Definition of small takeover
Thread Content
I would like to ask for a clear definition of the small nozzles on pressure vessels and pipelines.
There is no standard with such terms and definitions, it’s up to the poster to think ;P
In the new version of the special equipment catalog, those with a diameter less than 50 are no longer pressure pipes.
This post was last edited by xlxuiin on 2018-4-9 16:32. Where did it become clear that "small nozzles" do not belong to the category of pressure pipelines? ? ? ? ? ? ? ? ? ? ? The small nozzle of the pressure vessel and pressure pipeline of the petrochemical plant is located inside the first valve of the equipment or pipeline nozzle. It has the characteristics of small diameter and thin pipe wall. ； Small pipes mainly refer to the pipes connecting the pressure vessels, pressure pipes and valves, drainage guides, and liquid level gauges of petrochemical plants.
2014 Edition Special Equipment Catalog and 2016 Edition Solid Capacity Regulations
@xlxuiin: During the design stage, the wall thickness of this small nozzle can be thickened, and two angle bars or more suitable supports can be provided.； In the new version of the solid capacity regulations, small nozzles less than 250 are non-main pressure components and are not major repair items, and the corresponding qualifications are not necessary. Combining the above two points with the definition of pressure pipeline, the problem of small nozzle seems to be simpler.
There seems to be a way to make small takeovers simpler
Small pipes include pressure pipes, sampling pipes, trap pipes, vent valve pipes, low discharge valve pipes, thermowells, etc.
The examination rules are for those under 25. Generally, the welder test is about 50 pipes, which can cover the specifications of 25 and above. But once you meet the pipes below 25, you have to take the additional test, which is the so-called small pipe.
The structure of half-pipe joints, branch pipe seats and branch pipes of DN50 and below that are connected by welding and directly opening holes in the equipment body or pipes are collectively called small nozzles. like: Pipes connected to the container body or pipelines such as safety accessories, instruments (thermocouples, pressure gauges, liquid level gauges, flow meters), drainage guides, steam sweep lines, exhaust valves and jumpers, etc., generally within the first valve.