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SIGMA’s Engineering Team Devises a Solution to a Common Waterworks Infrastructure Problem: Aging Pipes 

In August 2019, SIGMA Corporation was invited by a large southeast wholesale Water Authority to put SIGMA’s 54″ Wedge Action Restraint for ductile iron through a stringent technical test. SIGMA hosted five prominent members from the Water Authority at SIGMA’s headquarters to devise a restrained joint solution for their in-ground 54″ ductile iron pipe, which had been manufactured to an outside diameter (OD) that had a different dimension to today’s industry standard OD. SIGMA’s Engineering Department for restrained joint products, headed by Satheesh Chandrasekaran, carefully investigated the situation and came up with a novel solution for the Water Authority using the existing products which included the restraint, gasket & sleeve to join both diameter pipes.

Preparations for the test were challenging as SIGMA had to incorporate a break-off top actuating bolt to accommodate the smaller OD of the ductile iron pipe. As the joint assembly would be used for a standard mechanical joint 54″ outlet, the SIGMA team had to design a modified mechanical joint sealing gasket in order to ensure proper joint compression and a leak-free assembly. With Authority members in attendance, the modified joint assembly was pressurized to 300 psi for 30 minutes without any joint separation or leakage. This engineering test was a total success.  SIGMA is the industry leader in providing Pipe Restraint Products. The company offers the largest nominal size range in the waterworks industry for ductile iron pipes, 3″ through 64″, and PVC pipes 3″ through 60″. The company’s engineering team has deep expertise in restrained joint technology. To learn how SIGMA can help troubleshoot restrained joint applications, please contact Satheesh Chandrasekaran at, Steve McDonald at, for product literature Donna Jones at