FUEL STORAGE TANK DEGRADATION WARNINGS as EARLY as 2003

Naturally and unnaturally occurring tank-bottom debris monitoring and removal should be part of a regular fiberglass and steel tank maintenance program.

April 2003 Tank Talk Magazine

Procedures and standards for tank-debris cleaning and monitoring nationwide do exist, but less than 10 percent of all tanks nationwide are on a program of regular maintenance that will preserve motor-fuel quality and prolong a tank system’s useful life. 

Fuel storage tanks are critical components within the infrastructure that supports the transportation industry around the world. During the last century, petroleum companies enhanced their capabilities to develop, refine, store and deliver a selection of quality fuel products. Because of advancements, the public expects nothing less than the finest quality of fuels when they fill up their vehicles.

However, fuel quality will become a larger issue for petroleum marketers if service station operators continue to neglect the technical details of “what’s going on in that storage tank.”

After many years of cleaning, filtering and servicing thousands of storage tanks across the nation, experts from Advanced Fuel Filtration Systems, Inc. have noticed several trends directly linked to the accumulation of many different constituents at or near tank bottoms.

Inherent in the refining, transportation and storage of fuels is the always-present, “naturally occurring debris,” including water. Industry veterans recognize that the refining process, with systems operating properly, creates predictable amounts of debris typically controlled by throughput volume and filtration. The emerging story is how to deal with the “unnaturally occurring debris” increasingly found in tanks today.

Recent history in the petroleum industry shows how this relatively new phenomenon began. In the early 1970s truly leaded fuel marketing strategies ended. Low lead fuels continued to be marketed until the late 1980s with the last traces of tetra ethyl lead in refinery piping removed with final retrofits during the late 1990s.

Removing lead from fuel systems – which has yielded significant benefits for air quality – has served as the starting block for a “cascade” of unnaturally occurring storage tank debris that often is evident as microbial organisms.

The clean-air phaseout of lead is significant because for years tetra ethyl lead in fuel (a natural poison) helped to control most microbial culprits.

More than 90 percent of the tanks we clean show signs of microbial activity – which includes colony massing and ionic wastes in water-fuel interfaces, bio films and tank-bottom debris fields. Additionally our tank-cleaning staff increasingly is finding what once was totally unexpected – sodium sulfur salts and calcium sulfites saturated in naturally occurring storage tank water-fuel interfaces. We suspect these additional contaminants to be generated by refinery scrubbers and drying beds operating at levels over capacity.

Microbial colony mass is visually seen in a measured bio film. Aromatically, it emits a telltale odor of sulfur dioxide (rotten eggs). Massing can be found in a continuous bio film or in pocketed cells. The lack of a visible bio film generally signals low microbial activity.

The unexpected becomes at the least, interesting and quite possibly a point of concern when resident sodium sulfur, sodium sulfide, sodium sulfites and microbial wastes combine in a catalyst of water to produce a “cauldron effect” at the bottom of a fiberglass or steel tank.

In short, what’s in the cauldron today is an ever-evolving mix of constituents. Our experience has shown that about 40 percent of tanks today exhibit the cauldron effect.

An arrival path for the debris could typically be a transported “contaminated product delivery” of sodium sulfur, sodium sulfate, sulfur dioxide or a microbe waste strain, microbials converted to a sodium sulfite in a naturally occurring catalyst of water.

This dangerous combination could become hydrogen sulfide, sodium hydrogen sulfite and sulfuric acid – complicated with a catalyst shift due to something as simple as temperature change. We have noticed a drop in pH values in naturally occurring water fuel interfaces in recent years. We recognize this as a signal for concern.

All of this contributes to the effect on a storage tank’s primary containment. Depending upon the tank’s material of construction, integrity may be affected by localized corrosion, pitting, and delamination – long before contamination reaches a dispenser filter or a fueling customer’s car or truck.

Some of the sources for this debris can be caused by: ? A scrubber at a refinery or a drying bed operating below set standards ? A bad fuel tank waste mix at a blending plant ? Loading racks ? Water suspended in fuel being transported through pipelines ? Less-than-pure ethanol or methanol additives ? Introduction of aggressive sulfur-consuming microbes ? Loose tank-top fittings, or ? Something as simple as a leaf stuck in a containment bucket drain valve at a gas station

Because of all these contributing factors, prudent operators of fuel-tank systems will find that they cannot afford to wait until debris ruins the tank or it’s contents – along with very high-tech engine parts found in today’s vehicles.

Joe C. Wilson is a registered environmental assessor and a principal with Advanced Fuel Filtration Systems, Inc., based in Corona, Calif.

Joe Wilson “God Rest His Sole” passed away a few years ago. He started making predictions and issuing Warnings, but no one was obviously listening or paying attention.Zane Miller is a professional engineer with the firm. I’m still here but no one has been listening to me either.