News & Updates

The Importance of Safety and Design for Fuel Tanks

Taken from Environmental Science & Engineering

Natural disasters, acts of vandalism and terrorism, fires and explosions are all major concerns for building and facility owners storing fuel on site. For above ground storage tanks, the Underwriters Laboratory (UL) 2085 listing has long been recognized as the “gold standard” for design safety. UL 2085- listed tanks provide fire protection (they have been fire tested at 2000 degrees for two hours), secondary containment, and protection from vehicle and projectile impact. But are the performance standards in this listing an adequate benchmark for what may happen in the real world?  Two incidents highlight the importance of having added protection and security. Both events took place at Department of Homeland Security facilities in the US. In each case a ConVault tank helped guard against catastrophic losses of property or life.

Tank explosion at US border patrol

New Mexico has seen explosions within fuel tanks involving low sulfur diesel fuel. In one, a static spark produced an internal explosion within a 6,000 gallon ConVault tank containing low sulfur diesel fuel at the US Border Patrol in Santa Teresa, New Mexico. Two people were close to the tank, one sustained very minor injuries and the other person was not injured at all. The ConVault tank design with six inches of concrete surrounding a steel tank helped prevent a catastrophic loss of life.

Fire destroys US Coast Guard boathouse

A huge fire completely destroyed a pier, boats, a service truck and a US Coast Guard boathouse at Menemsha Harbor on Martha’s Vineyard. The fire was only a few feet away from the marina fueling system, which included 500 and 1,000 gallon ConVault tanks. The thermal protection of the concrete as well as the shutoff and fusible link valve prevented this fire from becoming an even larger catastrophe.

The importance of safety and design for fuel tanks

ConVault ASTs carry the UL 2085 label but they step beyond the UL 2085 industry standard by offering added protection and performance verified by third party testing. They are designed with six inches of reinforced concrete protecting both the primary and secondary containment. In addition, they are designed with reinforcing rebar surrounding both the primary and secondary containment. ConVault AST’s have even been granted DT&E designation under the Safety Act for the Supporting Anti-Terrorism Technology. ConVault tanks are the only AST to have received this designation. The SAFETY Act is intended to provide critical incentives for the development and deployment of anti-terrorism technologies.

Learn More About ConVault

News & Updates

About STI SP001

What Aboveground Storage Tank Owners Should Know About the STI SP001 Inspection Standard

We regularly receive calls from people asking questions about the STI SP001 Standard for Inspection of Aboveground Storage Tanks. Typical questions include:

  • Does my new tank comply with the standard?

  • Do I need Certification by a Certified Inspector for my new 4,000 gallon AST?

  • How often do I need to have my tanks inspected to comply with the standard?

  • Can I, as the owner of the tank inspect the tank?

  • Why can’t my facilities technician or supervisor inspect my aboveground storage tanks (ASTs)?

Most of the answers to these questions are fairly simple and the callers can answer the questions themselves if they have a basic knowledge of the inspection standard and the intention of the standard. Therefore, we recommend that they purchase a copy of the SP001 Standard from the Steel Tank Institute. Below is a brief history of the STI SP001 inspection standard and a few easy to follow references to help our clients gain a basic understanding of the requirements.


The Steel Tank Institute (STI) developed the original SP001 “Standard for Inspection of In-service Shop Fabricated Aboveground Tanks for Storage of Flammable and Combustible Liquids” in 2000. (“Shop Fabricated Tanks” are built in a factory rather than being assembled on the job-site. “Field Erected Tanks” are assembled on-site and are covered by different provisions of the SPCC. This article concerns only Shop Fabricated Above Ground Tanks.) In 2005 the Federal Environmental Protection Agency (EPA) asked STI to form a more broadly based committee consisting of government organizations, petroleum service companies and general interest entities to review and amend the standard to serve as an inspection standard for Shop Fabricated and Small Field Erected Tanks. The committee revised the standard and issued it in July 2006 as the 4th Edition of STI SP001.


On page 3 of the standard it states “This standard provides inspection and evaluation criteria required to determine the suitability for continued service of aboveground storage tanks until the next scheduled inspection. The purpose of conducting inspections is to identify the condition of and changes to the AST.”

