Site work & quality
Service and maintenance of welding machines: what you can do yourself
Maintenance by machine type, hydraulic oil, clamps and heating element – and the boundary of what requires a workshop and calibration.
Why maintenance is quality management
A welding machine is a measuring tool, not just a frame with hydraulics. Welding pressure, heater plate temperature and flatness are the three factors that determine the joint, and all three gradually deteriorate with wear: the clamps slip, the heater plate loses temperature, the planer cuts unevenly, and the hydraulics develop leaks.
Therefore, maintenance is not something you do when the machine stops working. It is a routine process so that faults are detected before affecting a job – and so the welding log can be presented with a valid calibration. The daily routine is summarised in the checklist before taking the machine on site.
Maintenance by machine type
Machines have different wear parts and require different care. The table serves as a checklist for daily and monthly routines – the manufacturer's instructions always take precedence.
| Machine type | Daily / per use | Monthly | Requires workshop |
|---|---|---|---|
| Butt fusion machine, manual or CNC/controlled | Clean heater plate and planer, check clamps and cable and power supply, check hydraulic hoses for leaks | Lubricate moving parts according to instructions, check alignment of clamps, clean control unit contacts | Calibration, hydraulic oil change, repair of hydraulics and control unit |
| Saddle and branch welding equipment | Clean clamping surfaces, check angles and clamps, verify that the frame is level | Check travel and play in the carriage, inspect the planer guide | Calibration, frame straightening, replacement of hydraulic components |
| Electrofusion control unit | Check welding connectors/terminals and contacts, clear the memory before it becomes full (see the checklist) | Check scanner, cable and plug; test a sample printout or data export | Calibration of voltage/current, battery and electronics repair |
| Extruder and hot air tool | Clean melt channel and nozzle, check airflow and heating element | Check temperature stability, clean filter and blower | Calibration, replacement of heating element and motor |
General checklist based on manufacturer instructions and practical operation. Always follow the specific machine manual.
Hydraulics: oil, pressure and hoses
Hydraulic oil is the item most frequently forgotten. The oil must be of the type specified in the manual, and if using another brand, the specification must be equivalent – otherwise seals and valves can be damaged. If the oil is not changed, pressure conditions change and the machine cannot maintain the calculated welding pressure.
Check hoses and couplings for sweating and cracks before every use. A leak does not necessarily trigger an error message, but results in falling pressure during welding – which is only revealed in the log when it is too late.
The working pressure must remain within the range for which the machine was built. Exceeding it causes the joint to be pressed too hard and the pipe may deform in the clamps. If the machine is to run on a generator or long extension lead, read power supply on site – a voltage drop can cause a pressure drop that resembles a hydraulic fault.
Heating element and planer
The heating element is the most sensitive part of the machine. The coating must be intact, otherwise the plastic melt adheres and pulls strands out of the fusion face. Clean using the recommended method and never with sharp tools that scratch the coating.
The planer must take a clean continuous shaving across the entire face. Dull blades or misaligned guidance produce facing that looks neat but is not flat – wasting the rest of the welding process. Check the shaving: it must be uniform and without tearing marks.
The temperature sensor must be checked during calibration. A sensor that misreads by 2-3 °C noticeably alters the heating time on thick-walled pipes.
What you can do yourself, and what you cannot
You may carry out cleaning, lubrication, replacement of wear parts such as clamps, inserts and blades according to instructions, inspect cables and hoses, clear memory and update data. You must not open control or hydraulic enclosures, adjust pressure relief valves or replace components in the measuring circuit yourself – this requires specialist knowledge and subsequent calibration.
A machine that has been opened by anyone other than an authorised service centre should be re-calibrated before being used on a documented project. This is also what the client expects to see in the welding log.
Troubleshooting: typical electrical issues
Electrical faults on a butt fusion machine are rarely complex, but they can cost an entire workday if only discovered on site. Therefore, work through the checklist in the sequence in which the machine consumes power: plug and cable, direction of rotation, heating element, control unit.
The most overlooked fault on 400 V machines is incorrect direction of rotation. The planer motor rotates in the correct direction only when the phases are in the correct sequence. If the machine is connected to an installation where two phases are swapped, the planer runs backwards: it does not cut, or it judders and smears the shavings instead of removing them. At the same time, the hydraulic pump may stall or make noise because it is also direction-dependent. Otherwise, the machine appears to work – display and heating element function – so the fault is often mistaken for a dull planer.
