The EPISTLE Reference Data Library
an ontology for the Process Industry
David Leal, CAESAR Systems Limited
http://www.scadaonweb.com
EPISTLE - major sponsors and members
EPISTLE
PISTEP 2000
(UK)
POSC Caesar
(Norway)




 Cadcentre
 Det Norske
Veritas
 FMC Kongsberg
Subsea
 Intergraph
 Norsk Hydro
 Statoil
BNFL
bp
Conoco
Foster Wheeler
Energy
 Shell
USPI-NL
(The Netherlands)





ABB
Akzo Nobel
Fluor Daniel
NAM
Shell
EPISTLE: European Process Industry STEP Technical Liaison Executive
STEP : STandard for the Exchange of Product data (ISO 10303)
GbR mbH
http://www.scadaonweb.com
©
2
Acknowledgements to
POSC/CAESAR
What sort of thing is it?
64 31 NUTS 1”UNC
ASTM A453 GR660
32 30 STUDBOLTS 1”UNC, 5 1/ 2 ” ASTM A453 GR660
2 29 SUPPORT BRACKET
6-194-4
EN10204/2.2
EN10204/2.2
MANUFACTURERS DRAWING
Need one place to store the
meaning and map between
different terminology
ASTM A 453/A 453M - 660 CLASS A
ISO 15926 REFERENCE DATA LIBRARY
07.1 Nuts External Flanges
ASTM A 453M GR660, TP1
(3.1B)
07.1 Bolts/External Flnges
ASTM A 453M GR660, TP1
(3.1B)
07.1 Brackets/Supports
BS 1501-316-S11__________ (3.1.B)
ENGINEERING DATASHEET
GbR mbH
http://www.scadaonweb.com
©
3
Our starting point
 STEP - ISO 10303





begun in
1984
STandard for the Exchange of Product data
shape
FEA (Finite Element Analysis)
PDM (Product Data Management)
special models forshipbuilding, plant spatial layout, electrical
design
 engineering semantics - what things or relationships are ?
 real world vs designs/classes/specifications

 Parts Libraries - ISO 13584
 families of standard parts
 a methodology for unique part identification
 some use of set theory
not web
Complicated, ad-hoc information models - result of a learning process
GbR mbH
http://www.scadaonweb.com
©
4
ISO 15926
 Life cycle data for process plants
 including floating, flying, and with wheels
 simple basic model extended by class libraries (i.e. ontologies)
 STEP technology - EXPRESS




