Service
Anodising Tanks UK
Anodising tanks are almost always thermoplastic: polypropylene or PVC, welded rather than lined, because sulphuric acid electrolyte corrodes steel and any dissolved metal ends up as poor finish on the work. Beckox designs, fabricates and installs the wet end — tanks, extraction and pipework — from our Poole works. Rectifiers, chemistry and process control stay with your process house. Free site consultations.
Why anodising tanks are a thermoplastic duty
Sulphuric acid electrolyte is unforgiving. It attacks mild steel, and anything it corrodes puts dissolved metal into the bath, where iron or copper contamination shows up later as patchy, off-colour finish. A welded thermoplastic tank keeps metal out of contact with the electrolyte entirely, so the only things in the bath are the ones meant to be there.
Polypropylene and PVC are both fabricated here in Poole, and both are long-established acid-duty materials. As a general guide, published continuous-service temperatures put PP around 80°C and PVC nearer 60°C, with PP also offering better impact behaviour at low temperature; the resin supplier's data governs in every case. Our materials guide sets out the trade-offs.
What we build, and what stays with your process house
Being plain about scope saves everyone time. Beckox builds the wet end of an anodising line:
- Tanks and vats in PP and PVC, with the interfaces for support steelwork
- Freeboard, lip extraction flanges, splash containment and covers
- Ducting from the tank lip through to the fan or scrubber
- Acid-duty pipework, fill, drain and overflow arrangements
- Bunds, drip trays and secondary containment
- Mounting and support arrangements for cathodes, busbar and heat exchangers
- Installation on site by the people who fabricated the work
Outside our scope, and deliberately so: rectifiers and electrical design, busbar sizing, racking and jigging, bath chemistry, sealing technology and control of the anodising process itself. Those belong to your process house, chemistry supplier or line builder. We work to their tank schedule and duty figures rather than second-guessing them.
Tank features that matter on an anodising line
An anodising tank is not simply a box that holds liquid. The details decide whether the line runs cleanly for years or fights the operators every shift.
- Freeboard sized for displacement, agitation surge and lip extraction to work properly
- Flanged lip extraction slots on one or both long sides
- Provision for cooling coils or a plate heat exchanger, with brackets that do not foul the work
- Air or eductor agitation manifolds, supported and removable for cleaning
- Cathode and busbar support arrangements sized for the load the line builder specifies
- Drain, overflow and sludge-clearing points positioned for real maintenance access
- Ribbing and support to carry a full bath without bowing
Weld quality carries the whole thing. Thermoplastic tanks live or die on the corner and stiffener welds, which is what 44 years of doing one trade buys. See process tanks and vats for how we approach tank construction generally.
The tank set around the line
A typical surface-finishing line is a sequence of tank duties: degrease, rinse, etch, rinse, desmut, rinse, anodise, rinse, colour, rinse, seal. Each stage has its own duty and its own material call, and the rinse tanks between them are as much a part of the design as the process tanks, because carry-over and drag-out drive both quality and effluent volume.
Treating the line as one tank set, rather than a collection of separate vessels, keeps heights, lip levels and extraction runs consistent for the hoist and the ductwork. More on complete wet-process lines is on our plating lines page.
Acid fume extraction and scrubbing
Anodising baths give off acid mist, and hydrogen is evolved at the cathodes. Lip extraction at the tank edge captures fume at source before it reaches the operator or the roof steel, and the ducting has to be as corrosion-resistant as the tanks themselves. Fabricating both from the same thermoplastic keeps the whole path consistent.
Where discharge limits or neighbours require it, extracted air is passed through a packed-tower wet scrubber, in which the airstream meets a counter-current liquor over packing media so acid mist is absorbed before the fan discharges to atmosphere. We build the ducting and the scrubber vessels; the discharge consent and the duty figures come from your consultant.
Hard anodising and cooling
Hard anodising runs cold and draws heavy current, so the bath needs far more cooling capacity than a decorative sulphuric line, along with agitation vigorous enough to stop hot spots forming at the work surface. In fabrication terms, that means proper provision for heat exchangers, secure coil supports, and agitation manifolds that will not shake loose.
Cold operation also puts the material choice under scrutiny, since impact resistance falls as temperature drops. Bring the process figures to the enquiry and the tank can be built around them.
Re-tanking an existing line
Anodising tankwork splits between new-build lines and replacing tanks in a line that is already running. An old tank that has gone brittle, distorted or started weeping can be measured, fabricated off site and swapped in during a shutdown window, one tank at a time, so the line keeps running around the work. Sequencing the swap-out around your shutdown is worth planning at quotation stage, because the number of tanks, access and the window available drive how long the work takes.
Where a vessel is sound but locally damaged, repair is often the sensible route, and pipework and containment can be renewed in the same visit.
Surface finishing in the aerospace and engineering supply chain
Anodising sits deep in the UK aerospace, defence, optical and precision engineering supply chains, where finish specifications are tight and downtime is expensive. That environment rewards tankwork that is built once, properly, and installed by the people who welded it.
Beckox has fabricated for a client list that includes Rolls-Royce, Babcock Marine, Martin-Baker Aircraft, Merck, Sigma-Aldrich, CooperVision, Wessex Water, ITT Cannon, Tyco Electronics, Amphenol, Novanta, Cambridge Technology, Progressive Technology and Ryvita.
Talk to the fabricator, not a middleman
Design, fabrication and installation all happen from the same Poole works, so the person who quotes the tank is the person who understands how it will be welded and how it will get through your door. Site consultations are free, and it is usually quickest to walk the line together with your process figures to hand.
Call 01202 736 725 to discuss an anodising tank, a full re-tank or the extraction that goes with it, or send drawings and duty details through our contact page.
PAGE REVIEWED — 30 July 2026