Our Square Clamp Range offers a modular approach to building structures without the need for welding, using galvanised steel tubes and fittings. These fittings are ideal for creating clean, contemporary designs in shop fittings, furniture, and other non-safety related constructions. The materials include galvanised steel, hot-dipped cast iron, and malleable iron.
For more information about our Square Clamp Fittings, view our brochure by clicking the adjacent image.
Square Fittings for Box Section Tube: Sizes, Finishes and Codes
Square fittings join square hollow section (box section) tube without welding. You tighten the bolts with an Allen key and the joint locks in place, and you can take the frame apart later and reuse the fittings. We stock 20 fittings for 25x25mm and 40x40mm square tube, each in galvanised or matt black e-coat, plus the square tube to go with them.
Shop fitters, interior designers and architects use them for furniture, displays and stands where the look of the frame matters. We quote within one hour, Monday to Friday, 8am to 5pm, with next-day delivery on stock orders.
The Range by Size
Every fitting below comes in both finishes. Codes ending S25 or S40 are galvanised; the same code with a Z on the end is matt black, for example 125-S25 and 125-S25Z.
Saddle bracket (LUG-25 galvanised, LUG-S25Z matt black)
Yes
Not listed
That is 19 fittings for 25x25mm tube and 13 for 40x40mm. "Not listed" means we do not list that fitting in that size: call before you design around it.
How Square Fittings Work
Weld-free. The fittings connect to square tube with bolts, tightened with an Allen key, so the joint locks in place without welding or specialist tools.
Reusable. Undo the bolts and the frame comes apart. The fittings can be used again, which suits displays and stands that change.
Flat faces. Square tube gives flat surfaces to build on, which makes it the choice for desks, tables, shelves and benches.
Not for safety rails. Square fittings are not suitable for safety applications such as handrails or guardrails, whatever the fitting name. For those, use round tube with key clamp fittings, or our key clamp handrail kits.
Not Sure What You Need?
Send a sketch, a photo or your measurements. We draw it up free and quote within one hour.
How to Choose
Pick the tube size. 25x25mm has the widest choice of fittings: 19 of the 20. If you want 40x40mm, check each fitting you need is listed in that size first.
Count the joints. Work round your frame and note what each joint does: a corner (125 elbow, or 128 three-way elbow where three tubes meet), a T (101 or 104), a cross (119, or 158 for four sockets), a foot (131 footplate or 132 base flange), or a straight join (149 coupling).
Choose the finish. Galvanised or matt black, per fitting.
Add the tube. Order square tube cut to your lengths with the fittings, so everything arrives together.
Choosing a Finish
Finish
Code ending
Best for
Galvanised to BS EN ISO 1461
S25 or S40
Outdoor use, and semi-outdoor commercial settings
Matt black e-coat (RAL 9005)
S25Z or S40Z
Indoor furniture and displays where appearance matters
Square Tube to Match
We supply steel square hollow section tube made for our square fittings, in 3m lengths and cut to your size free. Lengths up to 6m are available on request: contact us if you need more than 3m. Collection from our site is available.
Industrial-style furniture. Desks, tables, shelves and benches, and DIY builds such as bookshelves and kitchen islands.
Retail displays. Display racks, product shelving and signage frames that can be taken apart and rebuilt when the layout changes. See also shop fit clamps in round tube, and our free shop fit design service.
Trade show stands. Stands you can take down, reuse at the next event and adjust to the space you are given.
Storage racks and frames in workshops and back rooms.
Protected outdoor spaces. Galvanised fittings suit outdoor shelving, furniture and signage frames in protected or semi-outdoor settings.
How to Order
Choose 25x25mm or 40x40mm tube.
Count the joints in your frame and pick a fitting for each from the table.
Choose galvanised or matt black.
Give us the tube lengths. We cut square tube to size free.
Request a quote with your list of codes or a sketch, or call 01905 779944. We quote within one hour, Monday to Friday, 8am to 5pm.
Why Buy Square Fittings from Fisher Alvin
Both sizes in stock, with next-day delivery on stock orders.
Square tube cut to size, free.
Quote within one hour, Monday to Friday, 8am to 5pm.
Free design service. Send a sketch or drawing with measurements and we list the fittings your frame needs.
Founded in Birmingham in 1912, now based in Cradley Heath.
Square Fittings Questions
What sizes of square tube do the fittings suit?
Two sizes: 25x25mm and 40x40mm square tube. 19 of our 20 fittings are made for 25x25mm and 13 for 40x40mm.
How do square fittings fix to the tube?
With bolts that you tighten with an Allen key, and the joint locks in place. No welding is needed.
What is the difference between S25 and S25Z?
The tube size is the same. S25 and S40 codes are galvanised; codes ending Z are matt black e-coat, RAL 9005.
Can I use square fittings for a handrail?
No. Square fittings are not suitable for safety applications such as handrails or guardrails. Use round tube with key clamp fittings instead.
Can square fittings be used outside?
The galvanised fittings are suitable for outdoor use and semi-outdoor commercial settings. The matt black e-coat is recommended for indoor use.
Do you sell the square tube?
Yes. Steel square tube and black steel square tube in 25x25mm and 40x40mm, in 3m lengths cut to your size free. Lengths up to 6m are available on request.
Can I take a frame apart and reuse the fittings?
Yes. Square fittings can be disassembled and reused, which suits displays and stands that change.
