Product Spotlight: SIGMA ONE-LOK™ SLDE with Re-Rounding Feature
SIGMA is pleased to highlight our innovative SIGMA ONE-LOK™ Re-Rounding Restraint. This unique product solves the issue of out-of-round pipes without requiring additional equipment on the jobsite.
When large-diameter ductile iron pipe arrives out of round, it can stall an entire operation. A spigot end that won't seat into an MJ bell results in downtime, extra labor, and the need for creative workarounds that cost money and derail the schedule. SIGMA's ONE-LOK™ SLDE restraint product line addresses this problem with a patented, built-in re-rounding feature—a revolutionary design that turns the restraint itself into an installation aid.
A Common Problem on Large-Diameter Pipe
Out-of-round conditions become increasingly common as pipe diameter increases. Large-diameter ductile iron pipe — 30" and above — is more prone to ovality from handling, shipping, and storage simply due to its size and weight. When a joint requires a ‘field cut’, the problem is made more complicated because cutting pipe on-site removes the factory-formed bell or spigot end and can leave the cut end out of round, with no built-in feature to correct it. This makes achieving a proper spigot-to-bell fit especially difficult.
SIGMA Delivers the Ideal Solution
When the ovality issue arises, SIGMA's re-rounding feature delivers a simple, cost-effective, efficient solution for out-of-round, large-diameter pipes. Available on SIGMA's larger-sized pipe restraint products (30" and above + 24” upon request), the re-rounding feature is engineered directly into the restraint gland. There's no separate tool to source, transport, or maintain — the solution is built into the product itself.
Why It Matters: Time Is Money
SIGMA's re-rounding delivers a fast, efficient, onsite solution that puts crews back to work and keeps the project moving.
The benefits:
No external equipment is required because the fix is already on the pipe.
Faster joint assembly enables crews to resolve out-of-round conditions in minutes, not hours.
Fewer delays keep installation moving on schedule.
Dual-purpose restraint and re-rounding aid are combined in a single component.
For contractors, that means less downtime, more footage installed per day, and a significant advantage on schedule-driven projects.
The Product in Action: Tucson, Arizona
Like many cities around the US, Tucson, Arizona’s water systems are reaching the end of their lifespan. As a result, the city has launched a major initiative to replace its aging infrastructure. Recently, Tucson’s South Park neighborhood was due for a transmission upgrade, and Project Superintendent Jaime Alvarez knew who to call: “SIGMA supplied us with 30” Restraints for a one-mile long water main. We have worked with SIGMA for years, and everything always runs smoothly. The products are good, the service is good, and that’s why we keep coming back.” SIGMA Territory Sales Manager Kane Connor adds, “We were able to supply our restraints with the re-rounding feature, which offered major advantages. The feature solves the problem of pipes going out-of-round, which can impair the assembly and the integrity of the system. The re-rounding feature restores the pipe to the correct shape during installation without any special equipment. Our team was able to deliver the product on time so the upgrade to the water main proceeded as planned.
Jaime continues: “The 30” Re-Rounding restraints are great, that feature really sets SIGMA apart. The ability to re-round the pipe onsite is incredibly valuable in terms of time and labor on these types of jobs.”
The ONE-LOK™ SLDE restraint is built to perform under real working conditions. The restraining gland and wedge segments act against the pipe with multiple wedge segments that increase resistance as line pressure rises — while preserving full joint flexibility and deflection after burial, across all nominal pipe sizes.
To learn more about this innovative product, please contact your regional office.