L Aluminium Angle 30 x 30 x 4 mm for Washdown Equipment Frames

01Why use an L angle in a frame that gets washed down?

Because it is the only shape that gives a corner, an edge and a drip line at the same time. A 30 x 30 x 4 mm L aluminium angle bolted along the inside of a cabinet corner closes the joint, stiffens two panels at once, and — if it is detailed the right way round — puts the only continuous edge where a squeegee can reach it. A square tube does none of that. A flat strip does one of the three.

What follows is not a description of the section. It is about the three places soil collects in an aluminium frame, which of them you can design out, which of them you can only manage, and how the choice of finish and fastener changes the answer. If the frame is going into a food, pharmaceutical or cosmetics environment, this is the part that decides whether the weekly clean takes twenty minutes or two hours.

02Where does soil actually hide in an aluminium frame?

Not on the flat faces. Flat anodised aluminium wipes clean easily. The problems are at discontinuities, and there are three that account for almost every failed hygiene audit on an aluminium frame.

03Which finish survives a washdown regime?

Three finishes are normally offered on this section, and they behave very differently once detergent is involved. The choice is not about appearance, it is about what happens to the surface after a few thousand cycles.

The one thing that matters more than the finish is when it is applied. Anodising before cutting leaves bare aluminium at every cut face, every drilled hole and every tapped thread. Those bare faces are the only places that corrode, and they are also the places that hold soil. Cut and drill first, then anodise, and if a thread must be masked, mask it deliberately rather than letting it happen.

04Which cleaning agents attack an anodised frame?

Anodised aluminium is amphoteric: it is attacked by both strong acid and strong alkali. Most food-industry detergents are mildly alkaline, which is tolerable. Caustic-based floor and drain cleaners are not, and neither are the strong acid descalers used for milkstone removal.

05How should the frame drain?

Every horizontal surface in a washdown frame will hold water unless it is given somewhere to go. A 30 x 30 mm L angle used as a skirt or a bottom rail creates a horizontal ledge by definition, so it needs a deliberate fall and a deliberate way out.

• Slope horizontal runs at 1 to 2 degrees toward a drain point. On a 1 m rail that is 17 to 35 mm of fall, which is visible and cheap to build in at the cut list stage and expensive to add later.
• Drill a 6 mm weep hole at the low end of every closed rail, and deburr it. A weep hole with a burr holds more water than no hole at all.
• Do not rely on the gap between two panels as a drain. It works until the sealant is applied, and then it does not.
• Keep the bottom rail at least 50 mm above the floor where the floor is washed, so the frame is not standing in run-off.
• Where the frame meets a floor or a plinth, use a radiused coving fillet rather than a square junction. A square internal corner between aluminium and concrete cannot be cleaned with anything wider than a toothbrush.

06Which fastener strategy is the cleanest?

There are three ways to join an L angle into a frame, and they rank differently on hygiene, on strength and on how easy the frame is to take apart for a deep clean.

Rivets are the third option and the one to avoid on anything that has to be cleaned periodically. A blind rivet leaves a mandrel hole, and a solid rivet cannot be removed without damaging the section. If the frame will be stripped for cleaning more than once a year, bolted joints with captive nuts are worth the extra cost.

07What an L angle cannot do

It cannot be a hygienic corner on its own. Two mitred L angles meeting at 90 degrees create a vertical seam down the inside of the corner, and that seam is the single most common finding in a hygiene audit of an aluminium frame. The fix is not a different angle — it is a corner that is either sealed as one piece or left open enough to clean, and both of those are assembly decisions rather than purchasing decisions.

It also cannot carry a heavy load at 30 x 30 x 4. At roughly 0.60 kg/m this is a light section; its job is to close and finish, not to carry. Where the same frame has to take a load, step up to the 40 x 40 x 5 at about 1.01 kg/m, or use a T-slot profile and let the angle do only the trimming.

08Questions from buyers specifying a washdown frame

Related sections and categories

Browse Aluminium Angle Profiles, Aluminium Sections, the 30 x 30 x 4 mm light duty angle, or see the 40 x 40 x 5 mm structural angle for the full section data.