Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
API Bull 2HINS-2009: In-Service Inspection of Mooring Hardware for Floating Structures – Technical Overview and Compliance Guidelines
API Bulletin 2HINS provides essential recommended practices for the in-service inspection of mooring components to ensure operational safety and structural integrity.
Scope and Purpose of API Bull 2HINS-2009
API Bulletin 2HINS-2009 (Bull 2HINS) is a guidance document published by the American Petroleum Institute that addresses the in-service inspection of mooring hardware used on floating offshore structures such as FPSOs, semi-submersibles, TLPs, and mobile offshore drilling units. While the bulletin does not establish mandatory requirements, it consolidates industry best practices for inspection planning, execution, and decision-making regarding mooring system integrity. The document covers critical components including mooring chains, wire ropes, synthetic ropes, connectors (shackles, swivels, H-links), and other hardware. Its primary purpose is to provide operators and inspection engineers with technically sound criteria for assessing continued serviceability, preventing failures, and extending the safe operating life of mooring systems.
The bulletin is closely aligned with other API recommended practices such as API RP 2I (In-service Inspection of Mooring Chain) and API RP 2SK (Design and Analysis of Station Keeping Systems), but offers more detailed field-level inspection guidance. It addresses both permanent and mobile moorings and considers the effects of service history, environmental exposure, and load conditions. The document places strong emphasis on systematic recording and traceability of inspection data to enable trend analysis and proactive maintenance.
Technical Requirements and Inspection Criteria
Inspection Planning and Intervals
API Bull 2HINS recommends that mooring inspection programs be developed based on risk, component type, service environment, and previous inspection results. Baseline inspections should occur prior to installation, followed by periodic inspections at intervals not exceeding five years for permanent moorings, with more frequent assessments for critical components or severe environments. The bulletin provides a tiered framework:
| Component | Baseline Inspection | Periodic Interval | Maximum Interval Under Normal Conditions |
|---|---|---|---|
| Mooring chain / common links | Before installation | 5 years | 10 years (if within acceptance criteria) |
| Wire ropes (spiral strand, six-strand) | Before installation | 3 years | 5 years |
| Synthetic ropes (polyester, nylon, HMPE) | Before installation | 2 years | 4 years |
| Connectors (shackles, swivels, H-links) | Before installation | 5 years | 10 years |
Acceptance Criteria for Chains
For mooring chain, Bull 2HINS details specific measurement and rejection criteria. Key parameters include link wear (diameter loss), elongation, surface cracks, corrosion pitting, and mechanical damage. The bulletin distinguishes between ordinary links, enlarged links, and end links. The following table summarizes the main acceptance thresholds:
| Parameter | Acceptable Limit | Rejection Criteria | Inspection Method |
|---|---|---|---|
| Link diameter wear / corrosion | Less than 10% reduction from original nominal diameter | ≥10% reduction in cross-sectional area equivalent to ~10% diameter reduction in wear plane | Vernier caliper, laser profile measurement |
| Link elongation (pitch) | Less than 5% increase over original pitch length | ≥5% elongation or visible distortion | Tape measure, gauging fixture |
| Surface defects (cracks, notches) | None detected or less than 1 mm depth | Any crack length > 5 mm or > 1 mm depth (MPI / ACFM) | Magnetic particle inspection (MPI), alternating current field measurement (ACFM) |
| Corrosion pitting | Pit depth less than 2 mm, density less than 10% of surface area | Pit depth > 3 mm or extensive clustered pitting | Visual, replication, UT |
Wire Rope and Synthetic Rope Criteria
For wire ropes, Bull 2HINS addresses broken wires, corrosion, diameter reduction, birdcaging, and socket condition. For spiral strand, more than 3 broken wires in one lay length in non-critical zones, or any broken wires within the socket area, typically triggers rejection. Synthetic rope criteria focus on abrasion, cut filaments, hockling, creep, and strength degradation based on periodic load testing or monitoring. The bulletin recommends that synthetic ropes be retired if visible fiber degradation exceeds 10% of the rope cross-section or if retained break strength (determined by sample tests) falls below 80% of the original minimum breaking load.
Tip: When performing in-service inspections, always refer to the original manufacturer’s data sheets and API Bull 2HINS tables for component-specific thresholds. Slight geometry variations can affect allowable wear limits.
