection and failed welds can be very costly and drive project delays.
Construction is a very competitive business, and construction companies and steel fabricators are constantly looking for a competitive advantage. Construction industry thought leaders are advocating for ‘Lean Construction’, also known as ‘Modular Construction’ or ‘Off-site Fabrication’'. In off-site fabrication, construction steps that would routinely be performed on site, such as welding, are instead performed in a factory setting. Companies that perform offsite construction are claiming cost savings of as much as 25% from the cost of fabricating assemblies on site.
Clearly there can be significant cost advantages in re-thinking how your construction or structural fabrication company is performing seemingly routine construction tasks such as welding.
You may find that you can benefit by evaluating which joints should be welded and which might be better off as bolted connections.
Also, for structural steel fabricators, does it make sense to be fabricating assemblies like embed plates on your own when they can be purchased at higher quality with significant net project cost savings available with specific new types of embed plates that are now available?
Part of the reason that companies are looking at offsite construction is that core construction skills, such as welding, can be scarce and are getting scarcer.
From a recent Commercial Construction Index from the US Chamber of Commerce, two-thirds of construction contractors report difficulty finding skilled workers. Furthermore, “most contractors have a moderate to high level of concern about the skill level of workers, with the majority [56%] expressing high concern.” By reducing the amount of onsite welding that has to be done, fabricators are able to allocate scarce onsite welding resources to the jobs that matter most.
Free up scarce field welding resources to perform more valuable work while you lower construction field welding costs.
As noted above, highly skilled construction workers are getting more difficult to find. Not having difficult to find skills such as field welding available to meet a project schedule can create costly project delays. Onsite field welding requires specialized skills but also sometimes specialized equipment such as fume extraction equipment as well as consumables and proper consumable storage. Steel construction welding codes will often require cleaning of rusty or paint marked surfaces to be welded, taking up valuable hours for each weld. Welding that must be done above floor grade requires either a lift or is done on a ladder, creating a safety hazard. Onsite welding creates safety hazards to others and a site fire hazard which increases overall site safety risk.
Clearly, there’s a cost, timeline and risk management benefit to allocating scarce field welding resources to only those structural joints that demand it.
EM-BOLT patented boltable embedded plates allow you to allocate scarce onsite welding resources to only those joints that require welds. EM-BOLT boltable embedded plates replace a common field welded joint, the beam or structural steel component to concrete joint with a boltable joint.
This advanced embed plate design eliminates the field welding and inspection costs associated with every traditional welded embed plate, leading to considerable construction project savings where they have been applied.
With EM-BOLT embed plates, you can rationalize where your scarce and expensive field welding and inspection resources are allocated to maximize project profitability. With our new thermal break solutions, you can also meet demanding energy codes while saving construction costs and shortening construction timelines.
You can learn more about the details of using EM-BOLT boltable embed plates below:
Interested in learning more about how EM-BOLT boltable embed plates save construction costs and time? Take advantage of the Guide below!
Would you like help with your concrete embedded plate engineering calculations? Reach out to us below.
Embedded plate Revit drawings of our standard series of products are also available, for Revit drawings go here.
To learn more about the advantages of EM-BOLT Boltable Embedded Plates, go here.