ISO/TR 7655:2022

Corrosion of metals and alloys - Overview of metal corrosion protection when using disinfectants

This document provides an overview of the corrosivity of disinfectants and corrosion protection when using disinfectants, including an overview of test methods that can be used to determine their corrosivity. This document is generic and applicable to organizations of all sizes in all industries, as well as to families and individuals, and it is intended to assist in determining appropriate health and safety measures regarding the use of disinfectants. The resolution of security issues related to the use of disinfectants is outside the scope of this document.

Corrosion des métaux et alliages — Vue d'ensemble de la protection contre la corrosion des métaux lors de l'utilisation de désinfectants

General Information

• Status: Published
• Publication Date: 15-Mar-2022
• ICS: 77.060 - Corrosion of metals
• Technical Committee: ISO/TC 156 - Corrosion of metals and alloys
• Drafting Committee: ISO/TC 156 - Corrosion of metals and alloys
• Current Stage: 6060 - International Standard published
• Start Date: 16-Mar-2022
• Due Date: 18-Dec-2022
• Completion Date: 16-Mar-2022

Overview

ISO/TR 7655:2022 - "Corrosion of metals and alloys - Overview of metal corrosion protection when using disinfectants" is a technical report that summarizes the corrosivity of disinfectants and practical approaches to metal corrosion protection during disinfection. The document is generic and applicable to organizations of all sizes, across industries, as well as to families and individuals. It provides guidance on corrosivity, test methods (Annex A) and a catalogue of commonly used disinfectants and their properties (Annex B). Security aspects of disinfectant use are outside its scope.

Key topics

• Classification of disinfectants by active ingredients and use (e.g., halogens, peroxides, alcohols, quaternary ammonium compounds, aldehydes).
• Corrosivity characteristics: the report explains that corrosivity generally increases with oxidizing power and acidity and highlights which disinfectant families are typically more aggressive to metals.
• Corrosion protection principles: recommended good practices for reducing corrosion risks when disinfectants are used, including reliance on product data and industry guidance.
• Test methods overview (Annex A): a descriptive summary of laboratory and application-relevant methods that can determine disinfectant corrosivity to metals.
• Disinfectant properties (Annex B): physical/chemical properties, mechanisms, application scope and typical uses of common disinfectants.
• Terminology and context: the report references ISO terms and related definitions to support consistent understanding.

Practical applications

ISO/TR 7655:2022 is useful for:

• Facility and maintenance managers assessing corrosion risk in hospitals, public transport, food processing, HVAC, and communal areas.
• Corrosion engineers and materials specialists selecting compatible metals, coatings and protective strategies where disinfectants are used.
• Disinfectant manufacturers and suppliers documenting and communicating product corrosivity and recommended precautions.
• Cleaning and disinfection service providers for training and operational procedures to avoid equipment or surface damage.
• Regulatory bodies and public health agencies wanting a technical overview to complement infection-control guidance.
• Households and small organizations seeking basic guidance on safe disinfectant use to prevent metal damage.

Practical measures promoted by the report include following product specifications, using manufacturer corrosion data, implementing appropriate material selection and coatings, adopting suitable application methods and training personnel in safe use.

Related standards

The report draws on ISO terminology and related ISO documents (e.g., ISO 8044:2020 for corrosion terms and ISO 15190:2020 for disinfectant definitions) and was prepared by ISO/TC 156 (Corrosion of metals and alloys). For implementation, consult product-specific standards and test-method standards referenced in Annex A.

Standards Content (Sample)

