Printable working document

Acetylene Plant Yearly Maintenance Checklist

Print this and take it to the plant. It is the yearly preventive-maintenance and inspection routine IIGAS works to on its own acetylene plants — every item with a tick-box, the set-points written next to the checks they belong to, and a sign-off block for your records.

Ask IIGAS to audit your plant

How to use this checklist

This covers the annual service — the once-a-year work that decides whether a plant lasts decades or wears out early. It does not replace the daily, weekly and monthly routine; those are set out separately in our acetylene plant maintenance schedule.

Work through it with the plant shut down, vented, nitrogen-purged and electrically isolated. Tick each item as it is completed, record the readings, and keep the signed sheet in the plant Maintenance Log Book — it is the evidence that the plant has been operated and maintained to PESO and IS 8471 requirements.

The set-points quoted are those of the IIGAS KIGL-DA plant family, taken from our operation manuals. Plants from other builders — and older IIGAS models — differ. Always work to the manual and nameplate for your own plant, and to the statutory requirements that apply where it is installed.

Before you start — isolate, vent and purge

Nothing else on this list may begin until the plant is safe to open. Acetylene must never be compressed or worked on in the presence of air.

Shutdown and make-safeAll items mandatory
  • Plant shut down, carbide feed stopped and hopper isolated.
  • System vented to zero — generator below 0.03 kg/cm²g before any cap or cover is opened.
  • Whole plant purged with dry nitrogen. Never purge with air, and never compress acetylene–air mixtures at any pressure.
  • Oxygen content tested at the outlet after purging and recorded. Acceptance is below 2.8%; IIGAS recommends working to 0.5% or lower.
  • Electrical supply isolated and locked off; permit-to-work raised; non-sparking tools issued.
  • Ignition sources removed from the area; fire extinguishers checked and in position.

The yearly inspection

1 · Acetylene generator and carbide feed
  • Generator drained completely and the tank interior cleaned of sludge and lime deposit.
  • Agitator shaft, bushes and seals inspected for wear; clearances checked and worn parts replaced.
  • Agitator gearbox oil changed; drive gearboxes replenished to the specified grade and level (6-monthly interval — confirm both were done).
  • Carbide hopper, screw feed and compression disc inspected; rubber seat renewed if worn or hardened.
  • Hopper interference vent valve leak-tested submerged at 1.1 kg/cm²g; head screw tightened to no more than 40 in-lb.
  • Hydraulic system checked — oil topped to within 50 mm of the fill, relief valve verified at 12 kg/cm²g, static-conducting belt intact.
  • Water-level float switches proved at the low (1000 mm) and high (1200 mm) alarm points.
  • Temperature control proved at the 58–60 °C operating band and the 70 °C high-temperature trip.
  • Carbide acceptance re-checked against Grade-A: yield not less than 300 L/kg, dust within limit, sized to IS 1040; every batch inspected magnetically and visually for metal and rock.
2 · Purification and drying
  • Purifier opened, spent media removed and fresh purifying media charged to the specified mass.
  • Purifier shell and internals inspected for hot-spot damage, corrosion and channelling of the bed.
  • Low-pressure drier calcium chloride charge renewed; drain proved clear.
  • High-pressure driers opened, cleaned and recharged with fresh drying media.
  • Scrubber cleaned; lime slurry drawn off and the discharge line proved clear.
  • Gas sampled after purification and purity recorded against the plant’s rated figure.
3 · Acetylene compressorModel-specific — confirm against your compressor manual
  • Crankcase drained and refilled with the specified non-detergent oil; strainer cleaned.
  • Suction and discharge valves lifted, cleaned, inspected and reseated; valve caps torqued to the manual figure (tighten to the lower limit of the range).
  • Piston rings inspected and end gap measured against the manual tolerance; rings renewed if out of limit.
  • Gudgeon pin, connecting-rod and crankpin bushes checked for play — these are the source of knocking, not the main bearings.
  • Cooling water circuits flushed; intercooler and aftercooler cleaned; sacrificial anodes in the water tank renewed.
  • High-pressure cut-out proved to stop the machine at its set pressure and restart only on the low setting.
  • Final-stage back-pressure valve proved at its set point (12–14 kg/cm²g on IIGAS plants).
  • Drive belts, guards, alignment and mountings inspected; belt tension set.
4 · Manifold, cylinders and gas path
  • Charging manifold stripped, cleaned and reassembled; valves and non-return valves overhauled or renewed.
  • Flashback arrestors on the generator and manifold serviced, drained and function-tested.
  • Filling hoses and connections inspected for damage, and connection threads checked for correct type.
  • Whole gas path leak-tested with soap solution at working pressure — never with a flame.
  • Cylinder acetone content and porous mass condition checked on the sample cylinders due this year.
  • Cylinder hydrostatic-test dates reviewed and overdue cylinders withdrawn from service.
5 · Safety devices and instrumentationProve every device — do not assume
  • Every safety valve proved: lifts at set pressure, no discharge below the reseat margin, and reseats cleanly (on IIGAS plants: opens 1.15, no discharge to 1.11, reseat 0.8–1.1 kg/cm²g).
  • Generator pressure switches proved on their bands and the maximum generation pressure confirmed not to exceed the plant rating.
  • Instrument-air low-pressure alarm proved at 7 kg/cm²; regulated control air confirmed at or above 2 kg/cm².
  • Fail-safe action proved — on power or air failure all motors stop except the agitator.
  • Pressure gauges and temperature indicators calibrated or replaced; calibration certificates filed.
  • Gas detection and alarm system function-tested with test gas; response and audibility confirmed.
  • Emergency stops, interlocks and trip logic proved from each initiating device.
6 · Electrical, utilities and structure
  • All motors inspected — mountings, ventilation, current draw and running temperature recorded.
  • Earthing and bonding continuity tested across the plant, including the static-conducting belt.
  • Flameproof fittings, glands and enclosures inspected for integrity in the hazardous area.
  • Cooling-water pumps, lines and strainers cleaned and flow verified.
  • Structure, platforms, ladders and handrails inspected; corrosion treated and paintwork made good.
  • Ventilation openings and flame paths confirmed clear and unobstructed.
7 · Records and statutory compliance
  • PESO licence current and conditions reviewed against actual plant use and storage.
  • Pressure-vessel and cylinder statutory inspections up to date, with certificates on file.
  • Maintenance Log Book written up, including every reading taken during this service.
  • Operator training records reviewed and refresher training scheduled where due.
  • Written SOPs and emergency procedures reviewed against current plant configuration.
  • Findings list raised for every defect found, with owner and target date against each.

