Fabrication drawings are often overlooked, but they are one of the most important steps in complex construction. The drawing will have detailed how elements are built, put together and installed. A good fabrication will give the on-site contractor the exact measurements and number of elements needed to complete the project. If the fabrication is inaccurate, it will cause delays and damage on-site.
Types of fabrication drawings
When working with steel structures, in particular, you can expect to receive three types of fabrication drawings. Each one plays an important part in the construction process and a single project that is complex will require all three drawings. Be aware that even these refer to the type of drawings and not the quantity. Each type will require more than one drawing in a variety of views. The mark of a good fabrication drawing is the presence of only necessary information.
1. Single part drawing: These drawings focus on complex details of the work. They hold specific information for the cutting, dimensions and weight of necessary materials.
2. Assembly drawing: These give information to the welder on how to join all the parts. They include information on finishes and a bill of materials.
3. General arrangement drawing: This is the master plan. It shows how all the parts fit together and contains multiple drawing angles.
What happens when the fabrication drawing is incorrect?
If incorrect or unfinished fabrication drawings are sent to the on-site construction team, things can go terribly wrong. Below are the most common scenarios.
1. The steel structure is assembled incorrectly
If the drawings are obscure or left up to interpretation, the on-site manager could assemble the structure badly. The structure will no longer uphold the same safety specifications and will take more effort and material to disassemble. This is one of the worst problems and it costs the most to fix.
2. Construction starts without the fabrication drawings
Fabrication drawings go through a series of strict quality assurance (QA) tests. This opens the process up to delays. If rushed, the on-site construction manager will be pressured into starting construction. This means even more delays and a waste of materials. It’s important to only begin construction when you have the correct fabrication drawings.
3. Incorrect amount of materials
A sub-par fabrication drawing means you might not order the materials you need. In the middle of construction, a hold up due to lack of materials can cripple your tight schedule.
4. Damaged to people and property
If a steel structure is assembled incorrectly, it won’t have the intended structural integrity. The structure could fail and damage other areas of the construction site – or worse, hurt a nearby worker.
The review process
Before a fabrication drawing is sent to the construction site, it goes through a strict review process. The people who complete the drawings pay incredible amounts of attention to detail. An on-site visit is often necessary to gauge the full scope of the project. The drawings are reviewed in-house by the supervising manager. Next, the correct drawings are sent to stakeholders or relevant parties who review them. Changes are then made and the drawings go through a final review before being sent to the construction site.
CAD or pen and paper?
Computer Aided Design (CAD) helps to ensure the quality and calculations of the fabrication drawings. However, there are still practitioners who prefer using pen and paper for the initial design. Fabrication drawings are almost always checked with CAD software to make sure that the calculations and weight values are correct.
If you think you need fabrication drawings for your construction project, then we can help. Feel free to send us an email and we can discuss the parameters of your project.