1. Introduction
Purpose of instrument insulation boxes in harsh environments.
Common problems caused by improper selection (temperature instability, water ingress, frequent maintenance).
Importance of correct design, materials, and heating system.
2. Core Technical Requirements
2.1 Dimensions and Structure
Standard size: 600(H) × 600(W) × 500(D) mm; optional: 800(H) × 600(W) × 500(D) mm.
Removable structure (body + door + base).
Door opening angle ≥135° for easy installation and maintenance.
2.2 Materials
| Component | Recommended Material | Thickness | Notes |
|---|---|---|---|
| Outer shell | 304 Stainless Steel | 1.5–2.0 mm | Brushed or polished finish |
| Inner liner | Galvanized steel / 304 SS | 0.5–1.0 mm | Anti-corrosion treatment |
| Insulation layer | Eco-friendly thermal material (e.g., polyurethane, mineral wool) | 25–30 mm | Ensures 15±3 °C stability in winter |
| Sealing | EPDM rubber gasket | – | Integrated seamless design |
| Observation window | Double-layer plexiglass | – | Installed at door center |
2.3 Heating & Temperature Control
Heating coil: S-shaped finned tube, material: 304 SS Φ14×2.0.
Inlet at top rear, outlet at bottom rear.
Equipped with condensate drain valve and heat-dissipating fins.
Operating temperature inside box: 15 ± 3 °C under winter conditions.
Optional: dial-type thermometer (≤60 mm diameter).
2.4 Installation Interfaces
Pre-punched knock-out holes for impulse lines and cables.
Pressure tube entry: 3 × Φ22 mm (top and bottom).
Cable entry: Φ20 mm (outer) with EPDM sealing ring.
2″ instrument support pipe with sliding rails for flexible positioning.
2.5 Base and Surface Treatment
Base frame: L50×4 angle steel, height 600 mm.
Surface treatment process: degreasing → pickling → phosphating → galvanizing → polishing/brushing.
Ensures corrosion resistance and uniform appearance.
3. Optional Designs
| Design Option | Description | Application Scenario |
|---|---|---|
| Diagonal door type | Door opens diagonally for compact spaces | Limited installation areas |
| Front door type | Standard frontal access | General installations |
| Hot water heating | Alternative to steam for medium-temp environments | Non-steam plants |
| Integrated thermometer | Real-time monitoring | Cold regions |
4. Common Pitfalls & Solutions
Too thin insulation layer (≤20 mm) → unstable winter temperature → use ≥30 mm insulation.
Incorrect heating coil material → corrosion & leakage → use 304 SS seamless tubes.
Poor sealing design → water ingress, short circuits → use EPDM rubber gasket + double locking.
Improper hole sealing → heat loss → apply cable glands with rubber rings.
5. Documentation and Delivery
Supplier shall provide:
Installation & operation manual.
Material certificates and inspection reports.
Test records and quality certificate.
Nameplate (304 SS, 150×40×2 mm, Arial 72 font).
6. Conclusion
A well-designed instrument insulation box is not just a protective shell, but an integrated system ensuring measurement reliability in low-temperature environments. Correct selection of size, materials, insulation thickness, and heating method directly impacts long-term maintenance cost and safety.