TECHNICAL ISO/TR
REPORT 7655
First edition
2022-03
Corrosion of metals and alloys —
Overview of metal corrosion
protection when using disinfectants
Corrosion des métaux et alliages — Vue d'ensemble de la protection
contre la corrosion des métaux lors de l'utilisation de désinfectants
Reference number
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Overview . 2
5 Corrosivity and main properties of commonly used disinfectants .2
6 Good practice for metal corrosion protection when using disinfectants .6
6.1 General . 6
6.2 Corrosion hazards . 6
6.3 Corrosion protection measures. 6
Annex A (informative) Overview of test methods to determine the corrosivity of
disinfectants . 9
Annex B (informative) Commonly used disinfectants for disinfection of infectious disease .10
Bibliography .42
iii
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.
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).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys.
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.
iv
Introduction
This document provides information on protection against metal corrosion risks when disinfectants
are used in response to infectious diseases.
Governments, regulatory agencies and other professional organizations around the world have issued
guidelines in response to pandemics, but these contain no specific information on metal corrosion
protection when using disinfectants.
This document provides supplementary information intended to help organizations, families and
individuals, as well as other stakeholders, take more effective actions to prevent users from being
injured and reduce or avoid possible risks of metal corrosion during the use of disinfectants.
v
TECHNICAL REPORT ISO/TR 7655:2022(E)
Corrosion of metals and alloys — Overview of metal
corrosion protection when using disinfectants
1 Scope
This document provides an overview of the corrosivity of disinfectants and corrosion protection
when using disinfectants, including an overview of test methods that can be used to determine their
corrosivity.
This document is generic and applicable to organizations of all sizes in all industries, as well as to
families and individuals, and it is intended to assist in determining appropriate health and safety
measures regarding the use of disinfectants.
The resolution of security issues related to the use of disinfectants is outside the scope of this document.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
organization
company, corporation, firm, enterprise, authority or institution, person or persons or part or
combination thereof, whether incorporated or not, public or private, that has its own functions and
administration
[SOURCE: ISO 30000:2009, 3.10]
3.2
risk
combination of the probability of occurrence of harm and the severity of that harm
[SOURCE: ISO 15188:2001, 3.6]
3.3
disinfectant
agent capable of causing disinfection
[SOURCE: ISO 15190:2020, 3.8]
3.4
corrosivity
ability of an environment to cause corrosion of a metal in a given corrosion system
[SOURCE: ISO 8044:2020, 3.14]
3.5
corrosion protection
modification of a corrosion system so that corrosion damage is reduced
[SOURCE: ISO 8044:2020, 5.1]
3.6
common areas
spaces and amenities provided for the use of more than one person
Note 1 to entry: Canteens, lifts/elevators, stairs, reception areas, meeting rooms, areas of worship, toilets,
gardens, fire escapes, kitchens, fitness facilities, store rooms, laundry facilities.
[SOURCE: ISO/PAS 45005:2020, 3.11]
4 Overview
4.1 Disinfecting is an important process of defending against infectious diseases, which can corrode
metals. When disinfecting, avoid corrosion, injury and, if possible, discomfort to individuals, damage
to the environment that can affect public health and damage to baggage, cargo, containers, vehicles,
articles and mailbags.
4.2 Guidance on disinfection for the prevention of infectious diseases provided by public health
agencies can include information on the corrosivity to metals.
4.3 Professional disinfectant-related institutions can provide detection methods of metal corrosion
caused by various types of disinfectants under different testing or application conditions, and reports
on corrosion tests for commonly used metals for public use or reference.
4.4 Disinfectant manufacturers can test the corrosivity of their products to metals and clearly note
it on their instructions, provide corrosion data of their products to commonly used metals and put
forward protective measures for reference.
4.5 When disinfecting, organizations, families or individuals, use disinfectants according to the
relevant guidance documents and product specifications on metal corrosivity. Corrosion risks cannot
be neglected and effective measures are important to avoid corrosion hazards; disinfection service
providers are commonly required to receive training in the safe and effective use of disinfectants to
avoid corrosion.
5 Corrosivity and main properties of commonly used disinfectants
Commonly used disinfectants can be classified by active ingredients into alcohol disinfectants, halogen
disinfectants, peroxide disinfectants, guanidine disinfectants, phenol disinfectants, quaternary
ammonium disinfectants and other disinfectants; classified by use into object surface disinfectants,