Entity/Relationship language - similar to UML (static class diagram)
simple exchange file representation
API - bindings to C, C++, Java
XML representation - horrible
 Consequences
 hard wired information model - voted on by ISO, and not easily
extensible
 extension by standard instances held in external files (class
libraries) - also standardised by ISO - externally maintained
registry with continuous revision
GbR mbH
http://www.scadaonweb.com
©
5
Acknowledgements to
POSC/CAESAR
A thermowell
GbR mbH
http://www.scadaonweb.com
©
6
Thermowell (Dry Well) POC (01.01.08)
Properties
Functional Parts
Thermowell insertion length
Thermowell Instrument Connection
Thermowell standout length
Thermowell Process Connection
Thermowell lag length
Thermowell total length
Thermowell
Estimated Dry Weight
Physical Parts
Measured Dry Weight
Internal thread
Thermowell internal bore
Thermowell stem
Subclasses
Flanged
Thermowell
Welded Flange
Thermowell
Screwed
Thermowell
Van Stone
Thermowell
NORSOK
I-001 Rev. 3 T01
Thermowell
Solid Forged
Flanged
Thermowell
GbR mbH
http://www.scadaonweb.com
Welded
(Weld-in)
Thermowell
©
Socket Weld
Thermowell
Straight
Stem
Thermowell
ISA
S20T2501
Thermowell
Stepped
Stem
Thermowell
Tapered
Stem
Thermowell
7
Thermowell Stem (Dry Well) POC (01.01.08)
Properties
Thermowell stem larger
outside diameter
Thermowell stem tip
outside diameter
Physical Wholes
Thermowell stem tip thickness
Thermowell
Thermowell Stem
Thermowell internal bore
Subclasses
ISA
S20T2501
Thermowell
NORSOK
I-001 Rev. 3 T01
Thermowell
Stepped
Thermowell
Stem
Straight
Thermowell
Stem
Tapered
Thermowell
Stem
NORSOK
I-001 Rev. 3 T01
Thermowell stem
Properties
Upper limit thermowell stem
outside diameter
Wake / natural frequency ratio
ISA
S20T2501
Thermowell Stem
GbR mbH
http://www.scadaonweb.com
©
Thermowell stem outside
diameter at support
8
Part type and materials
cast iron
engine part
SG cast iron
rotating part
crankshaft
SG cast iron crankshaft
unmachined-surface part
V6 crankshaft
Rover 75 crankshaft
machined-surface part
SG cast iron grade XYZ
part with oil holes
Rover 75 crankshaft rev1.2
GbR mbH
http://www.scadaonweb.com
©
9
ECM and ERDL (ISO 15926) Structure
Standardised in
ISO 15926-2
Standardised in
ISO 15926-4 WD
Basic concepts
Core
Classes
Standardised by
e.g. ISO /IEC/
ANSI/ BS/DIN,
represented using
ISO 15926
Common terminology
Conceptual
Process Design
Detailed
Process Design
Conceptual
Engineering Design
Standard Classes
Detailed
Engineering Design
Product catalogs
represented
using ISO 15926
Commodity Classes
Procurement
Construction
Manufactured Item Classes
Commissioning
Maintenance
GbR mbH
http://www.scadaonweb.com
©
10
ERDL - size of the problem
 basic concepts ~ 200
product/artifact, activity, state, composition, connection
 core classes ~2000
thermowell, pump, pipe, flange, raised face flange
 first release of standard classes ~ 20000 - more to come
ISAS20T2501 thermowell
 commodity classes ~ 1 million for big owner-operator
 manufactured items ~ ?
A design/specification is a class.
GbR mbH
http://www.scadaonweb.com
©
11
ERDL - how to define the classes
 basic concepts ~ 200
information modellers - theoreticians with an industry background
 core classes ~2000
teams of domain experts - initial tutorials from the information modellers
heat transfer team, piping team, rotating equipment team, etc.
 first release of standard classes ~ 20000
further work by domain experts
conversion of existing standards - using standard procedures
 commodity classes ~ 1 million for big owner-operator
uptake of methodology by industry
 manufactured items ~ ?
GbR mbH
http://www.scadaonweb.com
©
12
Key concepts
start with real world things:
 product/artefact
A distribution of matter through space and time, that is regarded
as the whole life of an object by some business process
 product life segment/activity
A product for a particular period of time.
 product at instant/state
A product at an instant in time.
then sets/classes of real world things;
then classes of class, etc.
GbR mbH
http://www.scadaonweb.com
©
dictionary
13
ERDL Scope













piping
valves
rotating equipment
heat exchangers
electrical machinery
electrical distribution
core classes in each area
instruments
connections
activities (for plant design, operation, maintenance)
civil/structural
documents (for plant design, operation, maintenance)
properties (for classes defined above)
units
GbR mbH
http://www.scadaonweb.com
©
14
Some experiences
 keep the hierarchy flat - without two many intermediate
layer
 not a strict hierarchy, but a directed graph
 intermediate abstractions are 'woolly'
 people argue about them endlessly
product

rotating equipment

pump
Is this really needed?
Does it have a precise definition?

expander
GbR mbH
http://www.scadaonweb.com
©
15
Use of classification of class
 Makes 'woolly' classes less visible
 but still there - power set
product

pump
rotating equipment class


expander
GbR mbH
http://www.scadaonweb.com
©

indicates the responsible
team of domain experts
16
Use of classification of class
 Filtering for drill down
product
instrument class
generic class



