The Evolution of the SIGMA Universal Restraint

Dennis Wilson, Technical Sales Coordinator in Conversation with Satheesh Chandrasekaran, Engineer for Restraint Products at SIGMA   

Are you curious about why SIGMA developed a Universal Restraint? 

We introduced the SLO, our Universal Restraint, at the end of last year in the Canadian market. Our engineering team, led by Stuart Box and Satheesh Chandrasekaran, brought this new product to market in record time. SIGMA engineers employed the product development concept of “recombination”. Basically, this means that you take two ‘tried and true’ products, and combine them to create a third, new product with improved functionality. This summer I sat down with Satheesh to find out how Engineering pulled off this product development coup. 

Dennis: How did the SLO come about? 

Satheesh: We received feedback from our sales team that contractors in the field would like to see a single restraint that worked on various types of pipe. They wanted something that was not specific, and that could be used on various pipe materials – steel, ductile, PVC. We visualized how such a universal restraint might behave, particularly on PVC pipe, and we were up for the challenge. 

Dennis: What was your biggest hurdle? 

Satheesh: Our team had a meeting to analyze the potential for a universal product in 2020. We needed to blend the functionality of two SIGMA wedge action restraints: the SLCE for PVC Pipe and the SLDE for Ductile Iron Pipe. This sounded easy on paper! Our toughest engineering hurdle was determining how to reconcile the difference in the wedges used for products related to different pipe materials and yet be consistent with market requirements. How could we achieve a break off torque, which on the SLDE is 80 - 90 ft-lbs, while it’s only 50-60 ft-lbs for the SLCE? We needed to find a torque range to work on both ductile and PVC. 

Dennis: How did you overcome the torque challenge? 

Satheesh: We looked for answers from a proven product, the SIGMA Universal Flange (SFU). The SFU also works on ductile iron, PVC, and steel pipe. We used the exact same engineering principles for determining the bolt torque for the SLO as for the SFU, which has been tested, and proved to work on various types of pipe.

We also used the same engineering principles for the wedges used in the SFU for the SLO - with some minor modifications to accommodate for the Mechanical Joint. We had to make changes to the insert design, based on our internal testing, and to meet the UL, and FM approval requirements. Further, in order to differentiate this restraint from the existing restraints we changed the coating color to orange. 

Dennis: What’s your proudest moment on this project? 

Satheesh: We moved quickly to bring the product to market. We had our first concept meeting to spitball the idea in March 2020, which was during the start of COVID. We released the new product in October 2022 after extensive testing and approval. Everyone worked together as a team to make it happen. And we’re pleased to offer this restraint to the Water Works Industry as a genuinely universal restraint, which will work on various types of pipe, including steel. 

We also introduced the interlocking arrangement of wedge and bolt to accommodate for the pipe hardness difference between ductile iron, PVC, and steel pipe. 

Dennis: What do you see in your crystal ball when you look into the future of Pipe Restraint Products? 

Satheesh: Canada is the first market to accept the SLO. When we were at ACE23 in Toronto the feedback was overwhelmingly positive. Canadian customers are very comfortable with the concept of a Universal Restraint. We’re talking with a number of distributors in North America about the SLO too. We expect the Waterworks Industry will embrace this type of restraint in the near future, because it will make life simpler for our customers, distributors and contractors: One restraint for various types of pipe makes sense! 

If you have a question about SIGMA’s Pipe Restraint Product line, please contact Dennis Wilson at dwilson@sigmaco.com or Satheesh Chandrasekaran at mcs@sigmaco.com.