API RP 2028-2002 (2010): Flame Arresters in Piping Systems – Technical Requirements and Compliance Guide

Scope and Applicability of API RP 2028-2002 (2010)

API Recommended Practice 2028, originally issued in 2002 and reaffirmed in 2010, provides guidance on the selection, installation, operation, and maintenance of flame arresters used in piping systems within onshore oil and gas production facilities, pipelines, and related process environments. The document addresses both deflagration and detonation arresters for flammable gas and vapor service.

The scope covers:

End-of-line and in-line flame arrester applications
Systems handling flammable gases and light hydrocarbon vapors
Arrester performance under steady and transient flow conditions
Integration with vent systems, tank breather valves, and flare headers

API RP 2028-2002 (2010) is applicable to new installations as well as the retrofitting of existing piping systems where flame propagation risk exists.

Technical Requirements for Flame Arrester Systems

Performance Classification

The document classifies flame arresters based on the type of flame they must stop:

Type	Flame Condition	Characteristic
Deflagration (low pressure)	Subsonic flame front	Typically < 2 m/s; arresters located within 10 pipe diameters from ignition source
Detonation (high pressure)	Supersonic flame front (C-J wave)	Requires robust element and housing; may include stabilizers and transition sections
End-of-line	Flame exiting pipe end	Simpler design; often used on vents and tank openings
In-line	Flame traveling inside pipe	Must handle sustained pressure and repeated thermal cycling

The recommended practice specifies that all flame arresters must be tested in accordance with ISO 16852 or equivalent recognized standards to verify their ability to stop the intended flame condition.

Design and Material Specifications

Element material: Typically 316 stainless steel, Hastelloy®, or other corrosion-resistant alloys.
Housing construction: Carbon steel with optional internal coatings for sour service (NACE MR0175/ISO 15156).
Maximum allowable pressure drop: Shall not exceed the system design limit at maximum expected flow rate.
Temperature rating: Must cover ambient and process extremes, with allowance for flame heating.

Tip: When specifying an in-line detonation arrester, ensure the piping layout includes a sufficient straight-run length upstream and downstream as recommended by the manufacturer, typically 5-10 pipe diameters, to ensure proper flame development and arrester performance.

Installation Requirements

API RP 2028-2002 (2010) prescribes installation practices to avoid bypassing the flame arrester’s function:

No valves, fittings, or other obstructions between the flame source and the arrester element.
All joints must be leakproof; gasketed flanges are preferred over threaded connections for larger sizes.
The arrester must be oriented so that any liquid accumulation drains away from the element – typically horizontal or with a slight incline.
Clear access for inspection and removal must be provided.

Warning: Improper orientation (e.g., vertical with element at the bottom) can cause liquid or debris blockage, drastically reducing the arrester’s ability to stop flames and increasing pressure drop.

Implementation Highlights and Best Practices

Selection Criteria

Engineers should evaluate the following parameters before selecting a flame arrester:

Maximum experimental safe gap (MESG) of the gas or vapor mixture.
Maximum expected volumetric flow and pressure under normal and upset conditions.
Presence of liquid carryover, particulates, or polymerizing substances.
Ambient temperature range and process fluid conditions.
Certification requirements for the jurisdiction (e.g., ATEX, IECEx, or UL).

Maintenance and Testing

The recommended practice outlines inspection intervals and procedures:

Visual inspection every 3–6 months for end-of-line units; every 12 months for in-line units.
Pressure drop measurement at each inspection to detect element fouling or blockage.
Functional testing after any repair or modification affecting the flow path.
Records of all inspections, tests, and replacement must be kept in accordance with facility procedures.

Best Practice: Establish a baseline pressure drop at installation and track deviations. A 25% increase above baseline should trigger a maintenance shutdown and cleaning. This proactive approach extends element life and maintains certified flame-stopping capability.

Critical: Never use a flame arrester that has been subjected to a flame event without re-certification or replacement. The thermal and mechanical stresses can degrade the element integrity even if the flame was successfully stopped.

Compliance Notes and Reaffirmation (2010)

API RP 2028 was reaffirmed in 2010 without substantive technical changes, confirming its continued applicability. The 2010 reaffirmation incorporates editorial updates and references to newer testing standards such as ISO 16852:2008. Compliance with API RP 2028-2002 (2010) is often mandated by facility operating permits and insurance underwriters.

Key compliance considerations:

Demonstrate through documentation that all flame arresters meet the performance criteria of ISO 16852 or an equivalent recognized standard.
Ensure that any changes to piping or process conditions (e.g., increased flow rate, different gas composition) are reviewed against the original arrester selection – a new hazard analysis may be required.
For offshore installations, see API RP 14J and API RP 14C for additional requirements; however, API RP 2028-2002 (2010) remains the primary source for flame arrester specification.

Frequently Asked Questions

Q: What is the difference between API RP 2028-2002 (2010) and ISO 16852?
A: API RP 2028-2002 (2010) provides application-specific guidance for piping systems in the oil and gas industry, while ISO 16852 is a product standard that defines testing methods and performance requirements. The recommended practice references ISO 16852 for arrester qualification and adds installation and maintenance requirements tailored to onshore production facilities.

Q: Can a deflagration arrester be used for detonation service?
A: No. Deflagration arresters are not designed for the higher flame speeds and pressures of detonations. Using an undersized or incorrect arrester type can result in flame transmission and catastrophic failure. Always consult the manufacturer’s certification data and match the arrester type to the worst-case flame condition identified in the hazard assessment.

Q: Does the 2010 reaffirmation introduce any new technical requirements?
A: The 2010 reaffirmation did not change technical requirements; it updated references and editorial corrections. Facilities already compliant with the 2002 edition remain compliant. However, users should verify that the arrester’s test standard (e.g., ISO 16852 edition) is current.

Q: Are there specific requirements for flammable liquids or dual-phase flow?
A: API RP 2028-2002 (2010) focuses on flammable gases and vapors. For liquids or two-phase mixtures, refer to API 2210 or NFPA 69, and consult with a specialist because flame arresters may not provide reliable protection. The recommended practice recommends careful evaluation of condensation or liquid carryover during operation.

This article is based on API RP 2028-2002 (R2010) and provided for general informational purposes. Always refer to the latest published version of the standard for official requirements. — Published 2026

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