The design of the lock restraint joint in all sizes of the VRS-T® Ductile Iron pipe system provides angular deflection (360º) at every joint:

  • 5º for DN080 – DN150 sizes
  • 4º for DN200 – DN300 sizes
  • 3º for DN400 – DN500 sizes

This angular deflection, every 5 meters (16.4 ft), makes it possible to work around existing infrastructures in very tight constraints. With welded steel pipe in the same conditions it would be necessary to mitre/weld every joint.


Frequently site specific conditions require custom design of components to safely address these special conditions.   This photo shows a special expansion joint, designed/fabricated to provide axial expansion capabilities along a DN300 pipeline, because of severe slope conditions.


In the operating processes to manufacture Ductile Iron used in the VRS-T® system, special chemical additives are used to create a special balance of spheroidal graphite in all pipe and fittings in this system.   This special balance of spheroidal graphite improves the ductility and increases the lateral strength of these materials to higher levels than are available from any other manufacturers.


Extensive burst testing has been completed; and, these tests have shown that a VRS-T® lock restraint joint, which has been properly assembled/installed, will withstand bursting pressures up to 350 bars (5,075 psig).   Once the VRS-T® lock restraint joint has been properly assembled/installed, it is very difficult to damage this joint.


PNP Supply provides a wide selection of High Pressure Ductile Iron pipe and fittings, unmatched anywhere in the world market. The sizes of standard pipe and fittings range from DN080 through DN500; and, DN600 pipe and fittings, as shown in THE PHOTO, are available with special production. The range of fittings includes seventeen (17) different fittings and accessories in all sizes; refer to the Quotation Worksheet in the HOW TO ORDER section of this website.

For more information on the advantages of Ductile Iron pipe and fittings, please visit the BENEFITS page.