Danfoss Gasketed and Semi-Welded Plate Heat Exchangers

Introduction

This installation manual provides guidance for the installation, commissioning, operation, and maintenance of gasketed and semi-welded plate heat exchangers manufactured and supplied by Danfoss. It is intended for personnel responsible for these tasks. Reading this manual thoroughly before commencing any work with the heat exchanger is recommended.

This manual applies to all gasketed and semi-welded plate heat exchangers from Danfoss. Danfoss is not liable for any damage resulting from incorrect installation, use, or maintenance, or failure to comply with the instructions in this manual.

Please note that Danfoss plate type heat exchangers are designed and built for optimal conditions specified by the customer during the calculation process, as indicated on the nameplate. Sudden pressure peaks or surges during start-up or shutdown can severely damage the heat exchanger and should be prevented. Danfoss is not responsible for damage caused by operations deviating from the original design criteria.

Drawings and figures in this document are for illustrative purposes only.

Always comply with local regulations and legislation when handling the plate heat exchanger.

Only qualified personnel should handle the heat exchanger during lifting, transportation, installation, commissioning, and maintenance.

Safety Alert Notices

Always observe the following when installing or servicing plate heat exchangers:

• Comply with national/local safety regulations.
• Ensure the heat exchanger is free from pressure and completely drained and flushed with clean water where possible.
• Ensure the heat exchanger is cooled down to ambient temperature between 10 - 40 °C (50 - 104 °F).

Warning symbols indicate safety alerts that should be carefully observed to prevent:

Identification of the Heat Exchanger

Nameplate

All Danfoss plate heat exchangers are equipped with a nameplate on the front (head). Additional nameplates may be present if specified by the client.

The nameplate details the main technical specifications. Before installation, verify that the intended process complies with the nameplate data.

• Never exceed the values stated on the nameplate.
• Do not alter or repaint the nameplate.
• Avoid aggressive cleaning detergents on foil stickers/labels.
• Do not remove the nameplate.

Examples of nameplates for single plate and semi-welded heat exchangers are provided, detailing information such as production date, type designation, serial number, dimensions, temperature and pressure limits, connections, and fluid types.

Design and Components

The heat exchanger frame consists of a frame plate (head), a pressure plate (follower), a carrying bar, a guiding bar, and a column. Tie rods press the plate pack together.

The gasket material is selected based on temperature and chemical resistance requirements.

Single Plates

A single plate pack consists of single plates with flow gaskets to seal the pack. The number of plates determines the total heat transfer area.

Semi-welded Plates (Plate Cassettes)

A plate cassette comprises two single flow plates welded together, forming a sealed flow channel. Cassettes use individual ring and flow gaskets to seal the plate pack, preventing media intermixing. This design allows for different gasket materials for ring and flow gaskets.

Gaskets

Danfoss plate heat exchangers use:

• SonderLock gaskets
• Hang-on gaskets (Type A, B, AD, AE, A2, B2)
• D-Lock™ gaskets
• Glued gaskets for sanitary applications (using FDA-compliant DOWSIL™ 786 Silicone Sealant or 3M 1099).

Right (R) / Left (L) Plates

Most plates can be used as either right or left plates by turning them 180°. Semi-welded cassettes are not turned.

Right Plate: Media flows from porthole F2 to F3 or F3 to F2.

Left Plate: Media flows from porthole F1 to F4 or F4 to F1.

Diagrams illustrate the flow for single plates and semi-welded cassettes, indicating connections (F for head, B for follower).

Accessories / Optional Components

• Insulation Jackets/Covers: Available for thermal insulation (mineral wool) or condensation risk applications (closed cell PU foam).
• Drip/Condensation Tray: Collects residual water after drainage or condensation. Available in insulated and uninsulated types.
• Safety Cover: Recommended for temperatures above 45°C or with aggressive fluids to prevent human exposure.
• Inline Filter/Filtration: Recommended if fluid contains particles larger than the plate channels. Filters are supplied in AISI316L or Titanium.
• Instrumentation (for marine applications): Includes thermometer, drain/air bleed valve, and pressure gauge.
• Sectioning: Intermediate frames with corner pieces can combine multiple heat exchangers for applications like pasteurization. Available for IS and FS frames.
• Connections: Various types available, including standard flanges, threaded holes, stud bolts, welded-on pipes, and dairy type connections (SMS, RJT, DS, DIN). Elbow flanges are suggested for multi-pass units to simplify servicing.

