Guide

The acetylene plant maintenance checklist: 63 tasks hourly to yearly, from the people who build the plant

By Mithillessh Garg, Director (Gas Supply)

A carbide-to-water acetylene plant is maintained on five cycles: 13 hourly checks on the shift round, 10 daily tasks before start-up, 18 weekly, 15 monthly and 20 yearly, 63 scheduled tasks in all, plus purifier regeneration at least every 3 weeks. KIGL issues this regime with its plants and runs it at its own works.

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Scheduled tasks: 63: 10 daily
Hourly shift round: 13 checks
Purifier regeneration: Never more than 3 weeks in service between regenerations
Agitator: Runs 5 minutes in every 15
Generator interior clean: Annually for smaller plants; after 60

Why a published checklist from the builder is different

Every safety audit KIGL has carried out at a customer's acetylene plant has found the absence of something the plant's own maintenance schedule already prescribes: an hourly log not kept, a vent valve not checked, an oil pump nobody looked at. The discipline is not missing; it is not being run. This page is the regime that ships with a KIGL-DA plant, set out so an operator can hold the works to it and a buyer can see what owning a plant commits them to.

Frequencies below are the builder's. Where a task is listed at more than one frequency, that is layering, not repetition.

Hourly: the shift round

#	Check	What you are looking for
1	Drain condensate from both wet flashback arrestors	Drain until bubbles appear in the water; close slowly
2	Verify generator water level at both check valves	Acetylene from the upper valve, water from the lower
3	Feel the generator with your palm — above the water line, below it, at the bottom	Above water cooler than below; bottom the same as just below the water line; nothing unbearable
4	Look at the far end of the agitator shaft at the drain-valve end	Rotating. If not, the shaft is broken: stop the plant
5	Drain the cooler-condenser condensate	Outlet gas near room temperature
6	Drain the low-pressure drier condensate	Close as soon as gas, not liquid, comes out
7	Drain the compressor suction and interstage traps	Until condensate appears; stop as soon as acetylene follows
8	Check compressor cooling-tank overflow and water temperature	Flow present; increase it if the tank runs warm
9	Record all compressor pressures: suction, each stage, manifold, oil	Inside the plant's stated bands; oil pressure above suction
10	Drain the high-pressure driers	In the sequence the manual gives, one unit at a time
11	Purge the scrubber and purifier drains	Every half hour to hour
12	Leak check by smell (garlic) and soap solution on suspicion	No leaks; stop the plant to repair — never rectify a leak while running
13	Cylinder weighing and filling records	Every cylinder weighed in and out

Every shift

Drain each purifier bottom and the regeneration pipeline near the exhaust fan. Run the silver nitrate purity test on the purifier outlet. Test the compressor low-pressure switch at the end of the shift: it must stop the compressor before suction falls to the point where it would pull a vacuum on the generator.

Daily, before start-up — 10 tasks

Check that the agitator runs 5 minutes in every 15.
Check that the agitator runs during each hopper feed.
Check the agitator stuffing boxes for leaks.
Check the residue drain valve for water leaks.
Open the generator safety valve by hand to check it moves and reseats.
Check the hydraulic piping for oil leaks.
Check the scrubber water level; refill if required.
Drain water condensate from the acetylene compressor oil.
Check the compressor oil level; top up with non-detergent oil of the specified grade.
Refill the high-pressure drier with anhydrous calcium chloride — a void in the bed is an explosion risk, and carried-over moisture degrades the cylinders' absorption capacity.

Weekly — 18 tasks

Grease the hopper fill cover and hopper lugs; renew a damaged gasket.
Fill the grease cup over the screw-feed bushes.
Check the oil level in both screw-feed hydraulic reservoirs.
Check the screw-feed oil pressure at both reservoirs.
Drain, flush and refill both generator flashback arrestors, purging five times to remove air.
Soap-test the generator safety valves for leaks at operating pressure.
Test the low-water-level alarm: drain through the low-level valve until it rings and confirm the screw feed will not run.
Fill the low-pressure drier with anhydrous calcium chloride.
Drain and refill the scrubber, plant stopped.
Check the compressor oil for moisture; change it if grey.
Check the cooling-tank anodes; replace when worn to pencil thickness.
Soap-test the cooler-condenser condensate valves.
Soap-test the compressor condensate valves.
Soap-test the high-pressure drier condensate valves.
Inspect the manifold pigtails: any broken braid wire or any visible permanent bend means replacement.
Soap-test the manifold and station valves.
Check and clean the cylinder spray systems.
Check the screw-feed mechanism: belts, gearbox noise, oil-pump relief setting. Belts on the screw feed and compressor are static-conducting; no other kind is fitted.

Monthly — 15 tasks

Test the high-water-level alarm.
Test the residue drain valve's sensitivity against the water meter.
Test the temperature safety instrument: lower the set point below the indicated value and confirm the alarm.
Soap-test the generator safety valves at the vent-side union.
Soap-test the hopper vent valves.
Top up the agitator gear reducer.
Top up both screw-feed gear reducers.
Drain, clean and refill the compressor cooling tank.
Check the screw-feed drive belt.
Check the compressor motor drive belt.
Check the oil-pump drive belt.
Inspect all acetylene piping for condition and leaks; repairs only with the plant shut down and purged.
Clean or change the air-compressor drive belts.
Drain and refill the air-compressor oil.
Check all instrument-air piping for leaks.

