Selecting the wrong flare system creates compliance liability that outlasts the initial capital decision by years. This guide covers the eight evaluation criteria that production, midstream, and plant engineers must assess before specifying or purchasing a flare system for any regulated facility.
1. Identify Your Regulatory Baseline Before Comparing Equipment
The applicable EPA subpart governs minimum Destruction and Removal Efficiency, monitoring requirements, and documentation format. Purchasing equipment before confirming the regulatory basis leads to either over-specification (unnecessary cost) or under-specification (compliance failure).
For upstream oil and gas production facilities, EPA 40 CFR 60 Subpart OOOOb (effective January 2024) requires 98% control efficiency for storage vessel emissions at sites with 6 tons per year or greater VOC throughput. For gas processing plants and midstream compressor stations, Subpart OOOO or state-specific BACT requirements may govern. For refineries and chemical plants, NSPS Ja or permit-specific limits apply.
Establish the applicable subpart and its specific combustion efficiency and monitoring requirements as the first step, before issuing a request for quotation to any manufacturer.
2. Define the Full Gas Stream Parameter Range
Flare systems are sized for a specific gas stream. Providing incomplete or average parameters to a manufacturer results in equipment that performs well at one operating condition and fails at others. Four parameters define the gas stream:
| Parameter | What to Provide | Why It Matters |
|---|---|---|
| Flow rate range | Minimum and maximum Mcf/day or MMscfd | Determines tip size, turndown ratio requirement |
| Gas composition | BTU content (min and max), H2S %, CO2 % | Drives combustion design, metallurgy selection |
| Operating pressure | Expected header pressure range in psig | Required for gas-assist and sonic tip selection |
| Site altitude | Feet above mean sea level | Affects combustion air density and thermal rise |
If future well production could increase flow rates beyond current estimates, inform the manufacturer during the quoting process. Undersized flares cannot be upsized in the field without significant modification cost.
3. Select the Right Flare Type for the Application
The five primary flare types each suit different combinations of flow rate, site constraints, and BTU content. The correct type selection is a technical decision, not a preference.
| Flare Type | Best Application | Key Requirement |
|---|---|---|
| Air-assist | Variable BTU gas, mid-range flow rates | Grid or generator power for blower |
| Sonic tip | High-pressure, consistent BTU streams | Minimum 15-60 psig operating pressure |
| Gas-assist | No power available, consistent fuel gas supply | Reliable high-pressure fuel gas header |
| Low-flow combustor | Tank battery, low and intermittent flow | Auto-ignition, BTU may be <300 BTU/scf |
| Emergency/utility | Relief valve and blowdown service | Sized for maximum credible relief scenario |
For facilities with multiple sources — production vessels, storage tanks, compressor blowdowns — a single flare system may need to handle multiple stream types with different flow rates and BTU content simultaneously. Discuss multi-stream design requirements with the manufacturer before finalizing specifications.
4. Verify DRE Performance Data Across the Turndown Range
A 98% Destruction and Removal Efficiency requirement under EPA OOOOb applies across the flare’s operating range, not only at the design maximum flow rate. Request the manufacturer’s combustion performance data at a minimum of four flow conditions:
10% of rated capacity (minimum stable flow), 25% of rated capacity (low normal operation), 50% of rated capacity (mid-range normal operation), and 100% of rated capacity (design maximum flow). DRE data should be from actual combustion testing or computational fluid dynamics analysis validated against test data — not extrapolated from adjacent tip sizes.
The DRE formula is: DRE = [(Mass In – Mass Out) / Mass In] x 100%. A system that achieves 98.5% at maximum flow but 94% at minimum flow fails the OOOOb 98% floor during the low-flow periods that make up the majority of operating hours at most production sites.
5. Evaluate Manufacturer Engineering Depth
The flare system market includes both manufacturers and distributors. Understanding the difference protects buyers from performance risk and limits warranty exposure.
Manufacturers design and fabricate their own combustion tips, conduct in-house combustion testing, employ combustion engineers who can provide site-specific performance calculations, and hold the engineering liability for the equipment’s DRE performance. They can provide site-specific combustion guarantees backed by actual test data on their specific tip geometry.
Distributors source combustion tips from third-party tip manufacturers and resell them, often without in-house combustion engineering. They may not be able to provide DRE performance data specific to your gas stream parameters and cannot offer performance guarantees beyond what the upstream tip manufacturer provides.
Ask prospective suppliers directly: Do you design and test your own combustion tips? Can you provide DRE test data for this specific tip design at my expected flow range? If the answer is no to either question, the supplier is a distributor, not a manufacturer.
6. Confirm Materials of Construction Match the Service
Flare tip materials must withstand the chemical and thermal environment of the specific gas stream being combusted. Specifying standard materials for sour gas service, high-temperature service, or corrosive gas composition accelerates tip failure and reduces DRE before the next scheduled maintenance interval.
For gas streams containing H2S above 100 ppm, specify 316L stainless steel or higher-alloy materials for all wetted combustion zone components. For high-BTU gas streams or high-heat-release applications, Alloy 625 (Inconel 625) or equivalent nickel alloys provide superior thermal resistance and fatigue life. For standard natural gas service with low sour content, 304 stainless steel tip construction is acceptable at most operating temperatures.
