FUELING SYSTEM EQUIPMENT OPERATIONAL ISSUES
FUELING SYSTEM EQUIPMENT OPERATIONAL ISSUES
11-05-2017 Subject and Concerns
Corrosion in Tanks and Secondary Containment Sumps
Damaging corrosion effecting retail and commercial small, low pressure fuel storage tanks and product delivery and secondary containment components associated with these tanks.
Corrosive conditions in Gasoline and Diesel retail and commercial bulk fuel storage tanks.
- Effecting both glass and steel primary storage tank containment boundary integrity.
- Effecting in both glass and steel tanks installed standard and intimate connection fittings.
- Effecting in both glass and steel tanks submerged turbine (STP) motor pumps, motor pump supporting, pump positioning columns, automatic tank (ATG) fuel level floats and monitoring probes.
Corrosive conditions in Gasoline and Diesel retail and commercial bulk fuel storage tanks critically effecting integrity of fueling system in tank and downstream components.
- Effecting under dispenser pressurized Diesel product line shear valve operation and its ability to be tested and or automatically close after an impact and shear event.
- Causing unrecognized fuel leakage within a dispenser cabinet of metering, control valve and filtering component connections.
- Causing inaccurate and irregular measurement of fuel volumes dispensed.
- Causing in tank pump motor column support separation and primary tank bottom damage and integrity failure.
- Causing ATG accelerated magnetic retentivity failure and inability to accurately monitor actual fuel volume delivered and or level and volume of fuel stored in tank.
- Causing at fill an inability to restrict bulk fuel delivery causing tank overfill.
- Causing motor and other connection access bung and riser integrity failure in glass and steel tanks.
Corrosive atmospheric conditions in Gasoline and Diesel retail and commercial bulk fuel storage tanks.
- Abnormally low PH acidic atmospheric values in a tanks empty of fuel stored saturated vapor space (ullage).
- Abnormally low PH acidic atmospheric values in a tanks empty of fuel stored saturated vapor space (ullage) and moisture.
- Abnormally low PH acidic atmospheric values in a tanks empty of fuel stored saturated vapor space (ullage), moisture and oxidizer (oxygen).
TANK CONTAINMENT BOUNDARY INTEGRITY CORROSION ISSUES
Damaging corrosive constituents causing issues in Gasoline and Diesel retail and commercial bulk fuel storage tanks.
Formation of ferrous oxides on STP motor columns, associated and attached tank connection fittings and internal tank wall surfaces. The constituent described for lack of a simpler term as a “rusticle” The rusticle consists of up to 35% iron compounds including iron oxides, iron carbonates and iron hydroxides. The remainder of the structure is actually a complex community of symbiotic or mutualistic microbes including bacteria and fungi that use metal and impurities found in the metal as a source of food, causing microbial corrosion and collectively producing the mineral compounds as waste products forming the rusticle. Structurally, rusticles contain channels to allow water to flow through, and they seem to be built up in a ring structure similar to the growth rings of a tree.
It should be clear that when ferrous oxide “rusticles” form it can be assumed that underneath corrosion is occurring. Corrosion occurring one should assume some degree of damage to the attached surface is occurring as well.
IN TANK and DOWNSTREAM COMPONENT INTEGRITY CORROSION ISSUES.
Damaging corrosive constituents causing fueling system component issues downstream of the associated tank.
Compounding fueling system component issues downstream the term “velocity corrosion” comes into play. As the ferrous oxidation accumulations dislodge in time due to fuel loading and motor column frequency oscillation (vibrations) from tank internal STP motor columns they are ingested and ground into fine solid (.05 microns or less) extremely abrasive METAL debris. Over time this abrasive debris carried within the fuel flow will dead head accumulate in product piping, dispensing filters, dispenser metering and control valve components and damage internal safety shear valve closing platforms.
The discussion gets now more interesting regarding what might be (The Problem) causing the corrosion that signals (Symptom(s) of the Problem) with the happening formation of a “Rusticle” in the first place. The path for problem resolution regarding corrosion in tanks is more likely recognizing the Problem rather than concentrating efforts to treat the symptoms of the (A) problem. If one logically was to compare the operating dynamics of a typical Retail or Commercial fueling system today to let us say a 1969 vintage Lunar Orbiter and Lander or a more recent successful Shuttle Launch reaching orbit resolution of a corrosion problem effecting the integrity of a SIMPLY ROUND tank on earth for some might seem to be somewhat simpler.
SECONDARY CONTAINMENT SUMP CORROSION and CONTAINMENT ISSUES
Damaging corrosive constituents causing fueling system component failures within secondary containment sumps associated tanks.
