SEMINAR ON

“HYGIENIC PIPING”

PRESENTED BY :Jyoti Valodra

What will the piping engineer learn ?

1. What is the purpose of hygienic piping?

2. How to apply general piping engineering principles for the hygiene sector 3. Comparison of steel pipe vs glass/plastic.

4. Hygienic piping standards?

2. Introduction

Hygienic piping finds application in Food, Pharma and Beverage industry. Due to the increase in automation, on-line CIP has come into existence in these sectors. In hygiene systems, about 4/3rd time is spent on process engineering and 2/3rd time is devoted for the cleaning and disinfection process. All surfaces in contact with the product (say food) must be inert to the product under the conditions, of use and must not be caught, migrate to or be absorbed by the product

* BASIC ASPECTS OF HYGIENIC DESIGN & MANUFACTURE INCLUDE :1.HYGIENIC MATERIALS AND SURFACES2.DRAINABILITY3.CLEANABILITY4.AVOIDANCE OF DEAD SPACES

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Hygienic piping installation Clean-in-place

• All surfaces in contact with food must be smooth and non-porous so that tiny particles of product, bacteria, or insect eggs are not caught in microscopic surface crevices and become difficult to distodge, thus becoming a potential source of contamination.

• Mechanical considerations of the cleaning-in-place process are seldom of significance. Adhesive forces must be considerably reduced during cleaning; this is most often accomplished chemically. Surface active detergents have to be able to overcome capillary forces. The composition of the ions in solution also influences the Vander Waals forces and the electrostatic forces.

2. Application of Hygine Piping

Food, Pharma and Beverage Industry: Due to the increase in automation, online CIP has come into existence. In hygiene systems, about 1/3rd time is spent on process engineering and 2/3rd time is devoted for cleaning and disinfection process. The main aim of hygiene piping engineering is to produce a safe product.

3. Pipes

One problem that arises in piping design of hygienic systems is that the ASME B31.3 Process Piping Code does not provide stress intensification factors for ASME BPE fittings which are designed/manufactured differently than the ASME B16.9 fittings used by Markl in determination of the ASME SIFs. This means that diligent designers have to use judgment in applying the B31.3 code. Have any authorities noted concerns with fatigue cracking in bio/pharm piping components: 1) cracks that have resulted in piping failures, or 2 inadequate sterilization?) cracks that can contribute to inadequate sterilization?

Standard followed: DIN 11850/ ISO 2037. The piping layout helps to determine the functional safety of the product transport. It is important that all parts in the network receive an equally intense treatment with the cleaning detergents, and that the pipe network can run completely empty.

4. Materials of construction

Materials used in the construction of Hygienic piping must fulfil certain specific requirements. 4.1 Non-toxicity4.2 Stainless steel4.3 Polymeric materials

4.1 Non-toxicity As the presence of toxic elements in the food is unacceptable, the designer has to take care that only non-toxic materials of construction are used in direct contact with the product. Stainless steels are the logical choice for materials of construction for process plant in the food industry but, depending on the application, some polymeric materials may have advantages over stainless steel such as lower cost and weight or better chemical resistance. However, their non-toxicity

4.2 Stainless steel

Generally stainless steels offer excellent corrosion protection, and they are therefore widely used in the food industry. The range of stainless steels available is extensive and the selection of the most appropriate grade will depend on the corrosive properties (in terms not only of the chemical ions involved but also the pH and the temperature) of the process and of the cleaning and antimicrobial chemicals. However, the choice will also be influenced by the stresses to which the steel will be subjected and its machinability, formability, weldability, hardness and cost.

AISI, DIN and EN designations of stainless steels commonly used in the food industry are given in Table .