It is important to note that the inspection standard SP001 does not apply to new AST installations. This standard is meant to give guidance to tank owners and inspectors evaluating existing ASTs, to assist them in determining if Shop Fabricated and Small Field Erected Tanks are suitable to be kept in operation and to determine how often they must be reinspected. The standard incorporates risk-based inspection considerations that tie the intensity and frequency of the inspections to the risks associated with different types of tank configurations.


Among other factors, the standard takes a number of conditions into consideration such as; if the tank has a leak detection system, if it has secondary containment and if the steel bottom of the tank is in contact with the ground.

Based on many considerations, the standard classifies tanks into three categories. Depending on the risk a tank system poses to the environment if kept in service it is ranked as a category 1, 2 or 3 tank. Category 1 tanks pose the least amount of risk and category 3 the highest.

See table 5.4 of the standard, reproduced here, for examples of tank configuration and AST category. Please note that if the AST, other than its legs or supports, is in contact with the ground or a concrete slab, it is prone to corrosion and increased susceptibility to leakage. Shop Fabricated Tanks in contact with the ground or a concrete base are almost always vertical tanks. Such tanks are placed in Category 2 or 3. ASTs which are elevated, have a leak detection system, have spill control and have no part of the tank in contact with the ground (other than legs or supports) are classified as category 1 tanks.





AST in contact with ground


2 or 3

Elevated tank with spill control and with no part of AST in contact with ground



Vertical tank with RPB and spill control



Vertical tank with double bottom and spill control



Vertical tank with RPB under tank and spill control



Double-wall AST



AST with secondary containment dike/berm




Note: CRDM means Continuous Release Detection Method – or Leak Detection System
RPB means Release Prevention Barrier


The standard requires different inspection types and different inspection intervals based on the tank size, tank category, and the risk it poses.

In Table 5.5 of SP0001 (see below), those portions pertaining to shop fabricated tanks up to 30,000 gallons have been highlighted showing inspection schedules for the different AST categories.

A Category 3 tank for example, with a capacity of 30,001 to 50,000 gallons must have a Formal External Inspection by a Certified AST Inspector, and a leak test by the owner every five years, plus a Formal Internal Inspection by a Certified AST Inspector every 10 years in addition to periodic inspections by the owner as required by the SPCC. Compare the vigorous inspection requirements above with Category 1 tanks, such as those made by Convault, with capacities up to 5,000 gallons which do not require any Formal External or Internal inspection by a Certified Inspector. Convault type tanks will only need to have Periodic Inspections by the owner or designated employee. Even tanks of 5,001 to 30,000 gallons capacity in the Category 1 classification will only require Formal External inspections once every 20 years when the owner performs required Periodic Inspections.

In Table 5.5 Use The Following Designations:
P – Periodic AST inspection
E – Formal External Inspection by Certified Inspector
I – Formal Internal Inspection by Certified Inspector
L – Leak test by owner or owner’s designee
( ) indicates maximum inspection interval in years. For example, E (5) indicates formal external inspection every 5 years.


Shop Fabricated AST Size (US Gallons)

Category 1

Category 2

Category 3

 Shop Fabricated  ASTs

0 – 1100
(0-4164 liters)



P, E&L(10)

1101 – 5,000
(4168-18,927 liters)


P, E&L(10)

[P, E&L(5), I(10)]
[P, L(2), E(5)]

5001 – 30,000
(18,931 – 113,562 liters)

[P, E (20)

[P, E (10, I(20)]
[P, E (5), L(10)]

[P, E&L(5), I(10)]
[P, L(2), E(5)]

30,001 – 50,000

[P, E (20)

P, E&L(5), I(15)

P, E&L(5), I(15)

 Portable Containers




** Owners shall either discontinue use of portable container for storage or have the portable container DOT (Department of Transportation) tested and recertified per following schedule (refer to Section 9.0): Plastic containers – every 7 years; steel portable container – every 12 years; Stainless Steel container – every 17 years.


