National Grooved piping system is reliable and is faster to install than welding, threading or flanging,

resulting in lowest installed cost. It can be adopted to suit standard pipe with cut grooves or standard

and light wall pipe with rolled grooves. Triple sealing of the (-shaped pressure responsive gasket is

made from specially compounded rubbers with low compression set property. Couplings perform

equally well under pressure and vacuum. Couplings with Tri-seal gaskets are highly suitable for

higher vacuum service and dry systems subject to freezing. Couplings are available for flexible and

rigid system. Grooved end fitting are machined to AWWA C606 cut groove standard Products are

offered with RAL 3000 alkyl enamel rust preventive paint as standard and hot dipped galvanised

coating is available optionally.

HOUSINGS

Ductile iron housing segments conforming to ASTM-A 536 Grade 65-45-12 fully enclose the gasket. The housing keys

engage into the grooves around the full pipe circumference, securing the pipe ends together with a positive grip.

Housings are normally two identical castings for couplings through 12" (323.9 mm) sizes. From 14" (355.6 mm) up sizes, coupling housings are cast in multiple identical segments to ensure concentricity and easy handling. The housing is designed to provide the optimum combination of pressure, stress relief and end load conditions while maintaining

reasonable weight and manufacturing characteristics. Every grooved pipe coupling , flange adaptor, reducing coupling

has a similar key section. This engages fully into the groove tying the joint integrally to the pipe.

GASKETS

The sealing efficiency of gaskets is such that the Gasket forms an initial seal as it is stretched over the pipe

Ends. As the housing segments are installed and secured the pressure responsive gasket is slightly compressed to

form a leak-tight joint. The strength of the seal is further enhanced by internal line pressure that creates downward

pressure on the lips of the gasket. The gasket also seals well under vacuum conditions up to 1 OinHg (-0.35 Bar) which

may occur when a system is drained. Please refer to the Gasket selection guide for additional details and gasket

materials. Gasket are pre-lubricated for easy assembly of coupling.

BOLTS AND NUTS

Oval neck track bolt conforming to ASTM A 183 with minimum tensile strength of 110,000 psi or square neck

carriage bolt to ASTM A449 with 120,000 psi minimum tensile strength permits tightening of the nuts from one

side with a single wrench. Nuts conform to ASTM A 194. Bolts & Nuts are electro galvanized to ASTM B 695.