Disassembly and Assembly of Plate Heat Exchangers

Newly purchased plate heat exchangers are pre-assembled as a single unit and can be installed directly as a whole. Disassembly is generally unnecessary; however, if required, it must be performed meticulously by experienced personnel following strict guidelines to ensure proper sealing and functionality after reinstallation. Improper handling can lead to sealing failures, plate deformation, or irreversible damage.

Key Procedures for Disassembly and Assembly

1. Thickness Measurement Before Disassembly

Before disassembling, use a steel ruler to measure the total thickness of the plate pack at the four corners (top, bottom, left, right) and record these values. During reinstallation, strive to restore the original thickness. If adjusting the number of plates, recalculate the correct total thickness. For example, 80 BR50 plates yield a nominal thickness of: 80×(３.８+0.６)=352mm

The allowable deviation after tightening should be less than 1% of the nominal thickness (e.g., 347–357 mm for the example above).

2. Uniform Bolting for Even Tightening/Loosening

Plate heat exchangers are typically secured with 6–12 bolts, which must be tightened or loosened uniformly to avoid uneven stress distribution.

- Disassembly (Loosening Bolts):

Start with the central bolts, then proceed to the corner bolts. Loosen bolts incrementally: begin with 1–2 turns per bolt, gradually increasing the number of turns and repeating until fully loosen. Monitor the total plate thickness at the four corners during loosening, ensuring horizontal deviation does not exceed 10 mm and vertical deviation does not exceed 25 mm.

- Assembly (Tightening Bolts):

Begin by tightening the corner bolts, followed by the central bolts, in small increments, repeating the process multiple times. Maintain the same deviation limits for thickness asymmetry as during disassembly.

3. Torque Control for Bolt Operations

Use a wrench of specified length to apply appropriate torque. For example, M30 bolts on BR50-type heat exchangers require a 500 mm wrench. Many foreign-manufactured units include a torque-limiting wrench that slips to prevent over-tightening, which can over-compress gaskets or dent the corrugated peaks of plates—damage that caused plate perforation and报废 at a domestic sugar factory. Avoid using excessively long wrenches or excessive force, as these can irreversibly damage components.

4. Plate Handling and Inspection

After disassembly, hang plates on the equipment frame. If cleaning is needed, place them on a flat surface (never on uneven ground or in stacked piles) to prevent bending or deformation. Reinstall each plate to its original position immediately after cleaning.

- Never strike plates with a hammer: Impact can alter the internal structure of stainless steel, reducing corrosion resistance.

- After cleaning, inspect all plates (using a leak detection agent) and gaskets for damage. Once confirmed intact, reassemble the unit by gradually tightening the bolts according to the specified sequence.

Following these steps ensures proper sealing, prevents mechanical damage, and maintains the efficiency of plate heat exchangers. Consistency in force application and precise thickness control are critical to successful disassembly and assembly.