About the cotter pin installation of high pressure pipeline check valve
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We are users of a certain domestic brand valve. We have now discovered a technical problem and would like to get your analysis and answer. Today, we dismantled and inspected the 10-inch and 1500LB check valves on two high-pressure water injection pipelines, and found that: There is a pin hole on the lock nut of the valve core, but no pin is installed. Please help with this: I would like to ask why the pin hole is not installed with a pin when it leaves the factory? Will there be a high risk to operation if the pins are not installed? Do the pins need to be installed by the user? What are the requirements for the material of the pin? Does it need to be bidirectional stainless steel? Thanks!
If it is corrosive, use stainless steel cotter pins. If it is not corrosive, use ordinary ones. As for whether it is installed at the factory, it depends on whether the screw mouth has a corresponding nut hole. If it matches, it's probably fallen off. Can be replaced. If it is, there is no anti-air, and it really means that there is no pretense. If this is the case, you will have to drill holes again if you want to install it. For reference.
There are corresponding holes on the screw. The problem is that both valves have no pins, which is strange, as they don't look like they are installed. We plan to buy it and install it. Thank you for the professional analysis!
Oh, especially for valves used in pipelines with flammable and explosive media, these details must be paid attention to. If you want a higher insurance factor, you can tighten it and then fix it by spot welding. When it needs to be repaired and disassembled, you can use an abrasive tool to remove the solder joints for disassembly. The harm caused by valve parts falling off in the pipeline should not be underestimated. For reference.
I am not a professional in valves, but I have a very layman question that I would like to ask.: The so-called cotter pin position mentioned above, is there any contact with the medium here? If so, what should I do if the cotter pin rubs against the bolt or nut and generates sparks when the valve is opened or closed or the flow is adjusted? (Cotter pins are generally movable, and fluctuations in the medium may cause relative movement between the cotter pin and the fastener.) If this is a water injection pipeline as mentioned by the poster, then the setting of the cotter pin here is optional, as long as the nut has anti-loosening measures. (Generally, structures that can swing freely such as cotter pins are not used in places that are in contact with the medium, right? ) It may not be a big problem for non-flammable and explosive media. If it is used for flammable and explosive media, it may need to be carefully considered.
The cotter pin shakes as the medium fluctuates. Do you need to consider whether the cotter pin will become thinner or even break due to shaking and friction after a certain period of time. The broken cotter pin will impact into the equipment with the medium. How destructive is it? Carefully measure its destructive power.
For other people's products, if you have any problems when using them, you can communicate and find out first to see if something was missed during manufacturing or if there are special considerations in the design. If you add more by yourself, it will be troublesome and cause unnecessary losses.
The above reply is purely the opinion of a valve layman, please ignore it, bosses.
Thank you very much for the photo. My suggestion is to check the manufacturer's valve drawing. It is easy to find the corresponding drawing based on the part number, and then search it against the parts.