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Recommended de-watering for non-piggable piping after hydro test

Recommended de-watering for non-piggable piping after hydro test

Recommended de-watering for non-piggable piping after hydro test

(OP)
Hi all,
for piping systems that may not be piggable or does not have the equipement set up for pigging, what ways can you recommend for de-watering those kinds of systems after hydrostatic testing.

is turning on the well to have the wellhead flow stream displace the water a good idea?
Can air compressors be used?
what about cases where you have low-end traps, e.g. P traps or U leg in the system...

Any suggestions..

BTW, there are no low end drains installled
THANKS FOR YOUR HELP

As much as possible, do it right the first time...

RE: Recommended de-watering for non-piggable piping after hydro test

In the words of the old TV commercial "you're hosed Tommy".  Why anyone builds non-piggable lines is beyond me (with the pigging valves that came on the market in the last 20 years, there really isn't a valid reason for small-inch lines outside of a plant to not be piggable).  Also, building a line without ANY way to get hydrotest (let alone ongoing condensation) out is way on the wrong side of "marginal".

Having said all that, back before I got the pigging religion (after having repeated corrosion failures in small non-piggable laterals) I would unbolt a flange on one end of the tested system and shove in a pig.  Then I'd bolt on a blind with a fitting for an air compressor and open the far end.  Compressed air pushing a foam pig will dry up most lines in 2-3 runs (the foam pig may not last more than 1 run, have several on hand).  

That works for lines that are non-piggable due to lacking pigging equipment.  If it is non-piggable because of barred tees or comming into the branch on a tee or some other silliness, then my original statement holds--you're hosed.  Trying to evaporate the water with air will take a while (weeks), and you don't have a lot of other options.

David

RE: Recommended de-watering for non-piggable piping after hydro test

If you have a lot of water in the well stream itself, why bother drying the pipeline.  Fill at 10 fps or so and most of whatever is ahead of the stream to begin with will stay ahead of the stream.

If you just have to pig, as zdas says, unbolt a flange, or cut into the line and install temporary launchers and receivers.   

From "BigInch's Extremely simple theory of everything."

RE: Recommended de-watering for non-piggable piping after hydro test

How long will the system stand between hydrotest and commissioning? What was the water quality?  You can lose the line very easily before you even start up.  If it's a gas system, can the facilities at the other end cope with a big slug of water?  Will you get a hydrate scenario?

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04
 

RE: Recommended de-watering for non-piggable piping after hydro test

(OP)
Thanks all
@ Sjones: there's usually 1 day to 1 week between hydrotest and commissioning. The water quality is good from a silt, salinity, and PH standpoint. sometimes dry gas and other times mixture, but the first equipment downstream of the hydro test segment is usually a separator, and/or tank...

As much as possible, do it right the first time...

RE: Recommended de-watering for non-piggable piping after hydro test

For station piping, dried air is customary for us.  Open valve body bleed valves, drains, and determine how dry (what dewpoint temperature) you want to get to.

RE: Recommended de-watering for non-piggable piping after hydro test

(OP)
@DLiteE30: is your "dried air" suggestion with or without a pig?

As much as possible, do it right the first time...

RE: Recommended de-watering for non-piggable piping after hydro test

If you're in a gathering system, piping up from well to separator, your water's clean and with good PH, and you will be in service within one week, it doesn't seem like you will be losing any pipe due to corrosion or anything else.  Quality of the well stream isn't much of an issue before a separator, so no reason I know of to dry the line.  The separator is there to knock out water and other liquids coming from the well stream anyway.  Is the separator too small to take the residual water in the line, or ... something?

From "BigInch's Extremely simple theory of everything."

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