disinfectants for medical items, air disinfectants, hand disinfectants, skin disinfectant, mucous
membrane disinfectants, and disinfectants for infectious focus; classified by the microorganism killing
ability into high-level disinfectants, intermediate-level disinfectants and low-level disinfectants.
Annex B provides an overview of the physical and chemical properties, types, disinfection mechanisms,
application scope and methods of disinfectants commonly used in infectious disease disinfection.
Usually, peroxide disinfectants and halogen disinfectants are highly corrosive to metals in the range
of their disinfection concentration. In general, the corrosivity increases with the strength of oxidation
and acidity.
The corrosivity, active ingredients, main properties, uses, application methods, etc., of commonly used
disinfectants are shown in Table 1.
Table 1 — Corrosivity and main properties of commonly used disinfectants
Active ingredi-
Oxi-
ents of com- Alkalinity Corrosivity to Application
Type diz-abil- Main uses
a b
monly used or acidity metals methods
ity
products
The presence of
small amount of Disinfection of ob-
Immersion
formic acid in for- ject surfaces and
Formaldehyde No Acidic
maldehyde solu- medical devices,
Fumigation
tions can corrode etc.
Aldehyde
metals.
Disinfection of
Immersion
Acid, neutral Corrosive to car-
Glutaraldehyde No medical devices,
or alkaline bon steel
Wiping
etc.
Slightly corrosive
to stainless steel,
Immersion
alloy steel and Disinfection of
chrome-plated object surfaces,
Wiping
Peracetic acid Yes Acidic metal, and heavily medical devices,
Spraying
corrosive to com- air and infectious
mon metals such focuses, etc.
Fumigation
as iron, copper
and aluminium.
Peroxide Disinfection of
object surfaces, Immersion
Hydrogen per- Corrosive to met- medical devices,
Yes Acidic Wiping
oxide als skin and mucosa,
air and infectious Spraying
focuses, etc.
Disinfection of Immersion
Corrosive to met- object surfaces,
Ozone Yes Neutral Wiping
als medical devices,
air and water, etc. Spraying
Strong corrosive
to aluminium, low Disinfection of
Immersion
alloy steel and object surfaces,
Chlorine dioxide Yes Acidic carbon steel, and medical devices, Wiping
moderately cor- air and infectious
Spraying
rosive to stainless focuses, etc.
steel.
Corrosive to cop- Disinfection of
per, aluminium object surfaces, Immersion
Electrolyzed
and carbon steel, medical devices,
oxidizing water Yes Acidic Wiping
and not obviously skin, hands and
(EOW)
corrosive to stain- infectious focus- Spraying
less steel es, etc.
Disinfection of
object surfaces, Immersion
Potassium Corrosive to met- medical devices,
Yes Acidic Wiping
monopersulfate als skin, water and
infectious focus- Spraying
es, etc.
a
Alkalinity or acidity refers to that of commonly used disinfectant products.
b
Metal corrosivity is usually graded as no obvious corrosion, mild corrosion, moderate corrosion and heavy corrosion;
there is no unified corrosion classification standard for disinfectants so far, which will be developed in the future; in the
table, "corrosive to metals" only indicates the existence of metal corrosion, as a warning when using disinfectants; the
specific corrosion classification is related to the standards used in the test, the type of metal materials used, test conditions
and the basis for evaluation.
Table 1 (continued)
Active ingredi-
Oxi-
ents of com- Alkalinity Corrosivity to Application
Type diz-abil- Main uses
a b
monly used or acidity metals methods
ity
products
Sodium hy-
Heavily corrosive
Yes Alkaline
pochlorite
to aluminium,
steel and carbon
Calcium hy-
Yes Alkaline
steel, and mod-
pochlorite
erately corrosive Disinfection of ob- Immersion
Chlorinated so-
Yes Alkaline to stainless steel, ject surface, water
dium phosphate Wiping
which can cause and infectious fo-
Sodium di-
hydrogen embrit- cuses, etc. Spraying
chloroisocya- Yes Acidic
tlement or stress
nurate
corrosion crack-
ing of stainless
Trichloroisocya-
Yes Acidic
steel.
nuric acid
Disinfection of
Slightly corrosive
Immersion
medical devices,
Iodophor Yes Alkaline to aluminium and
skin and mucosa,
Wiping
Halogen
stainless steel
etc.
Disinfection of
Slightly corrosive
Immersion
medical devices,
Iodine tincture Yes Alkaline to aluminium and
skin and mucosa,
Wiping
stainless steel
etc.
Disinfection of
Slightly corrosive Immersion
D i br o m o d i - object surfaces,
to copper, alumin-
met-hylhydantoin Yes Acidic medical devices, Wiping
ium and carbon
(DBDMH) water and infec-
steel Spraying
tious focuses, etc.
Slightly corrosive
to copper, alumin- Immersion
Bromochlorodi- Disinfection of ob-
ium and carbon
methylhydanto- Yes Acidic ject surfaces and Wiping
steel, and almost
in (BCDMH) water, etc.
corrosion-free to Spraying
stainless steel
Disinfection of ob-
Wiping
No obvious cor-
Ethanol No Neutral ject surfaces, skin
rosivity
Spraying
and hands, etc.
Disinfection of
object surfaces,
Immersion
Isopropyl alco- No obvious cor-
No Neutral medical devices,
hol rosivity
Wiping
Alcohol skin and hands,
etc.
Disinfection of
Immersion
object surfaces,
Chlorhex- No obvious cor-
No Alkaline medical devices, Wiping
idine-ethanol rosivity
skin and hands,
Spraying
etc.
a
Alkalinity or acidity refers to that of commonly used disinfectant products.
b
Metal corrosivity is usually graded as no obvious corrosion, mild corrosion, moderate corrosion and heavy corrosion;
