Ammonia safety in China in focus at Gustav Lorentzen 2014 conference&nbsp;

Ammonia safety in China was one of the major themes discussed at Gustav Lorentzen 2014 held in Hangzhou, China. Two plenary lectures were dedicated to ammonia safety, analysing common accident causes and ways to ensure future accidents are prevented. The lectures emphasised the importance of education and lifelong training as well as enforcement of safety rules as key measures to ensure the safety of refrigeration operations.

In the lecture “Analysis of ammonia incidents that recently happened in China” Professor Jiang Shen from Tianjin University of Commerce investigated the main causes of incidents that have occurred in facilities utilising ammonia as a refrigerant. Evaluating 70 accidents over the last 5 years, he pointed out that almost 50% occurred as a result of ammonia releases due to failure in maintenance operations, while close to 40% of accidents resulted in fire due to fire regulation violation or improper use of materials.

Most accidents relate to lack of training and awareness of safety measures

The lack of professionally educated and trained personnel operating ammonia facilities was identified as one of the main factors in ammonia incidents. Ammonia refrigeration systems have been used in China for more than 60 years, but the large majority of accidents have happened in the last few years. According to Professor Shen, in the first 50 years of its use there were few casualties related to the use of ammonia thanks to operator education, which ensured a thorough understanding of the refrigeration system and the ability to maintain and repair ammonia refrigeration systems. This has rapidly declined in the last few years.

Besides improper handling and maintenance, Professor Shen highlighted other key causes of ammonia accidents in China, especially:

Illegal designs and installations
Improper manual defrost operations - hydraulic shock can result in pipeline burst
Aging or poor management of equipment and pipelines
Usage of materials that do not meet fire safety standards
Use of an open flame such as for example in the welding of pipelines, and other ammonia equipment

In addition, imperfect alarm devices, or their total absence, as well as staff being unable to evacuate a building, have contributed to serious casualties.

Education, safety code enforcement and new technology - key measures in improving safety

A number of safety codes apply to the design, construction and operation of any ammonia refrigeration plant in China. These include the:

Production safety law of the people’s Republic of China
Safety regulation for hazardous chemicals
Code for design of cold store GB50072-2010
Safety code for cold store GB28009-2011

To ensure safety, in addition to enforcing legislation, operators must have the knowledge needed to safely work on ammonia installations and all staff should receive regular safety training and drills.

Professor Shen noted that the introduction of CO2/ammonia cascade technology to minimise the ammonia charge and restrict its presence to a machinery room will play an important role in improving the safety of industrial refrigeration facilities in China. In addition, automated control systems need to be put in place to reduce the risk of human error - especially automatic systems for hot gas defrost, leakage prevention systems and a relief valves.

Statistics shows that most of accidents relate to service, not refrigerants

Another plenary lecture on “Environmentally safe and energy efficient solutions” by Alexander Cohr Pachai from Johnson Controls suggested most industrial refrigeration accidents are not related to or caused by refrigerants, but rather as a result of dereliction of proper workplace behaviour and safety guidelines. With a statistical representation of more than 40-60% of all accidents, service is by far the most dominant accident situation. In many cases this can be dealt with simply, by using detectors, marking unsafe working areas, and most importantly with training.

In addition, design engineers need to consider how valves are placed on site, while keeping manuals that are easily accessible to service and maintenance technicians. These must be kept up-to-date with regards to the valves used on the specific plant. Small details in components can cause problems on site.

According to Pachai, accidents can be prevented by proper preventive maintenance schedules including efficient pressure tests and regular inspection under the insulation to avoid otherwise unnoticed corrosion.