Glossary of Sealing Terms - Flanges and Gaskets
(ESA Publication No. 008/97, published November ’97)
This document has been prepared for use by original equipment manufacturers, engineering contractors and end users. The Glossary aims to provide the reader with a comprehensive background to terms used in describing aspects of sealing terminology, allowing the user access to technical considerations involved in safe and reliable sealing.
Contents
1. Introduction
2. Classification of Terms
3. Synopsis of Terms
4. Detailed Descriptions
5. Typical Flange and Gasket Layouts
6. Relevant Units and Conversion Factors
SI units
Multiples of SI units
Units of common usage in flange gasket terminology
Conversion factors
7. Relevant Standards
8. Standards issuing organisations and other relevant bodies
9. Common Abbreviations
10. Alphabetical Index
Other sections of this document provide the following information :
Section 2, Classification of Terms, describes the category of each term and its relation to other designated terms, according to the following structure :
1. Basic terms
1.1. Gasket materials and types of gaskets
1.2. Process terms
1.3. Flange types and flange accessories
2. Material Property terms
2.1. Deformation properties
2.2. Sealability
2.3. Chemical resistance
2.4. Various other properties
3. Assembly and application terms
4. Various other terms
Section 3, Synopsis of Terms, deals with each of the sealing terms in concise form, in English, French and German, listed according to the Classification of Terms (above).
Section 4, Detailed Description, gives a more extensive technical description of appropriate terms where necessary, according to the same classification of listing as in the Synopsis of Terms, then with the following structure :
1. Name of term
2. Definition
3. Unit
4. Colloquial terms
5. Related terms
6. Standards
7. Extended Description
7.1. Purpose
7.2. Test procedures
7.3. Comments
8. Cross references
Section 5, Typical Flange and Gasket Layouts, gives information on the most common types employed in the process industries
Section 6, Relevant Units and Conversion Factors, provides relationships between appropriate units
Section 7, Relevant Standards, describes the existing national and international standards which are involved in sealing technology
Section 8, Standards issuing organisations and other relevant bodies, gives details about the key groups involved in establishing standards which may have an impact on the European Union
Section 9, Common Abbreviations, gives the full description of relevant abbreviations
Section 10, Alphabetical Index, lists all terms alphabetically, including colloquial terms
Detailed Descriptions - example
In this section, the more complex sealing terms are given an extended technical description and listed in alphabetical order.
Assembly pressure
Classification : 3.0
Definition : Pressure generated on gasket during assembly
Unit :
N.mm-2 - metric
MPa - SI
psi - imperial
Colloquial terms :
Assembly stress
Sealing stress
Sealing pressure
Related term :
Gasket pressure
Minimum assembly pressure
Maximum assembly pressure
Standards :
DIN 2505
DIN 28090
pr EN 1591
Purpose : The assembly pressure is the pressure required to be applied onto the gasket surface to ensure that :
- the gasket is safely clamped between the flange surfaces
- unevenness, unparallelities and distortions are levelled out or equalised
- under operational conditions the required level of sealing is achieved by sufficient compression of the gasket
Normally, in industrial flanges the pressure is generated by bolts which are torqued. By this they transfer their tension as a force to the flanges and further to the effective area of the gasket. The total forces of each bolt related to the effective area of the gasket is the assembly pressure.
There are also alternatives to bolts for the generation of assembly pressure. For example, special clamping devices are available, although the pressure generated is generally low. These systems are therefore only suitable for light flanges and soft gaskets. Furthermore, screwed pipe connections are also available
Cost per copy (inclusive of postage) :
€
25 
or equivalent local currency :
| £ Sterling | 17 |
| SFr | 40 |
| US $ | 29 |
The document is complementary to the Guidelines for safe seal usage - Flanges and Gaskets which was published by the ESA in September 1998 (ESA Publication No. 009/98). As a special introductory offer, a copy of the Glossary and the Guidelines is available together at Euro 40 (or equivalent local currency) for the pair. Please see the Guidelines for safe seal usage - Flanges and Gaskets for detailed information.
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