Acidic atmospheres in primary tank empty spaces are obliviously migrating out of and into fueling system associated secondary containment sumps. Tanks when fuel is delivered typically become over pressurized whereas during the bulk fuel delivery event saturated hydrocarbon vapors migrate through over pressure rated fitting, and pump flange gaskets, manway seals and electrical through cap lead connection fittings. Tank over pressurization exceeding design during loading events are found to be common and wide spread throughout North America. During over pressurizing events saturated vapors have been tracked moving from one secondary containment sump to another through damaged or unsealed electrical conduits. For obvious reasons sump corrosion is typically not found as sever in diesel containment secondary’s as in gasoline storage tank associated containment sumps.
TANK CORROSIVE ATMOSPHERES
So what’s the Problem?
What’s causing the Problem?
Logical understanding of the Problem?
How to prevent the Problem?
The Problem in the tank.
There are bugs inherent in the Fuel. There always have been and there always will be. The bugs survive because they are diverse in nature and able to adapt within just about any known environment. When an encouraging environmental condition exists bugs inherent in all fuel will colonize. Colonizing activity will naturally produce atmospheres in the empty spaces of fuel storage tanks that can induce or encourage corrosion on a susceptible exposed surface.
What’s causing the Problem in the tank?
Failure to recognize the problem. Within a fuel tank exists food and a near perfect environment for microbial activity and colonization.
Logically understand the Problem in the tank?
First one recognizes there is a problem. Understand the terrarium environmental conditions that can or presently exist in fuel storage tanks. Creating and controlling a tanks empty space atmosphere will discourage microbial activity and colonization.
How to prevent the Problem in the tank?
Keep the tank full of fuel? If only it was economically that simple.
Keep moisture from entering the tank. Keep oxidizing atmospheres out of tanks.
Adopt API protocols for dry inert gas blanketing fuel storage tanks.
Establish an industry consensus standard or method for environmentally friendly corrosion control in small low pressure fuel storage tanks.
It is important to recognize that atmospheric conditions in a tanks empty space may or may not be conducive to corrosion. Tanks exhibiting corrosion issues typically are low throughput tanks storing fuel for economic reasons (lots of empty space) well below capacity. Depending on tank(s) venting manifold connection configurations and tank vent breathing to and from outside atmosphere more or less atmospheric moisture will condense as water on a tanks internal (wetting) surfaces. Suggested to prevent a corrosion (wetting) conducive atmosphere in the tanks empty space is the control of moisture (water) and oxygen (oxidizer) entering and mixing (cauldron effect) with hydrocarbon saturated vapor.
CONTAINMENT SUMP CORROSIVE ATMOSPHERES
So what’s the Problem?
What’s causing the Problem?
Logical understanding of the Problem?
How to prevent the Problem?
So what’s the Problem in the sump?
Low PH acidic and corrosive tank empty space atmospheres are migrating into sumps during a bulk fuel delivery. Atmospheres becoming acidic in moist oxygen rich sumps wetting sump component soft metal surfaces. Component assembly bolt corrosion increasing exposure for catastrophic leak or release.
What’s causing the Problem in the sump?
Failure to recognize the problem and association to saturated hydrocarbon vapor and or corrosive atmospheres in an associated tanks empty (ullage) space. Over pressurization of associated(s) tank during a bulk fuel loading event. Loose tank top and sump contained component fittings. Failure to adequately test tank top tightness for pressures now known to be present during a bulk tank loading event. Failure to recognize upon inspection imminent corrosion induced failure of component (mechanical leak detectors, functional elements, soft metal vent connections to tank empty spaces) assembly bolts and component connections. Failure to instruct bulk delivery personal in proper connect and drop tank loading procedures. Failure of transport carriers to maintain phase I vapor recovery equipment in working order. Failure of DOT transport inspection contractors to actually test transport Phase I vapor recovery systems for proper function. Failure of tank testing contractors on sites to actually test tank top tightness using adequate pressure leak decay pressures. Failure upon regular inspection to recognize sump wall penetration fitting and seal integrity failure. Failure of regulators to recognize inadequate mandated and or required test procedure methods.
Logical understanding of the sump corrosion Problem?
Saturated hydrocarbon vapors (fugitive emissions) are NOT SUPPOSED to leak out of a tank storing fuel and or into a secondary containment sump. Migration of these vapors from a tank into an associated secondary containment sump means the Tank is (leaking) Not Tight. If a tank is leaking vapors out then oxidizing atmosphere and water (moisture) corrosion encouraging constituents can leak in.
