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Lifeline & Equipment Construction (Piping, HVAC, Electrical/Telecom, Insulation & Fire Protection)

Construction · 建設分野 · Written by Tokutei Pass based on the official study texts; not copied verbatim.

Pipe Cutting/Threading, Pipe Joining, and Support Hangers

Steel pipes are cut using a 'pipe cutter' or hacksaw, and internal burrs left inside the pipe end are removed with a 'pipe reamer' to prevent flow resistance and erosion-corrosion.

For threaded steel pipe joints, PTFE seal tape is wrapped around the male threads and tightened with a 'pipe wrench'. For PVC solvent-cement joints, adhesive is applied to both socket and spigot and pushed straight to the mark without twisting.

Horizontal overhead pipes are supported by hanger bolts and 'hanger bands (tsuri band)', while large-diameter water mains and fire protection lines use 'ductile iron pipes' or flanged joints.

Pipe Cutting/Threading, Pipe Joining, and Support Hangers

Key points


  • Remove internal burrs after cutting steel pipe with a 'pipe reamer', wrap seal tape on male threads, and tighten with a 'pipe wrench'.

  • For PVC adhesive joints: chamfer, clean, mark the insertion depth, apply cement to both socket and spigot, and insert straight without twisting.

  • Support horizontal overhead pipes with 'hanger bands' and install 'flexible joints' at connections to vibrating equipment.
WordMeaning
Pipe cutter & Pipe reamer
Pipe wrench & Seal tape
PVC pipe solvent-cement joint (Secchaku setsugou)
Hanger band & Flexible joint (Tsuri band / Flexible joint)

Water Supply, Hot Water, Drainage/Vent, Sanitary, Gas, and Fire Protection Systems

Directly connecting potable water supply pipes to wastewater pipes ('cross-connection') is strictly prohibited to prevent backflow contamination. The banging shock caused by suddenly closing a valve is called 'water hammer'.

Hot water pipes are equipped with 'expansion joints' for thermal expansion. Indoor drainage pipes are laid with a continuous 'downward slope', fitted with 'drain traps (water seal)' against sewer odors and 'vent pipes' against seal loss.

After installation, water supply pipes undergo a 'hydrostatic pressure test', while drainage pipes undergo a 'full-water test and flow test'. Gas leak alarms are mounted near the ceiling for lighter city gas and near the floor for heavier LP gas.

Key points


  • 'Cross-connections' between potable water and wastewater pipes are strictly forbidden, and 'expansion joints' absorb thermal movement in hot water piping.

  • Provide drainage pipes with a 'downward slope', 'drain traps (trap seal water)', and 'vent pipes', then conduct full-water and flow tests.

  • Install city gas alarms 'near the ceiling' and heavier-than-air LP gas alarms 'near the floor (within 30 cm)'.
WordMeaning
Cross-connection
Water hammer (Suigeki sayou)
Drain trap, Trap seal water & Vent pipe (Fuusui / Tsuukikan)
Hydrostatic pressure test & Full-water test (Suiatsu / Mansui shiken)

HVAC Systems (Refrigerant Piping & Ductwork) and Thermal/Cold Insulation

When connecting copper refrigerant pipes for air conditioners, a flaring tool is used to form a bell-shaped 'flare', and after connection, 'vacuum evacuation (shinkuubiki)' is performed with a vacuum pump to remove air and moisture.

In air ductwork using rectangular or spiral round ducts, 'fire dampers (FD)' that close automatically during a fire are installed where ducts penetrate fire-compartment walls or floors.

Chilled water pipes and refrigerant pipes are wrapped tightly with cold insulation (such as glass wool or polyethylene foam) to prevent surface 'condensation' caused by ambient temperature differences and to reduce thermal loss.

Key points


  • Connect copper refrigerant pipes using 'flare joints' and always perform 'vacuum evacuation' with a vacuum pump after piping.

  • Install 'fire dampers (FD)' where HVAC ducts penetrate fire compartments to prevent fire spread.

  • Apply cold insulation to chilled water and refrigerant pipes to 'prevent surface condensation' and minimize energy loss.
WordMeaning
Flare processing & Vacuum evacuation (Flare kakou / Shinkuubiki)
Duct & Fire damper (FD)
Condensation prevention (Ketsuro boushi)
Thermal & Cold insulation work (Hoon / Horei kouji)

Electrical/Telecom Installation and Lifeline Occupational Safety

Indoor electrical wiring uses VVF cables, metal conduits, or flexible plastic conduits (PF/CD conduits), and conductors are joined using 'ring sleeves (with a dedicated crimping tool)' or push-in connectors.

In electrical work, 'grounding (earthing)' prevents shock during faults; before working, switch off the breaker and verify zero voltage with a 'voltage detector (kendenki)'; after completion, test insulation with a 'megohmmeter (Megger)'.

Optical fiber cables are pulled within allowable tension and bend radius limits. Before entering sewage pits or manholes, measure oxygen (>= 18%) and hydrogen sulfide (<= 10 ppm) levels and maintain continuous forced ventilation.

Electrical/Telecom Installation and Lifeline Occupational Safety

Key points


  • Join wires with a 'ring-sleeve crimping tool' or push-in connectors, and perform 'grounding work' and 'insulation resistance measurement (Megger)'.

  • Verify zero voltage with a 'voltage detector' after turning off the breaker before electrical work, and never wear cotton gloves with rotating drills.

  • Always measure oxygen (>= 18%) and hydrogen sulfide (<= 10 ppm) concentrations and ventilate continuously when working inside pits or manholes.
WordMeaning
Ring sleeve & Crimping tool (Acchaku kougu)
Grounding work & Insulation resistance tester (Secchi kouji / Megger)
Voltage detector (Kendenki)
Oxygen deficiency & Hydrogen sulfide poisoning prevention

Lifeline and Equipment Work (Practical)

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Official references