Sign-off

The service is not complete until it is signed. Record the readings taken during the work and file this sheet in the Maintenance Log Book.

Record of completion
Plant / model
Serial number
Date of service
Hours run since last service
Carried out by
Verified by (plant in-charge)

If any item on this list could not be completed, record it as an open finding with a target date — a partially completed annual service should never be signed off as done.

What a yearly service should turn up

On a well-run plant the annual service is mostly confirmation: clean media, sound bushes, valves lifting where they should. What it exists to catch is the slow drift — a purifier bed beginning to channel, an agitator bush wearing oval, a safety valve reseating late, a gauge reading a little high. None of those stop the plant on the day they start, and all of them are expensive if they are found a year later.

The two findings that matter most are a safety device that no longer proves, and a gas path that is not as clean as the log says. Both are why the checks above are written as prove, not inspect.

If you would rather have this done independently, IIGAS carries out acetylene plant safety and operations audits on plants of any make, and services and upgrades the plants we build.

Related products

Frequently asked questions

On six fixed intervals — daily, weekly, monthly, half-yearly, annual and multi-year. This checklist covers the annual service; the daily and weekly routine keeps the gas path clean and proves the safety devices between annual services.
Draining and cleaning the generator, inspecting the agitator shaft and bushes, recharging the purifier and driers, stripping and cleaning the charging manifold, servicing the compressor, proving every safety valve and trip, and bringing the statutory records up to date.
Trained plant personnel or the plant builder’s service engineers. The work involves opening the gas path and proving safety devices, so it should be done by people who know the plant, under permit, with the system vented and nitrogen-purged.
Because acetylene and air must never be mixed or compressed — the mixture is hazardous at any pressure. The plant is purged with dry nitrogen, and the oxygen content at the outlet is tested and recorded before carbide is charged or the compressor is started.
A bound Maintenance Log Book recording every check, drain and part change, plus calibration certificates, statutory inspection certificates, the current PESO licence and operator training records. Keep the signed checklist with them.
Yes. IIGAS services and upgrades the plants we build, and carries out independent safety and operations audits on acetylene plants of any make, anywhere we can travel to.

Need a gas supply or a gas plant?

Talk to International Industrial Gases Ltd about cylinders, bulk supply, medical gases or a turnkey acetylene gas plant.