Pipe connection GI38 black

Tube Fitting GI38 is an expanding tube mount in PA6 for round tubes. The principle is simple: the mount is pushed into the tube end, and as the screw is tightened the expander body is pressed out against the inside of the tube. The nut sits in the lower part of the plastic body, so you get a threaded mounting point in the tube without welding, drilling or riveting. If you build frames, carts or machine stands from standard tube, that means feet, wheels, adjusting screws and threaded rods can be mounted with a single turn of the screw; releasing the mount the day the structure is rebuilt goes just as fast.

The series covers tube diameters from 16 to 50 mm in twelve versions, with intermediate steps at 19, 20, 22, 25, 28, 30, 40 and 45 mm. The thread is M6, M8 or M10 depending on size. Each version is also matched to a specific wall thickness between 1.0 and 2.0 mm, and that is the detail that most often goes wrong when ordering. A mount for tube 20x1.5 mm expands against a different inside diameter than a mount for 20x2.0 mm, even though the outside diameter is the same. So check both outside diameter and wall thickness on your tubes before you choose. The overall height stays at 42 to 44 mm through the whole series, so the mount fits even in short tube stubs, and all sizes share the same mounting principle if you need to mix dimensions in one and the same structure.

The body is injection molded in PA6, a nylon that combines toughness with good wear resistance. The material takes up the tolerance variations that always exist in cold drawn and welded tube, and the expanding function relies on the ability of the plastic to spring without cracking. Screw and nut are in zinc plated steel. The color is black with a matte surface, a discreet finish that blends in against painted as well as untreated steel tube.

In Swedish engineering workshops this type of mount sits in machine guards, conveyor frames, workbenches, material carts and railings built from round tube. Designers use the threaded mount to put leveling feet in frame legs, so that machine tables can be leveled on uneven concrete floors. Maintenance departments appreciate that the mount can be taken apart: during a rebuild the screw is loosened, the mount is pulled out and reused in the next configuration. And since the fitting fills the tube end it works as a plug at the same time, which keeps chips, dust and wash water from collecting inside the tube.

Compared with welded threaded bosses you avoid heat damage and repainting; compared with a through bolt you avoid visible holes. The expanding mount leaves the outside of the tube completely untouched, which matters when the frame has to look good in a retail space or be wiped down in more sensitive premises. It also means that galvanized and stainless tubes can be used without breaking the surface layer, and the corrosion protection stays intact.

A few practical tips before mounting. Deburr the inside of the tube end, otherwise sharp edges can damage the expander body as it goes in. Tighten the screw step by step and feel when the mount locks; over tightening gives no extra grip and only loads the plastic for no reason. PA6 handles oils, greases and most cleaning agents found in a workshop, but keep in mind that nylon takes up moisture and can swell slightly in very wet environments. Exact dimensions for each version, including the expander diameter, are in the manufacturer's data sheet.

Not sure which combination of tube diameter, wall thickness and thread you should choose? Get in touch with us and we will sort it out together.