FFS Forum: Fire Damage Assessment – Tips and Guidance on FFS in the Aftermath of a Process Plant Fire (Part 2 of 2)

Editor’s Note: This is Part 2 of a two-part column on Fire Damage Assessments. It focuses on the important topic of establishing “Heat Exposure Zones” and how to conduct Level 1, 2, and 3 assessments after a fire.

Introduction

In the last edition of the Fitness-for-Service Forum, published in the July/August 2021 issue of Inspectioneering Journal, I began the discussion of Fire Damage Assessments (FDA). In Part 1, I provided a big picture overview of the process of assessing equipment in a post-fire “return- to- service” effort, discussed the involvement of regulators, and highlighted the importance of properly identifying damage mechanisms. In this follow up article, I’m going to talk about the important topic of establishing Heat Exposure Zones and discuss Level 1, 2, and 3 fitness-for-service assessments.

Heat Exposure Zones

Heat exposure zones and the corresponding heat zone maps are enormously important tools in fire damage assessments. They are the key to all the work that follows.

What is a Heat Zone Map?

A heat zone map is a drawing of the plant, with a color-coded overlay indicating the maximum temperature experienced in different areas. Various temperature ranges are associated with Heat Exposure Zones, as defined in API 579, Part 11.

Figure 1 shows an example of a simple heat zone map. Process equipment is included in the drawing with colored areas corresponding to Zones 1 through 6.

The plan view covers the entire area of the fire, but since temperature can vary with elevation, several elevation views at different cross-sections may also be necessary.

How is a Heat Zone Map Created?

Creating a decent heat zone map takes both experience and skill. It requires very detailed detective work worthy of Sherlock Holmes.

The map team must:

• Have knowledge of what types of damage are associated with what temperatures, and
• Have the skill and detail orientation to pick out specific evidence of damage.