Tank Outlets, Overflows & Sumps

Welded-in Fittings

A direct extension of the liner, Welded in Fittings are generally welded at the factory. However, fittings may be installed in the field using adhesive or heat seal. When piping is inserted into the tank, a strait tube is provided to fit over the pipe and sealed with a hose clamp. External fittings extend through pipe outlet with a mating flange. These fittings are generally 60 Mil or 3/32 in.

Location is critical: No stress should be applied to the outlet during installation or service.

Pump size is critical: Excess flow rate can cause a venturi effect and collapse the tube. Gravity feed is most desirable when using this type of fitting.

Bulkhead Fittings

Material – PVC – CPVC – Teflon®

Easily Installed. A compression seal is accomplished by a ring nut outside the tank. PVC fittings are available in sizes 1/2 in. through 6 in. Teflon® fittings provide excellent corrosion resistance. Because Teflon® is soft, care must be taken to not to damage threads during installation. Teflon® sizes are: 3/4 in., 1 in., 1-1/2 in. and 2 in.


Material – CPVC

Advantage: Strength. A compression seal is accomplished by stainless steel nuts and bolts. This is very desirable when a valve or pump is mounted on immediate piping. The Posi-Flange provides a female thread fitting. No metal is exposed to solution.

Overflow Skimmers

Corrosion Protection Replacing traditional overflows with rigid pipe and bulkhead fittings make for a better fitting, longer lasting and less expensive liner.


It is most desirable to install these access ports at the factory. The location of the manway is critical. Bolt holes are punched or drilled in the field to ensure that they are placed in the proper location. The manway should not be used to lift or support the liner.


Sumps are installed during liner fabrication. Correct dimensions and location of the sumps are important for a proper fit.


The perfect method for fastening liners is our WittClipTM. WittClipsTM secure the liner to the tank creating a better fit than traditional rope and grommets.

2211 E.L. Anderson Blvd.
Claremore, OK 74017


Mailing Address:
P.O. Box 488
Claremore, OK 74018-0488

Phone: (918) 342-0083
Toll Free: (800) 323-3335
Fax: (918) 342-3932

Since 1972 we have been the industry leader in providing flexible PVC corrosion resistant liners. Flexible liners are a cost effective alternative to bonded Linings and coatings. Flexible PVC liners are used in plating tanks, chemical tanks, storage tanks, waste water treatment pits, secondary containment, cooling towers, pits, sumps, solar heated water storage tanks, or anywhere liquid containment or corrosion protection is desired.

Industries served include metal finishing, plating, anodizing, aerospace, oil and gas, mining, municipal water treatment, and food and agriculture. Witt offers a variety of materials such as Koroseal®, Spectra Blue® and Exceline®.  Witt Lining Systems also offers alternatives to PVC, custom fabricating Teflon® , Kynar® PVDF , and XR-5® liners. Wiitt offers a variety of liner grades and thicknesses to suit your lining need.  Links

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