June 1, 2016

Hazards Assessment for HVL Pipelines

Highly-volatile liquids (HVLs) have unique characteristics if unintentionally released from a pipeline. Officials should verify the product transported as part of the initial hazards assessment phase of response.

Phillips 66 Pipeline LLC transports the following HVLs:

  • Ethane
  • Butane
  • Propane
  • Mixtures of these individual components after processing

HVL products are transported in liquid form in the pipeline, but they become gaseous and form vapor clouds if released.   Identification of vapor clouds, their concentration and their location are important during the hazard assessment phase of response.  Vapors are highly flammable, heavier than air and tend to settle to the ground, especially in low-lying areas.

Vapor clouds vary in size depending on wind and humidity conditions.  Fire hazard is higher on a calm day, because vapors remain more concentrated.  Vapor clouds can drift from the immediate vicinity of a leak.  As the gas disperses in the air, the vapor cloud may be detectable only by a calibrated gas detector.

When responding to a potential pipeline leak, emergency officials should refrain from all tactical response until advised by a Phillips 66 Pipeline LLC representative.  Appropriate personal protection equipment (PPE) is needed when responding to an HVL release.  Vapors displacement oxygen and can result in asphyxiation. When in contact with skin, vapors can cause severe freeze burns.

Some HVLs contain hydrogen sulfide (H2S). Light concentrations of H2S will cause throat and eye irritation as well as breathing difficulty.  Heavier concentrations of H2S will cause dizziness similar to intoxication and may lead to serious breathing issues.

Refer to the Pipeline and Hazardous Material Safety Administration’s (PHMSA) “Emergency Response Guidebook” (ERG) or download our “Critical Pipeline Safety Information for Emergency Responders” brochure for more information regarding flammability range, flash points and vapor pressure for HVLs and other products transported by Phillips 66 Pipeline LLC.

Contact a Phillips 66 Pipeline LLC representative if you have questions regarding hazards assessment for HVL pipelines in your jurisdiction, or call: 1-800-231-2566.