17.1 Introduction
The main function of piping in a food processing plant is the transport of
material. Next to the transport function, piping can be used for processing of
material, for example by heating/cooling, mixing, or to provide holding time.
This chapter starts by summarising the current requirements for the design of
stainless steel piping, and then gives the possible applications of plastic and
flexible piping. The chapter also discusses the growth of microorganisms in
piping systems and the use of antimicrobial coatings and antifouling coatings.
Product recovery from piping systems is briefly discussed, followed by some
thoughts on the design of food manufacturing plant.
17.2 Pipingdesign:goodpractice
A unit of pipe is cheap and easy to clean in comparison with vessels, pumps,
extruders and other equipment. To maintain this inherent benefit of simple
cleanability some guidelines must be followed when designing pipework:
∑ Piping material should be food-grade, non-absorbent and resistant to the
product and cleaning-in-place (CIP) fluids.^1
∑ Internal surfaces should be smooth,^1 also where piping is welded.^2
∑ Couplings should be avoided when possible. The first option should be
bending followed by welding. When unavoidable, hygienic couplings should
be used^3 and a preventative maintenance scheme drawn-up for seal
replacement.
17 Improvingthe hygienicdesign of pipes
H. Hoogland, Unilever R&D Vlaardingen, The Netherlands