Implementation and Compliance Notes
Recordkeeping and Traceability
A core requirement of Bull 2HINS is the establishment of an auditable inspection trail. Each mooring component should have a unique identification number (e.g., chain serial number, wire rope tag). Inspection dates, findings, measurements, and decisions (retire, repurpose, refurbish) must be recorded and retained for the entire life of the component. The bulletin includes sample inspection report templates and recommends digital storage for trending.
Personnel Qualifications
Inspectors should be trained and certified in accordance with recognized schemes (e.g., ASNT SNT-TC-1A for NDT, API individual certification programs where applicable). The bulletin stresses that personnel performing visual inspections of mooring hardware should have specific experience with offshore mooring equipment and be familiar with failure modes such as fatigue, corrosion, and wear.
Warning: API Bull 2HINS is a guidance document and does not substitute for engineering judgment. Inspectors must consider site-specific conditions and loading history. Components meeting nominal acceptance criteria may still require early retirement if subjected to extreme events such as storms, snag loads, or fires.
Regulatory and Contractual Use
While API bulletins are not mandatory codes, they are frequently referenced in regulatory frameworks (e.g., BOEM, BSEE in the U.S., or C-NLOPB in Canada) and are often incorporated into mooring management plans by operators. Classification societies such as ABS, DNV GL, and Lloyd’s Register may accept Bull 2HINS methods as equivalent to their own rules. Compliance with the bulletin can demonstrate due diligence in a safety case or incident investigation.
Best Practice: Operators that systematically implement Bull 2HINS recommendations often achieve measurable improvements in mooring reliability. Planned inspection and retirement cycles reduce the likelihood of in-service failure and associated production downtime.
Critical: Failure to inspect mooring components at the recommended intervals or to adequately document findings can lead to catastrophic loss of station-keeping capability, posing risks to personnel, the environment, and assets. Always follow the most recent edition of the bulletin and applicable jurisdiction requirements.
Upgrades and Revisions
Since Bull 2HINS was published in 2009, users should check the API website for any subsequent re-affirmations, errata, or addenda. Many operators supplement the bulletin with company-specific specifications and consider the latest research on mooring integrity, including corrosion fatigue in chains and aging behavior of synthetic ropes. The bulletin remains a foundational reference as of 2026.
Frequently Asked Questions
Q: Is API Bull 2HINS-2009 a mandatory standard?
A: No. It is a bulletin (guidance document) and is not legally binding on its own. However, it is widely adopted by industry and may be contractually required or referenced by regulators. Operators are encouraged to apply the recommended practices as part of a comprehensive mooring integrity management program.
A: No. It is a bulletin (guidance document) and is not legally binding on its own. However, it is widely adopted by industry and may be contractually required or referenced by regulators. Operators are encouraged to apply the recommended practices as part of a comprehensive mooring integrity management program.
Q: Does the bulletin cover all types of mooring configurations?
A: Yes, it applies to catenary, taut-leg, and semi-taut moorings used on permanent and mobile floating units. The inspection criteria are component based, so they can be adapted to various configurations. The bulletin also provides guidance for both new and second-hand hardware.
A: Yes, it applies to catenary, taut-leg, and semi-taut moorings used on permanent and mobile floating units. The inspection criteria are component based, so they can be adapted to various configurations. The bulletin also provides guidance for both new and second-hand hardware.
Q: What is the recommended approach for inspecting synthetic ropes under the bulletin?
A: API Bull 2HINS recommends a combination of visual examination, dimensional checks, and non-destructive evaluation (e.g., magnetic resonance imaging for internal damage). It also advocates for periodic residual strength testing on representative samples removed from service. Detailed criteria for abrasion, cut filaments, and creep are provided.
A: API Bull 2HINS recommends a combination of visual examination, dimensional checks, and non-destructive evaluation (e.g., magnetic resonance imaging for internal damage). It also advocates for periodic residual strength testing on representative samples removed from service. Detailed criteria for abrasion, cut filaments, and creep are provided.
Q: How does the bulletin relate to API RP 2I and API RP 2SK?
A: API Bull 2HINS supplements these recommended practices by focusing specifically on field-level inspection techniques and acceptance criteria. API RP 2I addresses chain inspection in more detail, while API RP 2SK covers design and analysis. The three documents together form a cohesive framework for mooring system integrity.
A: API Bull 2HINS supplements these recommended practices by focusing specifically on field-level inspection techniques and acceptance criteria. API RP 2I addresses chain inspection in more detail, while API RP 2SK covers design and analysis. The three documents together form a cohesive framework for mooring system integrity.
Article prepared in 2026. Always refer to the latest API publications and competent engineering advice for operational decisions.