Hydrotesting with an oxygen scavenger

[flashpipe]

If there is a more appropriate forum, please send me that way.
We are a petroleum engineering and manufacturing company. We are manufacturing pipe for a client and must hydrotest each pipe using ammonium bisulfite in the water as an oxygen scavenger. Since our environmental permit does not permit us to release the hydrotest water into the environment in this case, we are developing plans to recycle the water during the test to reduce the volume to be disposed of. Since we have not performed this procedure before, I have several questions:
1. Can we add all of the ammonium bisulfite to the water prior to the start of the first test?
2. Is it necessary to monitor the concentration of ammonium bisulfite during the hydrotesting procedure? If so, what is the most cost effective method to do this?
3. Is it better to monitor the O2 level in the water with each set of pipes we hydrotest?
Your help is appreciated.

 

[BarrieC]

Sounds like your water treatment plant need some attention if you have to use a such a high dosing rate. Either you are not de-oxygenating the water or your drawing air into your system from somewhere.
Regards,
Barriec

 

[PeterCl]

flashpipe

ammonium bisulphite is commonly used as an oxygen scavenger in carbon steel submarine pipelines filled with seawater, prior to hydrotest.

If you're in a pipe mill, are hydrotesting each joint as part of the manufacturing process, have access to fresh water I'd start with a dispensation request to delete the requirement for chemical treatment, on environmental grounds.

If you have to use ammonium bisulphite please get some local support from the chemical suppliers, they should be able to advise appropriate treatment rates for the residency period, how to monitor effectiveness, re-use of treated water & secondary treatment before re-use. This stuff consumes oxygen and can be dangerous in confined spaces. You also need suitable spill procedures. Water treated with an excessive amount of ammonium bisulphite can be corrosive to carbon steels.

Good Luck.

PeterCl