Services
Industrial Furnace Maintenance & DGUV-3 Inspection
Safety, Compliance and Consistent Process Quality
Industrial furnaces are typically the most temperature-critical assets in production. A failure affects not just the furnace, but all running heat treatment processes, delivery schedules and quality records. Unplanned downtime on hardening and tempering furnaces costs, on average, 3–5× more than a scheduled maintenance visit.
NTH Therm offers structured maintenance contracts for all furnace types (own systems and third-party equipment) with clearly defined service scopes, fixed response times and complete documentation for your QMS.
What an NTH Therm Service Visit Covers
Thermal Inspection:
- Multi-point temperature uniformity measurement in the working chamber
- Calibration / verification of all thermocouples and temperature sensors
- Heating element inspection for power loss
- Inspection of seals, compensators and atmosphere inlet fittings
Electrical and Safety Inspection (DGUV-3 per DIN VDE 0100-600):
- Visual inspection: control panel, cables, terminals, protective conductor
- Electrical measurements: insulation resistance, protective conductor resistance, touch current
- Functional tests: RCD, emergency-stop chain, motor protection, door safety circuit
- Voltage drop, phase rotation measurement
Mechanical Inspection:
- Bogie hearth, guide rails and locking mechanism
- Lubrication of moving parts (bogie, door mechanism, dampers)
- Light curtain, proximity switches, limit switches
- Insulation inspection for cracks, settling and damage
Control System Check:
- Functional test of all programme positions and safety circuits
- PLC programme and recipe data backup
- Data logging and recording function verification
Maintenance Contract Scope
| Service | Interval |
|---|---|
| Full DGUV-3 electrical inspection | Annual |
| Multi-point temperature uniformity measurement | Annual |
| Thermocouple calibration | Annual |
| Heating element inspection | Annual |
| Mechanical inspection | Annual |
| PLC data backup | Annual |
| Light-curtain check | Annual |
| Atmosphere sensors (carburising / protective gas) | Semi-annual |
| Remote PLC maintenance | On call |
| Spare-parts stocking | Ongoing |
| Operator training | As required |
Maintenance for Atmosphere-Controlled Furnaces
Carburising, protective-gas and atmosphere furnaces require greater maintenance intensity: oxygen probes have a limited service life (12–18 months in continuous operation), seals age through thermal cycling, and gas supply components wear through contact with aggressive media.
For these systems we recommend semi-annual inspections, particularly when they are used for safety-critical heat treatment processes to CQI-9, AMS2750 or equivalent standards.
Remote PLC Maintenance
For NTH Therm systems we offer remote PLC maintenance via secured VPN. This allows us to:
- Diagnose and adjust control programmes remotely
- Read fault logs and localise causes before a technician is dispatched
- Carry out recipe adjustments and parameter optimisation remotely
- Apply software updates
Remote maintenance reduces average fault diagnosis time to under 60 minutes, regardless of the furnace location within Europe.
Third-Party Furnace Maintenance
We service brand-agnostically: chamber furnaces, bogie-hearth furnaces, conveyor furnaces and carburising furnaces from other European and international manufacturers. Prerequisite: provision of technical documentation and wiring diagrams. For systems without complete documentation we first carry out a chargeable technical condition survey and produce the missing records.
Frequently Asked Questions
How often does an industrial furnace need to be maintained?
The DGUV-3 electrical safety inspection (BGV A3) is legally required annually under DIN VDE 0100-600, regardless of manufacturer. In addition we recommend an annual mechanical and thermal inspection. For atmosphere-controlled furnaces (carburising, protective-gas annealing), we recommend semi-annual inspection, as oxygen probes and seals are subject to greater wear.
What documentation do I receive after a service visit?
You receive: DGUV-3 inspection report (DIN VDE 0100-600), temperature uniformity protocol (multi-point measurement in the working chamber), maintenance record listing all work carried out and parts replaced, and a list of recommendations for predictive maintenance. These documents are mandatory for ISO audits and quality management certifications.
What is the difference between a maintenance contract and ad-hoc call-outs?
A maintenance contract gives you fixed annual pricing, scheduling priority, reduced hourly rates for intermediate call-outs and proactive appointment reminders. Ad-hoc call-outs are subject to current availability and are billed at standard hourly rates.
What happens in an emergency outside business hours?
We typically respond within 4 hours: by phone, remotely or with an on-site visit. Maintenance contract customers receive priority treatment.
Can you maintain furnaces from other manufacturers?
Yes, we service and inspect independently of brand. Please provide the technical documentation and wiring diagrams in advance. For third-party systems without documentation we first carry out a chargeable condition survey.
How does maintenance affect process quality?
Directly. A chamber furnace whose thermocouple has drifted by 8 °C will systematically produce too-soft or too-hard parts during tempering, without being apparent in normal operation. Carburising furnaces with a failing oxygen probe lose carbon potential precision and generate scrap. Regular calibration protects your product quality.