Price issues for CLASS series pipe flanges and PN series pipe flanges
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I asked this question in the HaiChuan QQ group yesterday and today; maybe I didn’t express myself clearly, or perhaps others thought it was too simple and didn’t respond properly. So I’m writing in the forum to ask for advice from friends with purchasing experience. The problem originated from the fact that when our company carried out the design work, as it was a turnkey project, costs had to be reduced; as a result, all materials were selected from the PN B series, which is the so-called series with a small outer diameter. However, the small outer diameter series has many disadvantages, so we want to switch to the PN A series, which is the large outer diameter series. Of course, if there is no impact on price, we will use the CLASS series in US standards. So there is the following question: 1: I heard that the purchase of pipe flanges is based on weight. I think that for the same tonnage, the price should be the same whether PN A or PN B is used; I’m not sure if that’s indeed the case (I know that in reality, due to the wall thickness, when switching from the B series to the A series at the same DN, the actual tonnage varies because of the differences in wall thickness; however, I think the difference isn’t significant, as the weight per meter of pipe for the B series can be lighter, heavier, or equal to that of the A series.) 2: If the CLASS series, that is, the American standard series, is used, is it more expensive than the PN series at the same tonnage? I’m not sure if my meaning is clear; typing is not easy, so I hope experienced friends can offer some guidance. Thank you!
Why not post it in Brother Zhao’s one-on-one thread? @boyirensheng
1: I heard that the purchase of pipe flanges is based on weight. I think that for the same weight, the prices for PN grades A or B should be the same; I’m not sure though. For some specifications, the prices are identical, while for other specifications (with a large difference in weight), the prices differ. 2: If CLASS series, which is the American standard series, is used, will it be more expensive than the PN series for the same weight? This comparison doesn’t seem to be very meaningful, as valves that follow American standards require American-standard flanges, while those that follow Chinese or European standards need corresponding flanges. If we really want to find a solution, I have an idea: we can create custom flanges. In many power plant projects I work on, American-standard valves are connected to pipes that follow Chinese standards, and this is done by contractors in order to save costs – they create custom flanges whose dimensions are the same as those of American-standard flanges except for the inner diameter, which is adjusted to match Chinese Standard B series pipes. I have a lot to do today, so I’ll reply briefly for now
Thank you, Teacher Zhao, for your guidance. 1: Some specifications have the same price, while others (with a large difference) have different prices (for example, for DN500, the outer diameters are 530 and 508 respectively; is this considered a significant difference?) If we calculate it, which one is more expensive? ) 2: This seems to have little significance, as valves that follow American standards require American-standard flanges, while those that follow Chinese or European standards need corresponding flanges. If we really want to find a solution, I have an idea: we can use custom-made flanges. In many power plant projects I work on, American-standard valves are connected to pipes that follow Chinese standards; this is done by contractors in order to save costs, by creating custom flanges whose dimensions are the same as those of American-standard flanges except for the inner diameter, which is adjusted to match Chinese Standard B series pipes. (If it were an American-standard flange, then American-standard valves would definitely be used.) The significance of the comparison is this: if I use only American standards for a project and only European standards for another project, will there be a significant difference in the purchase prices of pipes and valves? Is it because the standard series are different that the prices vary? ) I hope Teacher Game Theory can give some more guidance when he is free! @boyirensheng @ValveMingMing
Create a material list, reach out to several suppliers for quotes, and the price differences will be clear at a glance
Then three material lists need to be prepared, and the amount of work involved is obvious
1: Some specifications have the same price, while others (with a large difference) have different prices (for example, for DN500, the outer diameters are 530 and 508 – is this considered a significant difference?) If we calculate it, which one is more expensive? ) This specification is definitely more expensive than 508, as the national standard uses 530 as the common specification. 2: This seems to have little meaning, because if the valves are of American standard, then American standard flanges must be used; if they are of national or European standard, then corresponding flanges are required. If one really wants to find a solution, I have an idea: create non-standard flanges. In many power plant projects I work on, American standard valves are connected to pipes that follow the national standard, and this is done by contractors in order to save costs – by using non-standard flanges whose dimensions, aside from the inner diameter, match those of American standard flanges, with only the inner diameter being compatible with national standard B-series pipes. (If it were an American standard flange, then American standard valves would definitely be used.) The significance of the comparison is this: if I use only American standards for a project and only European standards for another project, will there be a significant difference in the purchase prices of pipes and valves? Is it because the standard series are different that the prices vary? I have calculated this issue before; it depends on the specific specifications. Some are more expensive according to Chinese standards, while others are more expensive according to American standards. It really depends on the specifications and pressure levels used. You might think this is a vague answer, but that’s just how it is
There is still a significant gap between design and procurement; sometimes it’s as if people on the Moon are talking to those on Mars. I’m 100% sure President Ming doesn’t understand what we’re talking about.
Although I am a sophomore, I am not very familiar with forums, so I only pay attention to the Piping and Valves section. I don’t know about other locations
Bro Zhao, who specializes in elbows, has been dealing with valves all along. Boyirensheng – don’t you know him? :o
It’s someone Brother Zhao knows; the one who offers one-on-one services is someone I’m not familiar with