High point vent and Low point drain

Date 03-18-2007 08:18

They are used for hydrotesting on pipelines and piping systems. A high point vent allows air to escape when filling the pipeline with water and the drain at the low point is for...well draining.

Air pockets ina pipe when hydrotesting will cause instability in the pressure gauges.

By sabir

Date 03-18-2007 08:37

So this High point vents and Low point drain comes on the pipe or it comes on the Header or Receiver used for hydro testing. In case if it is on the pipe, then how it is fitted on to the pipe and where. Will it be taken off from the pipe after the hydro testing?

By NDTIII

Date 03-18-2007 09:25

They are usually welded to the pipe using a welding boss or some kind of fitting and are usually about 3/4" to 1" diameter with a socket weld and a valve. No they will remain part of the line.

By sabir

Date 03-18-2007 12:31

Should we consider this fitting as part of BOM or MTO.

By NDTIII

Date 03-19-2007 12:06

I'm not sure what you mean by BOM or MTO.

By js55

Date 03-19-2007 13:52

If there are no 'vents' to accomodate a hydrotest, and a hydro is specified, you have two choices it seems to me. Request a revision to the drawings which will allow the installation of some sort of vent fitting(which is most likely an oversight on the part of engineering), in which case it would now be a part of the MTO/BOM. Or, you can vent through your hydro test head, which is generally either flange bolted to the pipe end or welded.

By js55

Date 03-19-2007 13:54

Which choice you make would depend on how much hydrotesting you plan on doing on the future. If this is an isloated case I would push for a drawing revision. If you anticipate doing lots of hydro's I would build a test head.

By dbigkahunna (****)

Date 03-20-2007 16:57

Also low point drains are useful in removing accumulated water in low spots before freeze up in cold climates. Flanges can be used as vents and drains for hydro-test. However, when you break a flange, you have a chance of leaking when the line is put in service. Or if one of the monkeys forgets to tighten the durn thing(s)