Can a safety valve be equipped with an upstream shut-off valve?

A gate valve is generally installed in front of the safety valve; if a globe valve is used, once the safety valve activates, the pressure release speed will be slower due to the change in flow direction. This post was last edited by XZZ000888 on 2007-12-31 20:49.]

A stop valve can be installed, but it must be sealed with a lead seal.

Agreed; that’s exactly how we do it in our factory. The valves are sealed with wire seals, so even if the personnel on duty are confused, they can’t move the valves, as they are locked in place. This not only ensures safety but also facilitates maintenance and testing without having to shut down the system. This post was last edited by limingshuguang on 2008-1-2 at 12:47.]

Generally, a shut-off valve should not be installed; if one is installed, it must be sealed with lead

The original poster’s question has been answered: lead seals! Some companies with strong safety measures use locked tags for this purpose! There’s no need to post further replies. This post was last edited by mine on 2008-1-2 at 21:21

According to the standards, no valves may be installed in front of the safety valve

No valves may be installed in front of the safety valve; if such valves are present, it constitutes a design error. In devices equipped with safety doors, the device is not allowed to operate if the safety door is damaged

I agree with the view from floor 8; installing any valve in front of the safety valve is not in compliance with safety standards.

It is generally not allowed; there are strict requirements for installation, and lead seals must be used to keep it fully open!

A stop valve can be installed, but it must be ensured that the valve is fully open and sealed with a seal. It seems that the Boiler and Pressure Vessel Regulations stipulate that safety valves must be equipped with upstream and downstream manual valves; boilers of a certain size or larger must have dual valves to serve as backups for each other.

I. According to TSG ZF001-2006 \"Regulations on Safety Technical Inspections of Safety Valves\", section B4.2 – Inlet and outlet pipes: Generally, shut-off valves shall not be installed on the inlet and outlet pipes of safety valves. When such valves must be installed, they need to be sealed with lead seals and kept in the fully open position. The pressure rating of the shut-off valves must be consistent with that of the inlet and outlet pipes of the safety valves, and the nominal diameter of the inlet and outlet ports of these shut-off valves should be no smaller than that of the flanges on the inlet and outlet sides of the safety valves. II. The requirements for the installation of safety valves as specified in the \"Regulations on Safety Inspection of Pressure Vessels\" are as follows: 1. Safety valves shall be installed vertically, and they should be placed in the gas phase space above the liquid level of the pressure vessel, or on pipes connected to the gas phase space of the pressure vessel. 2. The cross-sectional area of the connection pipe between the pressure vessel and the safety valve, as well as the openings in the fittings through which they connect, must not be smaller than the inlet cross-sectional area of the safety valve. The connecting pipes should be as short and straight as possible. 3. When two or more safety valves are installed at one connection port of a pressure vessel, the area at the inlet of that connection port shall be at least equal to the total cross-sectional area of the inlets of these safety valves. 4. It is generally not advisable to install stop valves between the safety valve and the pressure vessel. To enable online calibration of safety valves, a rupture disc device can be installed between the safety valve and the pressure vessel. For pressure vessels containing media with extremely high, high, or moderate toxicity, flammable media, corrosive or viscous media, or valuable media, in order to facilitate the cleaning and replacement of safety valves, a shut-off valve may be installed between the safety valve (rupture disc device) and the pressure vessel only with the approval of the technical responsible person in charge of pressure vessel safety at the entity using the vessel, and after reliable preventive measures have been put in place. During the normal operation of the pressure vessel, the stop valve must remain fully open (sealed or locked). The design and diameter of the stop valve must not interfere with the safe venting function of the safety valve. 5. The installation location of the safety valve should facilitate inspection and maintenance. This post was last edited by lyhh9024 on 2009-3-16 16:23.]

The answer above has already been given in great detail, so I won’t say anything more. Generally, shut-off valves are not allowed to be installed on the inlet and outlet pipes of safety valves. When it is necessary to install such valves, they must be sealed with lead seals and kept in the fully open position. The pressure rating of the shut-off valves should match that of the inlet and outlet pipes of the safety valves, and the nominal diameter of the inlet and outlet ports of these shut-off valves should be no smaller than that of the flanges on the inlet and outlet ports of the safety valves