Convault tanks of 5,000 gallons or less capacity are CATEGORY 1 TANKS. Owners of Convault ASTs of this size are NOT required to employ Certified AST Inspectors to inspect their tanks to comply with the standard’s requirements, but can be in compliance with the standard by inspecting the tanks themselves or having their employees inspect them. Convault tanks larger than 5000 gallons, are also self-inspected and only require inspection by a Certified Inspector after 20 years of service.

What qualifications are required for the owner to self-inspect his tank, and how does he know what to inspect?

Section 4 of the SP001 standard defines the qualifications of the Owner’s Inspector as follows: “Periodic inspections are to be performed by an owner’s inspector. The personnel performing these inspections shall be knowledgeable of storage facility operations, the type of AST and its associated components, and characteristics of the liquid stored”.

Section 6 of the standard explains what is meant by the PERIODIC AST INSPECTION – and what needs to be inspected and kept in the owner’s AST records. These are simple and straight-forward tasks which can be performed by any competent owner or his employees. The standard makes it very easy to know what to do and what to check for by providing a check list in the standard’s Appendix C. The first section requires filling in information about the owner and the ID of the tank. The second section is the SP001 Monthly Inspection Checklist which consists of 9 easy to check, Yes or No questions such as; is there water in primary or secondary containment, are there visible signs of leakage around the tank, concrete pad, or ground, are all tank openings properly sealed, etc. The third section is the SP001 Annual Inspection Checklist which contains 27 questions with Yes or No answers and a space for comments. It should be noted that the Periodic Inspection must be performed in addition to the Formal External Inspections.

Simply put, the periodic inspection requirements are visual, documented inspections conducted by an owner’s inspector, to assess the general AST conditions, as best as possible, without suspending AST operations or removing the AST from service.

Convault strongly encourages the use of the Monthly and Annual Inspection Checklists provided in SP001, and, in fact, requires some of these items be checked on a weekly basis as part of the Convault warranty. A copy of Convault’s weekly/monthly/yearly checklist is available online at


  • You are NOT required to employ Certified Inspectors to perform inspections on shop fabricated Convault ASTs up to 5,000 gallons for most installations.

  • For shop fabricated Convault ASTs from 5,001 to 30,000 gallons you will need an External Inspection by a Certified Inspector once every 20 years for most installations.

  • Monthly and yearly inspections by the tank owner or a designated employee are required by SP001, and Inspection Checklists are provided in Appendix C of the document.

  • ConVault requires that the interstice be checked on a weekly basis.

  • A newly installed Convault AST will meet all the requirements of the SP001 checklists.

News & Updates

About SPCC Plans

Spill Prevention, Control and Countermeasure (SPCC) requires the attempted prevention of, preparedness for, and response to oil discharges as part of the Oil Pollution Prevention regulation (40 CFR part 112). Regulated facilities must develop and implement SPCC Plans that establish procedures and equipment requirements to help prevent oil discharges from reaching navigable waters or adjoining shorelines.

Who is subject to the SPCC rule?

The SPCC rule applies to owners or operators of facilities that:  Drill, produce, store, process, refine, transfer, distribute, use, or consume oil or oil products; and Could reasonably be expected to discharge oil to U.S. navigable waters or adjoining shorelines.Facilities are subject to the rule if they meet at least one of the following capacity thresholds:

Aboveground oil storage capacity greater than 1,320 U.S. gallons, or completely buried oil storage capacity greater than 42,000 U.S. gallons.

The following are exempt from the rule:

  • Containers with a storage capacity less than 55 U.S. gallons of oil;
  • Permanently closed containers;
  • Motive power containers;
  • Wastewater treatment facilities;
  • Hot-mix asphalt and hot-mix asphalt containers;
  • Residential heating oil containers at single family residences;
  • Pesticide application equipment and related mix containers;
  • Completely buried storage tanks subject to all the technical requirements of the underground storage tank regulations;
  • Intra-facility gathering lines subject to U.S. Department of Transportation’s pipeline regulations; and Underground oil storage tanks at nuclear power generation facilities.
News & Updates

Microbicide For Contaminated Fuel

Fuel is particularly vulnerable to water contamination during transport and storage. And, once you have water in your fuel system, you are vulnerable to an invasion of microorganisms. Once established, they entrench themselves in a thick layer of slimy deposits and create a number of problems including clogged fuel filters and fuel injectors, hazy fuel, leaking tanks, corrosion and increased service calls and complaints. However, these problems can easily be avoided.

