ISO 15138:2000

INTERNATIONAL ISO
STANDARD 15138
First edition
2000-11-01
Petroleum and natural gas industries —
Offshore production installations —
Heating, ventilation and air-conditioning
Industries du pétrole et du gaz naturel — Installations en mer —
Chauffage, ventilation et climatisation
Reference number
©
ISO 2000
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 � CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2000 – All rights reserved

Contents Page
Foreword.iv
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Abbreviated terms .2
5 Design .3
5.1 Introduction.3
5.2 Development of design basis.6
5.3 System design — General .10
5.4 Area-specific system design .11
Annex A (informative) Guidance to clause 5 Design.14
Annex B (informative) Equipment and bulk selection.41
Annex C (informative) Installation and commissioning guidance .61
Annex D (informative) Operation and maintenance.66
Annex E (informative) Data sheets .69
Annex F (informative) Flange standard.101
Bibliography.104
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 15138 was prepared by Technical Committee ISO/TC 67, Materials, equipment and
offshore structures for petroleum and natural gas industries, Subcommittee SC 6, Processing equipment and
systems.
Annexes A through F of this International Standard are for information only.
iv © ISO 2000 – All rights reserved

INTERNATIONAL STANDARD ISO 15138:2000(E)
Petroleum and natural gas industries — Offshore production
installations — Heating, ventilation and air-conditioning
1 Scope
This International Standard specifies requirements and provides guidance for design, testing, installation and
commissioning of heating, ventilation, air-conditioning and pressurization systems and equipment on all offshore
production installations for the petroleum and natural gas industries which are:
� new and existing;
� normally occupied by personnel and not normally occupied by personnel;
� fixed or floating but registered as an offshore production installation.
NOTE For installations that could be subject to "Class" or "IMO/MODU Codes & Resolutions", the user is referred to HVAC
requirements under these rules and resolutions. Should these requirements be of a lesser degree than those being considered
for a fixed installation, then this International Standard, i.e. requirements for fixed installation, should be utilized.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 8861, Shipbuilding — Engine-room ventilation in diesel-engined ships — Design requirements and basis of
calculations.
IEC 60079-10, Electrical apparatus for explosive gas atmospheres — Part 10: Classification of hazardous areas.
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
displacement ventilation
movement of air within a space in piston- or plug-type motion
NOTE No mixing of room air occurs in ideal displacement flow, which is desirable for removing pollutants generated within
aspace.
3.2
fixed offshore installation
all facilities located and installed on fixed offshore structures, which are provided to extract oil and gas
hydrocarbons from subsea oil and gas reservoirs
3.3
fixed offshore structure
structure permanently fixed to or located on the sea bed, including moored ships and hulls, which is held in position
by anchors or tensioned cables and is provided to (structurally) support topsides facilities
NOTE Vessels and drilling rigs, etc. which are in transit or engaged in exploration and appraisal activities are specifically
excluded from this definition.
3.4
fugitive emission
emission which is always present on a molecular scale from all potential leak sources in a plant under normal
operating conditions
NOTE As a practical interpretation, a fugitive emission is one which cannot be detected by sight, hearing or touch but may
be detected using bubble-test techniques or tests of a similar sensitivity.
3.5
open area
area in an open-air situation where vapours are readily dispersed by wind
NOTE Typical air velocities in such areas should rarely be less than 0,5 m/s and should frequently be above 2 m/s.
3.6
temporary refuge
TR
place where personnel can take refuge for a pre-determined period whilst investigations, emergency response and
evacuation pre-planning are undertaken
[ISO 13702:1999, definition 2.1.52]
4 Abbreviated terms
AC Alternating Current
AC/h Air Changes per hour
AHU Air Handling Unit
AMCA Air Movement and Control Association Inc.
API American Petroleum Institute
ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers
BS British Standard
CCR Central Control Room
CFD Computational Fluid Dynamics
CIBSE Chartered Institution of Building Services
CMS Control and Monitoring System
CVU Constant-Volume Terminal Reheat Unit
DC Direct Current
2 © ISO 2000 – All rights reserved

DE Driven End
DX Direct Expansion
EN European Standard
ESD Emergency Shutdown
F&G Fire and Gas
HAZOP Hazard and Operability Study
HSE Health, Safety and Environment
HVAC Heating, Ventilation and Air Conditioning
HVCA Heating and Ventilating Contractors' Association
IEC International Electrotechnical Commission
IMO International Maritime Organization
IP Institute of Petroleum
IP Integrity Protection
LFL Lower Flammable Limit
LQ Living Quarters
MODU Mobile Offshore Drilling Unit
NDE Non-driven End
NFPA National Fire Protection Association
NS Norsk Standard (Norwegian Standard)
QRA Quantitative Risk Analysis
r.m.s. Root mean square
5 Design
5.1 Introduction
Clause 5 together with annex A provide requirements and guidance on all aspects of the design of heating,
ventilation and air-conditioning (HVAC) systems for offshore installations for the petroleum and natural gas
industries. The HVAC systems form part of the safety services of the installation. The safety goals are to:
� prevent, through pressurization, the ingress of potentially flammable gas-air mixtures into all designated
nonhazardous areas;
� prevent the formation of potentially hazardous concentrations of flammable gaseous mixtures in hazardous
areas by provision of sufficient ventilation for the dilution, dispersion and removal of such mixtures;
� maintain ventilation to all equipment and areas/rooms which are required to be operational during an
emergency when the main source of power is unavailable;
� provide a controlled environment in which personnel, plant and systems can operate effectively, including
smoke control.
These high-level goals are supported by lower-level goals of a functional nature which are stated later in the
appropriate sections of this document.
Subclause 5.2 concentrates on functional requirements in the development of a basis of design for either a new
project or major modification to an existing installation. The requirements are related to:
a) platform orientation and layout;
b) hazard identification and hazardous area classification;
c) environmental conditions;
d) choice of natural or mechanical ventilation systems;
e) development of the controls philosophy;
f) material selection;
g) design margins and calculations;
h) design development and validation using wind tunnel testing or Computational Fluid Dynamics (CFD).
Ventilation may be natural (i.e. the wind) or mechanical or a combination of both. Throughout this International
Standard, the use of the term "ventilation" should be taken to include either natural or mechanical ventilation, as
appropriate.
Natural ventilation is preferred over mechanical ventilation where practical, since it is available throughout gas
emergencies, does not rely on active equipment and reduces effort required for HVAC maintenance.
For new designs, the development of a design basis may be progressed using the guidance and examples of good
engineering practice that are identified in this document, though it should be recognized that it involves a process
of iteration as the design matures and does not take place as the sequential series of steps used in this document
to facilitate presentation. The processes outlined here are equally applicable to major redevelopments to existing
installations, but some compromise may need to be made as a result of historical decisions regarding layout,
equipment selection and the prevailing level of knowledge at the time. The challenge of providing cost-effective
solutions in redevelopment may be significantly greater than for a new design.
The finalized basis of design may be recorded on data sheets such as those provided in annex E.
The completed design should be subject to hazard assessment review. The Hazard and Operability Study
(HAZOP) technique may be used for this.
In 5.2, objectives are identified which establish the goals. Functional requirements are outlined which will enable
the objectives to be achieved. The functional requirements are supported by technical guidance given in annex A,
which discusses the suitability of different techniques for different applications and identifies examples of good
engineering practice or cost-effective solutions that have been used in some parts of the world. The functional
requirements may be satisfied by other methods not identified in this document, but it is the respon
...