AISI DIN/EN Typical analyses     C% Cr% Ni% Mo% Ti% N%

304L eg: DIN 1.4307 (EN X2CrNi18-9) < 0.03 18 9      

316L eg: DIN 1.4435 (EN X2CrNiMo18-14-3)

< 0.03 18 14 3    

410 DIN 1.4006 (EN X12Cr13) < 0.12 13 < 0.75      

409 DIN 1.4512 (EN X2CrTi12) < 0.03 11.5     < 0.65  

329 DIN 1.4460 (EN X3CrNiMoN27-5-2) < 0.05 27 5.5 1.7   < 0.20

4.3 Polymeric materials

When choosing polymeric materials the following criteria should be considered: •Compliance with regulatory requirements and recommendations •Compatibility with food stuffs and ingredients (chemical resistance to oil, fat, preservatives) •Chemical resistance (cleaning and disinfectants) •Temperature resistance in use (upper and lower use temperature) •Steam resistance (CIP / SIP) •Stress-crack resistance •Hydrophobicity / reactivity of the surface •Cleanability, effect of surface structure and smoothness, residue accumulation •Adsorption / desorption •Leaching •Hardness •Resilience •Cold flow resistance •Abrasion resistance Processing technology (injection moulding, melt-extrusion, transfer-moulding, paste-extrusion, welding, various coating technologies)

If considering the use of Polytetrafluoroethylene (PTFE), it must be taken into account that PTFE can be porous and difficult to clean. But certain grades of modified PTFE and fully fluorinated co-polymers such as PFA have been proven to meet EHEDG requirements for cleanability.

5. Precautions in Hygiene Pipe Engineering a) It is difficult to clean dead water zones where the vessels connect to the main pipe. The use of double sealed vaIves or short T-pieces can avoid these dead water zones. b) Leftover product in bent sections of pipe: A bend in the pipe can be avoided by stationing the supports sufficiently close to one another.c) Product leftover in front of symmetrical reducations: Left - over product can be avoided by using asymmetrical reductions.

6. Good Sanitary Hygienic Design is Essential if

• The product is to be protected from microbial or other contamination. • Cleaning effectiveness is to be maximised and cleaning costs reduced.

7. Basic Principles of Sanitary Design

• AII surfaces in contact with the product (say food) must be inert to the product under the conditions of use and must not migrate to or be absorbed by the product. • All surfaces in contact with food must be smooth and non-porous so that tiny particles of product, bacteria, or insect eggs are not caught in microscopic surface crevices and become difficult to dislodge, becoming a potential source of contamination. • All surfaces in contact with the product must be visible for inspection or it must be demonstrated that routine cleaning procedures eliminate the possibility of contamination from bacteria/insects.• All surfaces in contact with the product must be readily accessible for manual cleaning or if not readily accessible, be readily disassembled for manual cleaning, or if CIP techniques are used, it must be demonstrated that the results achieved without being disassembled for manual cleaning, or if CIP techniques are used, it must be demonstrated that the results achieved without disassembly are the equivalent of those obtained with disassembly and manual cleaning.• All interior surfaces in contact with the product must be so arranged that the equipment/piping is self employing or self draining.• The piping must be so designed as to protect the contents from external contamination.• The exterior or non-product contact surfaces should be arranged to prevent harbouring of soils, bacteria or pests in and on the equipment itself as well as in its contact with other equipment, floors, walls or hanging supports.• In design, construction, installation and maintenance, it is important to avoid dead space or other conditions which trap food, prevent effective cleaning and may allow microbial growth to take place.

8. Pipe Unions

Pipe unions present a weak point in any system. The DIN 11851 standard is used for pipe fittings. In hygiene piping design, welded bonds provide an optimum safety when they are the result of inert gas welding. Should a solid joint not be desired on whatever technical grounds, screw or clamp joints now come into consideration.

Elbow Tee Tee U type ReducerCross

Hose Coupling

The standard design for a stainless screwed pipe connection (DIN 11851) requires a profile jacket. In this type of construction, there is always a crack between the socket and the thread. This disadvantage can be avoided by using a special profile gasket. An alternative is a clamp union. so-called tri-clamp. This consists of two identical clamp ferrules and a profile gasket, and is designed to avoid cracks, having been pre-stressed at a designed tension. The clamp joint can also be opened and closed without using a tool.

