PTFE at the hottest point: the seal on the steam valve ball head
A steam valve is opened, closed, opened again – hundreds of times a week, and at steam temperature. This is exactly where the ball head sits, and it needs a seal that can do two things at once: seal and glide. Rubber would drag here and burn out quickly. PTFE does both better: it is unaffected by heat and glides without sticking.
The price for this is stiffness. PTFE doesn't deform like a rubber ring; it takes on its shape permanently. That's why a PTFE ring that has been installed once is no longer a usable spare part when it comes to reassembly – it no longer seals the way it should. If you open the valve, plan for this ring as well.
When it's due
The steam valve drips or hisses even when fully closed. The steam tap turns unpleasantly stiffly or noticeably loosely. A limescale trace shows at the valve outlet. Or the valve is being overhauled anyway – in which case this ring belongs on the parts list.
At a glance
| Type |
PTFE O-ring |
| Location |
Ball head of the steam valve |
| Fits |
Order by part number; our documentation does not name a specific model |
| Scope of delivery |
1 O-ring, without ball head and without valve |
| Part number |
H.1.044 |
| Version |
Cross-section 2.62 mm, inner diameter 12.37 mm, PTFE. According to the documentation, replaces the older part H.1.003 |
| Installation |
Installation by a qualified technician recommended |
| Brand |
La Marzocco |
Important for installation
A steam valve carries steam under pressure – the machine must have cooled down and be depressurised before any work is done on it. We deliberately don't give step-by-step instructions here. PTFE rings should never be forced over edges: they tend to tear rather than give. After installation, the valve is operated several times and checked for leaks during operation. If you're unsure, this job belongs in a workshop.
Who it's for
For service companies that overhaul steam valves, and for cafés where the steam tap is the most-used part of the machine. Anyone who has dealt with a dripping steam valve knows you can't just sit it out – it never gets better, only louder.
What goes with it
We continue to stock the predecessor part as the O-ring 2.62 × 13.1 mm for the steam valve ball head – compare the number in your documentation before ordering. Complete assemblies are the KB90 steam valve in version E16 H15 and the complete steam assembly for the GB5. More seals can be found in the Original spare parts section.
From our workshop in Bern and Zurich: We briefly warm PTFE rings in warm water before fitting them. This makes them a little more pliable, so they can be slid over the edge instead of tearing. And after reassembly we operate the valve a dozen times before applying pressure – this lets the ring settle evenly. This is our own routine, not a manufacturer requirement. Once the steam tap closes cleanly again, our cappuccino test is done with Nutty Delight, which works particularly well with milk. Alternatively Cozy Chocolate; everything else is in Coffee beans.
No returns
Original spare parts are excluded from exchange and return. They are sourced specifically for each order and cannot be resold once they have been installed or test-fitted on a machine. So before ordering, check your machine's model, year of manufacture and serial number – or drop us a quick message and we'll clarify the fit together. Your rights in the case of defective goods remain unaffected.
Frequently asked questions
Is this the successor to H.1.003?
According to our documentation, this part replaces the older number H.1.003. We continue to stock the old part separately. Before ordering, compare which number appears in your service documentation.
Can I use a rubber ring instead?
Not in this position. PTFE was chosen here because of the temperature and its sliding properties. A rubber ring drags, hardens and fails sooner.
Is the valve included?
No. Only the O-ring is supplied, without ball head and without valve.
My steam tap drips. Is the ring enough?
Often, yes. If the valve seat is damaged by limescale, more is needed. Send us a photo or bring the valve in, and we'll tell you honestly what it needs.
Can I see the part at your place?
Yes. Come to our showroom in Bern at Gerberngasse 44 or in Zurich at Hagenholzstrasse 50b. Bring the old ring with you and we'll compare it directly.
Not sure which of the two numbers you need? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
