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as calcium carbonate (CaCO3 Na4
[Q^M I[ Q\ Q[ [\WQKPQWUM\ZQK IVL \PMZM UIa be a disposal issue too. But the scale will dissolve readily in EDTA solutions.
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A
If you want to inhibit BaSO4 some polymers might work if not
too supersaturated. The best way to ensure that BaSO4
doesn't form is to soften the water.
If the system is an oil production NIKQTQ\a UMKPIVQKIT ZMUW^IT UIa be the only option available for removing BaSO4
scale.
Proper technique for dissolved oxygen measurement
was just experimenting with a new dissolved oxygen (DO)
Q
centration is being influenced by the NACE International, Vol. 51, No. 4
A
meter. A question of proper technique has arisen that was not covered in the UIV]IT 1 _IV\ \W UMI[]ZM \PM W`aOMV concentration as a function of depth in a large tank of quiet seawater (6 by 9 by 6 m deep). If I lower the DO meter to the desired depth and wait for it to "stabi- TQbM º \PM XZWJM KWV[]UM[ \PM TWKIT W`a- gen and the meter reading continues to drop in value. I suppose I could use it to UMI[]ZM W`aOMV LQNN][QWV ZI\M[ QN 1 _MZM KTM^MZ 1N 1 ¹_QOOTMº \PM XZWJM Q\ LWM[ read a constant value that does not ap- pear to change as a function of depth within the tank. Any suggestions?
You seem to have answered your own question. If you don't move \PM XZWJM \PM UMI[]ZMUMV\ Q[ not valid because the local con-
April 2012 MATERIALS PERFORMANCE 13
This might be a ques- tion for an oceanogra- pher instead of a cor- rosion expert, but I
You might try diameinetetraa- cedic acid (EDTA) at pH 8 to 10; 3.87 ppm of EDTA-sodium tet- ramer (Na4
) for every ppm of Ba ). EDTA-
_QTT LW R][\ ÅVM J]\ Q\ KIV JM M`XMV-
XZWJM
A
Most DO meters require flow across the sensing elements. This can either be achieved by towing them while at sea or using a small
IZM \ZaQVO \W XZW^M IV M`XMZQUMV\ Q[ IV- IMZWJQK 1\¼[ ZI\PMZ TM[[ WN I XZWJTMU WV [Ia I [MI_I\MZ QVRMK\QWV [a[\MU
Editor's Note: Additional MP Blog items appear in the individual technical sections: cathodic & anodic protection (p. 29) and coatings & linings (p. 40).