Proven long-term corrosion protection for precast concrete pipe, concrete structures, and monolithic tunnels.

T-Lock® Lining

T-Lock® is a T-ribbed polyvinyl chloride sheet lining material designed specifically to protect new concrete trunk sewers, interceptors, manholes, structures, and monolithic tunnels against hydrogen sulfide gas, acids, alkalis, salt, and other forms of corrosion. Manufactured from high-molecular-weight vinyl chloride resins that are extruded under high temperature and pressure, T-Lock provides a dense, impervious, and continuous plastic lining. Applied during concrete casting, concrete flows around the molded T-ribs and permanently locks the liner into place as a part of the substrate. Since its introduction in 1947, T-Lock has provided outstanding resistance to chemicals and abrasions as well as delamination due to high ground-water back pressure.

Arrow-Lock® Sheet Lining System

Like T-Lock, Arrow-Lock® Sheet Lining System is a continuous, impervious, plastic lining that protects concrete in new projects as well as rehabilitation projects. Composed of thermoplastic polyvinyl chloride resins, it is flexible and  can be easily shaped over intricate forms, making it ideal for manholes, lift stations, digesters, primary effluent channels, sludge wet wells, primary sedimentation tanks, and headworks. Arrow-Lock consists of two distinct products: a proprietary PVC sheet liner with arrow-shaped ribs and the Arrow-Lock mastic, a two-part epoxy used to mechanically lock the lining to the concrete substrate.

The Arrow-Lock epoxy gel mastic fills voids and mechanically locks the lining permanently into place. Arrow-Lock is designed so that the mastic does not adhere to the flat PVC lining, allowing for any possible future ground water seepage to drain away in the channels without damaging the lining.

The mastic is designed to not adhere to the Arrow-Lock Sheet Liner. The absence of an adhesive bond between the PVC lining and the intermediate mastic allows possible future ground water seepage to drain away without damaging the lining.



Eastern, Midwest, and Texas: Bob Fisher, 936-524-4167, rfisher@nwpipe.com

Northwest, Southwest, Canada, and Mexico: Michael Saltikov, 951-232-6174, msaltikov@nwpipe.com

Technical Resources: Richard D. Mielke, P.E., Director of Engineering, 919-847-6077, rmielke@nwpipe.com

T-Lock and Arrow-Lock’s unsurpassed protective capabilities and proven long-term performance can result in substantially less overall costs compared to competitive products. With a legacy of providing concrete protection for over 70 years, T-Lock and Arrow-Lock:

• Provides outstanding resistance to a broad range of highly corrosive chemicals including hydrogen sulfide and other sewer gases as well as acids, alkalis, and salts.

• Remains permanently flexible. The lining can be easily shaped over intricate forms, corners, and edges to provide complete protection in difficult areas.

• Reduces ground water infiltration significantly and is unaffected by continuous exposure to high humidity or water.

• Forms a continuous lining over the entire structure with heat welded seams and bridges structure cracks without delamination.

• Is unaffected by the actions of fungus or bacteria.

• Can be repaired quickly and easily by removing the damaged area and welding another piece in its place.

• Have inherent provisions via mechanical bonding which prevents possible future ground water seepage to drain away without damaging the lining.

Whether applying to precast concrete pipe, concrete structures, or monolithic tunnels, the installation of T-lock and Arrow-Lock is performed by factory trained contractors. The end result is an impervious, smooth-finished liner designed to protect concrete pipe and structures against severe corrosion for decades. Below are the simple steps to install T-Lock.

STEP 1: T-Lock sheets are secured to the inner forms of the pipe or structure.

STEP 2: Reinforcing is set as required and outer forms are placed.

STEP 3: Concrete is pumped.

STEP 4: After forms are removed, liner sections are connected together by placing PVC welding strips over the joints and fusing by hot air welding. For precast pipe, liner joints are welded after on-site installation.

STEP 5: When installation and welding are complete, the entire lining is inspected as required (visual, holiday tester and manual probing). Any imperfections must be repaired before placing the lining in service.