there is no unified corrosion classification standard for disinfectants so far, which will be developed in the future; in the
table, "corrosive to metals" only indicates the existence of metal corrosion, as a warning when using disinfectants; the
specific corrosion classification is related to the standards used in the test, the type of metal materials used, test conditions
and the basis for evaluation.
Table 1 (continued)
Active ingredi-
Oxi-
ents of com- Alkalinity Corrosivity to Application
Type diz-abil- Main uses
a b
monly used or acidity metals methods
ity
products
Immersion
Disinfection of ob-
No obvious cor-
Phenol No Acidic ject surfaces and Wiping
rosivity
skin, etc.
Spraying
Phenol
Disinfection of ob-
Immersion
Halogenated No obvious cor-
No — ject surfaces, skin
Phenols rosivity
Wiping
and hands, etc.
Disinfection of Immersion
No obvious cor- object surfaces,
Guanidine Chlorhexidine No Acidic Wiping
rosivity skin, hands and
mucosa, etc. Spraying
Disinfection of
Polyhexameth-
No obvious cor- object surfaces,
ylene guanidine No —
rosivity skin, hands, air
(PHMG)
and water, etc.
Not obviously cor-
rosive to copper
Double-chain and stainless steel
Disinfection of
quaternary am- No — sheets, and slight-
Immersion
object surfaces,
monium salt ly corrosive to
Quaternary am-
medical devices, Wiping
carbon steel and
monium salt
skin and mucosa,
aluminium sheets.
Spraying
etc.
Single-stranded
Corrosive to met-
quaternary am- No —
als
monium salt
Disinfection of
object surfaces,
No obvious cor-
Ethylene oxide No Neutral medical devices, Fumigation
rosivity
skin, hands and
mucosa, etc.
Disinfection of ob-
Immersion
Potassium per- Corrosive to met-
Yes Alkaline ject surfaces, skin
manganate als
Wiping
and mucosa, etc.
Others
Disinfection of
Immersion
Compound object surfaces,
lysostaphin — — — medical devices, Wiping
disinfectant skin, hands and
Spraying
mucosa, etc.
Disinfection of ob- Immersion
Plant extracts
ject surfaces, air,
based disinfect- — — — Wiping
skin and hands,
ant
etc. Spraying
a
Alkalinity or acidity refers to that of commonly used disinfectant products.
b
Metal corrosivity is usually graded as no obvious corrosion, mild corrosion, moderate corrosion and heavy corrosion;
there is no unified corrosion classification standard for disinfectants so far, which will be developed in the future; in the
table, "corrosive to metals" only indicates the existence of metal corrosion, as a warning when using disinfectants; the
specific corrosion classification is related to the standards used in the test, the type of metal materials used, test conditions
and the basis for evaluation.
6 Good practice for metal corrosion protection when using disinfectants
6.1 General
6.1.1 It is important that relevant management and disinfection personnel, as well as the general
public have adequate knowledge of the physical and chemical properties, corrosivity, corrosion
protection measures and application methods of disinfectants.
6.1.2 Before planning and implementing disinfection, testers assess the corrosion degree of
disinfectants to metals. This can be based on relevant international, regional, national or industrial
standards. See also the overview of test methods that can be used to determine the corrosivity of
disinfectants in Annex A.
6.1.3 According to the assessment results and the importance of metal equipment or components in
the disinfected area, corrosion risks can be assessed in order to take measures to reduce the corrosion
hazards.
6.1.4 Before disinfecting important facilities, vehicles or equipment, personnel obtain the corrosivity
data of the proposed disinfectants to the corresponding metals, or select appropriate methods to test
their corrosivity. When disinfecting other metal objects, reference is made to the relevant disinfectant
corrosivity description or data, or relevant experience of correct use of disinfectant.
6.1.5 Alternative measures to mitigate or eliminate corrosion risks, on the premise of satisfying the
disinfection effect, include but are not limited to the following:
— replacement of disinfectants with less corrosive or non-corrosive ones;
— protection of the surface of the disinfected objects before disinfecting, such as plugging or coating
the parts or cracks where disinfectants are easy to accumulate, or painting or spraying anticorrosive
coatings;
— use of inhibitors that cause no damage to the disinfected objects during disinfecting;
— wiping or rinsing the surface of the disinfected objects with clean water to remove the residual
disinfectant after the contact time of disinfection.
6.2 Corrosion hazards
6.2.1 Halogen and oxidizing disinfectants can cause serious corrosion hazards during disinfecting.
6.2.2 If the disinfected objects contain metals and alloys prone to stress corrosion or hydrogen
embrittlement, halogen disinfectants are not permitted to disinfect key components in aviation
industry and important facilities. In other cases, through technical and economic comparison, halogen
disinfectants can be used with appropriate corrosion protection measures based on 6.1.5.
6.2.3 Oxidizing disinfectants usually corrode commonly used metals to varying degrees with
incorrect usage.
6.3 Corrosion protection measures
6.3.1 Under normal circumstances, alternative corrosion protection measures can be used when
