Lined Pipe for Food and Beverage Plants
The product side of a food plant is sanitary stainless and always will be. The chemical side is another matter: 50 percent caustic and concentrated nitric and phosphoric acid for clean-in-place, peracetic acid and hypochlorite for sanitation, saturated brine, sulfurous steep water and hot acidic stillage. Those streams pit 304 and 316 stainless, rust through carbon steel, and put iron into the product. Marspec Technical Products fabricates PTFE-, PVDF- and polypropylene-lined steel pipe spools and supplies the lined fittings and valves that carry them, shipping nationwide from Fairhope, Alabama. Call 251-625-4949 or contact us online.
We have lined steel pipe for more than half a century, and dairies, distilleries, corn mills and sugar factories all bring us the same problem in a different flavor.
Where lined pipe goes in a food plant
Clean-in-place chemical supply
A CIP system cleans with hot caustic at a percent or two, descales with nitric or phosphoric acid, and sanitizes with peracetic acid, hypochlorite or chlorine dioxide, cycling at roughly 140 to 170 °F. The skid dilutes from bulk, and the bulk distribution is the lined-pipe job: 50 percent caustic from the tank farm, concentrated nitric and phosphoric acid, 12.5 percent hypochlorite and peracetic acid concentrate running to skids in every department. Chloride from hypochlorite and nitric acid at strength pit stainless distribution headers first. PTFE carries caustic, nitric acid, peracetic acid and hypochlorite alike and covers a header that sees all of them; PVDF handles the acids and hypochlorite within its rating, and polypropylene-lined spools are available for caustic where a specification calls for them. Our caustic soda, nitric and mixed acids and chlorine and hypochlorite pages give the limits by liner.
Brine, whey, stillage and steep water
Cheese plants brine in saturated salt solution that picks up lactic acid and stress-cracks stainless; whey runs near pH 4.5 through evaporators and membrane plants cleaned with nitric acid. Distilleries and ethanol plants pump hot thin stillage at a pH near 4, with organic acids and chlorides that concentrate through the evaporators, and dose sulfuric acid for mash pH. Corn wet mills steep grain in sulfur dioxide water, hydrolyze starch with hydrochloric acid and regenerate sweetener ion exchange beds with acid and caustic. Breweries and wineries add tartaric and citric acid, sulfite and caustic bottle washing. Each is a chloride, acid or oxidizer service where a liner outlasts stainless; our brine and seawater page covers the brine side.
Sugar, oils, sweeteners and fermentation
Beet and cane sugar factories handle milk of lime, carbonation gas, sulfur dioxide and sulfurous acid, ion exchange regenerants and evaporator descaling chemicals. Edible oil refineries degum with phosphoric acid, refine with caustic, acidulate soapstock with sulfuric acid and bleach with acid-activated clay; biodiesel plants next door add methanol and sodium methylate. Fermentation plants making citric, lactic and amino acids run hot organic acids, sulfuric acid and ammonia through a product that is sold on its purity and color. A PTFE or PVDF liner adds no iron, nickel or chromium to any of them.
Process water, sanitation and wastewater
Plant water systems dose hypochlorite and chlorine dioxide, reverse osmosis units take acid, antiscalant and bisulfite, and packing plants spray peracetic acid and chlorinated water on the kill floor. Wastewater pretreatment adds dissolved air flotation with ferric, polymer and acid or caustic pH control, the same chemistry our water and wastewater page covers.
Liner, housing and the product-contact question
Hot CIP caustic belongs in PTFE, never PVDF, which strong caustic attacks; polypropylene is available for caustic within its 225 °F limit. Nitric acid, peracetic acid and hypochlorite are oxidizers that polypropylene does not tolerate at strength, so they go in PVDF or PTFE. Hexane and hot organic acids go in PTFE. For the housing, we recommend 304 or 316 stainless in washdown areas, because chlorinated foam cleaners rust a carbon steel housing from the outside even though the liner is untouched inside; carbon steel is fine in the tank farm. Most of what we supply to food plants carries chemicals, not product, so food-contact status rarely comes up. If a line will touch product, tell us, and we will confirm the resin and documentation for that service before we quote.
