Fitness for Service (FFS) Assessment as per API 579 / ASME FFS-1

API 579-1/ASME FFS-1 is the primary standard used across oil & gas, petrochemical, chemical, and power industries worldwide. Other recognized standards include BS 7910 (UK/offshore) and the nuclear R6 procedure. We work primarily under API 579-1 and also execute BS 7910 assessments when required.

When in-service inspection identifies corrosion, cracks, creep, pitting, hydrogen damage, geometric distortions, or fire damage or when equipment approaches or exceeds its design life and needs engineering justification for continued operation.

It calculates how long equipment can safely continue operating before damage reaches an unacceptable level. For metal loss, this uses corrosion rate and remaining wall thickness. For cracks, fatigue crack growth analysis. For creep, the MPC Omega method. The result sets inspection intervals and informs capital planning.

Level 1: Conservative screening with basic data, quick turnaround decisions.

Level 2: Detailed analysis with actual material properties and flaw dimensions, the most commonly applied level.

Level 3: FEA, fracture mechanics (FAD), and advanced computational methods for severe or complex damage.

A component that fails Level 1 may still pass at Level 2 or 3 with better data.

Pressure vessels, piping systems, storage tanks, boilers, reactors, heat exchangers, columns, separators, and structural components in both carbon steel and alloy steel, across all standard geometries and operating conditions.

It avoids unnecessary replacements, prevents risky repairs, and provides documented engineering evidence for continued operation that regulators, insurers, and internal risk teams require. In our experience, a properly executed FFS assessment saves the client far more than it costs.

Yes. Part 11 of API 579-1 addresses fire damage. We screen based on heat exposure, evaluate material property changes through hardness testing and metallography, and determine return-to-service suitability for each affected component.

RSF is the ratio of the damaged component's collapse load to the undamaged component's collapse load. API 579-1 specifies an allowable RSF (typically 0.90)  above it, the component passes. Below it, re-rating or repair is needed. Used in Part 4, 5, and 6 assessments.

The FAD is the method used in Part 9 to evaluate cracks. It simultaneously checks brittle fracture risk (Kr) and plastic collapse risk (Lr). If the assessment point falls inside the FAD curve, the crack is acceptable. It is the industry-standard approach for crack assessment in pressure equipment.

Level 1: 3–5 working days with complete data.

Level 2: 1–3 weeks.

Level 3 with FEA: 3–6 weeks including modeling and reporting.

For turnaround-critical situations, we provide preliminary findings within the first week.