SMALL BORE CONNECTION SCREENING
The most common integrity failure in process piping. Assessed systematically.
SBC screening that produces a risk register, not a report of further recommendations.
The Problem
Small bore connections are the single most common source of vibration-induced fatigue failure in process piping. Accounting for over 70% of vibration-related hydrocarbon releases on the UKCS, SBC failures are not edge cases — they are the expected outcome when vibration is not systematically assessed.
The physics is straightforward. An SBC — any branch connection or instrument tapping typically below DN80 — sits on a main process line that carries vibration energy from compressors, pumps, slugging flow, and pressure-reducing devices. The SBC has a mechanical natural frequency determined by its geometry, mass, and support configuration. When the excitation frequency approaches that natural frequency, dynamic stress at the weld toe accumulates. The weld is the weakest point. It cracks. The failure is rarely visible until it is a leak.
For large offshore facilities, there may be thousands of SBCs. Not all are at risk. But without systematic screening, operators cannot distinguish the critical few from the benign majority — and cannot demonstrate to regulators that they have tried.
Our Approach
Emveedo's SBC screening is structured as a three-phase assessment aligned to the Energy Institute AVIFF 2nd Edition methodology. Phase one is a systematic walkdown and data collection — every SBC catalogued, photographed, and characterised against excitation source, geometry, and support condition. Phase two is risk screening — each SBC classified against the EI LOF (Likelihood of Failure) matrix, with high-LOF connections identified for detailed assessment. Phase three is detailed fatigue analysis for high-LOF connections — mechanical natural frequency calculation, dynamic stress estimation, and fatigue life assessment against the appropriate S-N curve.
Our proprietary analytical workflows accelerate phase two and three significantly compared to manual assessment methods. For a facility with several hundred SBCs, this translates directly to faster delivery and lower total cost — without compromising the engineering basis.
The output is a complete SBC risk register: every connection assessed, classified, and where necessary, with a specific remediation recommendation. Operators receive a document they can present to HSE, include in their safety case, and use to direct maintenance spend.
What You Get
A complete SBC risk register: every connection assessed and risk-classified, detailed fatigue analysis for high-LOF connections, specific modification recommendations where required, and an executive summary suitable for regulatory submission or operator board-level reporting.
For brownfield and life extension scopes, we provide a maintenance prioritisation output — enabling operators to direct inspection and modification budget where fatigue risk is highest.
When You Need This
COMMON QUESTIONS
Frequently Asked Questions
What are small bore connections (SBCs)?
Small bore connections are branch connections, instrument take-offs, vents, drains, and similar attachments connected to larger process pipework. Although relatively small in size, they are amongst the most common locations for vibration-induced fatigue failures because they are highly sensitive to dynamic loading from the parent piping system.
Why are small bore connections vulnerable to fatigue failure?
Small bore connections typically have relatively low stiffness and experience amplified vibration when the main piping system is excited. Repeated cyclic loading can lead to fatigue cracking at welded connections, often without visible warning signs until failure occurs.
When should SBC screening be carried out?
SBC screening is recommended during FEED, detailed design, brownfield modifications, life-extension studies, and vibration investigations. It is particularly important where high flow velocities, pressure fluctuations, reciprocating equipment, or known vibration sources are present.
Which standards are used for SBC assessment?
Our assessments are primarily based on Energy Institute EI 3160 guidance, supported by recognised international engineering standards and industry best practice. Where project-specific requirements exist, these are incorporated into the assessment methodology to provide a clear and defensible integrity position.
What happens if a high-risk SBC is identified?
Where screening identifies an elevated fatigue risk, we investigate the governing vibration mechanism and recommend practical engineering solutions. These may include changes to connection geometry, support improvements, reinforcement, relocation, or detailed dynamic assessment where required.
Does every small bore connection require detailed analysis?
No. Most small bore connections can be screened efficiently using recognised engineering criteria. Detailed assessment is generally reserved for higher-risk configurations where screening indicates an elevated likelihood of vibration-induced fatigue or where operational experience suggests increased susceptibility.
Related Expertise
Piping Stress Analysis
Independent stress analysis for new design, brownfield modifications, and life extension assessments.
Learn more →Flow-Induced Vibration Assessment
FIV screening and detailed fatigue analysis for centrifugal compressor systems and high-velocity pipework.
Learn more →Acoustic-Induced Vibration Assessment
AIV screening and detailed fatigue analysis for pressure-reducing devices and relief systems.
Learn more →The EI AVIFF Guideline
Energy Institute Guidelines for the Avoidance of Vibration Induced Fatigue Failure in Process Pipework.
Learn more →