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API RP 2210-2000 (2015): Flame Arresters for Tank Vents in Petroleum Service — Engineering & Compliance Guide
Scope, technical requirements, selection criteria, and compliance notes for using flame arresters on petroleum storage tank vents
Scope and Purpose of API RP 2210-2000 (2015)
API Recommended Practice 2210 (originally published in 2000 and reaffirmed in 2015) provides engineering guidance for the selection, installation, operation, and maintenance of flame arresters used on vents of aboveground storage tanks (ASTs) storing petroleum products. The standard applies to normal (atmospheric) vents, emergency vents, and vapor-recovery vents that are subject to potential ignition sources such as lightning, static electricity, or adjacent fires.
API RP 2210-2000 (2015) is a benchmark for facilities seeking to prevent flame propagation into tank vapor spaces. It covers both deflagration and detonation scenarios, outlining performance criteria that flame arresters must meet to be considered effective. The practice does not apply to flame arresters on process equipment, marine vessels, or transport vehicles — its scope is strictly limited to fixed, grounded petroleum storage tanks.
Tip: When selecting a flame arrester per API RP 2210, always verify that the flow capacity at the permissible pressure drop exceeds the maximum venting rate of the tank (both normal breathing and emergency relief). Mismatched capacity can result in tank overpressure and structural damage.
Technical Requirements
Performance Categories
The standard classifies flame arresters by their ability to stop two distinct flame propagation types:
- Deflagration arresters — designed to stop subsonic flame fronts typical of initial ignition inside or outside the tank.
- Detonation arresters — capable of stopping supersonic flame fronts with shock waves that can occur in long vapor-recovery piping.
Arresters must pass endurance burn tests to ensure they can withstand continuous flame impingement for a specified duration (typically 15 minutes) without allowing flame transmission. Flow resistance must not exceed values that compromise tank pressure/vacuum protection.
Material and Design Specifications
All flame arrester elements must be constructed from materials compatible with the stored product and resistant to corrosion. Housing and element materials commonly include:
- Housing: cast iron, ductile iron, carbon steel, or stainless steel (for corrosive vapors).
- Element: crimped metal ribbon (stainless steel or Monel), perforated plate, or wire gauze with specific gap widths determined by the Maximum Experimental Safe Gap (MESG) of the vapor.
| Parameter | Deflagration Arrester | Detonation Arrester |
|---|---|---|
| Flame speed range | Subsonic (< Mach 1) | Supersonic (Mach 1–3+) |
| Endurance burn time (minimum) | 15 minutes | 15 minutes |
| Maximum hydraulic gap (mm) | 0.5–1.0 (depending on MESG) | 0.3–0.8 (stricter due to shock) |
| Flow resistance (pressure drop) | ΔP ≤ 10% of set pressure | ΔP ≤ 10% of set pressure |
| Certification tests | Deflagration test per UL 525 / ISO 16852 | Detonation test per UL 525 / ISO 16852 |
Marking and Certification
API RP 2210 requires that each flame arrester be permanently marked with:
- Manufacturer name and model
- Flow direction arrow
- Maximum allowable pressure drop
- Endurance burn rating (time)
- Approval body and test standard (e.g., UL 525, FM 6031, or ISO 16852)
Warning: Flame arresters can become blocked by accumulated product residue, dirt, or polymerized vapor. Schedule regular inspections per API RP 2210 Table 2 (recommended intervals based on service severity). A blocked arrester can cause tank under‑pressure (collapse) or overpressure during emergency venting.
Implementation Considerations
Installation Best Practices
The standard emphasises that the flame arrester must be installed as close as practical to the tank nozzle or vent pipe termination. Long downstream piping can turn a deflagration into a detonation; therefore, the arrester’s design should match the actual piping configuration. Key installation rules include:
- Mount the arrester with the flow arrow pointing away from the tank (outward).
- Use gaskets compatible with the product and temperature range.
- Provide support for heavy arresters to prevent loads on the tank nozzle.
- For emergency vents, ensure the arrester does not reduce the venting capacity below the required emergency flow rate (per API 2000).
Maintenance and Inspection
API RP 2210-2000 (2015) recommends visual inspection of flame arrester elements at least every six months, with more frequent checks for services prone to fouling (e.g., waxy or asphaltic products). Cleaning methods must avoid damaging the element gap dimensions:
- Approved methods: steam cleaning, solvent flushing, or compressed air (from the outside inward).
