flange dn32

When they talk about the dn32 flange, many people immediately imagine something simple, ordinary. Like, small diameter, there shouldn't be any problems. But it is precisely in these seemingly standard positions that pitfalls lie, which emerge during installation or, worse, during operation. I went through this myself more than once.

Why is DN32 not just an inch and a quarter pipe?

The first thing you encounter is confusion in standards. The customer sends a request: “need dn32 flange?” You open the drawing, and there is an outline according to GOST 33259. Or, for example, according to ASME B16.5 Class 150. And these are completely different products in terms of geometry, especially in the thickness and diameter of the centers of the holes. If you make a mistake and install the wrong one, docking will become a headache.

Here it is important to work with a manufacturer who keeps all these differences in his head and in his catalogs. For example, I have repeatedly asked for such “little things” to the siteShanxi Hongkai Forging Co.,Ltd. Their specifications clearly differentiate products according to different standards, which saves a lot of time. Their website -hkflange.ru- in this regard, it is quite informative; you can quickly navigate by standard sizes.

And one more thing about the material. For DN32, regular carbon steel, say St20, is often ordered. But if the environment is aggressive, even in such a small diameter you should immediately look towards alloy steels such as 09G2S or 12Х18Н10Т. It would seem like a small thing, but if you don’t lay it down at the ordering stage, it will be more expensive to redo it later.

Experience with sealing surfaces and real jambs

The most painful lesson I learned about five years ago was related to a batch of DN32 flanges. The order was urgent, we took what was in stock from one supplier. According to the passports, everything is smooth: steel, dimensions. But during pressure testing the line began to leak along the flange connections.

They began to take it apart. It turned out that the problem was with the type of sealing surface. We needed flanges with a raised face (RF), but they came with a smooth face (FF). The difference is tenths of a millimeter in height, but for a paronite gasket this turned out to be critical. It simply did not cover the entire area and “undermined”. I had to remove the entire batch and wait for the correct ones. Since then, the first question in the technical specifications for me was not only DN and pressure, but also the type of surface.

By the way,Shanxi Hongkai Forging Co.,LtdThis is clearly stated in the product description - butt welded flanges, flat, with different types of designs. For a quick repair, we then just took dn32 flanges from them with a projection in accordance with GOST 33259, and the issue was closed. It is important that they do both according to GOST and ASME, which is often a lifesaver for projects with imported equipment.

Installation subtleties that the instructions are silent about

It would seem that it would be so complicated: I welded two dn32 flanges to the pipelines, tightened them with studs - and it was done. But no. Especially in tight channels or on multi-level overpasses. People often forget about aligning the holes for the studs before the final tack. If you grab the flange “as is” without aligning the holes with the mating part, then you won’t be able to insert the pin. You will have to heat it and turn it, and this is an unscheduled thermal shock for the metal.

Another practical point is tightening. For DN32, smaller wrenches are often used, and there is a temptation to hold out “from the heart”. This is a mistake. Over-tightening leads to compression of the gasket and, paradoxically, to future leakage. You need precise torque, using a torque wrench. At one site we even compiled a simple reminder for plumbers on tightening torques for different DNs, including oursflange dn32. The number of incidents has decreased noticeably.

And yes, about thermal expansion. On short straight sections with DN32 it is not so critical, but if the flange pair is located at the transition between the fixed support and the compensator, the correct clearance for compression/tension must be left. I saw how, due to its absence, the studs burst after the first warm-up of the line.

When you need non-standard: going beyond the catalog

There are situations where the standard dn32 flange is not suitable. For example, you need a transition from DN32 to DN50, but not a welded one, but a flanged one, so that you can disconnect it. Or a flange with a non-standard arrangement of holes for fasteners is required due to its proximity to the structure.

This is where the ability to manufacture according to customer drawings is important. From the company descriptionShanxi Hongkai Forging Co.,Ltdit is clear that they offer it. We once ordered a blind flange (plug) from them for DN32, but with an additional drainage fitting on the side surface. They did it without any problems, according to our sketch. This greatly simplified the design of the cut-off unit.

The main thing in such cases is to provide the most detailed drawing with tolerances. And don’t expect a non-standard product to be ready in three days. But the presence of such an option from a manufacturer who mainly works with forgings and forged flanges, such asHongkai Forging, speaks of flexibility. They are positioned as a manufacturer in one of the forging centers of China, and for non-standard forgings this is logical.

Choosing a supplier: price versus reliability

At the beginning of my career I often chased a low price. I found the cheapest supplier for dn32 flanges - and good. Until I encountered the fact that the batch included products with microcracks in the body of the forging. Not visible visually, only after magnetic particle testing. It’s good that they checked it randomly before installing it on a critical unit.

Therefore, now the key factor for me is not so much the price, but the predictability of quality and technical support. So that you can clarify the material, get a certificate with real, and not “paper” ones. mechanical properties. When a manufacturer, like the company mentioned, directly declares work in accordance with GOST, ASME, EN, this is already some guarantee that he understands the requirements.

My conclusion is this: the dn32 flange is not just a consumable. This is a full-fledged element of the system, on which its tightness and safety depend. There are no trifles here. You need to clearly know the environment parameters, standard, connection type. And work with those who understand this at the level of manufacturing technology, and do not just resell hardware from the nearest warehouse. Actually, this is what normal work, without rush jobs and complaints, is based on.