The Solution: Microbicide

Most of the problems associated with microbial attack can be easily avoided. All it requires is two simple elements:

  • Drain water frequently. Removing water robs the microorganisms of the single most important element for growth
  • Use FQS 1.5 Microbicide to treat the fuel system

Microbicide can fully eradicate microbial populations in fuel systems in as little as 8 hours.  It’s a quick and inexpensive way to protect the valuable investment you have in your fuel storage system and now you can purchase it in our online marketplace.

News & Updates

Winterize Your Fuel System

With winter approaching now is the perfect time to review your fuel storage safety and maintenance procedures. Ensuring uninterrupted power and safe dispensing systems begins with preventative maintenance. Tank owners should be performing regular maintenance and inspection on their tanks as required by warranty and by many state/local codes. Water is one of the most harmful elements to the integrity of your fuel storage system. Therefore owners should remove snow from the top of aboveground tanks. Water from melting snow can cause rust and corrosion on the exterior of steel jacketed tanks and can significantly damage your fuel system leading to corrosion, clogged fuel filters and fuel injectors and possibly even tank failure. While ConVault aboveground storage tanks are covered with a low maintenance concrete exterior which requires much less maintenance than traditional steel tanks, they should still be regularly inspected and monitored for leaks.

Maintenance tips include:

  • In Winter Remove Snow From the Tank Top
  • Use A Biocide Additive To Maintain Fuel Quality
  • Visual Inspection to Check for Leaks and/or Tank Failure
  • Fittings and Pipe Nipples Should Be Repainted / Powder Coated to Prevent Rust (Except Stainless Steel)
  • Seal Any Cracks In the Concrete: ConVault tanks can be sealed with an acrylic for added protection
  • Monitor Tank For the Presence of Water! Eliminating Water from your fuel storage system will increase tank life. Water causes corrosion by providing the right environment for microorganisms to thrive.

How does water enter your fuel storage system?

  • Through your Fuel Jobber
  • Air Moisture During Rainstorms/Snowstorms
  • Air Moisture from the Tanks Normal Venting Process
  • Improperly Sealed Tank Connections

How can you prevent water from entering your fuel system?

  • Seal and caulk all tank Connections
  • Obtain fuel from a reputable supplier
  • Install PVV caps instead of your normal vent caps
  • Use a filtration system with a coalescing element in it

What to do if water has contaminated your fueling system?

  • Use a Biocide Additive!
  • Remove Water with a Small Hand Pump (Thief Pump)
News & Updates

What is UL 2245?

UL 2245 Standard for Safety Below-Grade Vaults

UL 2245 standards cover below-grade vaults intended for the storage of flammable or combustible liquids in an aboveground atmospheric tank. Below-grade vaults are designed to contain one aboveground tank which can be a compartment tank. Adjacent vaults may share a common wall. The lid of the vault may be at or below-grade.

Below-grade vaults should be constructed of a minimum of 6 inches (152.4 mm) of reinforced concrete or other equivalent noncombustible material and form a complete, liquid-tight enclosure that does not allow external ground water to permeate through the vault walls. Below-grade vaults can be evaluated as secondary containment vaults.

Below-grade vaults covered by these requirements do not include an evaluation of components, such as ventilation equipment, leak detection and monitoring equipment, overfill protection equipment, and access ladders.

Below-grade vaults are intended for installation and use in accordance with the manufacturer’s instructions and the following fire codes: the Flammable and Combustible Liquids Code, NFPA 30, the Automotive and Marine Service Station Code, NFPA 30A, and the Uniform Fire Code, Appendix II-J.

Below-grade vaults covered by these requirements may be shipped in parts that require final assembly in the field. When field assembly is required, detailed installation instructions shall be provided.

News & Updates

Critical Operations Power Systems

By Jeanne Murphy Murck, VP Operations
About the Author

Mission Critical…Critical Power… In our business, we have often heard these terms. Many advertise mission critical fuel oil systems that supply diesel to generator sets. The term has been used in the data center business for years. But what do these terms mean in a code-mandated context and how do they apply to you or your client’s facility?

