Many companies within Alberta have been using tanks constructed to an API 12F specification for the storage of flammable or combustible products. You may or may not know that the use of these tanks contravenes the Alberta Fire Code.
Below you can find documents from the Alberta Government identifying API 12F tanks as inappropriate and listing tanks that do meet requirements of the Fire Code. The Government has also released an upgrading program for existing storage tanks. A Standata with the details of this program can be found below.
- Storage of Flammable or Combustible Products
- Upgrading Existing API Tanks Under the Alberta Fire Code
Disclaimer
This document is intended to be guidance to assist storage tank owners to understand venting requirements for aboveground storage tanks. It is not intended to replace any regulatory requirements or accepted venting standards. If there is a conflict in information found in this document and those found in the referenced documents of the Standata for existing API 12F tanks, the latter shall prevail.
Background
Tanks (including those used by the oil service industry) which contain flammable or combustible liquids are regulated by the Alberta Fire Code. Consult MSDS flash point information to determine which products those include. A flash point below 93.3 Centigrade would qualify as flammable or combustible. Despite API 12F tanks not being a listed specification for storage tanks acceptable to the Fire Code, a good many of these tanks are in use in the oil service industry. The Alberta Government recently issued a province-wide variance permitting tanks built to the API 12F specification to be used if certain technical provisions were present. The major deficiency with this type of storage tank is related to venting. Under the 12F specification a tank can be designed to not include emergency venting if the tank is used in a remote location. Unfortunately, tanks without emergency venting are situated close to built-up areas. A good illustration of the consequences of inadequate ventilation on a tank exposed to fire can be viewed here.
Satisfying the Variance
Tank owners may continue to use non-ULC listed tanks if they are upgraded as stated in the Variance. The owner must establish who the authority having jurisdiction is. You may access this list on the PTMAA website here. If the municipality is not listed, application must be made to the local fire department.
Typical API 12F Tank Prior to Upgrading
An engineered drawing which includes notes identifying which tanks must be upgraded must be sent to the authority having jurisdiction. For tanks located in PTMAA jurisdictions a permit application must be completed and submitted along with the drawings. The authority having jurisdiction will review the drawings to ensure all aspects of the Fire Code and Variance are being complied with. The final part of the process is to register the tanks with the PTMAA if they are not already registered. To qualify for registration you will require evidence from the authority having jurisdiction that the application has been approved by a Safety Codes Officer. All upgrading must be completed by December 31, 2011.
Secondary Containment
To qualify for the Variance the tank farm must have secondary containment that meets Subsection 4.3.7 of the Fire Code. If the containment is earthen the engineer must certify the dike provides a permeability of not more than 10-6 cm/sec to the flammable or combustible liquids contained in the storage tanks. If a membrane provides the secondary containment it shall conform to ULC/ORD-C58.9.
Venting Requirements
Emergency relief vent devices shall be vapour-tight and permitted to be either of the following:
- Designed and sized according to API 2000, NFPA 30 or ULC-S630, or
- Designed by a P.Eng. and tested in accordance with maximum internal pressures, as specified by API 12F.
Emergency venting may also be accompanied by use of the following:
- larger or additional relief devices
- a gauge hatch that permits the cover to lift under abnormal internal pressure, or
- a manhole cover that lifts when exposed to abnormal internal pressure
All manufactured devices shall be stamped with the following information:
- Start-to-open pressure
- Pressure at which the valve reaches the full open position.
- Flow capacity at full open position. Flow capacity shall be expressed in cubic feet per hour of air or cubic meters per hour of air at 60° F (15.6°C) and an absolute pressure of 14.7 psi (101 kPa).
Choosing the Right Vent(s)
When choosing vents that are appropriate for a particular tank, several factors must be considered:
- The amount of vapour that must pass through the vent under normal operating and emergency conditions.
- The design pressure and vacuum of the tank. Pressure relief valves must open before the pressure limits of the structure are met. Emergency vents are typically rated at a particular flow capacity at 2.5 psi. This pressure is much greater than the maximum design pressure of a 12F tank. The vent vendor must be able to offer a solution that will recognize the required vent capacity based on tank diameter and height and the design pressure of the tank. To illustrate the attention that must be paid to this difference, compare the product offered by one vendor that has an 8” pressure/vacuum vent that will provide the same vent flow capacity as another who would recommend a 16” vent for a 400 bbl tank. The latter company is taking into account the design pressure of the specific tank and not using the standard 2.5 psi rating for the vent.
