Chemical and gas work guide
Review hazards and checks for each example, then prepare an assessment and work documents for your actual site.
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Local documents and scope
For Great Britain, connect the Risk Assessment with the Method Statement to explain both hazards and the safe sequence of work (often called RAMS). Use a PTW when the activity and site procedure require it; it does not replace the assessment. Brief the crew through a Toolbox Talk. Northern Ireland has a separate regulatory context: consult HSENI before applying these references there.
- Risk Assessment
- Method Statement
- Permit to Work (PTW)
- Toolbox Talk
- Inspection Checklist
This is a planning reference. Verify numerical limits, permits and qualifications for the jurisdiction, sector and equipment. Record fresh site measurements, people and signatures for each job.
From example to site use
- 1
Define the job
Identify equipment, location, sequence, people, nearby activities and access. Separate preparation, execution and close-out, and record hazards observed at the site.
- 2
Match controls to each step
Consider elimination, substitution and engineering controls first, then procedures and PPE. Assign an owner, a verification method and stop-work conditions for each control.
- 3
Connect documents and site checks
Choose the local assessment, procedure and applicable permits, then brief the crew. Add drawings and checklists, reassess changes and retain the output for this job.
Task hazards and checks 10
Shell & Tube Heat Exchanger Inspection & High-Pressure Water Jet Cleaning
- Potential hazards
- Tissue penetration by high-pressure water, chemical burns from residual fluids
- Checks to verify and specify on site
- Isolate, release and verify pressure and contents before opening. Use the design code and approved procedure for test pressure, medium and sequence; define exclusion and stop criteria.
- Check the SDS, compatibility, containment, extraction, leak isolation and emergency response. Select test targets, limits and respiratory protection for the actual substances and exposure.
High-Pressure Hydrogen Compressor Packing Replacement
- Potential hazards
- Explosion due to hydrogen leakage, asphyxiation due to nitrogen purging
- Checks to verify and specify on site
- Isolate, release and verify pressure and contents before opening. Use the design code and approved procedure for test pressure, medium and sequence; define exclusion and stop criteria.
- Check the SDS, compatibility, containment, extraction, leak isolation and emergency response. Select test targets, limits and respiratory protection for the actual substances and exposure.
Toxic Chemical Piping Valve & Gasket Replacement
- Potential hazards
- Splashing of residual liquids during flange disassembly, toxic gas poisoning
- Checks to verify and specify on site
- Isolate, release and verify pressure and contents before opening. Use the design code and approved procedure for test pressure, medium and sequence; define exclusion and stop criteria.
- Check the SDS, compatibility, containment, extraction, leak isolation and emergency response. Select test targets, limits and respiratory protection for the actual substances and exposure.
Flare Stack Tip Replacement & Ignition System Maintenance
- Potential hazards
- Falls due to high winds, fire exposure if residual gas ignites
- Checks to verify and specify on site
- Avoiding height work; platforms and collective fall protection; Fall restraint/arrest equipment, anchors and required clearance; Access, fragile surfaces, openings and falling-object controls; Weather, work conditions, equipment inspection and stop criteria; Site rescue method, people, equipment, communication and readiness.
- Combustible removal/shielding; opposite faces, lower areas and openings; Fire watch, extinguishing equipment, post-work watch duration and completion time; Gas, vapour, fume and dust assessment, testing and ventilation; Vessel/pipe residues, cylinders, hoses, flashback protection and equipment checks.
Function Check of Emergency Response Equipment
- Potential hazards
- Impact from hose detachment during high-pressure water discharge, gas inhalation
- Checks to verify and specify on site
- Isolate, release and verify pressure and contents before opening. Use the design code and approved procedure for test pressure, medium and sequence; define exclusion and stop criteria.
- Verify task-specific training, qualifications and procedures. Record process and equipment protections, exposure controls, emergency arrangements and the responsible person's checks in the work plan.
PSA Adsorption Tower Lower Automatic Valve Inspection
- Potential hazards
- Crushing due to unexpected valve operation, respiratory issues from adsorbent dust
- Checks to verify and specify on site
- Check manufacturer procedures, guards, energy isolation and release of stored energy; account for people and tools before restart.
- Check the SDS, compatibility, containment, extraction, leak isolation and emergency response. Select test targets, limits and respiratory protection for the actual substances and exposure.
Internal Visual Inspection & NDT of High-Pressure Hydrogen Storage Tanks
- Potential hazards
- Asphyxiation in confined space, explosion caused by lighting leakage
- Checks to verify and specify on site
- Space identification, need for entry, access and escape routes; Entrants, outside attendant, person in charge and communication; Atmospheric test targets, acceptance criteria and repeat/continuous monitoring; Isolation of incoming substances and energy; locks and stored-energy checks; Ventilation, respiratory protection, contaminant controls and failure response; Site rescue method, people, equipment, communication and readiness.
- Equipment, circuits, supplies, backfeed, induced voltage and stored energy; Disconnection, prevention of re-energisation, locks and tags; Voltage detector, functional check, absence-of-voltage result and tester; Earthing/short-circuiting where required; adjacent live-part protection and boundaries; Completion, personnel clearance, lock removal and re-energisation authority.
High-Pressure Hydrogen Tanker Unloading & Charging Bay Connection
- Potential hazards
- Crushing due to vehicle rolling, hydrogen gas explosion due to static discharge
- Checks to verify and specify on site
- Separate vehicles and pedestrians; check visibility, reversing and loading areas. Set speed and signalling for the site, and stop for unstable loads or ground.
- Isolate, release and verify pressure and contents before opening. Use the design code and approved procedure for test pressure, medium and sequence; define exclusion and stop criteria.
DCS/PLC Panel Inspection & Field Transmitter Calibration
- Potential hazards
- Unexpected process shutdown due to interlock failure, electric shock from live parts
- Checks to verify and specify on site
- Equipment, circuits, supplies, backfeed, induced voltage and stored energy; Disconnection, prevention of re-energisation, locks and tags; Voltage detector, functional check, absence-of-voltage result and tester; Earthing/short-circuiting where required; adjacent live-part protection and boundaries; Completion, personnel clearance, lock removal and re-energisation authority.
- Verify task-specific training, qualifications and procedures. Record process and equipment protections, exposure controls, emergency arrangements and the responsible person's checks in the work plan.
Cooling Water System Biocide & Corrosion Inhibitor Chemical Replenishment
- Potential hazards
- Gas explosion if different chemicals mix, chemical eruption when opening containers
- Checks to verify and specify on site
- Check the SDS, compatibility, containment, extraction, leak isolation and emergency response. Select test targets, limits and respiratory protection for the actual substances and exposure.
Fresh site records
Record date, location, equipment ID, responsible people, crew, permit references, measurements, times, testers, inspections and changes. Do not reuse previous signatures or readings.
Official references
These sources support local terminology and scope. The examples are editorial planning prompts from Smart JSA Bridge, not official forms.
- HSE · Risk assessment template ↗
- HSE · Method statements ↗
- HSE · Permit to work systems ↗
- HSENI · Five steps to risk assessment ↗
https://smartjsabridge.com/en-GB/guideline/chemical