Kroll & Ziller Rubber-Steel Gaskets: Engineered Sealing for Plastic and FRP Flanged Systems

Kroll and Ziller Gaskets

Introduction

When it comes to sealing plastic or fiberglass-reinforced plastic (FRP) flanges, traditional gasket solutions often fall short, leading to leaks, misalignment issues, and costly maintenance. Plastic and fibreglass materials have reduced torque ratings that make rigid gaskets inefficient and prone to leaks. 

Kroll & Ziller (K&Z), a globally trusted German manufacturer, offers an advanced solution designed specifically for these challenges. Through its Canadian master distributor, Fibreglass Solutions, K&Z's rubber-steel gaskets provide a unique combination of low-torque sealing, enhanced flexibility, and superior pressure resistance, making them ideal for industrial systems using non-metallic flanges. This blog explores the complications with conventional gaskets, the design innovations behind K&Z’s gasket technology, and the diverse applications they serve.

Why conventional gaskets fall short on plastic/FRP flanges

Plastic and FRP flanges have lower torque requirements than metallic flanges, which makes traditional gasket types—compressed non‑asbestos, spiral‑wound, PTFE—too rigid to properly seal without damage. As a result, elastomeric full‑face gaskets became standard, but they too suffer from:

  1. Poor performance with slight flange misalignment
  2. “Crimping” when stretched over flange bolt holes
  3. Misaligned bolt holes that tear the gasket during installation
  4. Installation difficulty in tight spaces since full‑face gaskets require proper alignment and placement before bolting 

These issues led field engineers to define a "wish list" for an ideal gasket:

  • Soft elastomer suitable for low torque
  • Ability to seal despite slight misalignment
  • Ring-style profile to avoid crimping
  • Easy installation, even at live tie-in points 

The K&Z Advantage: Ring gasket with rubber-steel core

Enter Kroll & Ziller rubber‑steel ring gaskets, available through Fibreglass Solutions in Canada. They deliver:

  • O‑ring–like sealing without needing grooved flanges via the O-ring profile on the inner diameter of the gasket
  • Secondary sealing due to the main crowned body of the gasket, which easily absorbs high surface pressures
  • These factors combine for a low torque sealing requirement, often under FRP flange torque ratings
  • High rigidity from a vulcanized carbon‑steel insert, increasing extrusion resistance and simplifying installation in tight spaces
  • Self-centring OD – the ring design allows for partial bolt-up before the gasket needs to be placed, ensuring easy access and fast installation
  • Reliable sealing under pressure – proven leak-free during ASME B31.3 spools up to 700–900 psig with ANSI Class 150 gaskets 

Built for real-world applications

K&Z offers gaskets from 1″ to 60″ and in a variety of elastomers— including neoprene, nitrile, EPDM, and fluoroelastomer—making upgrades and replacements seamless. Fibreglass Solutions stocks standard sizes in Canada for fast delivery.

Beyond basics: K&Z’s extended product suite

Thanks to K&Z’s German engineering, the G‑ST series includes:

  • Profiled gaskets: hybrid flat-and-profile for extra misalignment tolerance
  • Wedge rings: adjust flange gaps up to 8°, ideal for on-the-fly alignment
  • ISO kits: include insulating bolts/washers for galvanic isolation of dissimilar flanges 

They also offer custom-dimension seals with temperature-rated elastomers up to ~200 °C, for industrial, potable water, gas, hydrogen, food, and petrochemical pipelines.

Takeaway

If you're working with plastic or FRP flanged systems, Kroll & Ziller rubber-steel gaskets tick every box:

Key Feature                                                                            Benefit

Low bolt torque seal                                                              Compatible with low-torque FRP flanges

Ring profile                                                                              Prevents crimping, easy install

Steel insert                                                                             Self-aligning, rigid, pressure‑resistant

Secondary sealing lip                                                            Two levels of leak protection

Broad elastomer range                                                         Chemical and temperature adaptability

 

  • High performance, ease of use, and reliability
  • Proven in stringent ASME testing
  • Made in Germany, stocked in Canada for quick delivery

Get started!

Want to see how K&Z gaskets will perform in your system? Fibreglass Solutions offers:

  • Samples
  • In‑depth technical comparisons with full-face gaskets
  • Support for selection, design review, and system installation

Contact Us today!