Gasketed plate-and-frame heat exchanger

01

Choose the gasket from design temperature, pressure and fluid

R. Pramanik of Fluor Daniel India, writing in Gas Processing News (2016), states that the design pressure of a gasketed PHE is governed by the gasket material and is limited to approximately 16 barg, in some cases up to 25 barg. Design temperature is also gasket-limited: approximately 135 °C with nitrile butyl rubber (NBR) and approximately 180 °C with ethylene propylene terpolymer (EPT), rising to approximately 260 °C with compressed asbestos fibre. [1]

The same article names EPT and NBR as the standard gaskets, EPT for non-fatty or non-oily duties and NBR for oil and fat, with HNBR and FKM as other options, and notes that gaskets are fixed to plates by glue or by mechanical means. Where the vendor lacks experience with a gasket, it describes an immersion test at operating temperature on a piece no more than 8 mm thick for at least 15 days, with hardness change no more than 15 IRHD for fluoropolymers and 10 IRHD for others, and volume change no more than 15%. For glue, the final peel strength in newtons should be five times the gasket width in millimetres. [1]

Elekheat's published gasket table gives NBR −15 to 130 °C for water, seawater, mineral oil and salt water, and EPDM −25 to 150 °C for hot water, steam, acid and alkali. [3] Editorial note: the two sources give different upper limits for the same rubber family, so ask the gasket supplier for the rated continuous temperature of the exact compound.

Editorial calculation: for an assumed 10 mm wide glued gasket, the peel-strength rule gives 5 × 10 = 50 N. [1]

Give the supplier both fluids and their chemistry, oil or fat content, design and operating temperatures and pressures, cleaning chemicals and temperatures, and whether glued or clip-on gaskets are required.

02

Specify plate thickness, gap and chevron angle

Pramanik notes that plates carry no corrosion allowance; thickness depends on the differential pressure across the plate, the corrugation and the material's ductility, and lies between 0.5 mm and 1 mm, with the minimum specified by API 662. The gap between adjacent plates is 2.5–5 mm, and the chevron angle β1 lies between 25° and 65°, governing heat transfer and pressure drop. [1]

For fouling, the article cites API 662 Appendix A for a minimum 10% fouling margin, possibly 25% for crude oil service, and a recommended minimum wall shear stress of 50 Pa; it warns that adding channels or plate width lowers velocity and can raise fouling. [1]

As one published example, Elekheat lists a plate of 604 × 266 × 0.5 mm with 0.109 m² heat transfer area, 4 mm plate spacing, 50 mm corner holes, DN40 flanges, working temperature up to 180 °C and working pressure of 0.6, 1.0 or 1.6 MPa. [3]

Editorial calculation: at 0.109 m² per plate, 10 m² of heat transfer area needs about 10 ÷ 0.109 ≈ 92 plates, before the supplier adds or removes plates for end plates and pass arrangement. [3]

03

Ask for certified thermal and pressure-drop ratings

Bell & Gossett explains that the AHRI Liquid to Liquid Heat Exchanger programme under ANSI/AHRI Standard 400 certifies gasketed plate heat exchangers by third-party witnessed laboratory testing. Tested total heat transfer must be at least 95% of the published value and tested pressure drop no more than 115% of it; before August 2015 the pressure-drop limit was 110%. [2]

Bell & Gossett gives the programme scope as gasketed plate units using water or sea water (glycols not yet included), capacity up to 240,000,000 Btu/h and flow up to 20,000 gpm, for HVAC in the U.S., its territories and Canada. It adds that ASHRAE Standard 90.1 has required waterside economizers to comply with AHRI Standard 400 since its 2010 version. [2]

Editorial calculation: 240,000,000 Btu/h × 0.29307 W per Btu/h ≈ 70.3 MW, and 20,000 gpm × 0.2271 m³/h per gpm ≈ 4,540 m³/h. [2]

04

Elekheat TG frame sizes: port size, flow, design pressure and plate area

Ask each supplier for the plate model, pattern and chevron angle, plate and gasket materials, number of plates and passes, and the thermal calculation against your duty.

05

Plates, gaskets, fixed and movable frame plates, tie bolts and ports

06

Design pressure and temperature per side, plate thickness, gasket compound and area for a plate-and-frame unit

Design pressure and design temperature are both set by the gasket compound here, so fix the gasket before comparing plate counts or areas. [1]

07

Send the duty, gasket and rating data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Fluids: [hot side; cold side; oil or fat content]
Duty: [heat load; inlet and outlet temperatures; flows]
Pressure: [design per side; allowable pressure drop]
Plates: [material; thickness; chevron or pattern]
Gaskets: [compound; glued or clip-on; rated temperature]
Rating: [AHRI 400 certification if in scope; fouling margin]
Frame: [material; connections; space for extra plates]

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