Every three weeks at most

Purifier regeneration, in a rotation with progressively shorter intervals. Time in service never exceeds three weeks. Regeneration temperature is logged hourly for the first four hours and two-hourly after; the bed is cooled at once if it runs warm, and any discoloured material is replaced.

Yearly — 20 tasks

Withdraw the generator from service, letting both hoppers empty on the last shift.
Clean and inspect the generator interior: drain, remove the agitator coupling, open the manholes, flush, scrape with wooden tools only, clear the spray nozzles and the riser to the arrestors, renew gaskets. Annually for smaller plants; after 60,000 m³ for larger.
Check the agitator packing and shaft.
Check the water-inlet spray system.
Check the control diaphragms.
Check the carbide valve seats.
Inspect the hoppers and hopper gaskets.
Check and adjust the safety relief valves.
Check the hydraulic system for leaks and top up the reservoir.
Check the hydraulic cylinders for operation, leaks and rod damage.
Check the oil level in every gearbox.
Check the screw-feed drive chain and belt.
Drain, clean and refill the flashback arrestors.
Check the generator valves and gauges.
Check the residue drain valve operation.
Check the water-inlet valve: opens on rising temperature, closes on loss of air.
Purge the air–acetylene mixture from the generator at restart, building and venting pressure repeatedly before gas is sent forward.
Operational check of the whole alarm and trip system: low level, high level, high temperature, instrument air.
Clean the acetylene and air compressor suction and discharge valves.
Clean the valves and valve seats across the plant; renew gland packing.

Also yearly: clean the high-pressure drier oil separator and recharge the calcium chloride beds; blow out the charging manifold with nitrogen and touch up rust before purging and restarting.

Longer cycles

Interval	Task
Every 2.5 years	Clean the cooler-condenser water side: flush with hot water, mild descaling if scaled
Every 5 years at 8 h/day	Regrease the acetylene compressor motor
After 60,000 m³ of acetylene	Generator interior clean on larger plants
After 200,000 m³ of acetylene	Flush the high-pressure drier interior and re-oil the chain rings
Every 2 months in storage	Conservation check on a plant not yet commissioned; after 12 months, repaint and revarnish

The records that go with it

A shift log of 40 parameters across every stage, hourly; a hopper-recharging log; a cylinder filling record with weight in, acetone added and weight out; purifier records of every repack, regeneration and purity test; and a maintenance log book. The end-of-shift yield in m³ per kg of carbide is the one figure to watch above all others — it falls weeks before anything else goes wrong.

KIGL runs this regime at its own works and audits customers' plants against it. If you operate a carbide-to-water plant of any make and want the schedule as a printable table, or an audit of your plant against it, send an enquiry.

— frequently asked questions

What are the daily checks on an acetylene plant?

Ten, before start-up: the agitator timer and its run during hopper feed, agitator stuffing boxes for leaks, the residue drain valve for leaks, the generator safety valve opened by hand, hydraulic piping for oil leaks, scrubber water level, water drained from the compressor oil, compressor oil level, and the high-pressure drier refilled with anhydrous calcium chloride.

Why does the agitator have to run after the plant is shut down?

Because lime slurry settles and sets if it is left still. The agitator runs 5 minutes in every 15 around the clock, driven by a timer on the control circuit that stays on when everything else is switched off at the panel. A generator left unstirred over a holiday is the commonest cause of a broken agitator shaft.

How often is the purifier regenerated?

Each chemical purifier is regenerated before it has been three weeks in service, in a rotation with progressively shorter intervals, and repacked when the purity test forces regeneration too often. The silver nitrate purity test on the outlet gas is run every shift; a failed test takes the purifier out of service at once.

How often should the generator be opened and cleaned?

Yearly for smaller plants, or after every 60,000 m³ of acetylene on larger ones. The tank is drained, the agitator coupling removed, the manholes opened and the interior flushed and scraped with wooden tools only — never metal, because of the spark risk — before the gaskets are renewed and the plant is purged and leak-tested at restart.

Why are safety valves on the list three times?

Deliberately. They are opened by hand daily to prove they move, soap-tested for leaks weekly and monthly at operating pressure, and taken down and adjusted yearly. A reader who sees the same item at three frequencies assumes a mistake; it is the opposite.

Which hourly check matters most?

Two that need no instrument. Feel the generator with the palm of your hand above the water line, below it and at the bottom: above must be cooler than below, the bottom the same as just below the water line, and nothing unbearable to touch. And look at the far end of the agitator shaft by the drain valve: if it is not turning, the shaft is broken and the generator must not be run.

References

Bureau of Indian Standards. (2003). Acetylene Generators — Requirements (IS 8471:2003, First Revision).
Bureau of Indian Standards. (2023). Acetylene — Code of Safety (IS 14814:2023, First Revision).

Enquiries

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State the gas or equipment, the quantity or capacity, and your location. KIGL will confirm the grade, the cylinder or plant size, and whether the location can be served from Noonmati, or through the agent network.

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guwahati@kigl.co.in