The internal steam line of the R58 – pre-formed, not for re-bending
The R58 is a dual boiler machine, and its steam boiler needs to be connected to the steam valve. This job is done by a pre-formed pipe that follows a precisely defined path inside the housing – past the boiler, wiring and housing wall, without touching anything along the way.
Because this pipe gets hot during operation and expands thermally, its shape is no accident. The bends absorb the expansion. A re-bent or makeshift replacement pipe puts the connections under constant stress, and at some point it is not the pipe that cracks, but a threaded fitting.
When it's due
Steam or a damp spot at one of the pipe connections is the first sign. With steam, you often hear it before you see it: a faint, steady hiss inside the housing that comes and goes with the boiler pressure.
A second case is mechanical damage: a dent, a bent section after a service or a cracked connection. You can only see either of these with the housing open.
Internal scaling shows up as a decline in steam performance that does not respond to descaling – in that case the cross-section is permanently narrowed.
At a glance
| Type |
internal steam pipe, pre-formed |
| Installation location |
between steam boiler and steam valve, inside the machine |
| Fits |
Rocket R58 |
| Scope of delivery |
one pipe, without sealing rings and without fittings |
| Part number |
A27NI04646, formerly A279904646 |
| Version |
pre-formed |
| Installation |
Installation by a qualified technician recommended |
| Brand |
Rocket |
Important for installation
The pipe carries steam under boiler pressure and runs inside the housing next to live components. The machine must be disconnected from the mains, fully depressurised and cooled down. Always counterhold when tightening the fittings, and do not bend the pipe into position: it must fit both connections without stress. We deliberately do not provide step-by-step instructions here.
Who it's for
For workshops repairing the steam side of an R58.
For owners of an R58 with a steam leak inside the housing – this is not a case for continued use, but one for a service appointment. Length, diameter and material are not documented for this item.
What goes with it
The steam side of the R58 also includes the complete steam wand and the hot water spout for R58 and R60.
For the lines of the R58, we stock the hot water line and the return line.
The machine category can be found under Rocket R58 and R60 spare parts.
Our approach to steam leaks inside the housing: we never look for them by hand, but with a strip of kitchen paper on a wooden stick. Steam under boiler pressure is invisible and scalds instantly – the paper shows the spot before you get too close to it. This is our safety routine from Bern and Zurich, not a manufacturer requirement. Once the machine is sealed again, we make a round of cappuccinos with the Cozy Chocolate, because the milk foam immediately tells you whether the steam is coming out dry again.
No returns
Original spare parts are excluded from exchange and return. They are sourced specifically for each order and cannot be resold after installation or test fitting on the machine. So before ordering, check the model, year of manufacture and serial number of your machine – or drop us a quick message and we'll work out the fit together. Your rights in the event of defective goods remain unaffected.
Frequently asked questions
Why are there two numbers in the table?
The manufacturer has changed the item from A279904646 to A27NI04646. Both refer to the same pipe.
Can I re-bend the pipe to make it fit?
Please don't. The shape absorbs the thermal expansion. A re-bent pipe puts the connections under constant stress.
Are sealing rings included?
No. What you get is the pipe. Sealing rings and fittings are separate items.
Can I keep using the machine with a small steam leak?
We strongly advise against it. Steam under boiler pressure is invisible and hot, and the line runs next to live parts.
Can I see the part at your showroom?
Yes. We're in Bern at Gerberngasse 44 and in Zurich at Hagenholzstrasse 50b. Bring the removed part with you, and we'll compare it with the replacement on site so you only take home what really fits.
Questions about the fit or the serial number of your machine? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