disinfecting different metals.
6.3.2 Alloy steel is often used as a key component of vehicles or important facilities, while carbon steel
is often used for guardrails in common areas, steel structure components or concrete reinforcement,
etc. When disinfecting alloy steel or carbon steel without a surface protective layer, the disinfectant can
corrode it to varying degrees. Even if there is a surface protection layer, when there are defects on the
surface of the protection layer (such as pinholes, cracks, or scratches) that exposes the substrate, the
substrate can be corroded, eroded or interface corroded, leading to peeling and debonding, and finally
affected by chemical corrosion. Commonly used anti-corrosion methods include using low-corrosive
or non-corrosive disinfectants, setting up a complete and corrosion-resistant protective layer, and
thoroughly rinsing after disinfection.
6.3.3 Aluminium alloys are commonly used in vehicle parts, building doors and windows, etc.
Disinfectants usually corrode them to varying degrees. Generally, corrosive disinfectants are not used
to disinfect the aluminium alloy parts of vehicles to avoid possible accidents; when used in other less
hazardous environments such as building doors and windows, in addition to choosing less corrosive
disinfectants, it can also be wiped or rinsed with clean water after the disinfectant contact time has
passed.
6.3.4 Stainless steel is the commonly used type of metal. The classes of stainless steels have relatively
good corrosion resistance, but some of them can also be corroded by exposure to some oxidizing
or halogen disinfectants. Corrosion forms of stainless steels usually include but not limited to the
following:
— Pitting corrosion can be caused by exposure to halide disinfectant solution. It is a kind of local
corrosion, resulting in shallow to deep penetration. Halide-induced pitting corrosion is a typical
corrosion phenomenon of corrosion-resistant austenitic stainless steel.
— Crevice corrosion occurs in small, shielded crevices, which are prone to corrosion when the
equipment is immersed in the non-flowing corrosive disinfectant solution.
— Stress corrosion cracking and hydrogen embrittlement can cause serious harm. Increasing
corrosion cracks on stainless steel are caused by residual stresses applied to the steel and exposure
to the corrosive disinfectant solution. Relieving stress or reducing the corrosivity of disinfectants
is helpful to slow down or avoid corrosion cracking.
6.3.5 Titanium has outstanding corrosion resistance, and conventional disinfection concentration
does not cause titanium metal corrosion.
6.3.6 When disinfecting other metals, the corrosivity of the disinfectant is a major factor to consider,
including confirmation that its corrosion does not cause safety hazards, or the corrosion does not affect
its appearance or function.
6.3.7 When disinfection is conducted in different environments, alternative protection measures
can be taken based on the possible risk levels caused by corrosion, including but not limited to the
following.
— When disinfecting aircraft including its components, corrosivity tests of disinfectants are carried
out according to aviation-related standards and disinfectants are selected that meet the industry
requirements or disinfectants without obvious corrosivity.
— When disinfecting other vehicles (such as ships, trains and automobiles), related standards and
technically and economically feasible disinfectants are selected. See also the overview of test
methods that can be used to determine the corrosivity of disinfectants in Annex A.
— When disinfecting metal parts of important infrastructures or structures that can affect safety (such
as steel structure bridge and their metal accessories, airports, stadiums, amusement facilities and
other metal structures, etc.), non-oxidative or non-halogen or non-obvious corrosive disinfectants
are preferred, or other corrosion protection measures as listed in 6.1.5 are taken.
— When disinfecting metal parts of medical apparatus and instruments or important equipment,
appropriate disinfectants and disinfection methods are selected that are comprehensively in
accordance with the corrosion resistance of the metal material to be disinfected, the corrosivity
of disinfectants, disinfection methods and other conditions. When there is no reference data or
experience, a specific test evaluation is required.
— When disinfecting other environments or objects with less risk of corrosion (such as common
areas, streets, shopping malls, hospitals, tourist attractions, non-motor vehicles, etc.), oxidation
disinfectants or halogen disinfectants or non-obvious corrosive disinfectants can be used without
causing health hazards and corrosion safety hazards. When using oxidizing or halogen disinfectants,
clean water is used to wipe or rinse after the disinfection contact time has passed, or less corrosive
disinfectants are chosen, or alternative measures are adopted as mentioned in 6.1.5.
Annex A
(informative)
Overview of test methods to determine the corrosivity of
disinfectants
An overview of test methods used to determine the corrosivity of disinfectants is given in Table A.1.
Table A.1 — Test methods to determine the corrosivity of disinfectants
No. Test method Scope of application
