As a mechanical engineer who worked for years in the heating ventilation and cooling industry, Gunter Schlicht recognized the benefits of the convoluted flange as a lighter weight,easier to handle product than the standard flange. He also saw it as an opportunity to improve the performance and economic feasibility of flange connections in the thermoplastic piping industry. At the time, the convoluted flange was only available in Europe, so he set out to bring it to the USA.

Improved Piping Products, Inc. (IPP) was founded in 1979 by Gunter and Susan Schlicht as
a California corporation and is a privately held family business.

The first iteration of the convoluted flange had an even cross sectional wall thickness which Mr. Schlicht later found, through finite element analysis, resulted in varying pressure ratings from size to size. Using the same analytical software, he determined the exact critical load bearing areas and allocated more material mass in order to bring the product into compliance with the code, optimize the weight and provide a safety factor of 2 for each size. These products are marketed under the label IPP Deltaflex® and are available in a variety of materials, from ductile iron to stainless steel to polypropylene.

Serving Customers World-Wide

Improved Piping Products’ fittings are sold to customers world-wide in the following industries:


Water Service
Waste Treatment
Plant Process

Pulp and Paper

A Complete Line of HDPE Fittings

After nearly two decades in production of metallic products for the thermoplastic industry, the company launched its first HDPE fittings in the late nineties with an offering of small
diameter Flange Adapters. Over the years, IPP has expanded its sizes and pressure ratings and now offers a full line of straight-line fittings in all sizes, from ½” to 63” (2”- 63” for HDPE parts), including our unique, patented Deltaflex® flanges. Learn more about our quality piping products.

In 2008, IPP opened a 45,000 square foot HDPE production facility in San Antonio, Texas, providing the HDPE pipe industry with Flange Adapters, MJ Adapters, Reducers and other straight-line HDPE fittings, in sizes 16” through 63”. Then, in August of 2010, IPP expanded its presence in San Antonio with the acquisition of a 55,000 square foot warehouse. It now serves as the main IPP distribution hub, offering 24 hour shipping with no expedite fees for in-stock products. Learn more about our shipping policy.

Thanks to our team of dedicated employees and a tremendous vote of confidence from our customers, IPP continues to provide high quality, economical, highly engineered piping
products for the thermoplastic industry after more than 30 years since inception.

Industry Involvement and Certifications

IPP is a member of the Plastics Pipe Institute, an organization dedicated to furthering the use of HDPE pipe. IPP’s team also regularly attends meetings of the American Society of
Mechanical Engineers (ASME).

IPP’s products have all been tested and approved by the National Sanitation Foundation (NSF) for the delivery of potable drinking water.