Fin-fan air coolers with the fans below the bundle, pushing ambient air up through the finned tubes. Designed and built in Stafford by Spiro-Gills Thermal Products, supplied and supported in the GCC by Petromarsh.
Tap a part to see what it does. The red line is the hot process fluid in the tubes, the blue lines are the cooling air pushed up by the fans.
Finned tube bundle. Rows of finned tubes held in a side frame. The fins multiply the outside surface, because air carries heat far less well than a liquid.
Plug headers. Welded boxes at each end that collect the fluid and turn it between passes. A threaded plug opposite every tube gives access for cleaning, plugging and re-rolling.
Process nozzles. Inlet and outlet connections, flanged to your piping class. With an even number of passes both sit on the same header.
Plenum. The chamber between fan and bundle. It spreads the air from the round fan over the rectangular bundle face.
Fan ring and fan. An axial fan turns in a close-fitting ring under the plenum. Fans sit in the cool inlet air, which is easier on blades, bearings and belts.
Motor and V-belt drive. A motor at grade drives the fan shaft through belts and sheaves. Everything is reachable from the ground or a low platform.
Structure. Steel legs and beams that carry the bundles, fans and drives, on a pipe rack or at grade, with walkways for maintenance.
The process fluid flows inside finned tubes. Fans below the bundle push ambient air up across the fins, and heat passes from the fluid through the tube wall and fins into the air. No cooling water is needed, which matters in the Gulf.
Air is cheap and always there, but it carries heat poorly. Fins raise the outside surface 15 to 25 times, so the bundle can stay a practical size.
The hot fluid enters a header, runs through one or more tube passes and leaves cooler or condensed. More passes raise velocity and heat transfer, at the cost of pressure drop.
Thermal design is run in HTRI Xace. With the offer you receive the API 661 datasheet, a general arrangement (GA) drawing, and a noise assessment of sound power per fan and sound pressure at 1 m.
Every air cooler is a set of choices: where the fans sit, how the bundles are arranged, and how the header is built. Tap a type to see when to use it.
The most common layout. Fans and drives sit in the cool inlet air and are easy to reach. Air leaves the bundle at low velocity, so some hot air can recirculate.
The usual choice on refinery and gas plant pipe racks across the GCC.
The fans sit above the bundle and draw air through it. Air leaves at higher velocity through a fan stack, so less hot air recirculates, and the plenum shades the bundle.
Chosen where the outlet temperature must stay close to a high Gulf ambient.
Two bundles lean against each other, so a large surface fits a small plot. A-frames suit steam condensers, because sloped tubes drain condensate.
Used for turbine exhaust and process steam condensing.
Horizontal bundles are the standard. Vertical bundles, with air blowing sideways, are used on small packaged coolers and compressor skids where plot space is short.
The standard API 661 header. Each tube has a threaded shoulder plug opposite, so single tubes can be cleaned, plugged or re-rolled without opening the whole header.
The header face is a flanged cover plate. Taking it off opens every tube end at once for cleaning, so it suits fouling services, but the large gasket limits pressure.
Round pipe headers with tubes welded in. Pipe takes very high pressure with thin walls and no gasketed joints, but tubes cannot be cleaned mechanically.
Common on high-pressure gas compression and injection duty.
Inside, the tube material is chosen for the process fluid. Outside, the fins must stand up to high ambient temperature, sand, sun and salty coastal air.
| Part | Carbon steel | Stainless and duplex | Other options |
|---|---|---|---|
| Header boxes | Plate, forgings and pipeSA-516 Gr 70 · SA-105 · SA-106 Gr B | 304L, 316L, duplex 2205SA-240 · SA-182 · SA-312 | Low-temperature carbon steel, impact testedSA-516 with SA-20 · SA-333 · SA-350 LF2 |
| Tubes | Seamless or weldedSA-179 · SA-214 · SA-334 | 304L, 316L, duplexSA-213 · SA-249 · SA-789 | Admiralty brass, copper-nickelSB-111 |
| Fins | Aluminium, the usual choice1000-series aluminium strip | Stainless steel welded finsfor hot or corrosive air | Copper fins, or galvanised carbon steel welded finshot-dip galvanised |
| Plugs and gaskets | Shoulder plugs in carbon or stainless steel, with soft iron, aluminium, copper or stainless gaskets matched to the header materialSA-105 · SA-182 | ||
The datasheet names the code. Spiro-Gills follows it, plus your company specification where one applies.
Requirements for air-cooled heat exchangers in petroleum, petrochemical and natural gas plants: headers, tubes, fins, fans, drives and structure.
Pressure design of the header boxes, plugs and nozzles, with the U stamp where it is required.
CE marking for Europe. UKCA under the Pressure Equipment (Safety) Regulations 2016 for the UK.
Rating software from Heat Transfer Research, Inc. Not a code, but the industry reference for air-cooler thermal design.
Sound power found from sound pressure (3744) or sound intensity (9614) measurements. Used to check the noise guarantee.
Material specifications, and qualified welding procedures and welders for headers and tube-to-tubesheet joints.
Non-destructive testing methods, and certified mill certificates for every pressure part.
Nozzle flange ratings and dimensions, matched to your piping class.
Company specifications for air coolers from Saudi Aramco, ADNOC or Shell, applied on top of API 661.
The offer comes with the HTRI thermal design, the API 661 datasheet, a GA drawing and a noise assessment. Your engineers red-line them, you approve the design twice before production starts, and you can witness the tests. Tap a step to see what happens.
Spiro-Gills Thermal Products has designed and built bespoke air-cooled heat exchangers and finned tube in Stafford since 1946, and has supplied them to more than 100 countries. Thermal design is done in HTRI, welding is to ASTM code, and the company holds ISO 9001:2015. Petromarsh is their exclusive representative in the GCC.
If you have an API 661 datasheet, send it. If you do not, the items on the right are enough for an HTRI design and a proposal.
