Are there any differences between butt-welded and socket-welded flanges for steel pipes lined with plastic or PTFE?
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Are there any differences between butt-welded and socket-welded flanges for steel pipes lined with plastic or PTFE?
The flanges for steel-lined plastic or steel-lined PTFE pipes come in two types: slip-on flanges and butt-weld flanges, and their main difference lies in the method of connection. A flat-weld flange refers to a flange whose two mating surfaces are flat; when in use, the pipes must first be welded together before being connected using bolts. The advantage of this flange connection is its ease of processing and maintenance, but it requires more time and equipment for installation. A butt weld flange refers to a flange whose mating surfaces are male and female, with the pipe and the flange being connected by welding. The advantage of this flange connection is its good sealing performance and resistance to high pressures; it is suitable for use in harsh environments such as high and low temperatures, as well as high and low pressures. However, this flange connection requires a higher level of technical skill and more sophisticated equipment. Therefore, when choosing a flat-face flange or a butt-weld flange, it is necessary to make the selection based on the actual circumstances. -
Previously, I was only exposed to two types of flanges for PTFE-lined steel pipes: one type has the flange pre-welded, with the entire pipe, including the flange, being lined with PTFE; in such cases, the flange is usually of the plate-type flat-weld type. The other type involves lining the pipe with PTFE separately, using a loose-flange design, and welding is generally not performed on pipes that already have a PTFE lining, as the high temperatures associated with welding can damage the PTFE coating.
Can pipes with a steel lining and higher-grade butt-welded flanges be used for owners dealing with hazardous media?
Of course it’s possible; the pipeline is first welded with flanges and then lined, and it has nothing to do with what kind of flanges are used
It’s possible to do it; once the flanges are welded, the lining process is the same