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Large-Flange™ ISO LF

Flange Installation

The primary method of fastening and sealing a Large-Flange™ is achieved by using multiple double-claw clamp assemblies to provide uniform compression of an elastomer gasket trapped between two mating flanges. The elastomer gasket is mounted on an aluminum centering ring that has tubular rims or extensions that protrude on either side of the gasket. These rims or extensions fit into centering ring locater grooves or counterbores on the corresponding mating flanges and conveniently center the gasket between the flanges prior to sealing. A reliable seal is then made by tightening bolts in an alternating crisscross pattern and thus applying uniform pressure around the entire flange sealing surface.

Large-FlangeTM double claw clamp

Typical Large-Flange™ ISO LF installation with double claw clamps


Other fastening methods include single claw clamps, bolted rotatable, bolted nonrotatable and non ISO standard MDC band clamps. Geometries for each fastening method are depicted below. 

Single claw clamps are ideally suited for applications where one of the mating flanges is flush mounted and fitted with threaded bolt holes. This is typical on most MDC gate valves constructed with Large-Flange™ ISO LF port flanges. Both the double and single claw clamp fasteners provide unlimited rotation or positioning of mating flanges prior to final tightening of bolts. 


Typical Large-Flange™ ISO LF installation with single claw clamps


Bolted rotatable adapter rings provide a convenient way of fastening claw style flanges to threaded ISO LF flanges, without the use of individual claw clamps. Rotatable bolt rings are ideally suited for use in applications where low profile geometry is required.

Rotatable bolt ring assembly


Bolted nonrotatable Large-Flange™ ISO LF flanges use bolts for fastening and are typically used where single claw fasteners are not desirable. They, too, are ideally suited for use in applications where low profile geometry is required, but do not offer rotatable construction.

Nonrotatable bolt ring assembly


Since the ISO LF standard does not provide the convenience of hinged clamping, MDC developed its own and unique band-clamp flange system that addresses this problem. The band-clamp style flanges are a modification of the Large-Flange™ ISO LF flange system. They provide the convenience of Kwik-Flange™ ISO KF hinged clamps for tube sizes from 2-1/2 to 8 inches in diameter. The band clamp uses a stainless steel strap fitted with an eye bolt and wing nut for quick assembly or disassembly. 

Typical band clamp installation

 Related Topics
 Large-Flange™ ISO LF Introduction
 Large-Flange™ ISO LF Parts Identification
 Kwik-Flange™ ISO KF Introduction
 ISO KF & LF Fittings Introduction