Owners are typically involved at only two moments: signing the contract and taking handover. Between those two points there are several things that become very expensive to fix later if they are not checked at the time. This article lists the acceptance milestones in construction order and what to look at during each.
Milestone 0 — Before signing: settling the technical proposal
This is not yet an acceptance milestone, but it is the most decisive one. You need these in hand before signing:
- The heat load calculation together with the input parameters used
- Layout and equipment arrangement drawings, showing the intended stacking pattern
- A schedule of the main equipment with type, origin and specifications
- Panel thickness and type for each area
- The scope of work, stating explicitly which items are included and which are not
If a quotation has arrived without a heat load calculation, ask again. See also the 7 questions to ask before signing.
Milestone 1 — Floor and site acceptance
Check before the envelope goes up, because afterwards there is no access:
- The floor insulation is the right type and the right thickness per the design
- The moisture barrier is installed, undamaged, with no open joints
- For deep-freeze stores: protection against floor freezing is in place
- The floor is level and rated for the design load
- Provisions for condensate drainage and cable routes are where the drawings show
This is the most important milestone. Faults in the floor are all but impossible to fix once the store is in operation.
Milestone 2 — Envelope and door acceptance
- Panels of the agreed type and thickness — check the labels and the material certificates
- Joints sealed, tongues seated evenly, no open gaps
- Doors close tight, with the gasket in contact around the whole perimeter
- For deep-freeze stores: the door frame heater elements are fitted and wired
- The latch can be released from inside — a mandatory safety requirement
- The pressure relief valve is fitted on sealed rooms
Milestone 3 — Refrigeration system and pipework acceptance
- Equipment of the type, origin and specification stated in the contract — check the nameplates against the schedule
- Pipework fully insulated, with no condensation forming
- The system leak test has been carried out and there is a report
- Evacuation before charging the refrigerant — ask explicitly whether it was done
- Air coolers positioned per the drawings, with adequate clearance to walls, ceiling and in the discharge direction
- Inspection records for the pressure equipment are in place
Milestone 4 — Electrical and control acceptance
- Control cabinet to the correct configuration, with the circuit diagram fixed inside the door
- Protection devices fitted and working: high-pressure and low-pressure switches, overload protection, phase-loss and phase-reversal protection
- Interlocks working correctly — test them against real scenarios
- Temperature sensors at representative positions, neither close to the air cooler nor close to the door
- The alarm system working — test it with a genuine over-threshold condition, not just by looking at the indicator lamp
- For stores with standby power: test the changeover
Milestone 5 — Commissioning and operational acceptance
The second most important milestone after the floor. Ask for a commissioning run long enough to reveal how the system actually behaves:
- The pull-down time from room temperature to the design temperature — against what was promised
- Temperature stability once reached, observed across several on/off cycles
- Temperature distribution within the room — measured at several points, not only where the sensor sits
- The defrost cycle operating correctly, with the air cooler clear of frost after each cycle
- Compressor current in steady-state operation, against the rated figures
- Condensate drainage running freely, not pooling, not freezing
Commission under a simulated load if possible, because an empty store behaves quite differently from a full one.
Milestone 6 — Documentation handover and training
- As-built process and installation drawings
- Control wiring diagrams
- Equipment schedule with specifications and origin
- Pressure vessel inspection records
- Operating instructions and the recommended maintenance schedule
- Reports from each of the earlier acceptance stages
- Training for the on-site operating staff, with a record of it
For stores serving export food or pharmaceuticals, this documentation is also what gets you through audits. See also the cold store acceptance checklist.
Frequently asked questions about cold store acceptance
Which acceptance milestone matters most?
Floor acceptance, before the envelope goes up. Once the store is finished there is no access to the floor, and faults in the insulation or the moisture barrier are all but impossible to fix once it is operating.
What has to be checked during commissioning?
The pull-down time against what was promised, temperature stability across several on/off cycles, temperature distribution at several points in the room, the defrost cycle operation, the compressor current, and the condensate drainage.
Why should commissioning be done under load?
Because an empty store behaves quite differently from a full one. An empty store pulls down fast and holds temperature easily, so a no-load commissioning result may not reflect what the system can really do.
What needs checking on the electrical and control side?
That the protection devices are fitted and working, that the interlocks are correct, that the sensors are at representative positions, and above all that a genuine over-threshold condition is used to confirm the alarm system works — not just a look at the indicator lamp.
What does the handover documentation contain?
As-built process and installation drawings, the wiring diagrams, the equipment schedule with specifications and origin, the pressure vessel inspection records, the operating instructions, the maintenance schedule and the reports from the earlier acceptance stages.
A schedule only holds when design, manufacture and installation sit with a single party. See the capability of cold storage contractor offered by Tan Long.
Related pages
- Cold store acceptance checklist for owners
- Cold storage installation process
- Criteria for choosing a cold storage contractor
- 5 cold store design mistakes
- Cold storage contractor services
Kỹ sư Nguyễn Toàn Thịnh (Giám đốc Kỹ thuật)
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