Regarding forged pipes
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According to the regulations, fittings with an outer diameter of 89 mm or less can be exempt from reinforcement calculations if certain conditions are met. I saw that the drawings prepared by the design institute meet these conditions for exemption from reinforcement calculations due to opening, but they used thick-walled forged pipes – was this done to account for the stresses on the pipes? May I ask how the wall thickness is generally specified?
The wall thickness is determined based on the design pressure, temperature, corrosion allowance, opening reinforcement calculations, and minimum wall thickness requirements. Some ordinary pipes cannot meet the above requirements; only those made of forged pipes can satisfy them.
It must meet the conditions specified in GB150 regarding the exemption from reinforcement calculations that require openings. I asked others about this, and some said that for all connections with a diameter of DN100 or less, forged pipes must be used, in order to take into account pipeline stress and vibrations
This post was last edited by 413343962 on 2016-7-29 at 14:51. Pipe stress needs to be taken into consideration; sometimes the stress on pipes is high, and ordinary pipes are not sufficient to handle it – forged pipes are required in such cases. Regarding pipe vibration, it comes down to empirical values; if such requirements exist, then forged pipes should be used. The 150 exemption applies to pipes under certain conditions; for example, no exemption is available for nozzles on the end caps, nor for inclined pipes on the cylinder body.
1. It’s both right and wrong. 2. It depends on the specific circumstances; a one-size-fits-all approach is highly unprofessional. When considering pipe stress, data is essential – pipe stress can vary in magnitude, and it’s necessary to know exactly what those values are as well as whether the calculation results are satisfactory. 3. Some use forged pipes, such as the LWN type; not all equipment with diameters of less than 2–3\" uses forged pipes
This post was last edited by zhangjuhua on 2016-7-29 at 20:11. If the pressure is greater than 2.5 MPa, reinforcement is necessary. It seems that for connections with a wall thickness of less than 8 mm and a diameter of no more than 50 mm, steel rods can be used for fabrication
I am aware of these restrictions, and everything I mentioned meets the requirements. The pipe fittings specified in the design drawings have a minimum wall thickness of 8 mm for DN25 pipes; forged pipes are used for this reason precisely due to their wall thickness, rather than because of differences in the structure of forged parts compared to pipe fittings or bars.
The issue is as follows: most design institutes or engineering companies in the country have their own set of standard drawings for equipment rooms, which specify the design pressure, design temperature, and the range of corrosion allowances for materials such as carbon steel, low-alloy steel, and stainless steel. Based on these standards, standard designs are provided for fittings with a diameter of less than 89 mm in the form of forged fittings, which can be directly selected as long as they fall within the specified ranges. Write down the standard drawing number. Those outside the range shall be designed by the designer themselves.