Is it necessary to install a manual bottom valve on the tank bottom?

1. If two valves are installed, the first valve should be a normally open valve, used solely to cut off the material flow when performing maintenance on the second valve, which is the one used in normal production. This valve has its switch setting adjusted as needed; there are also those that serve as a second valve added out of necessity due to leaks in the first valve. It is still necessary to conduct the identification based on your actual requirements. 2. The same applies to the remaining issues; identification should be carried out according to your actual needs. Follow the operating procedures; once you understand the principles, it won’t be a problem.

I’ve spoken with people in this field before, who said that emergency shut-off valves should not be used as control valves; they must remain in the open position at all times, and only be closed urgently in the event of an accident requiring shutdown. However, most oil depots use these valves as control valves due to the convenience of being able to operate them remotely. I wonder if there are any relevant regulations regarding this

From the bottom outlet of the tank to the pump inlet, there are many valves. The first valve at the bottom of the tank outlet, also known as a root valve, is manual and stays open; it is not operated under normal circumstances. A emergency shut-off valve can be installed on the second valve as required. There is an inlet filter for the pump, and also a set of valves, namely manual valves, used to switch between the pump’s inlet filter and the discharge pump.

1. Currently, due to safety regulations, each storage tank installed newly must be equipped with a shut-off valve at its inlet and outlet; therefore, the valve assemblies at the tank’s inlets and outlets should consist of a manual valve, an emergency shut-off valve, and valves for each branch line. 2. In the case of existing storage tanks, if no additional shut-off valves can be installed between the inlets and outlets, the gate valve at the tank base can be replaced with a shut-off valve, or the various branches can also be equipped with shut-off valves. However, considering cost factors, the original gate valve at the tank base is usually replaced with an emergency shut-off valve. 3. If the tank root valve is a manual valve, it is recommended to close the manual valves at the tank’s inlet and outlet when the tank is at rest; if it is a cut-off valve, it is recommended to keep it in the open position. 4. Isolation valves must not be used for routine on/off operations; the isolation valve system should have its own independent SCS system to enable interlocking in emergency situations. 5. For cut-off valves, air-operated or gas-operated valves equipped with an emergency air storage tank should be used. 6. The tank root valve must not be operated frequently; it should be opened and closed regularly as well as maintained

Since our company’s emergency shut-off valves are electric gate valves, there is a relatively high possibility of internal leakage. Additionally, the first and third valves (branch valves) are both manual gate valves, and they too can experience internal leakage; therefore, under normal circumstances, when there is no inflow or outflow from the tank, these three valves remain in a closed state. Furthermore, our emergency shut-off valves are used as operating valves, but this does not affect remote operation and interlock control in emergency situations. Since we do not have tanks that store full pressure or highly toxic substances, a SIS system has not been installed. The interlock function of these emergency shut-off valves is implemented through DCS configuration, based on the signal from the level switches installed on the tank walls. I’m not sure why, regarding the sixth point you mentioned, it is strictly prohibited to operate the tank root valve frequently What are the issues with the daily operation of the emergency shut-off valve?

The function of an emergency shut-off valve is to cut off flow in the event of an accident. There’s no need to consider the possibility of leaks in the main valves, which would require frequent opening and closing of those valves. If the valve cannot be closed properly during an accident, it will lead to an escalation of the incident. There are several reasons why emergency shut-off valves should not be used frequently: 1. Frequent opening and closing of the valve can lead to complacency among operators, who may think that this valve isn’t meant to be used immediately in emergency situations. It’s similar to using the normal stop button instead of the emergency stop button when shutting down a compressor – if the emergency stop button is used regularly, people will become complacent and fail to think of using it in an emergency. 2. Frequent opening and closing of the valve can cause wear on the sealing surfaces, and prolonged use may lead to internal leakage in the valve. 3. When switching valves remotely, the remote signals often show abnormal readings; this is especially true during the process of loading and unloading materials from storage tanks. If remote control is used without on-site inspection by operators, it is very likely that the tank could overflow or the pumps could run dry

This valve has its switch setting adjusted as needed; there are also valves that are added as a second layer of protection in case the first valve leaks

The answer to this question by ysp54489189 is quite comprehensive. Emergency shut-off valves are generally required to be of the type that closes automatically due to mechanical spring action, so as to shut down in the event of failures in the instrument air supply or electrical systems. To prevent abnormal pressures in the instrument air supply from affecting the valve’s operation, each shut-off valve is equipped with an emergency air reservoir (to ensure that the valve can still be operated in emergency situations when there are problems with the instrument air supply system).

This post was last edited by A drop of oil_TJPN on 2018-3-17 at 13:51. The first valve after leaving the tank is a root valve, which is normally open and can be equipped with a pneumatic actuator to allow remote shutdown in emergency situations. Pneumatic control is usually applied to this valve. The second valve after leaving the tank is generally part of a valve assembly that enables switching between different processes or functions; this second valve is typically electrically operated, with signals sent to the DCS for remote control. As needed, interlocks related to certain pumps or the tank’s liquid level can also be connected to this second valve. The third valve after leaving the tank can, as needed, lead to the isolation valve between the tank groups, or directly to the pump inlet valve; this valve is usually kept in the open position. When used as a cut-off valve for a tank bank, it should be operable remotely.

According to the regulations set by safety supervision authorities, an emergency shut-off device is required, but it is not specified whether it should be installed at the base of the tank or at the second valve. Document [2014] No. 68 only states that \"alarm systems for high and low liquid levels in the storage tank should be installed in accordance with regulatory requirements, and automatic interlocks should be employed to shut off the tank’s feed valve when the liquid level is too high, as well as to stop material transfer when the level is too low.\" Therefore, in projects I have worked on, depending on the client’s requirements, some emergency shut-off devices are installed at the base of the tank, so as to enable cutting off the flow from the nearest point to the tank; others are placed at the second valve, as they can serve both as emergency shut-off devices and for normal operational purposes. For new projects, there is also consideration given to installing a separate emergency shut-off valve between the flexible connection and the second valve. In short, any of the options meets the requirements of the Safety Supervision Bureau.