Always check the direction of rotation the first time the machine is connected at a new location: start the planer briefly off-load and check that it pulls shavings and that the arrow on the machine matches the direction of rotation. If the direction is wrong, it is most easily corrected using a CEE phase inverter plug fitted between the wall socket and the machine cable. The phase inverter plug swaps two of the phases and thus the direction of rotation, without requiring changes to the installation. Switch off the machine before adjusting the plug, and only use a plug with the same number of poles and rated current as the wall socket (typically 5-pole 16 A or 32 A).
Other recurring electrical issues: an excessively long or thin extension cable causes a voltage drop, preventing the heating element from reaching temperature and causing the control unit to report a mains fault; an undersized generator cuts out when the planer and hydraulics start simultaneously – here, a portable power station with stable pure sine wave output can be an alternative, see power supply on site; moisture in the heating element causes earth leakage and trips the RCD, requiring the element to be dried and tested before reuse; and a CEE plug that has been stepped on causes intermittent faults due to a loose conductor.
| Symptom | Typical cause | First action |
|---|---|---|
| Planer does not cut, or judders and smears shavings | Incorrect direction of rotation due to phase sequence | Test run briefly, check arrow and shavings, reverse direction using CEE phase inverter plug |
| Hydraulic pump makes noise or does not build up pressure | Direction of rotation or air in the system | Check direction of rotation first, then bleed according to manual |
| Heating element does not reach temperature | Voltage drop across an excessively long/thin cable | Measure voltage at machine under load, use shorter or thicker cable |
| RCD trips upon start-up | Moisture in heating element or cable | Dry element, test insulation resistance, replace cable if damaged |
| Machine control unit reports mains fault | Unstable power supply, generator or loose conductor in CEE plug | Measure voltage under load, check plug and generator |
For information only. Fixed installations, plugs and fuses must be assessed by an electrician, and work inside control and hydraulic enclosures must be performed by an authorised service centre.
Calibration and service intervals
The machine should be verified and calibrated approximately every 12 months, and immediately if it has been subjected to impacts, extreme temperature fluctuations, repair or prolonged inactivity. You will receive a certificate to present during inspections.
If the machine has been idle for months, perform a test weld and check heater plate temperature and pressure behaviour before taking it onto a site job. It takes little time and catches faults that would otherwise only appear mid-job.
Why DK-VAND and water utilities check the certificate
DK-VAND certification applies to the products (pipes and fittings), but the water utilities' quality requirements for documented joints – e.g. during pressure testing and operational documentation – require the welding machine's calibration certificate to be valid.
The certificate and calibration date must be available for inspection; otherwise, the entire log from the welding machine stands on weak ground if a joint is brought into question. A machine with inaccurate pressure or temperature readings logs neatly, but incorrectly.
Signs that the machine needs servicing
The bead differs from usual (too low or uneven), the heating plate temperature deviates from the setting, the pressure shows erratic jumps, or the machine fails under approved parameters. Such signs require inspection and servicing, not just readjustment: send the machine to Holm & Holm so it can be quickly inspected, prepared and recalibrated.
INSTA-CERT, ISO 12176-1 and DVS 2207: what applies to what?
INSTA-CERT is an inter-Nordic certification scheme for periodic verification and calibration of butt fusion machines. The machine is typically verified every 12 months by a manufacturer-approved and accredited calibration partner, and the certificate can be presented during inspections.
The standards each play their own role: ISO 12176-1 defines the butt fusion welding process itself and the basic machine requirements (temperatures, pressures, phases and data records), while DVS 2207-1 together with DVS 2208 provides welding parameters and tool requirements – the technical foundation on which most welding tables are based. INSTA-CERT is not a welding standard, but a certification scheme: if the client requires the certificate, it must be provided; documentation according to ISO 12176-1 or DVS 2208 is the standard basis in most projects. Furthermore, a calibration certificate is no guarantee of a correct weld – the parameters must still be followed.
Calibration at Holm & Holm
Holm & Holm offers servicing, spare parts and calibration for machines from most manufacturers. It is quick and easy to send the machine to Holm & Holm: we handle preparation, calibration and fast return so that it is back in your workshop promptly. Hired machines always arrive calibrated and prepared from our workshop.
Frequency of use is decisive
If the equipment is used weekly, it typically pays to own it. If used for occasional projects, hiring is cheaper and carries no maintenance costs.
Hired machines arrive calibrated and fully prepared from Holm & Holm, saving you the burden of your own maintenance.
Advice first
If in doubt, call us before you buy. Holm & Holm offers advice on machines, materials and workflows, finding the solution that suits your tasks – not the other way around.