Function

Single-Pass Solution

Single-pass heat exchangers allow fluids to pass only once. All connections are on the head, simplifying maintenance and cleaning. They can be co-current or counter-current flow.

Multi-Pass Solution

Multi-pass heat exchangers allow fluids to pass multiple times. They feature connections on both the head and follower, often using combi-plates.

Multi-Section Solution

Multi-section plate heat exchangers can handle heating and cooling of multiple media. They function as multiple heat exchangers in one frame, divided by intermediate frames with corner blocks.

Installation

Before Installation

• Verify the assembly measure (A-measure) against the nameplate.
• If the measure does not comply, tighten the heat exchanger according to the "Closing the heat exchanger" section.

Foundation

• Install the heat exchanger on a flat, stable foundation providing adequate support and space for service.
• Ensure foundations and support frames can bear the weight of the full heat exchanger.

Space Requirement

• Ensure sufficient space around and above the unit for maintenance (e.g., plate/gasket replacement) and lifting equipment.
• General rule: 1.5 x Width clearance on sides, 0.5 x Height clearance above.
• Place the insulated drip/condensation tray before installing the unit.

Storage

• Short-term (less than 1 month): Ensure the unit is emptied/dried. Avoid areas with high ozone, salt air, or corrosive atmospheres. Close all connections to prevent debris entry. Store in dry conditions at room temperature (15-20°C, max 70% humidity). Lubricate tie rods and loosen them slightly to allow air flow.
• Long-term (more than 1 month): Follow short-term rules. Relax gaskets by loosening tie rods by ~10%. Grease tie rods. Place in a protective box to prevent moisture and damage. Examine packing monthly. For specific applications, consider filling with nitrogen gas (max 1 bar).

Raising / Lifting

• From Lying Position: Remove tightening elements. Lift unit off pallet. Place on timber beams. For ST frames, use a sling around the carrying bar. For IG, DG, FG, IS, DS frames, use slings around upper tie rods. Raise unit and move to upright position.
• From Upright Position: (For units > 2500 mm). Remove tightening elements. Secure lifting shackles in dedicated lifting lugs on header and follower. Use lifting slings (4 fixation points) to lift and move the unit. Mount securely to the floor. Remove slings.
• General Caution: Always use authorized personnel and proper lifting equipment. Ensure the unit's center of gravity is understood to prevent tilting or damage. Never use connections, studs, or tie rods for lifting. Avoid steel cables/ropes, chains, or damaged slings.

Transportation

• Units are typically supplied horizontally on a pallet, secured for forklift transport.
• Ensure the pallet is fully supported by forklift forks. Avoid tilting the pallet.
• Be aware of the center of gravity not being package-center-lined.

Installing Pipe Connections

• Identify flow inlets/outlets on the nameplate.
• Support heavy piping to prevent stress on the heat exchanger. Consult Danfoss for nozzle load information.
• Install shut-off valves for opening/closing/dismantling.
• Remove blind flanges or plastic caps before working on piping.
• Depressurize refrigerant sides before removing flanges.
• Install flexible connections on the follower to prevent vibrations and pipe expansion.
• Install vents on the highest point of upper connections.
• Fit safety valves according to pressure vessel regulations.
• Ensure piping systems are secured against pressure peaks and temperature shocks.
• Avoid welding on the heat exchanger; use earthing next to the welding point.
• Ensure process temperatures do not exceed nameplate limits to prevent gasket damage.
• When fitting threaded pipes, use a counter-hold to prevent rotation and potential internal gasket damage.
• For studded flange connections, insert gaskets before bolting. Tighten bolts evenly.

