Inspectioneering
Inspectioneering Journal

Small Bore Piping Inspection Programs: How a Serious Incident and Investigation Led to a Best Practice

By Anthony J. Rutkowski, Mechanical Integrity Specialist at A.J. Rutkowski, LLC, and Anthony M. Damron, RBI Staff Specialist at The Equity Engineering Group, Inc. This article appears in the November/December 2013 issue of Inspectioneering Journal.
17 Likes

Introduction

Small bore piping is present in many variations throughout numerous industries. This article will address an incident involving a small bore piping failure that occurred on a 140,000 BPD crude distillation unit in the refining industry. This incident not only resulted in a near fatality, but millions of dollars in repairs and lost production.

The incident involved a 3⁄4” bleeder valve attached to a bell head on a set of kerosene heat exchangers that were found to be performing ineffectively. These exchangers utilized cooling water on the tube-side to cool kerosene running through the shell-side. When it was found that the exchangers were not cooling the product effectively, operators working in the unit sprayed fire-monitor water onto the shell to help improve cooling. It should be noted that although this is a common practice in some refineries, this practice is NOT condoned throughout the industry as a whole. Adjacent to the kerosene heat exchangers being sprayed down with fire water were a set of naphtha preheaters which were used to heat, what unit operators called, “wild naphtha”, on its way to the debutanizer tower. It was called “wild naphtha” because of the high butane content in the process stream. The naphtha preheaters were insulated and the back heads had insulation blankets on them, as shown in Figure 1. The overspray from the kerosene cooler’s external cooling effort was soaking the insulation blankets on these heads.

Figure 1. Typical insulation blanket
Figure 1. Typical insulation blanket

These insulation blankets needed to be removed in order to detach the head covers to facilitate cleaning of the naphtha preheaters. During removal of the insulation blanket, one of the stainless steel wires used to hold the blanket in place was wrapped around the 3⁄4” bleeder valve on the bottom of the bell head when the waterlogged blanket slipped off of the head & fell to the ground. The 3⁄4” valve broke off between the valve and the head dumping the butane rich naphtha onto the exchanger below and flooding the area with the product.

Figure 2. The corroded nipple
Figure 2. The corroded nipple

An operator who had witnessed the incident tried to block in the exchangers, but the liquid ignited before he could finish. The operator was caught in the flames and was severely burned, but was able to escape.

The crude distillation unit was subsequently brought down at a cost of millions of dollars due to repairs and lost production.

Post-incident Investigation

An important question that came out of this post-incident investigation was, “how many small bore connections out there are exactly like this?” That question spawned a Small Bore Inspection Program that was later launched in a 340,000 BPD refinery. The Inspection Program included every small bore branch connection and root valve that was in hydrocarbon service at the refinery.

The following paragraphs will serve to explain how that Small Bore Inspection Program was carried out, as well as, address other efforts that were put in place to avoid this type of incident happening again.

This content is available to registered users and subscribers

Register today to unlock this article for free.

Create your free account and get access to:

  • Unlock one premium article of your choosing per month
  • Exclusive online content, videos, and downloads
  • Insightful and actionable webinars
GET STARTED
Interested in unlimited access? VIEW OUR SUBSCRIPTION OPTIONS

Current subscribers and registered users can log in now.


Comments and Discussion

Posted by Yogesh Kumar on June 29, 2019
Dear Authors, A very valuable a comprehensive... Log in or register to read the rest of this comment.

Add a Comment

Please log in or register to participate in comments and discussions.


Inspectioneering Journal

Explore over 20 years of articles written by our team of subject matter experts.

Company Directory

Find relevant products, services, and technologies.

Training Solutions

Improve your skills in key mechanical integrity subjects.

Case Studies

Learn from the experience of others in the industry.

Integripedia

Inspectioneering's index of mechanical integrity topics – built by you.

Industry News

Stay up-to-date with the latest inspection and asset integrity management news.

Blog

Read short articles and insights authored by industry experts.

Expert Interviews

Inspectioneering's archive of interviews with industry subject matter experts.

Event Calendar

Find upcoming conferences, training sessions, online events, and more.

Downloads

Downloadable eBooks, Asset Intelligence Reports, checklists, white papers, and more.

Videos & Webinars

Watch educational and informative videos directly related to your profession.

Acronyms

Commonly used asset integrity management and inspection acronyms.