- The flow capability of the vent where shape, screens, flame arrestors, etc., must be taken into account when determining what vent to install.
- Embedding an appropriately sized vent in a roof hatch is a relatively simple solution but if selecting a vent to replace a cover in its entirety, it is important that the holes on the vent cover match the holes available on the roof.
- Existing vents should be considered when determining what additional venting capacity is required. For example, for a tank that has an 8” thief hatch for pressure/vacuum conditions during product movement and thermal heating, the addition of a second 8” thief hatch may provide sufficient emergency venting.
NFPA 30 – 2.2.5.1.2 states, normal vents shall be sized to be at least as large as the filling or withdrawal connection, whichever is larger, but in no case less than 1-1/4 in. (32 mm) nominal inside diameter. Each storage tank must have emergency venting capacity in accordance with Table 1. Note that venting requirements in Table 2 apply to standard dimension tanks. Non-standard dimension tanks must have venting that is specifically designed for the surface area of the tank. All calculations shall assume no drainage systems are provided and no suppression systems are provided in the dike area. A drainage system would take spilled liquid away from the tank.
The wetted surface area (WA) for a vertical, cylindrical tank is calculated as the area of the shell to an elevation of not more than 30 feet above the bottom.
WA = (π) (d) (L)
A 400 barrel tank, for example, has a standard dimension of d = 12’ and L = 20’
(3.14) (12) x (20) = 754 ft.2 By interpolation, 754 ft.2 of tank area would require 446,360 standard cubic feet per hour of venting capacity.
Table 1
| Wetted Area (Square Feet) | Venting Requirement (SCFH) |
| 350 | 288,000 |
| 400 | 312,000 |
| 500 | 354,000 |
| 600 | 392,000 |
| 700 | 428,000 |
| 800 | 462,000 |
| 900 | 493,000 |
| 1,000 | 524,000 |
| 1,200 | 557,000 |
| 1,400 | 587,000 |
| 1,600 | 614,000 |
*SCFH is Standard Cubic Feet per Hour
Table 2
Venting Requirements
| Tank Capacity | Tank Capacity | Standard Diameter | Standard Height | Emergency Venting Discharge Required | Emergency Venting Discharge Required | Design Pressure | Maximum Pressure During Emergency Venting |
| (barrels) | (kiloliters) | (feet) | (feet) | M3/hr | Ft3/hr | Oz/sq. in | Oz/sq. in |
| 100 | 16 | 9.5 | 8 | 6601 | 233110 | 16 | 48 |
| 150 | 24 | 9.5 | 12 | 8272 | 292121 | 16 | 48 |
| 200 | 32 | 12 | 10 | 8527 | 301127 | 16 | 24 |
| 210 | 33.6 | 10 | 15 | 9688 | 342127 | 16 | 48 |
| 250 | 40 | 11 | 15 | 10277 | 362927 | 16 | 24 |
| 300 | 48 | 12 | 15 | 10728 | 378854 | 16 | 24 |
| 400 | 64 | 12 | 20 | 12640 | 446360 | 16 | 24 |
| 500 | 80 | 12 | 25 | 14363 | 507222 | 16 | 24 |
| 500 | 80 | 15.5 | 16 | 12890 | 455200 | 8 | 12 |
| 750 | 120 | 15.5 | 24 | 15393 | 543600 | 8 | 12 |
When selecting a vent which will accomodate the requried flow rate it is very important that the vent is set to open at a pressure lower than the design pressure of the tank. Most API 12F tanks have an internal design pressure maxmimum of 16 oz. (The popular 750 bbl tank has a design pressure of only 8 oz.) API 2000 states that internal design pressure is not to be exceeded by more than 20% when selecting vents. Therefore, the vent(s) for a 16 oz tank must be wide open at no greater internal pressure than 19.2 oz. For a tank with an internal design pressure of 16 oz the normal set to open pressure is 8 oz.