a) Use full immersion to disinfect metal products, such as immersion
disinfection of medical instruments or other articles.
b) Factory inspection of disinfectants.
1 Full immersion
c) Evaluation of corrosivity of chemical agents involved in transportation.
d) Disinfectant corrosivity comparison experiment, etc.
The environment in which metal products are disinfected by spraying, such as the
2 Spraying disinfection of an enclosed space or an open environment (e.g. airplane, vehicle,
road, steel structure, and public area).
The metal products are disinfected in a closed environment by fumigation with
3 Fumigation
disinfectant.
a) Corrosion test when metal products are disinfected by wiping
4 Wiping
b) Corrosion test of disinfection towel
5 Corrosion evaluation Evaluation of corrosion degree based on the test results of various disinfectants
It is useful to study corrosion behaviour or test corrosion data of various disinfect-
Study on corrosivity
6 ants under different test conditions, so as to provide a reference for the prevention
test of disinfectants
and control of infectious diseases when using disinfectants.
Other situations where test methods can be developed for specific purposes. For
7 Other methods example, for ships, high-speed railways, motor vehicles and other transportation
tools, as well as important infrastructure or structures.
NOTE It is useful to consider and include limiting values, such as disinfectant effective concentration, test parameters,
dosage of disinfectants, treatment time and metal corrosion rate.
Annex B
(informative)
Commonly used disinfectants for disinfection of infectious disease
B.1 Aldehyde disinfectant
B.1.1 Formaldehyde disinfectant
B.1.1.1 Physical and chemical properties and forms
Formaldehyde is a colourless gas with a strong pungent smell and can be burned. It has a boiling point
of -21 °C, an ignition point of 300 °C and a relative density of 1,067 (given that of air as 1). It condenses
into a solid formaldehyde polymer at normal temperature. It is easily soluble in water, alcohol and ether,
and its solubility in water at room temperature is about 37 %.
The chemical formula for formaldehyde is CH O. Formaldehyde has active chemical properties and is
easy to polymerize. Formaldehyde is moderately toxic and has strong irritation to skin and mucosa.
The carbonyl group of formaldehyde is easy to undergo an addition reaction with sodium bisulphite,
alcohol, ammonia, and derivatives of ammonia. Formaldehyde can be easily oxidized into formic acid,
which can be synthesized into dioxymethylene or paraformaldehyde under different conditions, but it
can be depolymerized and regenerated into formaldehyde when heated (especially heated with acid).
Formaldehyde used for disinfection is usually composed of 35 % to 40 % formaldehyde aqueous
solution or solid paraformaldehyde. The former, also known as formalin solution, is acidic and miscible
with water and ethanol; the latter is a white powdery polymer, containing 91 % to 99 % formaldehyde,
which continuously breaks down to formaldehyde gas at normal temperature (formaldehyde gas is
hardly soluble in water but soluble in hot water or alkali solution).
B.1.1.2 Mechanism of killing microorganisms
Through a competitive reaction, formaldehyde and cysteine interact to prevent the synthesis of
the essential methionine (one of the amino acids) in bacteria, while the synthesis of methionine is a
fundamental metabolism of the cytoplasm of microorganisms. Thus, the death of microorganisms is
caused by inhibition of the synthesis of the nucleus and the cytoplasm. Through nonspecific alkylation
of formaldehyde, formaldehyde molecules directly act on amino, sulfhydryl, hydroxyl and carboxyl on
protein molecules of the bacterium to produce methyl derivatives, destroy bacterial proteins and lead
to the death of microorganisms.
B.1.1.3 Application in the disinfection and sterilization of infectious diseases
a) Scope of application
When applied for disinfection of infectious diseases, formaldehyde has obvious toxicity, which affects
its application in sterilization. Low-temperature steam formaldehyde sterilizer and formaldehyde
gas fumigation disinfection cabinet are commonly used for disinfection. The low-temperature steam
formaldehyde sterilizer is mainly used for sterilization of some medical apparatus and instruments that
are afraid of humidity and heat. The formaldehyde gas fumigation disinfection cabinet is used in the
disinfection of medical supplies. Formaldehyde solution can be used for disinfection of contaminated
articles, treatment of pathological anatomic specimens, disinfection of medical apparatus and
instruments and formaldehyde gas fumigation disinfection.
b) Application methods
1) Low-temperature steam formaldehyde sterilizer: Formaldehyde gas is filled with pressure
steam under the condition of lower than 90 °C, so that formaldehyde and low-temperature
steam are mixed to sterilize medical apparatus and instruments which can be protected from
humidity and heat under vacuum.
2) Formaldehyde fumigation disinfection cabinet: Completely closed containers or special
formaldehyde fumigation disinfection cabinets are used under normal temperature and
pressure, with a relative humidity of 70 %, and then the formaldehyde gas is released by the
