passivation of new piping
passivation of new piping
(OP)
Gentlemen,
I have a very simple question. Traditionally, when constructing a piping system made of stainless steel (316L in this application), is the internal side of the piping passivated before use. I know that the outside of the pipe is to be pickled and passivated, but should the inside of the pipe be flushed with some pickling or passivation solution? This is a general question and not specific to any particular industry.
I have a very simple question. Traditionally, when constructing a piping system made of stainless steel (316L in this application), is the internal side of the piping passivated before use. I know that the outside of the pipe is to be pickled and passivated, but should the inside of the pipe be flushed with some pickling or passivation solution? This is a general question and not specific to any particular industry.





RE: passivation of new piping
a) how good the fabrication quality control was
b) what will be going down the inside of the pipe in operation
c) what are the consequences of corrosion
d) what was in the specification
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: passivation of new piping
a) The fabrication quality control is very good. Full visual inspection during fabrication, radiography and hydrotest after construction in accordance with B31.3 requirements.
b) There really should be nothing going on inside the pipe except transferring polymer and water from the injection facility into the well heads. Keep in mind, this polymer basically makes the water a bit more viscous.
c) Consequence of corrosion would be a leak in a moderatley high pressure line (approximately 50 bar). Since there are no toxic chemicals, hydrocarbons, lethal implications or anything similar, the risk of a release is very minimal. Remember, this is in essence water lines.
d) We are working off customer specifications which required external cleaning of the welds, but nothing mentioning internal passivation.
This whole situation is because of corrosion we are seeing in the pipes due to water which was left in the pipe for several months. After testing some pumps and equipment, we did not drain the water. The water had some chlorides and H2S, along with other chemicals typical with well water. The pipes sat with water in the hot Middle Eastern sun (Oman) for upwards of 7 months while another portion of the plant was being constructed. Over time, the pipes developed pits which worked their way into holes. Metallurgical review has stated this is typical of fresh water contamination in stainless steel and even if the pipes had been internally passivated, the leaks would still have occurred.
The basis for my question is because there is specualtion that the construction company should have passivated the pipes internally. They claim that it is not standard practice unless it is required by specification. For example the food industry or in the service of a specialty chemical. What I'm trying to do is take blame from the construction company and assign it to where it should exist, with the company not following preservation procedures after commissioning and testing of equipment. I was hoping to gauge a sampling of construction procedures to see how often internal passivation is done. For the record, in my 21 years as a quality manager in large construction projects, I have never passivated internal pipes, nor have seen it specified.
Regards gentlemen. Any input would be appreciated.
RE: passivation of new piping
RE: passivation of new piping
(1) We generally use 304L or 316L when welds are involved.
(2) Since steel tools may have been used in production, we passivate in and out.
(3) Even though the L grades tend to minimize the possibility of iron carbide precipitation at the grain boundaries, it's better to be safe and take care of it.
RE: passivation of new piping
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: passivation of new piping
RE: passivation of new piping
As stated above SS piping doesn't like exposure to stagnant water especially contaminated with or without the above mentioned bacteria
RE: passivation of new piping
http://ww
regarding the water inside the pipe for several months it could be a microbiological corrosion
http://ww
S
Corrosion Prevention & Corrosion Control
RE: passivation of new piping
Don't worry - until you went public with the problem, I doubt if anyone beyond Muscat had heard of it. I can see that all is still 'normal' there!
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: passivation of new piping
Strider 6, yes you are correct for the outside of the piping at the weld joints, however it is not so easy when dealing with long pipe runs to do the same internally. Also, we determined the corrosion was not based on MIC, although that was one of the initial concerns. Our metallurgist has also stated that we would have most likely seen the same corrosion activity if totally clean, potable water had been used. The additional corrodents only sped up the process.
RE: passivation of new piping
The Contractor is probably used to being under scrutiny - they'll not suffer for it.
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04