In place or off site
Cleaning in place keeps the unit on the pipework and returns it fastest. Stripping it out takes days and returns evidence about its condition. Neither is better; they buy different things.
01Choosing
The deposit decides what will work and the access decides what is possible
Cleaning methods divide on a single question: was the deposit ever in solution? Scale, protein, salts and product residue were, so chemistry can dissolve them back out and circulation can deliver that chemistry without anything being dismantled. Coke, cross-linked polymer, fibre, silt and marine growth never were, and no chemistry removes them at any concentration. Those come out mechanically, which means the unit has to be opened or the bundle withdrawn.
Getting that wrong is the commonest and most expensive mistake in this work. Circulating acid through a coked bundle achieves nothing but a disposal problem; jetting a plate pack is not a method at all. Where a cleaning cycle has been tried and failed, the useful question is almost never what to try next but whether the deposit was ever going to dissolve.
The second constraint is access, and it is often the binding one. A fixed tube sheet exchanger cannot have its shell side mechanically cleaned however hard the deposit is. A brazed plate unit cannot be opened. A unit with no standby and no bypass cannot be taken out of service for three days whatever the ideal method would be. In those cases the answer is what is achievable, not what would be best, and a contractor should say so.
02The binary
In place is quick and off site is certain about the unit
Before the method comes the binary: does the unit stay on the pipework or come off it. Neither answer is better and they are not bought for the same reason.
Cleaning in place
- Faster. Often back in service the same day or overnight.
- Cheaper. No rigging, no transport, no strip and rebuild labour.
- No spare unit or blanking needed while it is away.
- Cannot verify plate or tube condition. You get flow back, not evidence.
- Will not shift baked, coked or fibrous deposit.
- Produces a spent chemical stream that has to be disposed of.
Strip and clean off site
- Every plate or tube is seen, gauged and recorded.
- Cracks and thinning are found before they become a contamination event.
- Gaskets can be renewed while the pack is open, at no extra strip cost.
- The unit is pressure tested before it returns to service.
- The unit is out for days, not hours.
- Costs more, and needs access for lifting and transport.
03Comparison
Chemistry dissolves what was in solution and mechanical removes what never was
| Method | Removes | Unit stays on site? | What it proves |
|---|---|---|---|
| CIP circulation | Scale, protein, salts, soluble product residue | Yes, connected | Recovered duty. Nothing about condition |
| Strip and immersion | Everything reachable, including behind gaskets | No, days away | Plate and tube condition, crack testing, a test record |
| Hydro jetting | Coke, polymer, packed solids, hard scale | Unit opened or bundle pulled | Bores and bundle exterior clear. Finds wall loss under a lance |
| Ultrasonic immersion | Oil-bound deposit in fin blocks and small-bore cores | No, unit goes to a tank | Internal passages clean without abrasion |
| Chemical descaling | Carbonate scale, milkstone, beerstone, struvite | Yes, connected | Mineral removed. Needs passivation afterwards |
04In place or off site
Five methods cover the range, and each one is wrong for something
A specialist who cleans that unit type answers the request
Unit, deposit and postcode are enough to start. Your details go to a specialist who cleans that unit type. No obligation.