Is this Sour Service
Is this Sour Service
(OP)
We have a Pipe carrying water under pressure 15 Bar
The out side of the pipe is exposed to Sour Gas (pressure in MM of water coulum)
Is this coming under the scope of Sour service?
The out side of the pipe is exposed to Sour Gas (pressure in MM of water coulum)
Is this coming under the scope of Sour service?





RE: Is this Sour Service
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RE: Is this Sour Service
RE: Is this Sour Service
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdoweb/
RE: Is this Sour Service
The exposure of the water pipe to the sour gas does not qualify to be subject of the NACE MR0175, as per the Clause 7.1.1, due to the low partial pressure you have mentioned (assuming is less than 30 mm water column of H2S partial pressure and in absence or other contaminants, low ph, etc..). However, if the partial pressure is above the limit of 30 mm water column, then your pipe may qualify for the sour service classification.
Also, for my curiosity, where is that few mm H2S partial pressure coming from, obviously not from the atmospheric environment / pressure...
cheers,
gr2vessels
RE: Is this Sour Service
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdoweb/
RE: Is this Sour Service
S,
Corrosion Protection & Corrosion Control
RE: Is this Sour Service
RE: Is this Sour Service
RE: Is this Sour Service
As above, if the H2S partial pressure exceeds approx. 30 mm water column, then the environment is required to be classified as sour service. As you know, the effects of H2S on steels could be classified as those that require external stress, such as sulphide stress cracking (SSC), and those that do not, such as hydrogen induced cracking (HIC), and corrosion. The presence of carbon dioxide in the flue gas together with the sour environment tends to increase the corrosion rate in the steel; it may also increase the susceptibility of the steel to both SSC and HIC, with the effect on HIC being more pronounced. The fact that the sour environment is on the low pressure side of the stressed pipe makes no difference, the damage will occur, depending obviously on the extent of exposure to the flue gas components, pressure and temperature, the pipe material compliance with the NACE requirements (0175 or 0103 as applicable).
cheers,
gr2vessels
RE: Is this Sour Service
So do we insist on Hardness below the Finned Tube Resistaance welds? (If indeed the Partial pressure is in excessof 30 mm of water column)
RE: Is this Sour Service
gr2vessels
RE: Is this Sour Service
It is the coil (Which contains the water) that gets pressure tested with all the vigour, whilst the shell side, which is essentially considered structure with insulation/refractory does not get tested for leaks from gasket joints. This is the industrial reality.
There seem to be no guideline for this at all.
The point i am trying to make is, if the flue gasses that exert parrtial pressure greater than 30PPM of water column due to H2S, should there not be leak test for this joints.