It is important to recognize that atmospheric conditions in a tanks empty space may or may not be conducive to corrosion. Oxygen and moisture rich atmospheres are more likely to exist in a tanks associated secondary containment sump(s). Saturated hydrocarbon vapor corrosive or not migrating from the tank into the sump may then combine with constituents resident in the sump producing low PH moist and corrosive atmospheres.
Interestingly fueling sites when inspected may show corrosion in a diesel tank but no corrosion in an associated diesel containment sump. Gasoline fuel storage tanks may not show corrosion effects in a tank but show corrosion (Oxidized accumulation) in their associated sumps. Some sites a corrosive condition is present in all sumps gasoline and diesel. Corrosion in all sumps generally found is vapor migration paths through pump flange manifold gaskets and or electrical conduits connecting sumps. A fueling site could have one tank or all tanks over pressurized and leaking during a bulk fuel delivery causing problems.
How to prevent the Problem in the sump?
Keep the tank full of fuel? If only it was economically that simple. Keep moisture from entering the tank, associated and connected secondary containment sumps. Keep oxidizing atmospheres out of tanks, associated and connected secondary containment sumps. Adopt API protocols for dry inert gas blanketing fuel storage tanks and secondary containment sumps. Establish an industry consensus standard and methods for environmentally friendly corrosion control in small low pressure fuel storage tanks and associated secondary containment sumps. Adopt realistic tank pressure level leak test thresholds.
The problem may simply be to address tank over pressurization contributing to a corrosive conditioning atmospheric constituent getting into the sump. Efforts for treating a myriad of corrosion Symptoms in SUMPS and TANKS unfortunately has fatally delayed recognition and resolution of the Problem.
Protocol and procedure development
5 年Regarding Re: Diesel corrosion Unread post by CherokeeUST ? Mon Sep 16, 2019 11:13 am Ethanol is not the cause of corrosion??? Ethanol is mentioned 50+ times in the 2016 EPA corrosion report. One simple possible reason that trace ethanol is found in ulsd biodiesel blends is that both biodiesel and ethanol are polar molecules, so will be attracted to each other. If so, there should be trace biodiesel in gasoline blended with ethanol. Has anyone looked for biodiesel in ethanol blended gasoline? A new paper has just been released that monitors corrosion in B20 storage over a years timeframe. This is the first long term, in situ study, and shows the increased levels of MIC over time. It is a very good read. I'm interested as it ties in water and MIC. Dry the fuel, control the MIC. Two ways of control is removal of water, with SAE J1488 filtration, and prevention of water absorption with nitrogen blanketing. I understand that water can also be removed using heated nitrogen. This latest paper (Feb 20 2020) studied 6 tanks at two United States Air Force (USAF) bases for a year. It is coauthored by Dr. Bradley Stevenson, Associate Professor of Microbiology, Dept. of Microbiology and Plant Biology, University of Oklahoma. This peer reviewed paper was just published in Frontiers in Microbiology, "a leading journal in its field, publishing rigorously peer-reviewed research across the entire spectrum of microbiology."https://www.frontiersin.org/articles/10 ... 00167/full
Protocol and procedure development
5 年The comprehensive, in situ investigation presented here compliments several other laboratory-based studies (Leung et al., 2006; Bucker et al., 2011; Ching et al., 2016). Together, they illustrate the susceptibility of fuels containing biodiesel to microbial proliferation (fouling), fuel biodegradation, and MIC of associated infrastructure. Here though, we were able to directly link the presence and prevalence of biofilms to pitting corrosion in actively operating B20 storage tanks. We found that a mixed microbial community of filamentous fungi and acid-producing bacteria were able to proliferate in B20 biodiesel storage tanks, cause fouling, degrade fuel by metabolizing the FAME, produce organic acids, and accelerate steel corrosion under biofilms attached to metal surfaces. The same fungal species was responsible for “blooms” of biomass, providing a target for future mitigation strategies. Additional research is underway to characterize this most abundant fungal member of fuels and biofilms observed at both locations (Stamps et al., 2018). Despite the trade-offs in fuel stability due to susceptibility to microbial attack, biodiesel continues to be the most common and economical solution to reduce the environmental impact of petroleum diesel combustion. As such, the use of biodiesel will likely continue to increase worldwide for the foreseeable future. Operator vigilance in fuel quality and storage conditions is required including early mitigation through water removal, cleaning, and even biocide treatment. Each of these methods would likely be the most effective means of controlling fouling, degradation, and corrosion through the prevention of microbial biofilm establishment. While B20 presents new storage challenges to operators, risk assessments informed by this study will aid each operator in formulating the appropriate response if contamination is detected.