Installation of steam pipeline supports
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Hello everyone, I have a question: are there any specific instructions stating that steam supports cannot be lifted using screws? For one of our projects, the maximum steam pressure is 0.8 Mpa. We plan to install rigid supports (10m long) at each girder, and we intend to use screw hoists for lifting between the girders. However, the client has now stated that screw hoists are not allowed for the steam pipes, as they can cause lateral displacement (in the X and Y axes). Since many of our previous projects used lead screws, does that mean everything we did before was incorrect? Thank you!
We also never use lifting rods for our steam pipes. A technician once said they shouldn’t be used, but I’ve never found any regulations stating that they are prohibited. It’s better not to use them, as there are stress issues with steam pipes, so it’s better to be cautious.
Steam pipes require stress flexibility analysis, and spring supports should be installed where necessary. Try to use brackets instead of hangers.
Steam pipes are mainly subject to water hammer effects, which cause slight displacement and vibration in the pipes; selecting sliding supports should meet the owner’s requirements.
Thank you all for your replies. At present, we construct fixed brackets at the locations indicated on the design drawings, while sliding brackets are used in all other areas. In previous projects, sliding brackets were installed using screw rods for suspension; I would like to ask if anyone knows where such a method of suspension with screw rods comes from
Of course, hangers can be used, and screw jacks are also quite common. However, it’s a problem if screw jacks are used for all types of sliding movements – the piping system becomes too flexible and unstable, and accidents can easily occur in the event of water hammer or vibrations.
Steam pipes require stress flexibility analysis
This issue cannot be addressed in absolute terms; different industries have different practices. The chemical industry does not recommend the use of hangers, but in the power industry, hangers are commonly used for steam pipes – I saw this in a power plant in the southwest before.
The Northwest Electric Power Design Institute has a support and hanger design manual, which is now available online; it contains many different types of hangers. There is also no rule prohibiting its use. Moreover, rigid hangers allow for a 3° deviation, while spring hangers permit a 4° deviation; relevant details can be found in Chapter 8, 8.1.1-6 of DL/T5054-2016.
In my opinion, from the perspective of on-site use, hangers can easily cause pipe vibration; a large domestic design institute has even stipulated that their use is not allowed. Regarding steam pipelines, I personally believe that it is not advisable to use hangers. During the heating process, two-phase flow can occur in steam pipelines, which exerts certain stress on the pipelines (as some people have also mentioned this issue), posing a certain safety risk.
Additionally, I have another question for everyone: does the condensate pipe used for humidification in air handling units, which relies on steam for humidification, need to be installed using the same support methods as steam pipes? That is, by using fixed brackets and sliding brackets? The owner now wants us to use it, and I have not yet found any specifications or reference manuals that state it is not necessary. Has any friend encountered this?