A-LOK Primary Precast Monolithic Invert System

The A-LOK PRIMARY PRECAST INVERT SYSTEM provides an economical and efficient method of manufacturing quality concrete inverts in precast concrete manholes. The system allows the bench and invert to be formed during the initial manufacturing of the base.

The equipment consists of a cast “invert” plate which allows a 1” per foot slope across the bench to the channel. The channels are formed by interchangeable fiberglass inserts that are “quick bolted” to the cast iron dome. The inserts are constructed of full ½” fiberglass and coated with gel to promote durability against concrete's alkaline and abrasive nature. The hub areas of the insert are designed to facilitate match-ups between pipe and manhole channel inverts.


•Easily adaptable to existing casting equipment

    •Similarity to standard set-up procedures makes the system simple to use and time efficient

    •Helps control product damage by reducing in-plant handling of the product

    •Can decrease the amount of concrete poured in a base compared to adding concrete with Secondary Invert Systems

    •Simple to use

    •Time Efficient