Introduction of emergency shutoff valve of tanker (Part 1)

1. Product introduction

The emergency shutoff valve, also known as the sub-sea valve, installed at the bottom of the tank body of a tanker, is a vital safety unit in gas applications. The valve is sealed inside the tank. The valve body is equipped with a shutoff groove. When it is strongly collided, the valve body will break outside of the flange, separating the tank from the pipeline at the bottom of the vehicle, becoming an independent and closed tank, so as to prevent liquid leakage, greatly improve the safety of transportation. It is a key component for bottom filling and discharging of the tanker. As shown in Figure 1 below.

 Figure 1. Sub-sea valves of tankers

2. Composition of a emergency shutoff valve

The emergency shutoff valve is mainly composed of valve body, sealing mechanism, control mechanism, tank connecting flange and outlet flange, as shown in Figure 2 below.

Fig. 2 Composition of Sub-sea Valve 

(1. Valve body 2. Sealing mechanism 3. Control mechanism 4. Tank connecting flange 5. Outlet flange)

The control mechanism is composed of valve stem, valve seat and driving device. When installing the emergency shutoff valve, the sealing mechanism is placed inside the tank and connected with the tank bottom plate through the tank connecting flange; The sealing mechanism uses stainless steel spring force for axial automatic sealing, so that the sub-sea valve is in a normally closed state, and the opening and closing operations are carried out through the transmission mechanism.

A shut-off groove is set at the root of the valve body, which can effectively absorb the energy transmitted by the pipeline damaged by the collision of vehicles. The valve body breaks from the shut-off groove, separating the tank body from the pipeline, thus ensuring the integrity of the sealing mechanism, avoiding material leakage, and greatly improving the safety of transportation. It is adopted by many international and domestic petroleum companies, chemical liquid dangerous goods transportation and other enterprises.

3. Quality standards

The emergency shutoff valve comply with QC/T932-2018 (Road Tanker for Flammable Liquid Goods Transportation Emergency shutoff Valve) automobile industry standard.

4. Common Terms and Definitions

(1) Emergency shutoff valve

In case of emergency, the valve can be quickly closed manually or automatically. The emergency shutoff valve shall be closed during non-filling and discharging.

(2) Fluid pipeline

On the tanker, the pipeline between the emergency shut-off valve and the filling/discharging adapter, including pipeline elements.

(3) Shut off time

The time from the start of closing the emergency shutoff valve to the stop of liquid flow.

(4) Nominal pressure

It refers to the pressure rating of the valve, which is represented by PN and digits, for example, PN6 refers to the nominal pressure of 0.6MPa.

(5) Nominal diameter

It refers to the nominal inner diameter of the valve. It is represented by DN and digits, for example, DN100 represents 4-inch caliber.

(6) Pressure balanced emergency shutoff valve

Valves that cannot be opened by the medium's own transport pressure as the medium pressure on both sides of the valve remains in balance.

(7) Non-pressure balanced emergency shutoff valve

Valves that can be opened by the medium itself conveying pressure as the medium pressure on both sides of the valve remains in balance.

(8) Tank connect joint

Connecting the port between the emergency shut-off valve and the tank

(9) Pipe connect joint

Connecting the port between the emergency shut-off valve and the fluid pipeline

(10) Body

Parts directly connected with the pipeline (or equipment) to form medium flow passage

5. Installation of emergency shut-off valve

Before installing the emergency shut-off valve, please clean the tank and pipeline to ensure that there are no particulate impurities in the tank and pipeline to avoid damaging the valve closure. When cleaning the emergency shut-off valve, be careful not to damage the sealing ring or sealing surface of valve body to avoid leakage. If the flow of the emergency shut-off valve is insufficient or the valve is not closed tightly, the emergency shut-off valve shall be removed to check whether there is waste residue or other impurities blocking or damaging the valve.

When checking and repairing the valve, press the pressure plate and rotate it anticlockwise to take out the pressure plate, spring and valve disc at one time, and check whether the sealing ring is intact. If it is damaged, please replace it.

-----------------------To be continued...-----------------------

By  WONDEE Autoparts

2022-10-20