Operation

Commissioning

• Commissioning, operation control, maintenance, and repair must be performed by authorized, trained personnel.
• Check all connections for proper fitting and tightening. Verify A-measure against the nameplate.
• Check pressures and temperatures against nameplate specifications.
• Avoid thermal or mechanical shock to prevent premature gasket failure.
• Refrigerant systems must comply with local regulations.

Start-up Process - Single Plate Heat Exchanger

For liquid/liquid systems, start with the fluid closest to ambient temperature. Ensure no back pressure and that check valves prevent backflushing. Bleed valves should be safely openable.

1. Side 1 (Cold): Close valve 10. Open return valve (1), air bleed valve (2). Start pump (3). Gradually open supply valve (4). Close air bleed valve (2) once air is purged.
2. Side 2 (Warm): Close valve 9. Open return valve (5), air bleed valve (6). Start pump (7). Gradually open supply valve (8). Close air bleed valve (6) once air is purged.

Start-up Process - Semi-Welded Heat Exchanger

For systems with refrigerant and glycol/water, start with the glycol/water side first, then the refrigerant side.

1. Start liquid flow as described above.
2. For refrigerant flow: Keep shut-off valves closed while evacuating the unit. Gradually open the outlet valve for pressure equalization, then the inlet valve. Activate Side 2 as previously described.

Check During Operation

• Monitor for potential pressure pulses from pumps or control valves; rectify if found.
• Check for leakages.
• Ensure all vents are closed.
• Verify operating conditions (media, temperature, pressure) are within nameplate limits.

Water hammering can cause significant damage. Avoid abrupt fluid stops or direction changes.

If a wedge is inserted between the follower and carrying bar, remove it before commissioning.

Shut Down

Short Period ( < 12 hours)

1. Side 2 (Warm): Close supply valve (1), stop pump (2), close return valve (3).
2. Side 1 (Cold): Maintain flow until temperature is <40°C. Close supply valve (4), stop pump (5), close return valve (6). Close other valves and ensure the device is depressurized and drained.

Long Duration ( > 12 hours)

• Ensure drain valves (9, 10) and bleed valves (X, Y) are opened for drainage.
• For long-term shutdown (>1 month), flush with clean liquid and store in non-freezing conditions.
• Follow short-period shutdown procedure.
• Drain, rinse/flush, and dry the heat exchanger.
• Cover all connections.
• Lubricate tie rod threads.
• For shutdowns >1 month: Loosen tie rods to achieve A-measure nominal +10%. Cover the plate pack with black plastic. Refer to the "Storage" section.

Attach a warning notice reminding personnel to adjust tie rods before re-service.

Opening the Plate Heat Exchanger

Ensure the unit is depressurized, drained, and flushed before opening to prevent injury.

• Clean threads and lubricate lightly.
• Use appropriate tools (e.g., ratchet spanner).
• Mark the plate package before disassembly (diagonal line or numbering).
• Measure and note the assembly measure (A-measure).
• Shut down the heat exchanger and ensure it cools to ambient temperature.
• Drain both sides completely.
• Observe the following during opening:
• Check gasket attachment.
• Check plate/cassette alignment on the carrying bar.
• Press the follower towards the head.
• Check plate/cassette profile uniformity.
• Identify and confirm A-measure.
• Ensure no flow to any part of the unit.
• Clean and grease tie rod threads.
• Tie Rod Tightening Sequence:
• Loosen tie rods slowly in a specific sequence (Fig. 35).
• Avoid loosening all tie bolts at once.
• Use appropriate tools and lowest speed for hydraulic tools.
• Do not stand directly in front of tie rods during assembly/disassembly.
• The maximum allowable deviation of parallelism between header and follower is 5 mm.

Plates/cassettes have sharp edges. Use personal protective equipment (gloves) when handling.

