Hot Work - Strategies & Effective Practices to Manage and Mitigate Hazards | AIChE

Hot Work - Strategies & Effective Practices to Manage and Mitigate Hazards

Effective Practices to Manage and Mitigate Hazards

Reduce risk by elimination or substitution; move in-situ work to a less hazardous location

  • Fabrication and modification outside hazardous areas is prefera-ble with minimal hook up activities in situ.
  • Consider deferring hot work to a future turnaround or outage when inventories of flammable materials is the plant at a mini-mum or totally eliminated.
  • Move spark potential equipment such as air compressors outside hazardous areas and use long hoses.

Use alternative methods to welding or gas cutting.

  • Consider bolted connections vs. welding, mechanical cutting equipment vs gas cutting, use of plastic materials and adhesives rather than metals which rely on welding for installation

Create a safe working environment.

  • If welding cannot be avoided in a hazardous area consider building a working enclosure with continuous positive pressure to prevent fugitive gas entry

Defer hot work to a future turnaround or outage.

  • When the risk of hot work is considered unacceptable, considera-tion should be made to defer it until the plant is in a safer condi-tion

Analyze hazards and identify means of control.

  • Survey the worksite and look for potential sources of flammable or explosive substances. Look for open drains and ducting as a source of gas transport. Look for nearby vents and sample points and openings such as filter housings, removable orifice plates, pig launchers / receivers, etc. 

Understand operational status.

  • If the plant is unstable and a potential to trip resulting in depres-surizations exists, caution should be exercised before issuing Hot Work permits.
  • Transfers of flammable materials into storage systems presents the possibility of overfills and spills.

Recognize changes in process conditions.

  • Hot Work permits that extend over many hours need to be reevaluated to ensure the surrounding area and plant conditions have not significantly changed, and that the controls detailed on the permit are still valid.

Ensure resources to adequately assess safe work activities.

  • Time pressure and/or task complexity stresses placed on authoriz-ing personnel to get permits issued can compromise the safety process through the adoption of a “seems OK to proceed” mind-set. These situations are associated with a higher frequency of process breakdowns and the introduction of additional risks.
  • Specify degree of operator presence, consistent with magnitude of identified hazards.

Use hazardous area classification to prohibit specific activities and specify classification of equipment usage.

  • Hazardous zoning of the site enables the specification of the type of equipment allowed within each area.
  • Only electrical equipment meeting the requirements of the haz-ardous area classification should be used in those areas.  This can include, but is not limited to intrinsically safe equipment.  Note - intrinsically safe electrical equipment should be used in these are-as.

Use of sealing / pressurization to prohibit gas entry and access to ignition sources.

  • Electrical switch gear in hazardous areas should be sealed to pre-vent gas entry and / or subject to continuous positive pressure.
  • Control rooms, nearby offices or accommodation should be pres-surised to avoid gas ingress into areas where ignition sources are not necessarily controlled.

Use of ventilation to disperse gas concentrations.

  • Welding and cutting can generate hazardous fumes so ventilation may need to be provided.
  • Preferably, the worksite is well ventilated and not enclosed. 

Use of bonding and grounding to en-sure that static electricity does not accumulate and cause a spark.

  • Understand what processes and equipment are subject to static electricity.
  • Install grounding and bonding cables to applicable equipment.
  • Inspect grounding and bonding cables prior to performing hot work.
  • Replace grounding and bonding equipment if damaged or com-promised.

Continuous monitoring of the environment; stopping work if combustible gas levels are detected.

  • Gas testing should be carried out by certified gas testers.
  • Gas test equipment must be periodically calibrated and tested before use.
  • The authorized gas tester should instruct the work party on the type of continuous gas monitoring (audible alarm preferred) being used and ensure they know how to respond to rising % LEL levels.
  • Work should commence no later than 1 hour after the initial gas test is recorded.
  • If work is suspended for any period, another gas test should be performed before the Hot Work Permit is reissued and work re-commences.

Clear identification of equipment on the plant.

  • Ensure that the equipment to be worked on is correctly identified and labelled so that it will be correctly isolated and purged.  

Isolate, depressurize and purge equipment to be worked on as well as other potential nearby combustible fuel sources.

  • Lock Out / Tag Out should be linked to the permit and a necessary precursor for commencing work.
  • Good practice is to demonstrate the equipment is energy- and gas-free before hot work commences.

Clearing flammable materials away from any areas where potential sparks and/or molten metal could impact.

  • All flammable material within or near the work area should be removed including dust, debris, grease, chemicals, etc.
  • Ensure Safety Data Sheets for any materials which cannot be re-moved are examined for combustion vulnerability.

Use of Hot Work permits to manage activities, specify controls, manage simultaneous operations and communicate to others.

  • Avoid Hot Work simultaneously with hydrocarbon sampling, pig receiving and launching, breaking containment and non-routine process changes. 
  • Ensure no other line break work or hot work being performed close proximity (35 feet / 10 meters).
  • Opening sealed or pressurized electrical equipment such as junc-tion boxes, switches, light fitting, etc., located in hazardous areas should require a Hot Work permit.
  • Motorized vehicles, even those with engine limiters and spark arrestors, should be considered ignition sources and managed as such.

Use of fire watchers; dedicated worker on standby with extinguisher or charged fire hoses as well as communication capability in the event of a fire.

  • A dedicated firewatcher should be part of the work party for any naked flame hot work.
  • Firewatchers should be trained in this role and have the necessary extinguishers and/or charged fire water hoses on hand, as well as communication capabilities.
  • Firewatchers are responsible for ensuring any errant sparks, mol-ten metal or hot debris is properly contained by the fire blankets in use.
  • Firewatchers need to monitor heat being conducted to other, out of sight, areas.
  • The activities of the firewatcher should continue for at least 1 hour following completion of any hot work activities.

Protect areas where sparks and hot debris can impinge and be transported to other plant areas.

  • Fire blankets to capture falling molten metal, hot particles and sparks from impinging on other areas.
  • Wooden and other combustible floors, including scaffolding planks, should be swept, cleaned and wetted down to prevent ignition.
  • Cover ducting and conveyor systems with fire blankets to prevent the distribution of sparks and hot debris.
  • Ducts or conveyor systems near the worksite which could transmit sparks or combustible gases should be shut down.

Identify and seal areas where gas may be transported to the work site.

  • Ensure loops seals on drain systems are charged and openings covered with fire blankets to prevent sparks from entering.
  • Ensure duct systems which could transport escaping gas from oth-er areas are closed for the duration of the work.

Temporary defeat of IR detectors / automatic deluge systems during welding and cutting.

  • If automatic fire detectors are defeated for necessary Hot Work, firewatcher(s) need to monitor all of these areas for any source of fire, not just the hot work.

Ensure that all workers are competent to execute their responsibilities.

  • If automatic fire detectors are defeated for necessary Hot Work, firewatcher(s) need to monitor all of these areas for any source of fire, not just the hot work.

Ensure welding and cutting equipment is in good condition.

  • Provide training to all personnel in Hot Work policies and proce-dures.
  • Ensuring contractors have required craft qualifications.
  • Closely supervise all contractors to ensure they are aware of all hazards and how to respond to emergencies.

Communication is essential between the control room, the Operating personnel and the people conducting the work.

  • Communication with the control room at all times is essential.
  • If an emergency alarm is sounded, all Hot Work must immediately cease and any ignition sources extinguished before responding to the alarm.  All gas checks must be repeated before work can re-commence following an emergency alarm.