Technical inspections and technical supervision at a biogas plant: what to check and how to plan

A biogas plant is subject to several independent inspection regimes: technical supervision of selected equipment (exercised by the Office of Technical Inspection, UDT), periodic inspections of the building, measurements and tests of the electrical and lightning protection installations, and inspections resulting from fire protection and explosion safety. Because the dates and contractors differ, the best solution is a single register with a calendar and a responsible person.

Technical supervision

Technical supervision covers equipment whose failure poses a particular hazard, in particular pressure equipment (tanks, pipelines, boilers, heat exchangers with specified parameters), as well as other equipment named in the regulations, e.g. cranes and some short-distance transport equipment. At a biogas plant the candidates include compressed gas tanks, hot-water and steam boilers, compressed air tanks, and parts of the upgrading installation, if present. The type of supervision (full, limited, simplified) and the test dates depend on the type of equipment. Doubts are resolved by UDT or the designer, so always ask about the status of the equipment at the time of purchase.

Other mandatory inspections

Do not assume that the list above is complete — the scope depends on the installation and the permits.

Technical inspections as part of maintenance

• Daily: a walk-round, checking for leaks, levels, alarms, readings.
• Weekly: the condition of filters, oil, condensate, pumps.
• Monthly/quarterly: agitators, valves, sensors, calibration of analysers.
• Annual: inspection of the membrane roof, electrical measurements, thermography, engine service according to the DTR (operating and maintenance manual).
• Every few years: emptying and cleaning the digesters with an assessment of their technical condition.

Register and documentation

For each item of equipment, collect: technical documentation, declarations of conformity, operating manuals, test reports, repair history. Introduce a register of dates with a reminder 30–60 days in advance. An equipment card works well (number, location, responsible person, test date). Such documentation is also the basis for discussions with the insurer.

Example calendar (simplified)

Typical mistakes

• no register of equipment subject to supervision,
• expired tests,
• lack of qualifications of the person operating the equipment (e.g. a boiler room or equipment),
• documents scattered across binders, e-mails and contractors,
• no link with the insurance and the requirements of the CHP supplier.

Checklist

1. Draw up a list of all equipment and mark the items subject to supervision.
2. Set the dates and contractors for each type of inspection.
3. Collect the documents in one place (digitally and on paper).
4. Appoint a responsible person.
5. After every change to the installation, update the list.
6. Once a year, carry out an internal audit of compliance with the dates.

How to work with UDT

Before you order a test, prepare the equipment documentation, the rating plate, the reports of previous tests and access to the equipment (emptied, ventilated, with safe access). Plan test dates outside the period of peak production, and for critical equipment remember the time needed for downtime. Tests may require the installation to be switched off, so determine whether the gas will be directed to the flare or stored.

What about equipment supplied from abroad

Equipment from EU countries has a declaration of conformity and CE marking; in Poland supervision over its operation may still apply. Before purchase, make sure that the supplier will provide a complete set of documentation in Polish.

Inspections by suppliers and manufacturers

Besides statutory inspections, equipment manufacturers set their own service requirements as a condition of the warranty: for the CHP, oil and spark plug changes after a specified number of operating hours, for blowers the lubrication of bearings, for agitators seal replacements. It is worth including them in a shared calendar, because neglecting an inspection usually ends in loss of the warranty and often in a failure. Introduce a rule that no test or inspection is closed until the report reaches the register.

An example of the consequences of neglect

An expired test of pressure equipment can result in a ban on operation until the test is carried out. For an installation that has no reserve, this means downtime and lost revenue. Delays are therefore usually more expensive than the cost of a test that can be planned in advance.

The role of the internal audit

Once a year it is worth walking round the site with a checklist: are the rating plates legible, are the documents complete, are the dates in the calendar, do the authorised persons hold valid qualifications. Such a simple audit often reveals minor gaps that later turn into serious problems during an external inspection.