8. ValvesMainly butterfly or plug valves are used for hygiene application.

Butterfly Valve Butterfly Valve with Pneumatic Actuator

Diaphragm Valve Check Valve Reversal ValveBall Valve

9. Pipe Work

This requires good sanitary design and installation because apart from conveying material it is part of the ‘overheads’ which collect dust and dirt. Badly installed or maintained pipe work can be expected to leak and may be a source of direct contamination or, if the material is suitable, e.g. liquid sugar, be a pest, control problem. Also, pipes going to and from the flow plate should be stopped otherwise it will contribute to the wastage of the product. The type of support used is important to minimise dirt accumulation and making cleaning quicker. Piping should be installed at least 150 mm (6") from walls and floor to provide for thorough cleaning around it.When a pipeline is being installed which has couplings that use gaskets, be sure that the correct gasket is used and that the pipe work and coupling are both correctly aligned and tightened.

10. Sanitary Pumps

Pumps are so made that the impellers, gears or pistons can be easily removed for cleaning, thus making them adaptable for handling hygiene products. The pump may be fitted with a friction seal, instead of packing, and the body and rotors of the pumps are made of white metal, bronze or stainless steel. The pump housing is fitted with sanitary pipe connections.

Self-Priming Pump Centrifugal Pump Rotor Pump (Lobe Pump)

Surface treatment Approx. Ra values (µm)

Typical features of the technique

Hot rolling > 4 Unbroken surface

Cold rolling 0.2 - 0.5 Smooth unbroken surface

Glass bead blasting < 1.2 Surface rupturing

Ceramic blasting < 1.2 Surface rupturing

Micropeening < 1 Deformed (peened) surface irregularities

Descaling 0.6 – 1.3 Crevices depending on initial surface

Pickling 0.5 – 1.0 High peaks, deep valleys

Electropolishing   Rounds off peaks without necessarily improving Ra

Mechanical polishing with aluminium oxide or silicon carbide

Abrasive grit number 500 320 240 180 120 60

0.1 – 0.250.15 – 0.4 0.2 – 0.5 = 0.6 = 1.1 = 3.5

Surface topography highly dependent on process parameters, such as belt speed and pressure.

10. Surface Finish

Examples of surface treatments of stainless steel and resulting surface topography

3A standards:

The construction site of a modern biopharmaceutical, pharmaceutical or even some dairy plants today would present a very different picture than a similar site 20 years ago. Improvements in both hygienic design and installation practices have made enormous strides in this time period and much of this is the result of volunteer work on several industrial Standard Committees.

The ASME Bioprocessing Equipment (BPE) StandardIn 1988, the Standard used for installation of process piping systems in both the Dairy Industry and the Pharmaceutical Industry in the USA was the 3-A Sanitary Standard. The 3-A ‘program’ was introduced by the US Public Health Service in 1944, and in 1954, the use of the 3-A Symbol was initiated to show that processing equipment marked with the symbol met certain material, design and fabrication standards for cleanability and inspection.The increasingly stringent hygienic requirements of the evolving biotechnology sector led to the writing of a new Standard under the auspices of the American Society of Mechanical Engineers, namely the ‘ASME Bioprocessing Equipment (BPE) Standard’. The first edition was published in 1997, with revisions in 2002, 2005 and 2007. A 2009 edition will be released later this year.The BPE Standard deals with the requirements of the bioprocessing and pharmaceutical industries, as well as other applications with relatively high levels of hygienic requirements or bioburden control. BPE covers directly or indirectly the subjects of design of process equipment for cleanability and sterility, component manufacture, materials of construction, fabrication including welding, pressure systems (vessels and piping), examinations, inspections, testing and certifications. The BPE Standard applies only to those systems and components that are in direct or indirect contact with the product. It does not apply to those components that are not in contact with the finished product or part of the intermediate manufacturing stages. The BPE is an American National Standard that, by 2002, had become an adopted International Standard referenced in 29 countries.