Emergency Vent imbedded in a clean-out hatch
Getting the Work Done
For engineers and tank owners correcting vent deficiencies on tanks will likely involve the manufacturer of the tank. The PTMAA has compiled a list of companies who manufacture or distribute API tanks in Alberta. There may be some not included on the list that appears below but in most cases the manufacturer of the tank will be stated on the tank itself. It is not mandatory that the original equipment manufacturer is involved but the person doing the physical changes to the tank must be very familiar with vent specifications, set-to-open pressures, etc. Manufacturers likely will be able to source vents that will provide the necessary venting but it’s important the engineer working with the tank owner is involved to ensure the right vent is installed.
Safety
It is absolutely imperative that occupational health and safety regulations are followed when any work on tanks is performed. For example, Section 169, Part 10, of the Occupational Health and Safety Code, Fire and Explosion Hazards, requires the employer to ensure that hot work is not begun until:
- A hot work permit is issued,
- The work location is clearly or suitably isolated from combustible materials,
- Procedures have been implemented to ensure continuous safe performance of the hot work, and
- Testing shows that the atmosphere does not contain a flammable substance in a mixture with air, in an amount exceeding 20% of that substance’s lower explosive limit for gas or vapours.
Other relevant sections of that regulation must be complied with including 162, 163, 164 and 165 when doing hot work. The employer must have procedures and precautionary measures to ensure that flammable substances that are stored, handled, processed or present at a work site will not ignite unintentionally.
Vent Manufacturers
Amongst the brands of vents popular on API aboveground storage tanks are:
- Enardo
- OPW
- EBW
- Morrison Brothers
- Clay & Bailey
- Franklin
- Protectoseal
Tank manufacturers may provide additional vent supplier names.
API Tank Manufacturers
| Company Name | Address | City | Province | Postal Code | Phone | Website |
| AGI Envirotank | PO Box 879 | Biggar | SK | S0K 0M0 | 1-800-746-6646 | www.envirotank.com |
| AGR Tanks | PO Box 9049 Station Main | Sylvan Lale | AB | T1S 1S6 | 403-887-2927 | |
| Agro Sales Ltd | #1300, 717 7 Ave SW | Calgary | AB | T2P 0Z3 | 403-265-6633 | www.agrosales.com |
| Altus (formerly Nusco) | 1604 8 St | Nisku | AB | T9E 7S6 | 780-955-2051 | www.altusenergy.com |
| Clemmer Steelcraft | 4006 60 Ave | Innisfail | AB | T4G 1S7 | 1-800-661-2851 | www.clemmersteelcraft.com |
| DE-In Industries Ltd | PO Box 559 | Debolt | AB | T0H 1B0 | 780-957-2521 | www.de-in.com |
| Emerald Metalk | Site 7, Box 18, RR2 | Tofield | AB | T0B 4J0 | 780-662-9350 | www.emeraldmetal.com |
| GLM | 1508 8 St | Nisku | AB | T9E 7S6 | 780-955-2233 | www.glmprocess.com |
| Highland Projects Ltd | Box 2052 | Sundre | AB | T0M 1X0 | 403-638-4030 | www.highlandprojects.com |
| Hot Pass Welding | 4424 50 Ave | Calmar | AB | T0C 0V0 | 780-985-3838 | |
| Huge L Steel | PO Box 466 | Regina | SK | S4N 3A2 | 306-591-1401 | www.hugelsteel.com |
| Industrial Steelcraft | 4734 45A St | Lacombe | AB | T4L 2C7 | 403-782-7144 | www.envirotank.com |
| Northern Steel | Box 1718 | Tisdale | SK | S0E 1T0 | 1-888-674-8265 | www.northern-steel.com |
| NWP Industries | PO Box 6280 | Innisfail | AB | T4G 1S9 | 1-403-213-3425 | www.nwp.ca |
| Peaceland Fabricating | PO Box 331 | Hythe | AB | T0H 2C0 | 1-780-356-2200 | www.peaceland.ca |
| Prism Production Products | PO Box 728 | Forestburg | AB | T0B 1N0 | 1-877-264-1050 | |
| Remo Manufacturing | PO Box 728 | Redcliff | AB | T0J 2P0 | 1-403-548-0078 | www.envirotank.com |
| Scorpion Welding | Bay 102, 25 Chisholm Ave | St. Albert | AB | T8N 5A5 | 780-460-9954 | www.scorpionwelding.ca |
| Tanksafe Inc | #208, 3112 11 St NE | Calgary | AB | T2E 7J1 | 1-403-291-3937 | www.tanksafe.com |
