The way we fixed the risk of a leak in a drinking water fitting
The problem
A pipe fitting for drinking water systems, designed to be installed — often underground — by someone working on site, not in a lab.
The original design used four separate components, sold individually:
- a brass pipe connector
- a nylon ring
- a conical rubber seal
- a threaded cap
Once assembled, the cap compressed the nylon ring against the pipe, locking it in place. But the multi-step assembly, left to the installer, created a recurring problem: the nylon ring or the conical rubber seal could be left out during assembly.
On a visible fitting, that kind of mistake is caught immediately. On a fitting that ends up buried with the pipe, it only surfaces once water starts leaking — often too late, and far more expensive to locate and fix.
The solution
We proposed rethinking the product itself, not just the material.
The first step was eliminating two separate components — the nylon ring and the conical rubber seal — and replacing them with a single part: a glass-fiber-reinforced PA6.6 insert, overmolded directly with a rubber compound certified to KTW standards for contact with drinking water. No more loose parts that need to be positioned correctly one by one: the subassembly arrives exactly as it should be, with no risk of separation or misalignment.
The second step is the one we worked on the longest, and it’s also the part we’d rather walk you through in person than spell out in writing: a design solution that smartly separates two functions — mechanically retaining the pipe and sealing against leaks — so that fluid pressure, instead of being a risk to the seal, becomes a factor that reinforces it.
The third step was our own initiative: we proposed pre-assembling the entire fitting at the factory, with the new subassembly already fitted inside the connector body (the brass components remained supplied and assembled by the customer). The result for the installer: nothing to assemble, nothing to forget. Just insert the pipe and tighten.
The result
- From 4 separate components to a single overmolded subassembly that cannot be partially assembled
- A seal that performs better under pressure, not worse — the opposite of what happens with many traditional solutions
- A single supplier for the critical component, instead of two materials to manage separately
- No chance for the installer to leave a part out
The strongest validation? The solution we developed later turned out to be original enough to be patented — an indirect but concrete acknowledgment of the work behind it.
HTP designs and manufactures overmolded rubber-to-metal and rubber-to-plastic components for technical applications where mistakes aren’t an option. Got a sealing or assembly problem keeping you up at night? Let’s talk.
Foresti Alexander