- Never use wire brushes or sharp tools that could open the gap.
- After cleaning, measure element gaps with a feeler gauge to verify they are within manufacturer tolerances.
Success story: A Gulf Coast refinery implemented a quarterly cleaning program for flame arresters on crude oil tanks, reducing pressure drop by 60% and eliminating vacuum breaker activation events. Proper maintenance extended element life from 2 to 5 years.
Danger: Never install a flame arrester that has been certified only for deflagration on a vapor recovery system with long piping runs (> 10 pipe diameters). Such configurations can turn a deflagration into a detonation, which would pass through a deflagration‑rated arrester and cause a catastrophic tank explosion.
Compliance and Auditing
Although API RP 2210 is a recommended practice (not a mandatory code), it is commonly invoked by reference in regulatory frameworks such as OSHA 1910.106, EPA 40 CFR Part 112 (SPCC), and various state fire codes. To demonstrate due diligence, facilities should maintain the following records:
- Flame arrester specifications and certification documents (UL, FM, ATEX, or IECEx).
- Installation drawings showing location relative to tank and piping.
- Inspection logs with dates, findings, and cleaning actions.
- Pressure-drop test results verifying continued capacity.
- Training records for personnel performing inspections.
During an audit, authorities typically check that the arrester is listed for the specific service (deflagration or detonation), that the element gap matches the stored product’s MESG, and that no modifications have been made to the housing or element. Non‑compliance can lead to citations, fines, and increased liability in the event of an incident.
Frequently Asked Questions
Q: What is the difference between a deflagration and a detonation flame arrester?
A: A deflagration arrester stops subsonic flame fronts (typical of initial ignition), while a detonation arrester is engineered to stop supersonic flames accompanied by a shock wave. Detonation arresters have smaller element gaps and stronger housings. API RP 2210 requires the selection to be based on the worst‑case piping configuration and potential flame speed.
A: A deflagration arrester stops subsonic flame fronts (typical of initial ignition), while a detonation arrester is engineered to stop supersonic flames accompanied by a shock wave. Detonation arresters have smaller element gaps and stronger housings. API RP 2210 requires the selection to be based on the worst‑case piping configuration and potential flame speed.
Q: How often should flame arresters be inspected per API RP 2210?
A: The recommended practice advises visual inspection at least every six months. For services with high fouling potential (e.g., volatile crude, asphalt, or products prone to polymerization), inspections are recommended quarterly or even monthly. Cleaning intervals should be established based on observed condition.
A: The recommended practice advises visual inspection at least every six months. For services with high fouling potential (e.g., volatile crude, asphalt, or products prone to polymerization), inspections are recommended quarterly or even monthly. Cleaning intervals should be established based on observed condition.
Q: Does API RP 2210 apply to both fixed‑roof and floating‑roof tanks?
A: Yes. The standard applies to any aboveground storage tank that has a vent open to atmosphere — including fixed‑roof tanks, internal floating‑roof tanks (via their vents), and external floating‑roof tanks with rim‑seal vents. However, floating‑roof tanks with properly maintained seals that minimise vapor space may have different risk profiles; the standard’s guidance should be applied with engineering judgment.
A: Yes. The standard applies to any aboveground storage tank that has a vent open to atmosphere — including fixed‑roof tanks, internal floating‑roof tanks (via their vents), and external floating‑roof tanks with rim‑seal vents. However, floating‑roof tanks with properly maintained seals that minimise vapor space may have different risk profiles; the standard’s guidance should be applied with engineering judgment.
Q: Is API RP 2210 legally mandated?
A: API RP 2210 is a recommended practice, not a mandatory standard. However, it is widely referenced by regulatory bodies (OSHA, EPA, local fire codes) as a recognised and accepted engineering practice. Following RP 2210 helps demonstrate compliance with the general duty clause and can reduce liability in incident investigations.
A: API RP 2210 is a recommended practice, not a mandatory standard. However, it is widely referenced by regulatory bodies (OSHA, EPA, local fire codes) as a recognised and accepted engineering practice. Following RP 2210 helps demonstrate compliance with the general duty clause and can reduce liability in incident investigations.