Plastic Lined Pipe Fittings in Tennessee

Four streams set the terms for lined fittings in Tennessee. Hot acetic anhydride runs in Kingsport, wet chlorine on the Hiwassee, sodium hypochlorite on Presidents Island and concentrated sulfuric acid on the Cumberland. Each one fails a fitting in a different way.

From Fairhope, Alabama, Marspec Technical Products has supplied lined piping for more than half a century. We supply lined fittings in PTFE, PVDF and polypropylene and fabricate the custom spools that join them. Call (251) 625-4949 or contact us online with a fitting schedule.

Where Tennessee fittings meet their limits

Kingsport: keep the acid liquid

The Kingsport chemical site puts about 900 acres of plant on a 4,000-acre property. It has made acetic anhydride and acetic acid from coal since 1983. PTFE is the liner for both at process temperature, because PVDF is limited in hot concentrated acetic acid. Glacial acetic acid freezes near 62 °F, which makes outdoor elbows and tees on that service candidates for fully jacketed fittings. Our Kingsport page covers the rest of the Tri-Cities.

Charleston: let the chlorine out

On the Hiwassee River at Charleston, a membrane-cell chlor-alkali plant has about 200,000 tons of capacity. The cells split sodium and potassium chloride brines into chlorine, caustic soda and potassium hydroxide. Wet chlorine slowly permeates PTFE, so fittings on those lines need vented housings. Caustic and potassium hydroxide run above pH 12, which keeps PVDF off them. Fifty percent caustic starts to solidify around 54 °F, a second case for jacketed fittings. The Chattanooga page covers the polysilicon plant next door.

Memphis: nothing for hypochlorite to touch

Presidents Island has a sodium hypochlorite and caustic soda plant on 26 acres, with its own barge terminal. Iron, nickel and copper decompose hypochlorite, so a fitting needs an unbroken liner from flange face to flange face. Commercial 12.5 percent bleach runs at about pH 12 to 13, which puts it on PTFE. Our Memphis page covers the port's refinery and terminals.

Clarksville: where turbulence strips steel

Beside the Cumberland southwest of Clarksville, a zinc smelter commissioned in 1978 roasts, leaches and electrolyzes zinc concentrate and sells sulfuric acid as a by-product. Carbon steel holds concentrated sulfuric acid in slow, straight runs. Turbulence at elbows, tees and pump outlets strips its protective sulfate film, which is why the fittings fail first. PVDF handles the acid to about 93 percent at ambient; 98 percent acid goes to PTFE.

The fittings we supply

To change direction: 90° and 45° elbows and 90° reducing elbows. To branch: tees in equal and reducing sizes, reducing run tees, laterals, standard crosses, and short-stack tees and crosses. To measure: standard and lug-body instrument tees for temperature, pH and pressure instruments.

To change size or close a line: eccentric and concentric reducers, reducing flanges, including scalloped and straight-bore designs, and blind flanges. To make up a joint or hold heat: solid and armored spacers, and fully jacketed fittings that match jacketed spools. Custom lined spools run to 20 ft from our own shop.

PTFE-lined fittings in carbon steel and stainless steel housings are stocked, with PVDF and polypropylene lined to order. Every shape and its dimension table is on our lined pipe and fittings page; liner wall thickness and bolt torques are on Technical Details.

Jacketed fittings are one answer to an East Tennessee winter; clamp-on steam heaters and electric tracing are on our temperature maintenance page. Valves for the same lines are on our lined valves page and the Tennessee valve page.

Ordering a fitting that fits the old one

Replacement work usually starts with a fitting someone has already pulled. Confirm these before you call:

• Flange class, 150 or 300, and whether the old fitting had rotating or fixed flanges
• Liner material, from the flange markings or the line's piping specification
• Housing material, carbon steel or 304/316 stainless, and the jacket connections on a jacketed fitting
• Center-to-face or face-to-face length; our fittings follow ANSI B16.5 dimensions, so a standard shape fits a standard gap

A 1/2" spacer goes between a fitting and a valve whose raised faces differ in diameter. Spacers, strainers and sight glasses are also on the Tennessee accessories page.

Standards behind each fitting

Our lined pipe and fittings comply with ASTM F1545. The lined fittings we supply are welded to ASME B31.3 by welders certified to ASME Section IX. Every lined spool and fitting is spark tested at a minimum of 10,000 volts. Lined fittings carry identifying markings on their flanges in accordance with ASTM F1545.

From Memphis to the Tri-Cities

We ship to Memphis, Millington, Jackson, Clarksville, Nashville, Columbia, Chattanooga, Cleveland, Charleston, Knoxville, Oak Ridge, Kingsport, Johnson City and Bristol. Tell us your required date when you request a quote. Call (251) 625-4949 or contact us online, and see our state page for the wider industrial picture.

FAQ: Plastic Lined Pipe Fittings in Tennessee

Should acetic anhydride fittings at a Kingsport unit be PTFE or PVDF?

PTFE. PVDF is limited in hot concentrated acetic acid, while PTFE handles the acetyl streams at process temperature. Where glacial acid can freeze outdoors, use jacketed fittings or tracing.

Why do chlorine fittings at a Charleston-area plant need vented housings?

Wet chlorine slowly permeates a PTFE liner. The vents let it escape from behind the liner instead of collecting against the steel, so they must stay open through painting and insulating.

Which liner do you recommend for hypochlorite fittings in Memphis?

PTFE. Commercial 12.5 percent bleach holds excess caustic and runs at about pH 12 to 13, beyond PVDF's range. PVDF fits only dilute or lower-pH hypochlorite, and polypropylene is never used on it.

Carbon steel is common on concentrated sulfuric acid. Why line the fittings around Clarksville?

Steel survives concentrated acid only at low velocity, and it fails first at elbows, tees and pump outlets where turbulence strips its sulfate film. Lined fittings remove that limit, with PTFE for 98 percent acid.