RTV Silicone Sealing Method for Component Interfaces

NASA designed an inflatable habitat intended for space whose exterior incorporates an expandable layer known as the bladder – the main pressure shell of a module to which astronauts may reside while off-world. The bladder is made from a polymer material and is surrounded by protective layers to ensure it is not damaged and does not leak. On every module, there are two areas where the bladder and other flexible layers interface with the ends of a cylindrical core, at the bulkheads. Seals between the non-metallic bladder and the metallic bulkhead are critical in maintaining a safe pressurized environment for astronauts to live and work. With both bulkhead plates assembled, RTV silicone is deposited in specially designed channels which are sandwiched between the plates. After the channels are filled, a cure-in-place seal is formed between the bladder and the bulkhead. The RTV sealing method worked successfully during prototype testing as confirmed by a helium leak test and post-test visual inspection of the seals. In prototype testing, this method created a consistent and reliable seal between the bladder and bulkhead assembly replicated from the inflatable module design. The RTV sealing method may benefit terrestrial applications that may demand cure-in-place internal seals. The method could also innovate manufacturing processes for components by enhancing the speed of assembly while increasing seal integrity. Innovators at NASA Johnson Space Center have developed a method using low-viscosity RTV silicone to form durable seals between polymer bladder and metal bulkhead interfaces to be used for inflatable space habitats. As NASA continues to research the viability of inflatable space habitats made with flexible materials, much consideration is given to reliably maintain pressurized environments for astronauts through the use of advanced seals. In early inflatable test articles, seals between bladder and bulkhead interfaces were achieved using a combination of O-rings and gaskets alone. However, when planning for long duration missions, there was a concern that the compressive force of an O-ring could create a line load on the bladder and cause potential failure of the bladder material and overall seal. An RTV silicone sealing method was developed as a solution to this problem, and works with an arrangement of O-rings and gaskets that act as a dam to form a channel that maintains the placement of the RTV silicone. The RTV silicone sealing method may have commercial applications here on Earth as it can yield a cure-in-place seal that can form-fits to a complex channel. This sealing method has a technology readiness level (TRL) 5 (Component and/or breadboard validation in relevant environment) and is now available for patent licensing. Please note that NASA does not manufacture products itself for commercial sale.