Learn some safety knowledge about valves from a large accident

Nov 21, 2023 | News

In all kinds of pipe network systems, valves are called “throat”. Leakage, shutdown, and major accidents caused by valve performance and quality problems have brought immeasurable losses to the normal operation of industrial production, personal safety, and property (such as the Three Mile Island nuclear power plant accident in the United States that shocked the world). According to relevant statistics, the major production accidents caused by the world every year, 1/3 of which are caused by valve quality accidents.

In August 2020, the thermal power project of Madian Gangue Power Generation Company in China was undergoing thermal commissioning when a high-pressure steam pipeline suddenly broke, resulting in a major safety accident that killed 21 people and injured 5 people (3 of whom were seriously injured).

It is reported that the valve used by the factory is not a qualified high-quality dn25-dn3600 butterfly valve, and the cause of the accident includes improper operation as well, which shows that not only to select a good butterfly valve, but also to pay attention to the operation of the butterfly valve.

The cause of the terrible accident

After preliminary investigation and analysis, the main causes of the accident are: the weld seam of the main pipeline flowmeter valve at the steam outlet of the No. 2 boiler was cracked, and a large number of high temperature and high pressure steam spilled out, resulting in the breakage of the glass of the main control room, causing serious casualties in the main control room.

Causes of valve weld failure:

non rising stem gate valve DN100

  1. There are problems with the material of the pipeline, and the possibility is that the material of the main steam pipe is unqualified.
  2. The welding quality is not up to standard, the weld treatment process is not perfect, and 100% welding seam detection is not carried out after welding.
  3. The layout of the pipeline is unreasonable, and the accident pipeline is arranged in the 8m floor, which is the connection of the main steam pipe and the outlet pipe of No. 2 furnace in the factory, and also the boiler water supply platform. A large number of pipelines are cross-arranged and the space is limited, which leads to the expansion of the pipeline is blocked and the welding joint is easily broken due to thermal stress.
  4. There is a phenomenon of overtemperature and overpressure in operation.When using a gate valve,such as a bs5163 gate valve pn16,the control of temperature and pressure needs a lot attention.BS5163 is a British Standard specification for resilient-seated gate valves used for waterworks purposes. PN16 is a pressure rating that indicates the valve is designed to withstand a maximum pressure of 16 bar (232 psi) at a temperature range of -10°C to +80°

Precautions of applying valves

We have to learn from every single valve accident to avoid further accident from happening to the highest level.Here are some tips on the application of gate valves,including ggg50 butterfly valve,from TWT,one of the largest valve manufacturer:

1.The valve storage environment should pay attention to, should be stored in a dry and ventilated room, and blocked at both ends of the path.

2.The valve should be checked regularly, and remove the dirt on it, and apply anti-rust oil on its surface.

3.After the installation of the application of the valve, it should be regularly repaired to ensure that it works normally.

4.Check whether the sealing surface of the valve is worn, and repair or replace it according to the situation.

5.Check the trapezoidal thread wear of the valve stem and valve stem nut, whether the packing is outdated and invalid, and carry out the necessary replacement.