Details of HIF Design
View HIF Definitions
View Installation Instructions
Pipe Spool Connection
The High Integrity Flange connection used to join plastic lined pipe
spools to pipe spool consists of a passive and an active end, joined
together through a steel Load Bearing Ring.
The passive end is similar to the end of a standard pipe spool or fitting
except that if the end is of lap-joint or raised-face construction, and the
diameter of the metal flare on the pipe end or of the raised-face is
The active end consists of a Belleville Washer(s) (Coned Disc Spring) and
a Flat Washer (Force Distribution Ring) assembled behind the flare of the
At installation, the Load Bearing Ring is inserted between the metal faces
of the flanges or flared ends of the pipe. The joint is then bolted
together in the usual manner, except that the nuts and bolts are secured
with high torque values, thus establishing a highly preloaded assembly
with metal to metal carry-through of the structural load.
The Belleville Washer deflects during the boltup and, acting through
the Flat Washer, applies a predetermined, optimum sealing load to the
flared faces of the liners.
Fitting to Fitting Connections
All fittings in the High Integrity Flange system have passive ends. As
with the passive ends of pipe spools, if the end of a fitting is of the
lap-joint design, the diameter of the metal flare must be little larger
than with standard piping.
When a fitting is to be connected to a pipe spool, the adjacent face of
the pipe should be of the active end design. The fitting and pipe are then
joined together as described under Pipe Spool Connections.
In the situation where a fitting is to be connected to another fitting,
the adjacent passive ends of the fittings are joined together through an
Adapter. The Adapter consists of a Load Bearing Ring, two Belleville
Washers (Coned Disc Springs), two Flat Washers (Forced Distribution
Rings) and a flared plastic liner of PTFE.
When the joint is assembled, the adapter with the springs, washers and PTFE
liner insert is placed between the fitting flanges. As with the active
ends on the pipe spools, the Belleville Washers deflect and, acting
through the Flat Washers, apply predetermined, optimum sealing loads to
the flared liners of the fittings and adapters.
Automatic Load Compensation
Flanged connections in a High Integrity Flange system are all uniformly
sealed. Stored energy in the Belleville Washers automatically
compensates for any changes, such as deformation of plastic flares, that
would affect sealing forces, and stored energy in the highly pre-loaded
bolts copes with conditions affecting structural load.
Miscellaneous HIF Components/Materials
- HIF Vent Connector: T61717, 316SS
Porous Disc: Hastelloy "C"-276
- Thick (Plain) Washer: T61571-XXX
016-064, Powder Metal F0008-R
- Thin Washer: T61580-XXX
048-064, Carbon Steel Painted
- Belleville Washer: T61573-XXX
SAE 64150 Austempered to RC 42-48
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