Flexible Sump Entry Fittings: How to choose.

Petroleum storage system parts found in secondary containment sumps and containers are subject to harsh environmental and hazardous conditions. Pipe, fittings, and detection tools are at risk of critical failure due to the corrosive nature of the liquids, vapors, and microbes typically found in that type of containment. Flexible sump entry fittings are available in a variety of materials. Here’s how ZJI fittings materials compare to common fitting materials.

Rubber & Urethane (TPU)

Rubber and Urethane have commonly been mistakenly interchanged in the petroleum industry because of their flexible, smooth to the touch properties. 

Nitrile Rubber

Buna-N, more commonly known as nitrile rubber, offers a low cost for manufacturing a flexible fitting boot. A rubber boot allows for a flexible compression seal to a pipe or sump that does not require bonding or glue. Nitrile rubber is prone to degradation from cracking as it dries out and deterioration from microbes found in sump environments. Experience has shown that nitrile rubber is likely to shrink, dry, harden, and crack – all issues related to harmful leaks and containment failures.

Urethane (TPU)

Urethane (thermoplastic polyurethane) also has a low cost (comparatively) in manufacturing and allows for a flexible boot. Urethane is often thought of as the bridge between rubber and plastic. Urethane boots also allow for a flexible compression seal to a pipe or sump that does not require bonding or glue. Urethane suffers from similar degradation factors as nitrile rubber and is prone to early failure requiring potentially expensive repairs. It has proven to degrade significantly faster in a sump environment and, upon installation, is immediately at risk of microbial corrosion commonly found in secondary containment systems. These weaknesses result in hardened, crumbling boots and potentially dangerous leak risks. 


Fiberglass (FRP) fittings offer a rigid connection at the point of entry to sumps and containers. The longevity and durability of the material is excellent in comparison to rubber. Fiberglass installation requires glues and can often require significant cure times along with ideal temperatures. Fiberglass fittings can only be installed with fiberglass piping due to glue limitations – flexible and plastic (PVC) piping cannot be used. Fiberglass fittings require precise installation angles as there is very little tolerance with the fitting rigidity. Piping is subject to movement caused by vibration, site shock, and other conditions. Movement within the sump or container can potentially create cracks in fiberglass fittings.


ProTex is a material developed specifically for the sump environment. After observing the failure of nearly all flexible boots due to material deficiencies and understanding the limitations of fiberglass fittings, ProTex was created to withstand and endure the harsh container environment. ProTex is a proprietary co-polymer blend of materials specifically designed for the petroleum industry.  The core materials have proven to last more than 30 years in similar applications.  

ProTex has been proven fully compatible with all of the typical fuel types, including E10, E15, E85, and other biofuels; it’s antimicrobial by design to remove microbial corrosion risk; it retains elasticity over time, even after stretching from the original shape; it’s highly UV resistant for greater endurance in exposed above ground environments; it can be manufactured in nearly any configuration to meet design demands for the petroleum industry.  To date, there are no known material failures in the secondary containment environment. Choose flexible sump entry fittings made with ProTex from ZJI.