11. How to Avoid Contamination? One of the common features of poor sanitary design is the existence of inherent ‘dead spots’ or ‘dead ends’. They are better described as ‘filth traps’. It needs to be remembered that micro-organisms are very small, and that what is visually small to a human are to microbes the ‘ wide open spaces’ where they can multiply. Furthermore, if the cleaning does not remove material because design features shield it, then this becomes a ‘designed in’ source of contamination. It is therefore axiomatic that sharp corners, crevices and dead ends anywhere in the product are unsanitary.

12. How to Simplify Cleaning? Both design and installation are important to achieve this aim. Good sanitary design plus good installation , maintenance and cleaning makes possible maximum efficiency and cost effectiveness.

3A Standards for Centrifugal and Positive Rotary Type PumpsA. Material1. All metal pump parts having any surface in contact with the product shall be constructed of metal consisting of stainless steel, nickel alloy, or equally corrosion resistant material that is non-toxic and nonabsorbent. a) All product-contact surfaces shall be finished to an equivalent of not less than, 120 grit finish property applied.b) All outside surfaces shall be smooth and easily cleanable.2. Exteriors of structural parts not in contact with the product shall be of corrosion resistant material with E: smooth finish or shall be rendered corrosion resistant or painted and shall be so constructed as to be easily cleanable.B. Construction1. Openings: Inlets and outlets shall confirm with the 3A sanitary standards for fittings. 2. Shaft seal: Seal shall be of the sanitary type easily removable for inspection and cleaning, and shall be constructed of material not injurious to food products. 3. Gaskets: Single-service gaskets of the sanitary type or removable rubber type gaskets that can be easily cleaned shall be used

13. Hygienic Design Standards

14. Glass Pipe and Fittings Glass sanitary pipe made at a special tough pyrex glass is available in the market and a good many successful installations are in use in United States basically for the dairy industry. The glass pipe is of interest for two principal reasons: first as a substitute for stainless steel and, second because it can be used in many locations without dismantling for cleaning, thereby saving considerable labour in clean-up time. The transparent nature of the glass makes it possible to examine the pipe visually after cleaning by circulatory methods, and detect deposits if there are any. Standard stock sizes are 1,11/2.2.3.4,6 inches inside diameter. Lengths are 10 feet; longer or shorter are special. Normal operating temp: 0 -212 degF. 15. Plastic Pipe and Tubing Plastic sanitary tubing is now available in a variety of sizes from 1/8 to 4 inches inside diameter and in different weights. A popular brand Tygon B44 - 4X, for example is designed to convey processed milk and milk products. It is claimed to be non-toxic, fully transparent, and flexible at temp. below, 0 degF. It will withstand temperature of sterilisation; it is resistant to milk and food acids and strong sanitising agents. The following are standard sizes: 1", 1 ½”, 2",2½”, 3" and 4".

16. Welding of Sanitary Pipe, Fittings The sanitary stainless steel pipe was first used commercially with welded fittings around 1948.

Orbital welding

For critical pharmaceutical piping systems, it is better, when possible, to use orbital welding because of the superior quality of the welds and the repeatability of the process. Orbital welding provides precise control of the heat input into the weld that cannot be duplicated with manual processes and generally results in better corrosion resistance than manual welding. In situations where the use of orbital welding would create a deadleg or an unacceptable L/D, however, manual welding is preferred.

The orbital welding power supply employs pulsed arc GTAW (gas tungsten arc welding), formerly known as TIG (tungsten inert gas). Weld parameters, controlled by the power supply, include primary and background values of pulsed welding current, primary and background

Weld criteria facilitate hygienic designThe MJSC developed a set of weld criteria that, in addition to code criteria for adequate structural integrity, was designed to minimise the growth of microorganisms and promote cleanability. Orbital welds are smoother than manual welds and, when done properly, are free from crevices, pits and other defects that could harbour microorganisms. All welds must have complete penetration to the inside surface of the weld which, in bioprocess applications, is usually the surface that has contact with the product. Unpenetrated welds are entrapment sites for product and are difficult to clean. Process piping lines are sloped for drainability as gravity is the most efficient means of draining fluid from a system. Limits on inside diameter (ID) and outside diameter (OD) concavity and misalignment are set to promote drainability and cleanability of weld surfaces.

