Increased Nominal Availability of Large-Sized ONE-LOK Wedge Action Restraint with Re-rounding Feature for Ductile Iron Pipe

Sizes 30” and 36” have been added to the existing 42”, 48”, 54”, 60”, and 64” range are now in stock and ready to ship!

SIGMA delivers an innovative and convenient solution for the common issue of ductile iron pipes becoming slightly out-of-round:  the re-rounding feature on the ONE-LOK Wedge Action Restraint.  This unique feature enables the pipe to be restored to roundness during installation without using any internal equipment such as hydraulic jacking.

Steve McDonald, SIGMA’s Pipe Restraint Product Manager, explains the significance of the “re-rounding” concept of our wedge-action restraining glands for ductile iron pipes.

“The ‘re-rounding’ feature is a patented and revolutionary feature because it provides a solution for the occasional event when larger diameter ductile iron pipes onsite experience out-of-round or ovality issues. The re-rounding capability allows for immediate reconciliation of the ductile iron pipe’s diameter and ensures proper restrained joint assembly at time of installation. When required to utilize this re-rounding feature, the installer or contractor can bring the pipe back to its normal outside diameter, thus enabling the pipe spigot end to fit appropriately into the mechanical joint outlet or ductile iron pipe bell. No internal equipment is required, such as hydraulic jacking, that can cause damage to the integrity of the standard cement mortar linings or more expensive interior coatings.”

For information about this or other SIGMA Pipe Restraint Products, please contact Steve McDonald at