look at this seems shielded couplings are the best for underground!
THE DIFFERENCE BETWEEN A SHIELDED AND UNSHIELDED COUPLING
The shielded coupling is manufactured with a gasket, high-torque clamps, shear ring and coupling. What makes a shielded coupling unique is that it is encased in a metal structure (shear ring) allowing it to be protected from the ground’s surrounding pressures. Shielded couplings are typically used for underground applications, but can be used above-ground where the user sees fit. Many shielded couplings are engineered to conform to performance codes for the user to easily understand the functionality and strength of the product. For example, Source One Environmental’s
SilverBack XLconforms to
CSA B602,
ASTM D 5926 and
ASTM C 1173.
Unshielded couplings are made of similar material and composition as a shielded coupling, but do not include shear rings or high-torque clamps. While they do create a leak-proof seal, unshielded couplings are not recommended to be used in underground applications where shear forces and heavy earth loads are common.
CAN YOU AFFORD NOT TO USE A SHIELDED COUPLING?
With infrastructure, no company or contractor wants to dig up a repair or newly established lead to the mainline. Improved is the reason the industry feels confident in the shielded coupling. With increased strength of the stainless steel shield and high-torque clamps, shielded couplings ensure a tighter fit to withstand any shifting, shrinking or swelling that may occur.
When installing shielded couplings, the industry can feel assured that the connection only needs to be made once, bringing a great return-on-investment with time and labor. With that, the industry cannot afford to use anything but a shielded coupling for underground applications.