A place to look is the National Electric Code. Article 708 entitled “Critical Operations Power Systems” (COPS), was added to the NEC/NFPA 70. It was developed in response to natural disasters such as Hurricane Katrina and emergency events such as 9/11. This section includes the requirements for facilities that are truly defined and regulated as Mission Critical.

Mission Critical Sites

Mission critical sites are not just emergency systems as described in NEC Article 700 (or in NFPA 110 or NFPA 99). These are sites that have been formally classified by a municipal, state, federal or other authority having jurisdiction as critical because the facility must operate during the entire duration of an emergency event and beyond. Examples of facilities that can be classified as COPS or that may include Designated Critical Operations Areas (DCOAs) include police and fire stations, emergency operations centers, hospitals, various federal agency headquarters and federal data centers, and large airport air traffic control towers. These are the sites that, simply put, cannot lose power without affecting the security of the entire community.

Article 708 is unique in that it requires some things that previously would only have been considered best practices, including the following:

  • It mandates designing COPS for DCOAs in accordance with a formal risk assessment of natural and man-made hazards and providing physical security and construction methods in accordance with that risk assessment (708.4-5).
  • It requires routine testing and maintenance of COPS that is to be formally witnessed and/or documented by the local authority having jurisdiction (708.6).
  • It discusses the options on power sources for COPS. For prime mover-driven generator sets, it necessitates dual supplies be provided for fuel or water (e.g., use of bi-fuel generators).
  • It requires the COPS to have a minimum operating time of 72 hours with the DCOA at full load (708.22(C)).

How Core Engineered Solutions can Help you Comply

There are several key areas in complying with Article 708 that Core Engineered Solutions can help the design engineer or COPS end user address:

  • Risk assessments and physical security (Sections 708.4 and 708.5) – ConVault fuel storage tanks are UL 752 and UL 2085 listed and provide unmatched protection from natural and man-made hazards.
  • AHJ-witness and documented testing and maintenance (Section 708.6) – Core’s SafeSite line of fuel oil controls and advanced filtration systems allow a customer to fully and automatically test and maintain the fuel oil system components of a COPS.
  • Power supply and alternate operating capability (Article 708.20 & 708.22) – Core can help size fuel oil tanks and system components, keeping in mind the maintenance and redundancy requirements found elsewhere in the Article.

Need help with a Mission Critical Fueling System?

For more information fill out our FAST Plan Quote here or or call (703) 563-0320.

Glossary of Terms

Critical Operations Power Systems – Systems that are installed in vital infrastructure facilities that, if destroyed or incapacitated, would disrupt national security, the economy, public health or safety; and where enhanced electrical infrastructure for continuity of operation has been deemed necessary by governmental authority. COPS design criteria are specified by NFPA 70 Article 708.

Emergency Systems – As specified by NFPA 70 and NFPA 110, emergency systems are those systems legally required and classed as emergency by municipal, state, federal, or other codes, or by any governmental agency having jurisdiction. These systems are intended to automatically supply illumination, power, or both, to designated areas and equipment in the event of failure of the normal supply or in the event of accident to elements of a system intended to supply, distribute, and control power and illumination essential for safety to human life. See NFPA 70 Article 700, NFPA 110 Level 2.

Legally Required Standby Systems – Those systems required and so classed as legally required standby by municipal, state, federal, or other codes or by any governmental agency having jurisdiction. These systems are intended to automatically supply power to selected loads (other than those classed as emergency systems) in the event of failure of the normal source.

N+1 – A reliability term indicating that if a total of n units are installed, an additional unit is installed to ensure system reliability in the event of a single unit failure or to accommodate other activities such as periodic maintenance.

Optional Standby Systems – Those systems intended to supply power to public or private facilities or property where life safety does not depend on the performance of the system. Optional standby systems are intended to supply on-site generated power to selected loads either automatically or manually.


