Sanitary pipe fittings

Food processing, pharmaceuticals manufacturing, and biological research processes are naturally
sensitive to the presence of micro-organisms such as bacteria, fungi, and algae. It is important in
these processes to ensure the absence of harmful micro-organisms, for reasons of both human health
and quality control. For this reason, the process piping and vessels in these industries is designed
first and foremost to be thoroughly cleaned without the need for disassembly. Regular cleaning and
sterilization cycles are planned and executed between production schedules (batches) to ensure no
colonies of harmful micro-organisms can grow.
A common Clean-In-Place (CIP) protocol consists of flushing all process piping and vessels with
alternating acid and caustic solutions, then washing with purified water. For increased sanitization,
a Steam-In-Place (SIP) cycle may be incorporated as well, flushing all process pipes and vessels with
hot steam to ensure the destruction of any micro-organisms.
An important design feature of any sanitary process is the elimination of any “dead ends” (often
called dead legs in the industry), crevices, or voids where fluid may collect and stagnate. This includes
any instruments contacting the process fluids. It would be unsafe, for example, to connect something
as simple as a bourdon-tube pressure gauge to a pipe carrying biologically sensitive fluid(s), since
the interior volume of the bourdon tube will act as a stagnant refuge for colonies of micro-organisms
to grow:

Instead, any pressure gauge must use an isolating diaphragm, where the process fluid pressure
is transferred to the gauge mechanism through a sterile “fill fluid” that never contacts the process
fluid:

With the isolating diaphragm in place, there are no stagnant places for process fluid to collect
and avoid flushing by CIP or SIP cycles.