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Cleaning of SS pipes
(-----) 2006
After welding of small diameter of SS pipes we notice the HAZ black in colour. External side we go for pick/passivation. Is there any solution for internal cleaning where areas are not reached manually? or any other solution to avoid this black colour on internal sides of ss pipes.
Sreenathgatewall - Abudhabi, UAE
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First of three simultaneous responses -- 2006
Use an inert gas purge inside the pipes during welding. Avoid pickling the insides; it roughens surfaces and is very difficult to inspect. Clean and passivate the insides by pumping solutions & rinsewater. Blow dry with clean air. ASTM ASTM A380 [link is to the practice at TechStreet] gives useful information.
Ken Vlach [dec]- Goleta, California

Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
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Second of three simultaneous responses -- 2006
Setting up a slow purge of nitrogen or preferably argon thru the tube will significantly reduce the black oxide formed.
James Watts- Navarre, Florida
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Third of three simultaneous responses -- 2006
Purchase specification ASTM A967 / A967M [affil. link to spec at Techstreet] and recommended practice ASTM A380 [link is to the practice at TechStreet] and take you pick from multiple methods of cleaning up your welds.
Joseph Lockrem- Indianapolis, Indiana, USA
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