Introducing ZM Tube: Key Clamp Tube Built for Harsh Sites

We're excited to launch something new at Key Clamp Store. ZM Tube is 42.4mm key clamp tube with a zinc aluminium magnesium coating, made for the places where standard galvanised tube has a hard time.

It fits every 42mm key clamp fitting we sell, and it cuts, drills and fits just like the tube you already use. It comes in 3m lengths or cut to size.

ZM Tube 42.4mm, 3m length

£25.80 inc. VAT  £21.50 ex. VAT

View ZM Tube

Why we're launching it

We hear the same story from customers again and again. A handrail goes up on a seafront, a farm or a car park, and a few years later the cut ends and drill holes are starting to rust. The zinc on standard galvanised tube does a good job in normal conditions, but salt air, ammonia from livestock and constant damp all wear it down faster.

ZM Tube is our answer. It brings a coating technology already proven in solar farms, agricultural buildings and coastal structures to key clamp handrail for the first time on our shelves.

What is ZM coating?

ZM stands for zinc and magnesium. Instead of a coating of pure zinc, ZM Tube is protected by zinc alloyed with aluminium and magnesium, and each metal does its own job:

• ZnZinc corrodes first, sacrificing itself to protect the steel underneath
• AlAluminium forms a dense oxide barrier that slows down attack on the surface
• MgMagnesium helps form a stable protective layer that spreads across cut edges, drill holes and scratches

The coating goes on both sides of the steel before the tube is formed, so ZM Tube is protected inside and out. The weld seam is re-coated after welding, so there's no bare strip running along the tube.

Cut it on site without the worry

This is the part installers will like most. When you cut standard galvanised tube, you expose bare steel at the cut face, and in a damp or salty spot it can start to rust surprisingly quickly. The magnesium in a ZM coating helps a protective layer form across cut ends and drill holes as the tube weathers, so you spend less time touching up and more time finishing the job.

Where it makes the biggest difference

• Coastal and seafront handrail, where salt air eats into ordinary coatings
• Livestock buildings, penning and farm gates, where ammonia attacks galvanising
• Greenhouses and polytunnels, with constant warmth and humidity
• Car parks and walkways exposed to de-icing salt every winter
• Any job you cut to length on site and don't want to touch up every end

Stronger steel, lighter to handle

ZM Tube is made from S350GD high-strength steel. That allows a 3.0mm wall, so it weighs about 2.9kg per metre against roughly 3.1kg for standard 42.4mm galvanised tube. That makes it a little easier to carry and lift into place on site.

ZM Tube at a glance

What ZM Tube costs

A 3m length of ZM Tube is £25.80 inc. VAT, which is £1.99 more than 3m of standard galvanised tube. It uses the same 42mm key clamp fittings, so nothing else on your parts list changes. For ZM Tube cut to size, call us for a price.

Prices at 3 November 2026. Product pages always show today's price.

Want it cut to size, or planning a coastal, agricultural or car park job and not sure if ZM Tube is the right fit? Our team will happily talk it through. Call us on 0121 716 0606 or send us an enquiry with your drawings or photos. Please note that cut to size tube is not returnable.

For safety barriers, guardrail or anything load-rated, get in touch before you order and we'll check the design with you.

New to key clamp? Read why key clamp works so well for handrails or how our product codes work.