chemical method or by heating to fumigate and disinfect completely exposed articles.
3) Disinfection of contaminated articles by immersion in formaldehyde aqueous solution:
The general contaminated articles can be soaked in the solution with the concentration of
40 g/l for 1 h, and the seriously contaminated articles can be soaked in the solution with the
concentration of 80 g/l for 6 h to 8 h.
4) Disinfection of medical apparatus and instruments: The immersion in 70 % ethanol containing
8 g/l formaldehyde for 18 h to 24 h can meet the sterilization requirements; Immersion in the
formula composed of 40 g/l formaldehyde and 50 g/l borax for more than 12 h can meet the
sterilization requirements.
B.1.2 Glutaraldehyde disinfectant
B.1.2.1 Physical and chemical properties and forms
Glutaraldehyde disinfectant is a 5-carbon diacetal compound (1,5-glutaraldehyde), which molecular
formula is C H O . Acetal, cyanohydrin, oxime, hydrazone, etc. can be formed from it through addition
5 8 2
or condensation reaction. Its two active aldehyde groups can crosslink with protein.
Glutaraldehyde disinfectant stock solution is a colourless or light-yellow oily liquid, neutral and soluble
in water, alcohols and other organic solvents in any proportion. Its aqueous solution is relatively stable
under acidic conditions, while glutaraldehyde monomer is easy to polymerize into butanol unsaturated
polymer under alkaline conditions.
The addition of cationic surfactants to the glutaraldehyde solution can significantly increase its
bactericidal effect and is known as a potent glutaraldehyde compound sterilant, with a concentration of
1,0 % to 1,2 % equivalent to the bactericidal effect of 2 % original glutaraldehyde.
The forms of glutaraldehyde disinfectants are as follows:
— 2 % alkaline glutaraldehyde aqueous solution: It is made by adding 0,3 % sodium bicarbonate to a
2 % glutaraldehyde aqueous solution. As soon as glutaraldehyde is alkalized, its stability is greatly
reduced. Therefore, in recent years, when producing glutaraldehyde aqueous solution in China,
sodium bicarbonate is mixed in proportion and packed in small plastic bags. It is then put into the
glutaraldehyde aqueous solution before use to make it become alkaline glutaraldehyde with the pH
above 8,0.
— 2 % potentiated acid glutaraldehyde: It is made by adding 0,25 % primary alcohol ethoxylate in
2 % glutaraldehyde aqueous solution. With the pH value of about 5,0, it has strong stability, and can
be used for one month. Its disadvantage is that its spore-killing effect is inferior to that of alkaline
glutaraldehyde, and it is corrosive to metals.
— 2 % neutral glutaraldehyde: It is made by adjusting the pH value of 2 % potentiated acid glutaraldehyde
to 7,0 with sodium bicarbonate. Its advantages are that its spore-killing effect is similar to alkaline
glutaraldehyde and its stability is equivalent to that of the acid glutaraldehyde, and it can be used
for 4 weeks at room temperature.
— Compound synergistic glutaraldehyde: It contains 1,0 % to 1,2 % glutaraldehyde, surfactant,
sodium bicarbonate and sodium nitrite. The pH value of its aqueous solution is 6 to 7, which has the
advantages of a strong bactericidal effect and small corrosiveness to metal instruments. It can be
used for endoscope disinfection and instrument sterilization, and can achieve the bactericidal effect
of 2 % alkaline, neutral and acid glutaraldehyde.
B.1.2.2 Mechanism of killing microorganisms
The bactericidal effect of glutaraldehyde mainly depends on the alkylation of two active aldehyde
groups, which directly or indirectly act on different groups of biological protein molecules, resulting
in the loss of biological activity and the death of microorganisms. Glutaraldehyde directly acts on
bacterial protein and enzyme protein molecules. It destroys peptidoglycan and changes protein
molecular structure, making it lose its original biological activity and leading to bacterial death due to
cell respiratory metabolism disorder. Glutaraldehyde prevents the release of dipicolinic acid from the
outer layer of bacterial spores, thus preventing the germination of bacterial spores; at the same time,
the crosslinking can close the spore wall, resulting in the death of spores and fungal spores.
B.1.2.3 Application in the disinfection and sterilization of infectious diseases
a) Scope of application
When applied for disinfection of infectious diseases, glutaraldehyde is applicable to the disinfection
and sterilization of endoscopes, surgical instruments, oral cavity, gynaecology and other heat-sensitive
medical apparatus and instruments and precision instruments in medical and health units. It can also
be used for disinfection and sterilization of cosmetology and hairdressing appliances, and knives,
scissors and other articles for pedicures.
b) Application methods
Immersion or wiping is generally adopted. The cleaned and dried medical apparatus and instruments
and articles to be disinfected can be immersed in the glutaraldehyde disinfectant for 30 min to 60 min,
then rinsed with sterile water and dried.
For the disinfection of large equipment and precision instruments, it can be achieved by wiping the
surfaces with glutaraldehyde disinfectant 2 times, and then wiping with clean water after 20 min.
