ISO 23467:2020

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23467
ISO/TC 85/SC 6
Ice plug isolation of piping in nuclear
Secretariat: DIN
power plant
Voting begins on:
2020­09­14
Voting terminates on:
2020­11­09
RECIPIENTS OF THIS DRAFT ARE INVITED TO
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OF ANY RELEVANT PATENT RIGHTS OF WHICH
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DOCUMENTATION.
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Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 23467:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
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©
NATIONAL REGULATIONS. ISO 2020

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ISO/FDIS 23467:2020(E)

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© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ISO/FDIS 23467:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General requirements . 2
4.1 Personnel . 2
4.2 Equipment . 2
4.3 Preconditions . 2
4.4 Requirements of process . 3
4.4.1 Material of pipe . 3
4.4.2 Freezing medium . 3
4.4.1 Position of ice plug . 3
4.4.3 Ice plug jacket . 4
5 Preparation before operation. 4
5.1 Working environment . 4
5.2 Construction plan . 4
5.3 Tools of construction . 5
5.4 Protective measures . 5
5.5 Pipe testing before operation . 5
6 Ice plug construction . 5
6.1 Generation of ice plug . 5
6.2 Judgment of ice plug generation . 5
6.3 Removal of ice plug . 6
7 Quality assurance (QA) on ice plugging . 6
7.1 QA before ice plug performance. 6
7.2 QA during ice plug performance . 6
7.3 QA after ice plug performance . 7
8 Records and reports . 7
Annex A (informative) Reference table of ice plug jacket length . 8
Annex B (informative) Ice plug jacket types . 9
Annex C (informative) Flow chart to perfomance of ice plug isolation measure
(construction plan) .14
Bibliography .15
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ISO/FDIS 23467:2020(E)

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 non­governmental, 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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, Subcommittee SC 6, Reactor technology.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO/FDIS 23467:2020(E)

Introduction
This document provides terms and definitions for basic concepts of nuclear energy, nuclear technologies,
and radiological protection. Terminological data are taken from ISO standards developed by the any
ISO/TC 85 sub-committee and other technically validated documents.
In the field of nuclear power, when the equipment or pipeline shall be disassembled or removed to
overhaul, often need to be isolated. Under normal circumstances, the upstream and downstream of
the equipment will be isolated or the internal media will be sprinkled, but there will be no isolation
equipment or isolation equipment near the equipment or pipe, while taking into account the safety
(some systems as a reactor hot trap at any time shall be filled with water, some of the system of liquid
with radioactive, worried about radioactive escape, etc.) and economy (system mass, sparse for a long
time, heavy water degradation, etc.), pipes and equipment can't be isolated, for the maintenance work
brought problem.
Based on years of practical experience, the development of this document is feasible. At the theoretical
level, the relevant literature has been studied and reported on the ice plug isolation technology. In the
actual maintenance work, the use of ice plug technology to the pipeline equipment isolation, to achieve
good results. Based on these theoretical and practical experiences, it is recommended that some
technical indicators in the process of ice plug operation be standardized.
This document is designed to provide a standardized procedure for on­line isolation through the
freezing of the internal medium of the pipeline. It is expected that this document can be used to isolate
equipment without isolation facilities by ice plug technology. Standardized ice plug isolation technology
will facilitate the maintenance work.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23467:2020(E)
Ice plug isolation of piping in nuclear power plant
1 Scope
This document specifies requirements for the ice plug technique with liquid nitrogen or dry ice as
refrigerant (cryogenic medium) on metal pipes of nuclear power plants. The freezing liquid can be
water or water mixture (e.g. boric acid mixture).
This document specifies technical requirements of ice plug generation, formation judgment and
removal, measures before, during and after ice plugging and requirements for personnel and non-
destructive testing.
The application of the ice plug isolation technique is principally not allowed on cladded pipes or pipes
with internal coatings. The application for pressure test is not in the scope of this document and will be
qualified separately.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3452 (all parts), Non-destructive testing — Penetrant testing
ISO 9934 (all parts), Non-destructive testing — Magnetic particle testing
ISO 16810, Non-destructive testing — Ultrasonic testing — General principles
ISO 17637, Non-destructive testing of welds — Visual testing of fusion-welded joints
ISO 20769 (all parts), Non-destructive testing — Radiographic inspection of corrosion and deposits in pipes
by X- and gamma rays
3 Terms and definitions
For the purposes of this document the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
ice plug
process of locally freezing the liquid in the pipe by using a cryogenic refrigerant, and then forming
a solid block of ice in the pipe that can withstand a certain system pressure to isolate the pipeline
temporarily, for the convenience of maintaining downstream pipelines, valves and other equipment
3.2
ice plug jacket
set of device wrapped outside the pipe and containing a refrigerant capable of freezing internal medium
of the pipe to form an ice plug (3.1) for a period necessary for the isolation
Note 1 to entry: The length of jacket depends on the diameter of pipe. See Annex A for the length of jacket.
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ISO/FDIS 23467:2020(E)

