Can the flange cover be replaced by a plug-in plate and a flange?

The key to this question is to look at the usage environment of metal pipes, such as pipe pressure, etc.

Used in PN1.9MPa, DN300, normal temperature

Sometimes the flange cover cannot be found for a while, but the plug-in plate and flange are easier to find.

It can be replaced by a combination of insert plate and flange, but the strength of the insert plate must reach the corresponding level of pressure.

As long as the pressure issue is fully considered, it should be possible to replace it.

Are there any relevant standards? I checked many standards, including HG21547, but I couldn’t find any basis for disallowance.

PN1.9MPa and DN300 have higher pressure. You can check the plug-in board.

Pressure pipelines are not allowed according to the requirements, but in practice they can be modified under the conditions of ensuring safe use. In addition, adding a flange to a plug-in board is not as convenient as directly opening a blind plate and drilling bolt holes.

Chemical plants usually have a large number of insert plates and flanges of various specifications, but flange covers are generally not available. Check HG21547, the thickness of the concave and convex insert plates is 31mm, and the strength is satisfactory after verification. Check HG20601, the thickness of the flange cover should be 34mm, and such a thick steel plate is not easy to find. So it is still inconvenient.

The brother on the 9th floor said that this is generally not allowed. Is there any relevant basis?

It seems that the following basis can be used instead: HG/T 20570.23-95 "Setting of blind plates": 2.0.1.8 When the device is constructed in phases, blind plates should be installed at the cut-off valves for interconnected pipelines to facilitate subsequent construction. ； 2.0 .1.10 Other occasions where blind plates are required due to process requirements ；

HG/T 20570.23-95: 1.0.1 The blind plate is mainly used to completely separate the production medium to prevent the lax closing of the shut-off valve from affecting production and even causing accidents. From the appearance, it is generally divided into 8-shaped blind plates, insert plates, and gaskets (the insert plates and gasket rings are blind to each other). 1.0.2 The blind plate should be installed at the location where separation (cut-off) is required, such as the equipment connection port, the front and rear of the shut-off valve, or between two flanges. It is usually recommended to use an 8-shaped blind plate; insert plates (round blind plates) can also be used for one-time use parts such as pressure and purging.

The iron plate can be welded to the back of the flange. :victory:

Good idea, there should be no problem in terms of structure and strength, but I don’t know if there are any relevant regulations in this regard.

It should be ok, but the intensity needs to be high.

Of course there is no problem, the thickness of the plug-in board has been calculated.

There is an internal leakage in the diesel line shower valve in my installation. I used a figure 8 blind plate and flange to blind it! The leakage is not too big and the effect is concealed well!

Agree with the opinion of the 9th floor. We call it a plug here. As long as the screw hole and sealing surface are cut out, this requirement can be met. Generally, factories have the conditions for processing, and the thickness is determined according to the pressure level. Generally, δ=20mm is enough.

The 9th and 19th floors are talking about flange covers. This is the standard HG20601 "Steel Pipe Flange Cover (European System)". There are also called stuffing cover, stuffing plate, stuffing head, blind head, blind cover, blind flange, plug, and blocking plate. They all mean the same thing. My problem is that I want to use plug-in plate + flange to replace the flange cover, but I can't find the relevant standards or basis. A few days ago, our unit’s gasification device was equipped with a piece of DN300. The PN2.0 plug-in board suddenly leaked from the metal winding pad, causing the system to shut down. The company had to assess the relevant personnel for 5,000 yuan. The process system said that our plug-in board was not standardized. We who installed the equipment originally found a plug-in board for convenience, but it was installed incorrectly by mistake. We were fined with our hard-earned money. This time, we felt extremely guilty. Originally, we could just replace the gasket and reinstall it, but people said it was non-standard. We couldn't find the basis for it, so we had to replace it with a standard flange cover. The people in the process system became even more proud after seeing it. . . . This post was last edited by twinge on 2009-4-21 21:30 ]

Can it be "generally δ=20mm"? This thickness is the most important. In this example, δ≥16mm is calculated according to GB/T20801-2006 "Pressure Pipe Specification-Industrial Pipeline". According to the calculation and table lookup in "Practical Process Manual", both δ=22mm. Check HG21547 "Insert Plate". . . . 》The thickness is δ=31mm, check HG20601》. . . The thickness of flange cover (European system) 2.5MPa class" is 34mm. Applying HG20622 "Flange cover (American system) Class300", the thickness reaches 51mm.