Quality Control: Know Your Steel

Posted by Ken Brakefield

Quality Control: Know Your Steel

The absolute last thing you want in a fabrication project is for a steel structure to fatigue and fail.  Quality steel could be the secret to successfully avoiding this.  The key is to make sure the materials you are using for your structural steel fabrication project possess the quality you want to deliver. After all, the quality of the end product is only as good as the quality of the material being used and the fabricator you work with.

It’s important for your fabricator to know the quality of the steel before they begin work. Impure and improper measurements of base metals like nickel, copper or lead added to the iron and carbon to create the steel could create issues before your steel is even shipped to your fabricator. Welds can and will fail if the problems are not detected and the quality of the steel is compromised. Fabricators are dependent upon the steel mills to perform testing and provide the Material Certification and Test Reports of the steel to guide them in selecting the correct weld metals and forming of the fabrication project.

Materials Certification

Inspection forms an integral part of quality control. Its purpose is to check that the requirements of the specification are being complied with and to provide a report with proper records to the client. Inspection of the processes, procedures and materials required for the manufacturing of steel structures is vital.  

A major error in even one operation cannot be easily detected after the next operation has been carried out, and if not rectified immediately can significantly reduce durability. 

Structural steel inspections include material traceability, cutting, drilling, beveling, welding operations, fit-up, high-strength fastener installation, and dimensional accuracy throughout steel fabrication. This will help ensure that these components are durable, safe, and will perform according to their designed specifications.

Traceable Material

Good quality steel can be traced back to its origin through Material Test Reports (MTRs.) Steel mills test the materials as the steel is manufactured to supply these MTRs.  It is extremely important that these tests are accurate. The complex chemical and physical reactions that take place in the both the molten and solid state can produce defects in the material.

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Non-uniform properties can present problems during the processing, fabrication and subsequent service of metal components. “Different levels of carbon and other chemicals can change the welding requirements of the base metal,” explains Nick Nijakowski, Certified Welding Inspector with Swanton Welding. “The base metal and weld metal must be chemically compatible.”

The MTR must contain the following information: steel mill's name, heat number, batch number, final test result, steel pipe dimension (steel pipe diameter, wall thickness, length), quantity, steel grade, standard/specification, chemical analysis composition results, mechanical test properties results. If applicable, there also should be hydro test result,UT result, hardness test result, CVN impact results, metal graphic result etc. 

Seams and Laps

The major concerns in steel quality are seams and laps.  These are longitudinal base metal discontinuities. “When these run perpendicular to the applied stress they can become cracks,” according to Nijakowski.

“Welding over them could result in additional cracking.” Delamination and laminations are other mill style defects.  These are failures of the composite material that causes layers to separate with significant loss of mechanical toughness. These are detected either through visual inspection or with the help of instruments and equipment.

Selecting Your Steel Fabricator

The construction industry already faces many challenges.  These include everything from translating your design into an actual build to making sure you partner with companies that provide you with high quality materials. You want a structural steel fabricator that uses stringent inspections along with checks and balances to provide quality steel for your project.  Contact Swanton Welding for more information on our quality standards, and how we can help with your project’s success.

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