3.3
ice plug area
defined area on the pipe excluding the ice plug affected zone
3.4
refrigerant
cryogenic medium
medium which is used to generate an ice plug (3.1) inside of the pipes
3.5
freezing medium
freezing liquid
medium inside of pipes and components which have to be frozen
3.6
UT
ultrasonic testing
non­destructive testing of solid material using ultrasonic waves, for defects such as cavities,
nonbonding, and strength variations
3.7
RT
radiographic testing
non-destructive testing method of inspecting materials for hidden flaws by using the ability of short
wavelength electromagnetic radiation (high energy photons) to penetrate various materials
4 General requirements
4.1 Personnel
Managers and operators engaged in ice plug isolation construction shall undergo professional training
and safety training. For the implementation, only qualified and trained personnel should be deployed
(e.g. workers from specialized companies).
4.2 Equipment
4.2.1 Special ice plug jacket and other equipment (such as liquid nitrogen chamber, hoses, joints,
antifreeze gloves, protective masks, protective glasses) and tools shall be equipped. Measurement tools
(such as thermometers, pressure gauges, oxygen meters, etc.) shall be calibrated and validated.
4.2.2 Anti-freezing, anti-asphyxia and other related safety protection products shall be provided.
4.3 Preconditions
4.3.1 Pipes shall be filled with any fluids that can be frozen, and free of air.
4.3.2 The flow rate of liquid in the pipe should be as low as possible, preferably close to zero. Excessive
flow rate is not conducive to the formation of ice plug.
4.3.3 When the ambient temperature is lower than 43 °C, the surface temperature of pipe shall be
lower than 50 °C if the refrigerant is liquid nitrogen and shall be lower than 30 °C if the refrigerant is dry
ice. This is not required if validity is confirmed by mock-up test.
4.3.4 The distance between ice plug and heat source nearby (including welding parts) shall be
determined based on heat input and pipe diameter.
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ISO/FDIS 23467:2020(E)

4.3.5 Pipe to be isolated with an ice plug shall not be affected by the vibration and shock during the
operation.
4.3.6 Ice plug operation is prohibited for the pipe sections containing the following defects:
a) Crack affecting the strength;
b) Pitting affecting the strength;
c) Thickness of pipe thinned to an unacceptable level;
d) Breach;
e) Other conditions that may cause the pipe burst.
4.3.7 Ice plug operation is prohibited in the following pipe structures or fittings:
a) Pipe parts, such as plugs, thermocouples;
b) Pipe fittings, such as movable joints.
4.4 Requirements of process
4.4.1 Material of pipe
The pipe shall be made of metal (carbon steel or stainless steel). Technically speaking, for ice plug area,
welds are not allowed (no circumferential neither longitudinal weld). Unless it can be demonstrated
that there is no better solution, and that there are no defects in the welds, ice plug operations on welds
can be done. Cast copper pipe, cast iron pipe, cladded pipe and lining pipe shall not be subject to ice
plugging isolation.
Material inspection certificate or alternative consideration should be confirmed in order to avoid low
temperature brittle fracture, when applying ice plugs on carbon steel piping, which is connected to
most important components or pi
...