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Optimum Bore Design Process for Flange Face Static Sealing

IP.com Disclosure Number: IPCOM000226385D
Publication Date: 2013-Apr-02
Document File: 7 page(s) / 679K

Publishing Venue

The IP.com Prior Art Database

Related People

Yung Oey: INVENTOR [+4]

Abstract

The four-bolt flange to flange type connection lacks the external coupling/ sleeve whose job is to align the two inner bores concentrically which would produce the ideal designed condition. Undesirable deviation peaks when the 2 equal diameter bores are made at their extreme allowed eccentric locations. This often overlooked condition can negatively affect the system by the blockage of upstream flow area at the bore interface, the leakage/ fluid loss and the premature O-ring life. In the proposed solution, one bore (on the O-Ring side) is optimized to be larger than the other. In other words, that bore will always encapsulate the other at any condition including the allowed extreme eccentricity caused by manufacturing tolerances. According to one example of invention, the Bore Optimization Process utilizes the concept of inner and outer bore boundaries and will not over enlarge the bore than necessary.

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Page 01 of 7

Optimum Bore Design Process for Flange Face Static Sealing

Yung Oey, Steve Nguyen, James Liem Nguyen, Quang Do

ABSTRACT

The four-bolt flange to flange type connection lacks the external coupling/ sleeve whose job is to align the two inner bores concentrically which would produce the ideal designed condition. Undesirable deviation peaks when the 2 equal diameter bores are made at their extreme allowed eccentric locations. This often overlooked condition can negatively affect the system by the blockage of upstream flow area at the bore interface, the leakage/ fluid loss and the premature O-ring life. In the proposed solution, one bore (on the O-Ring side) is optimized to be larger than the other. In other words, that bore will always encapsulate the other at any condition including the allowed extreme eccentricity caused by manufacturing tolerances. According to one example of invention, the Bore Optimization Process utilizes the concept of inner and outer bore boundaries and will not over enlarge the bore than necessary.


1. Introduction

A typical four bolt flange to flange type of connection (shown in Figure 1) is often used in thermal equipment system to mechanically connect fluid lines. The two bores are equal in diameter and are concentrically aligned. The bore of each flange is primarily dimensioned and true positioned with respect to its own set of Datums ABC that is different from the other mating flange. The tolerance for both components may be different as well and that both units have no line connection flexibility. Today's Six Sigma manufacturing practice dictates a larger tolerance than the .005 eccentricity assumption made in most design standard handbook. Figure 2 shows a possible condition when the two equal diameter bores are at their extreme allowed eccentric positions. This can potentially affect the system equipment negatively in 3 ways:


Page 02 of 7

Figure 1: A Typical Four Bolt Flange

Figure 2: Bores at their extreme allowed eccentric positions


1) Upstream flow area blockage at the bore interface.


2) Leakage/Fluid Loss due to O-ring non-continuous sealing contact.


Page 03 of 7

3) Premature O-ring life due to irregular extrusion which spells downtime/ maintenance.

In the past, the bore eccentricity issue has been successfully alleviated by using a split flange connection as covered in specification SAE J518. In one of the European Patent Applications EP1800042B1 (Figure 3) a flange adapter 50 is disclosed to connect the bores. The flange adapter 50 allows for the positioning and centering of the bores. Limitations of such system are that the number of parts will increase and that it would not work for something other than a 4-bolt flange, i.e., an N-Bolt flange.

Hence, there is a need for an economical design, which can completely alleviate the bore eccentricity issue without using extra components, increasing weight or expanding envelope.

Figure 3: Figure 1 of European Patent Applications EP1800042B1


2. Propose...