| Universal Industries | 5014 65 St | Lloydminster | AB | T9V 2K2 | 780-875-6161 | www.uic.ca |
Selecting an Engineer
Application to the Authority Having Jurisdiction must be done by submitting engineered drawings which clearly identify tanks to be modified in compliance with the Variance. Site drawings and the plan to come into full compliance with the Fire Code must be prepared by an engineer licensed to practice in Alberta. A tank owner can retain the services of any professional engineer licensed in Alberta but it would be advised that a firm with experience in petroleum facility design is used. The PTMAA has briefed engineers on the upgrading program and the tank owner may benefit by using a firm that is familiar with the requirements and solutions to this regulatory issue. Engineers wanting to participate in these projects include:
| FIRM | CITY | PHONE | CONTACT |
| Yo-Star Enterprises | Edmonton | (780) 473-7162 | Albert Ratsoy |
| TWD Technologies | Sherwood Park | (780) 410-0542 | Mona Alkhatib |
| Five Star Engineering | Sherwood Park | (780) 499-9007 | Albert Biel |
| Emerson Engineering | DeWinton | (403) 938-3079 | Dale Emerson |
| Lexon Projects | Edmonton | (780) 435-7476 | Harold Steinbrenner |
| Tiamet Consultants | Calgary | (403) 640-9009 | Leon Mah |
| Hasegawa & Assoc. | Calgary | (403) 250-5261 | Bill Hasegawa |
| CTM Design | Calgary | (403) 640-0990 | Don Jonasson |
| Roosdahl Engineering | Saskatoon | (306) 382-2356 | Larry Roosdahl |
| Cold Creek Enterprises | Calgary | (403) 225-5770 | Dick Vathje |
| Petroleum Enviro Services | Edmonton | (780) 461-4799 | Greg Van Loenen |
| Hasegawa Engineering | Lethbridge | (403) 328-2686 | Mark Hasegawa |
| Williams Engineering | Red Deer | (403) 755-4063 | Henk Brenkman |
| Conestoga-Rovers | Calgary | (403) 271-2000 | Stephen Ball |
Engineered Drawings and Specifications
To get approval for tanks constructed to API 12F, drawings bearing a professional engineer’s stamp and seal must be submitted to the Authority Having Jurisdiction. In most cases the PTMAA is the AHJ but this can be verified on the PTMAA website. For drawings and specifications submitted to the PTMAA, each 12F tank must be covered under a general statement to the effect, “normal and emergency venting has been designed in accordance with API 2000, NFPA 30 or ULC S-630”. The Variance from the Fire Code allowing existing 12F tanks requires that all other aspects of the Code must be complied with. Engineers must prepare drawings as if the facility was not yet constructed. Other information that should be on the drawings or specifications include:
- Construction standard of all tanks on the facility (ULC/API)
- Requirements for fire extinguishers
- Location of loading/unloading nozzles (inside or outside dike and how spills might be collected)
- Tank capacities
- Distance to building and property lines
- Tank contents
- Spacing between tanks
- Detail on secondary containment (wall construction, liner, earthen, capacity, etc)
- Distance from tank wall to secondary containment wall
- Evidence of bonding and grounding of tanks
- Fencing
API 650 Tanks
The Alberta Fire Code permits use of tanks constructed to API 650 specification. Some of the features of tanks constructed to that standard is dependent on the requirements of the purchaser. The type of venting used on 650 tanks may be insufficient because the purchaser was not aware of the requirement for emergency venting. The PTMAA is currently investigating this issue with Alberta Municipal Affairs and directives may follow. If you have API 650 tanks at your facility and you plan on reviewing venting for 12F tanks it is recommended that you include any API tanks in your review and plan for upgrading.
Questions
A considerable amount of time has been provided to comply with the Fire Code but please be aware that services and equipment may not be available if your project is left too late. If you have questions about the Variance and the procedure to meet it, please do not hesitate to contact the PTMAA.