CHEMICAL ENGINEERING TRANSACTIONS

VOL. 62, 2017

A publication of

The Italian Association

of Chemical Engineering
Online at www.aidic.it/cet

Guest Editors: Fei Song, Haibo Wang, Fang He
Copyright © 2017, AIDIC Servizi S.r.l.
ISBN 978-88-95608- 60-0; ISSN 2283-9216

Chemical Safety Risk Evaluation and Early Warning
Approaches

Aili Wu, Weiwei Jiao

Hebei Agricultural University, Baoding 071001, China
422914122@qq.com

Today, China has witnessed a rapid development in the economy, which has seen an explosive growth of the
chemical industry. In this context, the safety risk of greater hidden dangers ensues. This paper describes the
definition and the classification of safety risks those chemical enterprises face now. There is a reasonable
level-to-level management of the risk sources in the chemical enterprises, where the concept of appropriate
risk capacity was also introduced. The dangerous substances are also accommodated to a controllable
probability of risk occurrence by controlling the appropriate risk capacity of chemical enterprises. A diamond
forewarning model for enterprises’ safety risk is thereby established. Not only that, the safety risk
management case in a chemical enterprise is cited to prove how the model proposed here is feasible and will
be available for risk management.

1. Introduction
As the social technology advances at a full speed, China's chemical industry has also gradually evolved into a
chemical industry park which integrates chemical production, product processing, reasonable storage,
effective transport and proper handling. Those chemical enterprises are fundamental to the safety and security
of chemical industry park due to their hazards of chemical substances and potential energy intensity (Zhang,
Q. et al., 2016, Torres-Vega, JJ et al., 2014). Chemical enterprises should be ensured at a safety level. They
should play a great effect on environmental protection while maintaining a high productivity as a major growth
pole of the national economy, thus contributing much to the harmonized and sustainable development of
economic production and nature world (Fabbri and Contini, 2009). It is certain that the assessment and early
warning of the safety risks in the chemical industry has a positive significance to answer for the steady
development of economy, people's life safety and the harmonious development of the ecological environment
(Fraaije et al., 2012). In recent years, the explosive growth of chemical industry has seen great safety hazards
(Moore et al., 2007). Since 2008, the number of sudden environmental incidents in China has been increasing
year by year. In response to this situation, the country has enacted relevant policies, and put teeth in three
measures of “total reduction, safety protection and improv quality” to guarantee the safety of chemical
enterprises, and underlined the importance of advancing the whole process of environmental risk
management (Lemley et al., 2010; Moore, 2006). Existing studies demonstrate that a reasonable safety risk
assessment system and early warning approach have a significantly positive impact on the probability of
sudden environmental accidents in chemical enterprises (Baesi et al., 2013). It is therefore of great practical
significance to explore chemical safety risk assessment system and early warning approaches.

2. Safety risk assessment of chemical enterprises
2.1 Risk and safety risk

The definition of risk focuses on the abruptness of an accident, i.e, on the premise of failure to anticipate the
consequences of an incident, it refers to the set of emergencies and their relevant consequences (Coulibaly et
al., 2017; Barlow et al., 2015). In the S.H.E management system, the risk is defined as the probability of
occurrence of the emergency within a certain period of time and the severity of the ensuing consequences
(Giannopoulos, G. et al., 2010).

DOI: 10.3303/CET1762259

Please cite this article as: Aili Wu, Weiwei Jiao, 2017, Chemical safety risk evaluation and early warning approaches, Chemical Engineering
Transactions, 62, 1549-1554 DOI:10.3303/CET1762259

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The safety risk for chemical enterprises attributes to sudden risk according to the risk classification. The
reason is that such risk has a high hazard to the environment and human health, and is characterized by
potentiality, concealment and long-standing impact (Godin et al., 2004). In other words, the safety risks of
chemical enterprises are usually hidden for a certain time and will not emerge immediately. However, once
outbreak, it will produce a violent impact on the human health and ecological environment (Bou-Diab and
Fierz, 2002). The risk source of chemical enterprises is shown in Fig. 1. This paper defines the safety risk
source of a chemical enterprise as a risk substance pertaining to production, consumption and discharge, and
under a certain impact of factors, can lead the surrounding to producing a risk substance which can trigger
unexpected accidents, as a tiny unit of safety risk.

