CAPABILITY | Thermal Sciences

Gas Pipeline Blowdown Risk Assessment

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Pipeline blowdowns — the release of high-pressure gases from a pipeline to the atmosphere — are a high-frequency event in production, transmission, and distribution systems. These blowdowns can generate several hazards, including low temperatures, vibrations, fire and explosion risks, and the release of greenhouse gases. Exponent helps clients navigate pipeline blowdown hazards through modeling, risk assessment, and process safety advising.

How can you keep your plant and piping safe during a planned or emergency blowdown?

If performed incorrectly, blowdowns can damage pipelines with low temperatures and excessive vibrations. Exponent's multidisciplinary team of mechanical engineers and thermal scientists can provide rigorous modeling to accurately predict piping temperature and vibration risk during blowdown. We also provide design and failure investigations related to these issues. 

Venting flammable gas also carries an inherent risk of fire or explosion. Existing standards, such as NFPA 56 and API 521, only provide guidance for a limited range of venting scenarios. Exponent has extensive experience using commercial software codes and computational fluid dynamics (CFD) modeling to accurately predict the extent of the safe area during venting for scenarios outside the scope of the standards. We also provide design analysis and regulatory guidance related to fire and explosion risk during pipeline blowdowns. 

Managing the environmental impact of pipeline blowdowns

Another blowdown risk is the environmental impact of releasing greenhouse gases from pipelines, which is significant and the subject of increasing scrutiny. These emissions can be reduced by flaring, transferring gas to a low-pressure system, or modifying processes to reduce blowdown events. We help reduce blowdown emissions by providing guidance on process changes. 

Hydrogen blowdowns

Exponent also advises on issues related to hydrogen blowdowns. In particular, the hydrogen blowdowns include higher flame speed and a wider flammability range than natural gas. This leads to an increased risk of ignition near the point of release. Exponent has the experience to advise on transitioning to and safely operating with hydrogen. 


Exponent offers rigorous pipeline blowdown process evaluations and modeling to address risks to facilities, people, and the environment.

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