• Some important terms: • Cleaning and Sanitising (or disinfection): Cleaning and sanitising are technologically distinct operations. However, since the objective is to achieve chemical, physical and microbiological cleanliness the combined operations are sometimes called cleansing, a term which is used in some milk and dairy legislation. Note that cleaning system components have both cleaning and sanitising functions. • Bactericide: A chemical agent which under defined conditions of use is capable of killing bacterial cells, but not necessarily bacterial spores. It is important to understand that the use of a bactericide will not effectively remedy poor cleaning. • Bacteriostat: A chemical agent which under defined conditions of use inhibits the increase in numbers of a bacterial population • Break point chlorination: The point at which the chlorine demand of a water has been reached, after which the free residual chlorine concentration increases in nearly direct proportion to additional amounts of chlorine added. • Buffer: A chemical agent or agents in solution which stabilise the pH. This is a measure of the acidity or alkalinity of the solution. During cleaning the pH of a buffered cleaner is not much changed by dilution or small amounts of soil. E.g. acidic tomato paste. • Chelating power: This enables a cleaning solution to hold unwanted ions, such as calcium and magnesium , in solution or to re-dissolve precipitated salts. This property is important with hard waters , as calcium and magnesium can interfere with cleaning and rinsing.

• Clean Out of Place ( COP) Remove food products and open containers from the area surrounding the equipment to be cleaned. Dismantle the equipment to expose the surfaces to be cleaned.• Clean in Place ( CIP) CIP is mainly used for cleaning liquid handling systems. It comprises a number of steps: 1. Drain the system of product. 2. Prepare the circuit(s), e.g. by switching controls to ‘clean’, installing key pieces or flowplates, confirming availability of detergents, etc. 3. Pre-rinse to remove product residues (gross soil) 4. Circulate hot detergent to remove residual soil. 5. Rinse with potable water of suitable quality. This rinse is the intermediate rinse if chemical sanitising and / or acid scale removal is included in the CIP cleaning. It is the final rinse if there is no further step in the CIP cleaning. 6. Sanitise to reduce microbial numbers to an acceptable level. 7. Final rinse with potable water of suitable quality. • Cleaning of Complex Systems In complex cleaning systems which are often large, a mixture of COP and CIP methods outlined above are usually used. • Assessment of Cleaning There is a great deal more to assessment than simple visual inspection although this plays an essential part. The first issue to address is ‘ what must cleaning deliver?’

Summing Up We have seen in this lesson about the importance of a hygienic piping system and the role of piping engineer in it. It is concluded that with proper hygienic engineering, we can serve humanity with safe products in food/ pharmaceuticals and the agro sector.

References Thermal Insulation 1. H.F. Rase and M.H. Barrow, Project Engineering of Process Plants, John Wiley & Sons Inc., New York , 1957 , PP: 476-479 2. W.C. Turner and J.F. Malloy, Thermal Insulation Handbook, Robert E., Krieger Publishing Co. Malabar, McGraw-Hill book Co., New York, 1981, PP 212-263 Hygenic Piping Engineering 1. NFPA FPI ( 1989) Canned Foods – Principles of Thermal Process Control, 5th Ed., The Food Processors Institute, 1401 NY 2. Stumbo, C.R. (1973) , Thermobacteriology in Food Processing, 2nd Edn., NewYork Academic Press. 3. Shapton D.A. & Hindes W.R. (1965), Some aspects Post Processing Infection in Proceedings of the Ist International Congress Of Food Science and Technology 1962 , Vol 4, edited by J.M. Leitch.