Request a material specification document that calls out the material grade for tip body, pilot assembly, air injection components (for air-assist systems), and all fasteners in the combustion zone. Standard hex-head carbon steel bolts in combustion zone applications are a failure point that material specs reveal before delivery.
7. Assess Lead Time Against the Compliance Deadline
New flare system fabrication lead times range from 8 to 20 weeks depending on the manufacturer’s order backlog and the complexity of the equipment. Compliance deadlines under OOOOb and state permit conditions do not adjust for equipment lead time.
If the gap between the compliance deadline and available fabrication lead time is less than 4 weeks, a rental flare system is the only path to on-time compliance. Rental flares allow a facility to meet the compliance deadline with a compliant temporary system while the permanent unit is fabricated.
When comparing rental options, confirm the rental provider’s average mobilization time from order to on-site installation, the performance specifications of the available rental units (not all rental flares are rated for all gas compositions), and the terms for extending the rental if permanent installation is delayed.
Hero Process Solutions maintains a rental fleet of air-assist flares, low-flow combustors, and vapor recovery units available for deployment across major producing regions. Visit our rental program page for specifications and availability.
8. Review Post-Sale Support and Field Service Capability
A flare system’s compliance performance over its operating life depends on the manufacturer’s post-sale field service capability as much as initial equipment quality. Four post-sale questions to ask before purchase:
Where is the nearest field service team? Manufacturers with direct field service personnel in the operating region can respond to pilot outages, tip inspections, and compliance documentation requests in hours rather than days. Manufacturers with no field presence outside their headquarters location create multi-day response times for issues that regulators classify as continuous compliance failures.
What is the warranty coverage on combustion tip components? Combustion tips are the highest-wear component in a flare system. Confirm the warranty period, what failure modes are covered, and whether warranty replacement requires return shipping to the manufacturer or on-site replacement by a field technician.
Are replacement tip and ignition components stocked domestically? International manufacturers with US distribution but no domestic parts inventory create 6- to 12-week replacement lead times for wear components. This creates compliance exposure when a tip reaches end of service life.
Can the manufacturer provide compliance documentation support? State and federal inspectors request combustion efficiency documentation, pilot monitoring records, and equipment specifications during compliance inspections. Manufacturers with in-house regulatory affairs support can assist with permit documentation, deviation reports, and corrective action responses. Distributors typically cannot.
Hero Process Solutions provides direct field service across the Permian Basin, Mid-Continent, Appalachia, and Rocky Mountain regions. Contact our engineering team at (918) 941-2166 or submit a quote request to discuss your application requirements.
Frequently Asked Questions
How long does it take to get a flare system fabricated and installed?
Standard flare system fabrication lead time is 8 to 20 weeks from order confirmation, depending on the manufacturer’s current order backlog and the complexity of the equipment. Installation, depending on site preparation requirements, adds 1 to 3 weeks. If a compliance deadline falls within the lead time window, rental equipment is the only path to on-time compliance. Always confirm lead time before signing a purchase order if a permit date or regulatory deadline is in play.
What is the difference between a flare manufacturer and a flare distributor?
A flare manufacturer designs its own combustion tips, conducts in-house combustion performance testing, employs combustion engineers, and holds engineering liability for DRE performance. A distributor sources tips from a third-party manufacturer and resells them, typically without in-house combustion engineering or the ability to provide site-specific DRE guarantees. For regulated applications requiring 98% DRE documentation, purchasing from a manufacturer rather than a distributor provides stronger compliance standing and clearer accountability.
Can I rent a flare system to meet a compliance deadline while a permanent unit is fabricated?
Yes. Rental flare systems that meet the same DRE performance requirements as permanent equipment are available for temporary deployment. Rental is the standard solution when compliance deadlines fall within the fabrication lead time window. The rental unit must meet the same EPA DRE requirement as the permanent equipment — confirm with the rental provider that the available rental units are rated for 98% DRE at your expected flow rate and gas composition before mobilizing.
What documentation should a flare manufacturer provide with the equipment?
A complete flare system delivery package should include: combustion tip engineering drawings with material specifications, DRE performance data for the specific tip design, pilot and ignition system operation and maintenance manual, recommended inspection intervals and maintenance procedures, and a combustion efficiency certification letter for permit file use. Manufacturers should also be able to provide application-specific combustion efficiency calculations showing compliance with the applicable EPA subpart requirements at the expected operating conditions.
What is the typical service life of a flare combustion tip?
Flare combustion tip service life depends on operating hours, gas composition, and tip material. Air-assist flare tips in standard natural gas service with 316L stainless steel construction typically achieve 5 to 10 years of service before requiring inspection and potential replacement. Sour gas service (high H2S) or high-heat-release applications at the upper end of the flow range reduce service life. Annual pilot inspections and tip condition assessments at 3-year intervals are the standard maintenance schedule for tips in continuous-duty upstream applications.
