A common problem I hear in the heavy duty industry today is sealing T-Joint applications effectively without the use of RTV Silicone (Room Temperature Vulcanization). Although RTV may be effective at times, most joints where this would be used are serviceable joints, which becomes an issue. When servicing these joints, the RTV needs to be scraped off hardware and re-machined, which causes issues as first fit (production) parts are often not reusable. Also there are issues where there is a multi-piece T-Joint assembly and only one segment needs to be serviced, but the technician needs to spend more time disassembling all parts before servicing due to the use of RTV. Additionally, there is always the concern of overfilling and negating the primary seal function or possibility of leak path in a joint with RTV.
To counter such issues, Parker has developed a proprietary solution - ParFab, a process which uses PIP (Press-in-Place) seals and in-house splicing technology to come up with a solution. Parker has developed a proprietary manufacturing process which uses the base elastomer (rubber compound) to splice, hence making the splice a lot better than most of the competition.
What is a T-Joint application?A T-Joint is a location in an assembly where you have three pieces of hardware coming together at right angles to each other forming the letter T in two planes. For example, in the picture shown above, the planes highlighted in blue and red form the T-Joint. It is often an issue sealing those locations as there is usually no overlap in sealing across both planes, therefore the use of RTV is used to fill the gaps.
How to seal a T-joint with a PIP seal without using RTVParker uses in-house splicing technology to create the ParFab series of seals. It is this technology that has enabled Parker to provide a PIP seal with additional pieces of rubber spliced to it to create a T-Joint sealing system with no leak paths. Since this design technology eliminates gaps between seals from the three different planes, it eliminates the use of RTV.
As shown in the FEA snapshot, the block of rubber that is spliced to the vertical plane compresses and extrudes into the PIP seal grooves in the horizontal plane, thus generating compression between the block and the PIP seal. The spliced pieces on the PIP seals in the horizontal plane help support the PIP seal when being compressed.
Parker has been able to incorporate its design experience and knowledge of PIP seals and ParFab technology to create this solution. With this solution, an RTV-less sealed T-joint is created, which can be serviced, replaced without any machining involved and is easy to install. Some key benefits are:
- Eliminates use of RTV: No RTV is needed for this solution. Hence saving time during installation both on the production lines and at dealer facilities providing aftermarket opportunities.
- Reduces installation time: When compared to competitive technology which includes multiple seals and RTV, in addition to using more fasteners, PIP Seals are easy to install and require far less load to compress, hence reducing installation time and saving money.
- Provides value add: Single out of the box solution compared to using multiple seal technologies from multiple suppliers in addition to using RTV.
- Improves serviceability due to multiple PIPs: Easy to service multi-piece T-joint sections. Disassembly of the entire T-joint is not required, hence saving time and money.
For assistance with materials or which liner seal is best for your application, please contact our Applications Engineers via our live chat service on Parker O-Ring & Engineered Seals Division's website.
This article was contributed by Vivek Sarasam, heavy duty mobile senior applications engineer Engineered Materials Group
Related content:
Sealing Fundamentals | Face Seal
Environmental Seal Enclosure 101
Racetrack Grooves: Can O-Rings be used in Non-Circular Groove Patterns?