Retrofit acceptance should check sealing, temperature and measurement, control records, mechanical actions, safety interlocks and loaded operation under agreed conditions. Energy projects also need consistent energy-metering and conforming-output boundaries. Set the test items, methods and pass criteria in the technical agreement before implementation.
Suneng trolley-furnace extension documents require the modified furnace to be tested as a whole, rather than testing only the added section. If the supplier provides records for a new cabinet or section alone, include the original equipment, new equipment and their connections in the acceptance scope. Confirm that the final working zone, measurement points and control records cover the modified furnace. An old report does not automatically represent the changed configuration.
1. Furnace structure, lining and sealing
Check the repaired structure, lining and insulation, doors and observation openings, and the seals at the trolley, lid, hood or hearth as applicable. Review material selection, thickness, installation quality and external surface temperature rise under the agreed conditions. These checks help identify heat losses and unresolved structural problems.
2. Heating, holding and temperature uniformity
Record no-load and representative loaded heating and holding behaviour, zone fluctuations, temperature uniformity and agreement between measurement, display and recorded data. Specify the effective working zone, test temperatures, load, measurement points, instruments and acceptance limits.
Where required, arrange a temperature uniformity survey (TUS) and a system accuracy test (SAT). A uniformity survey assesses temperature distribution across the defined zone; a system accuracy test checks the temperature-measurement system. They answer different questions and must not be substituted for one another. SAT in this pyrometry context means System Accuracy Test, not Site Acceptance Test. Retain the corresponding curves and test records.
3. Control-system stability and data
Where control functions change, verify the control system and its records separately. Check the programmable logic controller (PLC, which controls equipment actions according to programmed logic), operator interface, zone control, alarms, curve storage, export and permissions. Verify manual and automatic modes and their safety constraints. A new cabinet is insufficient evidence without functional tests and records.
4. Mechanical and conveying systems
- Trolley furnaces: rails, trolley travel, furnace doors and seals.
- Pit furnaces: lid movement, lifting and associated positioning.
- Mesh-belt furnaces: tracking, tension and conveying under the agreed load.
- Pusher furnaces: pusher action, trays, travel and jam handling.
- Roller-hearth furnaces: drives, synchronisation, roller material and maintenance access.
- Bell furnaces: hood, base, seals and atmosphere interfaces.
Arrange no-load, loaded and continuous operation appropriate to the equipment. Verify fault response and interlocks using agreed safe test procedures and include the results in handover.
5. Safety functions
Check the applicable overtemperature, fan, door-position, heating-circuit, emergency-stop and limit interlocks. For fuel-fired equipment, the project may also require checks of ignition, flame supervision, leakage alarms, purge, ventilation and fuel pressure. Atmosphere, furnace pressure, cooling and power-loss responses depend on the installed system. Testing must follow the agreed professional procedures for that equipment; this list is not an operating sequence.
6. Energy comparisons
Establish a baseline with the material, process, load, output, shifts and operating regime. Compare energy per unit of product over representative, consistent operating periods. Changes in production, loading, schedules or operating practice can invalidate a simple before-and-after comparison. Keep energy quantities separate from tariffs: lower fuel expenditure caused by a price change is not the same as lower energy consumption.
7. Why acceptance can fail
When acceptance does not meet expectations, review diagnosis, acceptance criteria, any unresolved system problems, shutdown and commissioning time, and the assessed capability of the retained structure. Resolve these uncertainties when defining the work rather than only at final handover.
8. If temperature remains uneven
Review lining condition, heating-element or burner distribution, circulation, thermocouples, control zones, doors and other seals, and the loading arrangement. Confirm the actual load and measurement method. A control setting alone cannot correct every heat-transfer or structural problem.
9. Suneng's retrofit support
Jiangsu Suneng Industrial Furnace Co., Ltd., founded in 2006 in Jiangyan District, Taizhou, holds National High-Tech Enterprise certificate GR202432008987 and ISO 9001 certificate 03824Q60289R3S, valid until 11 January 2027, and has multiple Chinese patents.
Assessment and implementation may include overhauls, energy retrofits, relining, controls, temperature-uniformity corrective work, curve records, energy evaluation and commissioning. Suneng's own equipment and some other-brand furnaces can be assessed subject to drawings, controls, components and actual condition. The linked service page and three-line 1,250 mm stainless-steel retrofit reference provide context; the scope and acceptance criteria remain project-specific.
10. Common questions
What should retrofit acceptance cover?
The agreed structure, lining, seals, heating, temperature performance, controls, mechanisms, safety functions, records, energy comparison and handover scope.
What if the temperature is still uneven?
Check the defined test conditions and investigate heating, lining, circulation, sensing, controls, seals and loading together.
Are electricity or gas bills enough to prove savings?
No. Bills must be reconciled with production, process, load, operating time, metering boundaries and prices.
How long does a furnace retrofit take?
The furnace type and size, retrofit scope, shutdown window, component lead times, installation and commissioning requirements determine the schedule. Agree the work and trial-run plan after reviewing the actual equipment.
Why might a retrofit fail to meet expectations?
Check whether the initial diagnosis was complete, the scope and acceptance criteria were clear, retained equipment constraints were assessed, and installation and commissioning time was sufficient. Establish the cause from project records before deciding on corrective work.
This is general retrofit-acceptance guidance. Use the technical agreement and applicable project requirements for the actual equipment.
Related Pages and Sources
- Furnace Retrofit and Overhaul Services (Chinese)
- Three 1,250 mm Stainless-steel Lines: Energy Retrofit
Related public sources: SAE AMS2750H: Pyrometry, Industrial furnace safety: general requirements. Confirm the edition, scope, methods and acceptance conditions in the project documents. Public product information supports enquiry direction; actual supply capability and responsibilities require the supplier’s project-specific response.