Maintenance

CIP Cleaning

• CIP cleaning allows cleaning without opening the unit. It is relevant for soluble fouling. Ensure all materials are resistant to the cleaning agent.
• Refrigeration units: CIP cleaning is not allowed on the refrigerant circuit; only on the brine circuit.
• Follow supplier instructions for cleaning agents. Circulate for 30 minutes to 4 hours.
• Rinse thoroughly with fresh water after cleaning (at least 10 minutes).
• Confirm with the cleaning agent supplier that it will not damage heat exchanger components.

Cleaning Agents Guidance

• Oil/grease: Water emulsifying oil solvent.
• Organic/grease: Sodium hydroxide (NaOH) max 1.5% (max 85°C).
• Stone/limestone: Nitric acid (HNO3) max 1.5% (max 65°C).

Nitric acid and Sodium Hydroxide can cause injury. Use protective eyewear and gloves.

Cleaning a Flow Plate

• Use a brush with stiff bristles (non-metallic) and low-pressure water. Lay plates flat for cleaning.
• Use suitable cleaning solutions based on fouling type and plate/gasket material.
• Welded cassettes can only be cleaned on the brine side.
• Single plates may be immersed in a solvent bath.
• Gaskets should ideally be removed before cleaning to prevent acid trapping.

Always wear protective equipment when handling plates or working with acidic/caustic solutions.

• Never allow cleaning agents into the welded side of cassettes.
• Never use abrasive materials (wire brushes, sandpaper, angle grinders) on plates, as this damages the surface and passivation film.
• Do not use Hydrochloride for stainless steel plates.
• Do not use Hydrofluoric for titanium plates.
• Rinse chemically cleaned plates thoroughly with fresh water before fitting.

Regular Service of the Plate Heat Exchanger

Perform service annually as a minimum:

• Check temperatures and flows against commissioning data.
• Inspect for any signs of leakage.
• Wipe clean painted parts and check surfaces for damage; touch up as necessary.
• Check and clean bolts and bars. Coat threads with molybdenum grease or corrosion inhibitor (avoid contact with plate gaskets).

A table outlines service intervals (PHE audit, leak detection, CIP cleaning, gasket replacement) for clean and dirty fluids/conditions.

Trouble-shooting

Common problems, causes, and solutions are listed:

• Leakage: Check rubber liners, flange gaskets, ring gaskets, pipe tension, plates for damage, assembly distance, gasket condition, and position. Vent the system if air is present.
• Insufficient Capacity: Adjust operating conditions, clean the heat exchanger, check for interchanged connections, ensure correct flow rate, flush/clean channels, check pressure indicator, verify fluid specification, and vent the system.
• Too High Pressure Drop: Check pressure indicator, verify fluid specification, vent the system, and check for air traps.

Gasket Failures: Often due to material aging, ozone exposure, extreme temperatures, pressure surges, chemical attack, incorrect assembly, or misaligned plates.

Decrease in Performance: Usually caused by dirty plate surfaces, pump issues, blocked channels, incorrect flow, or undersized auxiliary equipment. Check for refrigerant trap issues or incorrect assembly/flow direction.

For most leakage problems, unit dismantling is required. Mark leakage areas before disassembly.

"Cold leakage" may occur due to sudden temperature changes but often self-seals once temperature stabilizes.

After Sales Service

Ordering Parts

• Provide correct data: Plate heat exchanger type, serial number (from nameplate), and required parts.
• Indicate any design changes since commissioning.
• When ordering plates, provide the correct plate code index (indicating open port holes), plate material, thickness, thermal pattern, gasket material, and liner type.
• When ordering gaskets, specify the correct gasket material.
• Measure existing tie rod bolts for correct spare bolt dimensions.

Modifications to the Heat Exchanger

• Heat exchangers are custom-designed. Modifications for different capacities may involve adding/removing plates/cassettes.
• Consult Danfoss for redesign and approval of any changes to operating parameters. A new nameplate will be issued upon approval.
• Commissioning under modified conditions requires written Danfoss approval.
• Always use genuine Danfoss parts for guaranteed performance and product lifetime.
• Contact your local Danfoss representative for spare parts inquiries.

Scrapping

• Dismantle, sort, recycle, and scrape components according to local regulations and legislation.
• Follow local regulations for recycling and scrapping.