thermowell
instrument class

standard class



ISAS20T2501

ISA class

manufacturer class

J. Bloggs model XYZ
GbR mbH
http://www.scadaonweb.com

©
J. Bloggs class
17
Rules for the development of class libraries
 Stick to classes with precise definitions
 write the text definitions as you go
 Do not add 'collector' classes to structure the class library
 Use classification of class to provide structure
 Some classes can be defined by set theory and property
contraints.
 It is not practical to do this for all classes.
 Text definition of the form:
'A xxx is a <superclass of xxx> that
<distinction between xxx and its superclass>.'
GbR mbH
http://www.scadaonweb.com
©
18
Intersection of classes
cast part
cast engine
part
engine part
A complete definition of 'cast engine part' without words!
GbR mbH
http://www.scadaonweb.com
©
19
Intersection of classes
cast part
cylinder
block
engine part
Two subset relationships are not a complete definition!
GbR mbH
http://www.scadaonweb.com
©
20
Class hierarchy
core model
thing
physical object
‘product’ / artefact
product
for a period of time
product
at an instant in time
screwed thermowell
welded thermowell
thermowell
flanged thermowell
the one in my plant is one of these
GbR mbH
http://www.scadaonweb.com
©
21
Recording real world objects

The part with serial number 98/1234 is an instance of screwed
thermowell
<ScrewedThermowell>
<label>98/1234</label>
</ScrewedThermowell>

The part with serial number 98/1234 is an instance of product,
classified as a screwed thermowell
<Product>
<type resource=“#ScrewedThermowell”/>
<label>98/1234</label>
</Product>
GbR mbH
http://www.scadaonweb.com
©
22
Dictionary
core model
thing
class
class of
physical object
class of
‘product’ / artefact
class of product
for a period of time
class of product
at an instant in time
thermowell is one of these
screwed thermowell is one of these
GbR mbH
http://www.scadaonweb.com
©
23
Recording classes

Screwed thermowell is an instance of class of product
<ClassOfProduct ID=“ScrewedThermowell>
<label>Screwed thermowell</label>
<subClassOf resource=“#Thermowell”/>
</ClassOfProduct>

Relationship to the class ‘Product’ is implicit.
<ClassOfProduct ID=“Thermowell”>
<label>Thermowell</label>
<subClassOf resource=“#Product”/>
</ClassOfProduct>
GbR mbH
http://www.scadaonweb.com
©
24
Relationships and constraints
• Each ‘ISA S20T2501T’ Thermowell has one ‘ISA S20T2501TS’ Thermowell
stem as a part.
• Each thermowell has one thermowell stem as a part.
• Each product has zero, one or many products as parts.
* whole
product
composition
* part
thermowell
1 whole
thermowell stem
composition
thermowell stem
ISA S20T2501T
1 part
1 whole
ISA S20T2501 stem
composition
ISA S20T2501TS
GbR mbH
http://www.scadaonweb.com
©
1 part
25
Individual and class models
* whole
product
composition
* part
my_thermowell_stem is
part of my_thermowell
my_thermowell
my_thermowell_stem
classification
* whole
class of product
class of composition
* part
thermowell_stem is
part of thermowell
thermowell
thermowell_stem
allowed cardinality
GbR mbH
http://www.scadaonweb.com
©
26
ScadaOnWeb
gigabytes of
structured
data
Define semantics of
process monitoring data
with respect to web
ontologies
extract and download
subsets
variables
positions
states/times
semantics
GbR mbH
http://www.scadaonweb.com
©
27
Next steps for EPISTLE
 Exploit the current standards
 EXPRESS tools are mature, and scalable (but expensive)
 But
 Ontologies need publication and management
 Why develop EXPRESS based tools for ontology publication and
management, when there is a much bigger community out there
 Currently
 class libraries held as files corresponding to the ISO 15926
EXPRESS schema
 tools support import/export from a simple EXCEL spreadsheet
 class library development uses EXCEL
 Future
 domain class libraries published as an ontology on the web 
 retain use of EXCEL by domain experts 
WonderWeb
 ISO 15926 basic concepts as a web ontology ?
ScadaOnWeb
GbR mbH
http://www.scadaonweb.com
©
28
Conclusions
 Large body of work - searching for a formal
representation on the web
 Generic tools needed for access and maintenance
 merging libraries are particular problem
 Multi-layer structure
 need a consistent format for all levels
 no sharp distinction between data and meta-data (a design is a
class)
for more information
GbR mbH
http://www.scadaonweb.com
©
www.epistle.ws
www.posccaesar.org
www.uspi.nl
29