The package
Custom lined spools from 1/2" through 12" and up to 20 ft, with PTFE, PVDF or polypropylene liners in carbon steel or stainless housings, fabricated to your isometric with lined elbows, tees, reducers and instrument tees that conform dimensionally to ANSI B16.5. Pressure, vacuum and temperature ratings by liner are on our technical details page; evaporator circuits that pull vacuum are rated by size and liner.
Lined diaphragm valves are the usual choice on CIP chemical supply because they throttle, drain and have no cavity; lined ball valves give quarter-turn isolation at the tank farm; lined check valves sit at dosing pump discharges; lined sampling valves draw acid or caustic for titration. We assemble automated packages, actuators and switches mounted and tested, for CIP skids that sequence chemicals by PLC. See our lined valves page.
Lined strainers ahead of dosing pumps and spray balls, sight glasses on chemical feeds, PTFE spacers and spectacle blinds for isolating a skid, expansion joints and dip pipes are on our piping accessories page. Fifty percent caustic crystallizes near 54 °F and 85 percent phosphoric acid freezes near 70 °F, so outdoor bulk lines in most of the country get electric tracing or clamp-on steam heaters with heat-transfer compound from our temperature maintenance line, held below the liner's limit. Peracetic acid and hypochlorite are the exception: keep them cool.
Where the industry is
Wisconsin makes about a quarter of the nation's cheese across some 140 plants, Iowa leads in ethanol and corn wet milling with Cedar Rapids among the largest corn-processing cities anywhere, and Nebraska's packing plants run peracetic acid and caustic every night. Idaho's Magic Valley is one of the largest dairy processing regions in the country beside the potato and beet sugar plants, California processes most of the nation's tomatoes and wine in the Central Valley, and Louisville anchors the bourbon distilleries of Kentucky.
Standards and a quote
Our lined products comply with ASTM F1545, fittings conform dimensionally to ANSI B16.5 and are welded to ASME B31.3 by welders certified to ASME Section IX, and every lined part gets a minimum 10,000-volt spark test before it ships. Send a chemical list with concentrations and temperatures, a line list or a photo of the stainless header that pitted, and we will confirm the liner and quote spools, valves and accessories together. Call 251-625-4949 or contact us online. Custom spools fabricated in our own shop ship nationwide from Fairhope, Alabama.
FAQ: Lined Pipe for Food and Beverage Plants
Can one lined header carry both caustic and nitric acid for a CIP system?
Yes, if it is PTFE-lined. PTFE handles hot caustic and nitric acid alike, while polypropylene is for caustic only and PVDF for acid only. Plants that run separate caustic and acid headers sometimes specify polypropylene for the caustic and PVDF for the acid; we quote PTFE for both, since in a finished spool the liner is a small part of the cost.
Should the housing be stainless in a washdown area?
We recommend it. The liner protects the inside, but chlorinated foam cleaners and daily hosing rust a carbon steel housing from the outside. We supply the same lined spools in 304 or 316 stainless housings for wet areas and carbon steel for the tank farm.
Is lined pipe suitable for hot thin stillage and evaporator circuits at a distillery or ethanol plant?
It is. Stillage is hot, acidic and loaded with chlorides and organic acids, and PTFE- and PVDF-lined spools resist all of it. Evaporator circuits that pull vacuum are specified by size and liner from the ratings on our technical details page.
Will the liner contaminate a food-grade acid or sweetener?
No. PTFE and PVDF liners add no iron, nickel or chromium and nothing that discolors product, which is why fermentation and sweetener plants use them. If a line is product-contact rather than chemical supply, tell us so we can confirm the resin and documentation.