News & Updates

Emergency Power Fuel Oil Systems and Tank Sizing

By Jeanne Murphy Murck, VP Operations
About the Author

In our industry, there have been many articles and studies published related to the changes to fuel composition and the resulting fuel maintenance headaches. By making cleaner fuels that are better for the environment, we have removed additives that killed destructive bugs (microbes). These reformulated fuels are more likely to take on water that boosts the growth of these bugs and accelerates corrosion.

The Challenge

In the case of fuel oil used in emergency power, microbe growth is further intensified by the lack of turnover and the EPA limits to burning fuel for the purposes of exercising generators. If we had storms twice a month and the fuel in these tanks was actually needed more regularly, then the fuel would be consumed more rapidly and the bugs wouldn’t have as much time to grow. But, alas (or shall I say thankfully), true weather-related emergency events necessitating the use of back-up generators are not that frequent. Undoubtedly, we could say that these events are on the uptick due to climate change, but the through-put of these systems never approaches the level of that of a gas station, for example.

Here’s what happens when fuel sits:

  • it gets stale
  • it takes on water from the atmosphere
  • it can become contaminated with microbes
  • it becomes more susceptible to the formation of asphaltene and wax residues
  • its cetane number may decrease


Solutions to fuel quality issues that will arise in this setting typically include the following:

  • Periodically replacing fuel that has become stale due to lack of use. Most diesel in this country has some component of biodiesel in it and industry standards and engine manufacturers recommend storing any diesel that has biodiesel in it no more than six months.
  • Using a high quality fuel filtration system to remove water and particulate.
  • Cleaning the inside of the tank.
  • Using Biocide.

However, an important and often overlooked solution is the proper sizing of your fuel storage tanks to begin with! As stated in NFPA 110 (, tanks should be sized so that the fuel is consumed within its storage life. The NFPA 110 Handbook also recommends several moderately sized tanks over one large tank.

Using several moderately sized tanks that meet the total fuel oil storage requirements of an emergency power fuel oil system can be very helpful on a couple of levels – first, you ensure fuel is consumed and turns over within its recommended storage life and second, you mitigate the risk of having your only fuel tank contaminated.

For example, let’s assume that an engineer has calculated the fuel oil capacity requirements for the back-up power system at a particular site to be 20,000 gallons. He then decides to specify that all the fuel (aside from that in the day or belly tanks) be stored in one 20,000 gallon main fuel oil storage tank. What happens if that one and only tank becomes contaminated by sitting unused and becoming affected as noted above, OR by the delivery of a bad batch of fuel from the terminal? Or, what if the pumping system tied to that one main storage tank fails? During an emergency event, the system would not be able to perform as needed.

A better strategy would be to specify two 10,000 gallon tanks including redundant fuel oil pumping systems for each tank to ensure fuel will be delivered when needed and that your risk of having an entire fuel system of contaminated fuel is greatly mitigated. In conclusion, specifying one large tank puts the entire back-up power system’s proper functioning during an emergency event in peril.

Core Engineered Solutions can help you size the fuel storage tanks with these issues in mind, as well as the redundancy requirements found in NFPA 110, NFPA 99, and NFPA 70.

For more information email or call (703) 563-0320.

News & Updates

NYC Fuel Storage

Core has years of experience installing fuel systems in New York City—we are the experts in fuel systems for high rise buildings. We stay up-to-date with NYC regulatory compliance. In addition to fuel tanks, our integrated fuel system products include the following:

Emergency Power & Boiler Applications

This pre-engineered product integrates power distribution, fuel transfer, tank monitoring, and fuel polishing. The SafeSite FOC System starts as a power distribution panel and then intelligently integrates fuel system monitoring and pump control functions into one simple automated package.

Fuel Filtration Powered by DieselPure®

The removal of free-standing, saturated and emulsified water is critical to preventing premature fuel degradation and equipment failure. Created specifically to address the unique chemical properties of ultra-low sulfur diesel and bio-diesel blends, the DieselPure filter has a two-stage single pass design.

Flexible, Double-Wall Piping with Leak Detection

Specifically designed for hazardous fuels and gasses, there is no better pipe system when it comes to below-grade and aboveground tank fueling and marina fuel piping. Our Brugg pipe system is made of corrugated stainless steel primary and secondary pipes with reinforcement tape in the interstitial space.

NYC Piping