Generally, immersion is adopted for sterilization treatment. The cleaned and dried medical apparatus
and instruments and articles to be treated can be immersed in the 2 % glutaraldehyde disinfectant
or compound synergic glutaraldehyde disinfectant for 10 h, and then taken out sterilely, rinsed with
sterile water, and wiped sterilely before use. When applied for disinfection of infectious diseases,
glutaraldehyde disinfectant is mainly used for the following:
— Sterilization of beauty, hair and foot bath supplies: The instruments used for pedicures and
cosmetology can be sterilized. The sterilization can be achieved by immersing them into the
compound synergic glutaraldehyde, such as 2 % alkaline, acidic or neutral glutaraldehyde for 10 h,
and then taking them out, washing them with sterile water, and drying them with a sterile towel
before use.
— Sterilization of surgical instruments: 2 % glutaraldehyde, 1 % or 1,2 % compound synergistic
glutaraldehyde disinfectant can be used for sterilization of surgical instruments. Generally, surgical
instruments are immersed and disinfected for 10 h. After sterilization, they are rinsed with sterile
water.
— Sterilization and disinfection of endoscopes in medical and health units: Glutaraldehyde is a common
disinfectant for endoscope disinfection and sterilization. It has the advantages of high efficiency and
rapid killing microorganisms, little influence by organics, generally no damage to the endoscope,
low surface tension and easy rinsing. Generally, 2 % alkaline, potentiated acidic or compound
synergistic glutaraldehyde disinfectant can be used for disinfection for 15 min immersion, and the
sterilization is usually immersed for 10 h.
B.2 Peroxide disinfectant
B.2.1 Peracetic acid disinfectant
B.2.1.1 Physical and chemical properties and forms
Peroxyacetic acid or peroxyacetic acid, with molecular formula CH COOH, includes acetyl group and
peroxy group in its structure. Therefore, peroxyacetic acid has both acid and peroxide properties, which
is different from general organic acids and peroxides. It is a colourless transparent liquid, with acidity
and a pungent smell. It is volatile and soluble in a variety of organic solvents and water. The relative
density is 1,226 and the boiling point is 110 °C. Peroxyacetic acid is very unstable and decomposes
when exposed to heat, metal and water.
Peroxyacetic acid usually includes two forms as below:
— Peroxyacetic acid aqueous solution: The concentration of peroxyacetic acid is about 20 %, containing
about 0,1 % stabilizer (8-hydroxyquinoline). When it is stored at room temperature of 15 °C to
20 °C, its monthly decomposition rate is 2,88 %. It can be diluted with water to meet the required
concentration when applied for use.
— Mixed form peroxyacetic acid: The two ingredients A and B are normally stored separately and
mixed well before use. A is the treated glacial acetic acid, and B is mainly the proportioned hydrogen
peroxide solution. On the day before use, solutions A and B can be mixed at 10:8 or 12:10 (by
volume) and stored at room temperature. The peroxyacetic acid content can reach about 20 % on
the following day. If the temperature is lower than 10 °C, the reaction time can be appropriately
extended. If the temperature is about 30 °C, the concentration can reach about 20 % within 6 h after
mix.
— Solid peroxyacetic acid: A solid organic compound containing acetyl group that can be dissolved in
water and a solid compound containing peroxy group (-OOH) that can be dissolved in water are in
binary packaging. They are usually stored separately. When it is used, they are dissolved in water in
proportion to react chemically, so as to produce peroxyacetic acid. For example, 30 % acetylsalicylic
acid and 30 % sodium perborate monohydrate are used to prepare solid peroxyacetic acid, and a
40 % anti-corrosion buffering agent is added. When it is used, it can be dissolved in water to be
diluted to a peroxyacetic acid solution with the required concentration by adding the anti-corrosion
buffering agent. As another example, a binary package consisting of TAED and sodium percarbonate
is used as a solid peroxyacetic acid. The disinfectant in the binary package is of white powder,
which is dissolved in water to obtain colourless and transparent peroxyacetic acid, with a content
of 163 g/l, and then diluted with deionized water to reach the required concentration of the aqueous
solution when it is used.
B.2.1.2 Mechanism of killing microorganisms
With its strong oxidation effect, peroxyacetic acid firstly destroys the permeability barrier of spores,
and then destroys and dissolves the core of spores, so that DNA, RNA, protein, DPA and other substances
are destroyed and leaked out, causing the death of spores. Its strong bactericidal effect is due to the dual
action of acid and oxygen, and the action of active oxygen can be more important. Electron microscopy
revealed changes in the ultrastructure of spores of Bacillus subtilis var. niger after disinfection with
peroxyacetic acid, with not only the disruption of structures and permeability barriers such as the
spore coat and cortex, but also the disruption or dissolution of the core of the spores.
B.2.1.3 Application in the disinfection and sterilization of infectious diseases
a) Scope of application
Wh
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