Figure 1: Safety risk source of the chemical enterprise

2.2 Safety risk evaluation of chemical enterprises

For the safety risk assessment of chemical enterprises focuses on the violent and irreversible consequences
caused by natural irreversibility or improper activities of mankind, which are propagated through the
environment, and eventually undermine the ecological environment and human society to a certain extent,
provided that the narrow sense of safety risk source limited above is underlaid. The safety risk assessment in
chemical enterprise includes three parts, i.e. risk identification, risk assessment and safety risk decision, each
of which can be further subdivided, as shown in Fig. 2.

Figure 2: Safety risk assessment of chemical enterprise content

3 Construction of safety risk assessment model
3.1 Classification management of safety risk sources

When the classification management of safety risk sources is carried out for chemical enterprises, along with
the potential risks, dosages, storages and actual storage volumes which must be classified, great attention
must be paid to the inherent causes why safety risks occur, such as risks of production plants, human factors,

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etc. The key to the classification management of safety risk sources lies in the investigation of the
environmental risk sources, including hazardous substances, storage areas, production management and the
surrounding ecology environment, in general and detailed ways. Among them, the hazardous substances shall
be investigated in accordance with the relevant standards issued for substance hazards. As shown in Table 1,
the surrounding environmental conditions as investigated mainly include the sensitive targets within 500
meters around the chemical enterprises such as residential areas, rivers, hospitals and natural ecology
preservation areas, etc. After a reasonable classification of risk sources, different classes can be disposed
separately.

Table 1: Physical hazard criteria

substance
class

Level
Rats by oral
mg/kg

Rats by skin
mg/kg

The four - hour inhalation in mice
Mg/L

toxic
substance

1 <5 <1 <0.01
2 5<L<25 10<L<50 0.1<L<0.5
3 25<L<200 50<L<400 0.5<L<2

inflammable
substance

1
Flammable gases, substances between boiling point of 20 degrees
centigrade and 50 degrees Celsius

2 Flammable liquid, boiling point substances above 20 degrees Celsius
3 Flammable liquid, which remain liquid under pressure

explosive substances Under the influence of flame could explode

3.2 Computation of safety capacity

The basic concept of safety capacity is introduced in order to achieve the scale control on hazardous
substances. A quantitative relationship between the risk and the size of the hazardous substances is
constructed, so that it is critical to obtain the maximum safety capacity. The safety risks triggered due to the
scales of hazardous substances in the chemical enterprises include four parts, i.e. hazards of goods, inherent
safety risks, transport safety risks and safety capacity. The interrelation among these four parts is shown in
Fig. 3. The safety capacity of chemical enterprises mainly refers to the maximum and reasonable scale of
hazardous substances. This paper limits the types of hazardous substances in chemical enterprises. It is
supposed that there are only three types of explosive, flammable and toxic substances in chemical
enterprises. Based on safety risk capacity, the average risk on personnel can be figured out. Then the
chemical safety risk assessment model is built in combination with specific hazardous substances, refer to Fig.
4 for its main procedure.

C≤（C1·R1+C2·R2+C3·R3） (1)

Figure 3: Dangerous goods, the relationship between risk and security capacity

When the above expression is not true for C, the chemical enterprises must make some adjustments to the
scales of hazardous goods until it is true. In the equation, the risk of different hazardous goods is evaluated by
using the technology proposed by our country in the Labor and Social Security. A comprehensive analysis
shall be made on the hazards of dangerous goods themselves, and their process and technological risks and
toxic components.

hazard risk
Amount of various

categories of
dangerous goods

safety
endurance

Existing
dangerous

Source

Hazards

hazardous
article

Maximum safe traffic

Maximum Amount
of safety stock

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Figure 4: Capacity of chemical enterprise safety risk research ideas

