It has been over twenty years since the original I-CAR research on structural sectioning took place. That research resulted in a list of general sectioning guidelines for repair facilities to consider as a subjective business decision for partial replacement. Many things have changed over the years that have affected the general sectioning guidelines. However, nothing has had more of an impact as the increased use of advanced high-strength steel (AHSS) and vehicle maker design technology.

This article will address general sectioning guidelines, reinforce the necessity to follow the vehicle makers’ recommendations, examine the effect AHSS and design technologies are having on the decision process, and hopefully answer the question: are general sectioning guidelines still applicable? One thing is for sure, the number of collision damage situations that would even qualify for general sectioning guidelines is getting lower and lower each and every year.

The past
The following was published in the January-February, 1997 I-CAR Advantage:

“The I-CAR sectioning guidelines explain how to determine if a part qualifies for sectioning, and where the joint should be located if it does qualify. Sectioning should be done in a uniform area that allows enough clearance to perform quality welding operations. I-CAR recommends against sectioning in or near these areas:

    • suspension, engine, and drivetrain mounting locations.
    • holes larger than 3 mm.
    • compound shapes or structures.
    • reinforcements.
    • hinge locations.
    • seat belt D-ring attachment points.
    • locations where vertical and horizontal panels meet.
    • collapse or crush zones. (crush initiators)”

Figure 1. A cutaway of a B-pillar from a 2000 Subaru Legacy Outback wagon shows multiple reinforcements.

The first question to consider is; are there areas on late-model vehicles that would even qualify for general sectioning guidelines given all of this criteria? In other words, are there parts that have smooth and continuous areas that are not located in a collapse zone or near a mounting location, have no holes larger than 3 mm, are void of any reinforcements, and have no compound shapes or structures? The number of vehicles being built today with areas that meet all of these requirements is minimal, at best. Let’s examine a few of these criteria and relate them to today’s vehicles and then add some additional considerations into the mix; vehicle maker recommendations, advanced high-strength steel (AHSS), and location and design intent.

Uniform Areas; Compound Structures
As if general sectioning guidelines weren’t subjective enough, the terms “uniform area” and “compound shapes or structures” are both open to varying degrees of interpretation. The vehicle build technologies that have allowed vehicle makers to introduce new shapes and designs not formerly available using sheet metal stamping processes have certainly increased the complexity of vehicle design and incorporated many more compound shapes and structures into vehicle architecture.

The number of areas that a majority of industry professionals would consider a compound shape or structure has increased over the years. Uniform areas that are smooth and continuous have been greatly reduced. The exceptions to this may be hydroformed frame rails and unitized pillars, rocker panels, and rear rails. However, pillars and rocker panels present a different set of variables and obstacles.