4 Forewarning of safety risks
4.1 Preparations

In chemical enterprises, most of the raw materials and products used in the production are dangerous
chemicals, numerous in types and huge in quantity. Rather, these chemicals involve complicated chemical
process, large-scale experimental equipment and production facilities, so that the risk of incurring sudden
accidents are hidden, such as fire, explosion, toxicosis and leakage, etc., and these emergencies have
secondary hazards to the ecological environment. The key to effectively evaluate the safety risks of chemical
enterprises lies in effective classification management of risk sources with effective procedures, thus to
provide instructive suggestions for the emergency preparedness of chemical enterprises for safety risks.
According to the theory of risk symptoms, the risks on the production field are classified as the cause
symptoms and the status symptoms, etc. Different elements are subjected to the early warning approaches
which are combined with each other for use as the early warning mode of the whole process of risk. The early
warning mode of the whole process of risk is shown in Fig. 5. In this mode, the risk factors and its
consequences contained in the practical production field of the chemical enterprise are incorporated for
building the safety risk forewarning method, i.e. a diamond early-warning approach, as shown in Fig. 6. This
method defaults the conditional and random outbreak of arbitrary safety risks, but there is a complex
relationship among them.

Figure 5: The whole process of risk early - warning model

Figure 6: Diamond Risk Early - Warning Method

The results of
early warning

Conditions
warning

Reason for
warning

Status
early - warning

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4.2 Establishment of forewarning model of safety risk

Given that there are four major elements for risk early warning in practical production and combined with the
diamond forewarning approach, this paper proposes a diamond forewarning model for safety risk as shown in
Fig. 7. The model consists of risk forewarning analysis, risk symptom identification, early warning program
design and optimization and early warning program test.

Figure 7: Diamond chemical enterprise safety risk early - warning model

4.3 Verification of risk forewarning model

This paper takes a large-scale chemical enterprise as a case to verify the proposed diamond forewarning
model of safety risk in chemical industry. Most of the company's staple products are hazardous and toxic, and
produced in a streamline mode. It is difficult to control and early warning of the safety risk in this company,
The curve of total contingencies occurred in recent years in this company is shown in Fig. 8. It is the trend of
rising year by year. According to the actual situation of the company, given that the risks originate from toxic
and hazardous substances, the relationship between them is shown in Table 2. According to Table 2, a
systematic index - Safety Index (SI) is constructed. Based on the size and the variation trend of SI, the safety
risk of chemical enterprises can be warned early. By analyzing the SI of the chemical enterprise in recent
months, it can be seen from Fig. 9 that the safety risk of the enterprise is effectively controlled.

Table 2: Relationship between structural variables

structure variable mismanagement Unsafe behavior Material insecurity

Impact Factor direct indirect all direct indirect all direct indirect all
Unsafe behavior 0.49 0.49
Material insecurity 0.28 0.26 0.54 0.53 0.53
safety accident 0.31 0.65 0.96 0.59 0.36 0.95 0.67

2006 2007 2008 2009 2010 2011
5

Years

T
ot

al
n

um
be

r o
f i

nc
id

en
ts

o
f c

he
m

ic
al

e
nt

er
pr

1 2 3 4 5 6 7
0.50

0.75

1.00

Se
cu

ri
ty

In
de

Months

Figure 8: Total number of accidents Figure 9: Security Index trend chart

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5. Conclusion
Aiming at the explosive growth of chemical industry, this paper probes into the safety risk assessment of
chemical enterprises and advances the appropriate early warning approaches. The conclusions are drawn as
follows:
(1) Reasonable classification management of risk sources is the premise for safety risk assessment of
chemical enterprises. In the process of classification management, along with the classification of the potential
risks, dosage, storage methods and actual storage volume of risk sources, great attention should also be paid
to the inherent causes of safety risk.
(2) Risk Safety capacity can well characterize the scale of hazardous substances in chemical industry. The
probability of occurrence of safety risks in chemical industry can be controlled an effective regulation of safety
risk capacity.
(3) Diamond early-warning method is the basis for establishing rhombus forewarning model for safety risk in
chemical enterprise. The accidents occurred in chemical industry is taken as study case to verify the
availability and reasonability of the model, which has an instructive significance for practical chemical
production.

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