316SS fittinsg on Carbon steel, offshore environment - Hydraulic hose
316SS fittinsg on Carbon steel, offshore environment - Hydraulic hose
(OP)
Hi Guys,
Have done bit of a search but need some help.
We are currently looking at a project where we will be changing out some existing hydraulic and utility hoses on a offshore facility (located in tropical zone of southenr hemisphere)
Generally speaking every hose we supply will be supplied with 316SS hose end fittings attached. In this case the area we are going to still has the as OEM hoses with plated steel fittings in place. We have to change it all out and document what we have done/what is there.
What I need to know is whether or not the potential for galvanic corrosion or cracking is high if we replace the OEM hoses for ones which have 316 hose ends?
Hoses are not submerged, but it is in a humid marine environment
Hose media is hydraulic oil.
Hose will be attached to various pumps and winches.
I understand that for galvanic corrosion you need two metals which are separated in the galvanic series - which 316 and carbon steel are
An electrolyte- in this case it will be the salty sea air atmosphere
And electrical contact - well the fittings will be screwed together and have face seals.
Looking at the above you would probably say no straight away, but the size of the fittings in comparison to the pumps and winches is very small.
If you thing about a 9/16" JIC fitting as apposed to large hydraulic pumps, winches, cranes and the like. Even the larger hoses (2") are small in comparison to what they are connecting to.
Will this small cathode to anode ratio be enough to have corrosion at a level whee you would consider it negligible?
And is there any references that you know off that I can use as backing for the argument to use 316 hose fittings in place of plated steel?
At the end of the day if plated steel is required that is what we will supply, but I hate sending anything less than 316 offshore. 316 is easier to work with, doesn't need protective covering and such, and there is no issues in storage of the hoses before they are fitted – the plated steel hoses will corrode within days if not fitted and wrapped, its quite amazing to see carbon steel and 304ss grade perish so quick out there.
I know of other sites that do this on a regular basis and I have yet to hear a report of any problems, most guys I speak to say the benefits of the 316 outweighs any negatives, but this particular new customer needs us to build a case for it before we proceed.
Any Help would be much appriciated.
Have done bit of a search but need some help.
We are currently looking at a project where we will be changing out some existing hydraulic and utility hoses on a offshore facility (located in tropical zone of southenr hemisphere)
Generally speaking every hose we supply will be supplied with 316SS hose end fittings attached. In this case the area we are going to still has the as OEM hoses with plated steel fittings in place. We have to change it all out and document what we have done/what is there.
What I need to know is whether or not the potential for galvanic corrosion or cracking is high if we replace the OEM hoses for ones which have 316 hose ends?
Hoses are not submerged, but it is in a humid marine environment
Hose media is hydraulic oil.
Hose will be attached to various pumps and winches.
I understand that for galvanic corrosion you need two metals which are separated in the galvanic series - which 316 and carbon steel are
An electrolyte- in this case it will be the salty sea air atmosphere
And electrical contact - well the fittings will be screwed together and have face seals.
Looking at the above you would probably say no straight away, but the size of the fittings in comparison to the pumps and winches is very small.
If you thing about a 9/16" JIC fitting as apposed to large hydraulic pumps, winches, cranes and the like. Even the larger hoses (2") are small in comparison to what they are connecting to.
Will this small cathode to anode ratio be enough to have corrosion at a level whee you would consider it negligible?
And is there any references that you know off that I can use as backing for the argument to use 316 hose fittings in place of plated steel?
At the end of the day if plated steel is required that is what we will supply, but I hate sending anything less than 316 offshore. 316 is easier to work with, doesn't need protective covering and such, and there is no issues in storage of the hoses before they are fitted – the plated steel hoses will corrode within days if not fitted and wrapped, its quite amazing to see carbon steel and 304ss grade perish so quick out there.
I know of other sites that do this on a regular basis and I have yet to hear a report of any problems, most guys I speak to say the benefits of the 316 outweighs any negatives, but this particular new customer needs us to build a case for it before we proceed.
Any Help would be much appriciated.





RE: 316SS fittinsg on Carbon steel, offshore environment - Hydraulic hose
Its easy to google the basics of galvanic corrosion- its also an area effect of the cathode(noncorroding) to anode (corroding metal) where the greater the ratio the worse- there is more technical information but is more complicated.
RE: 316SS fittinsg on Carbon steel, offshore environment - Hydraulic hose
I have been looking up a bit on galvanic and bimetallic corrosion, but I cant find anything that specifically lists 316/carbon steel in environments similar to where we operate.
I have found some stuff on stainless steel and carbon steel mesh being welded together in high salt environments for use in concrete driveways, which suggests that in that circumstance it is ok.
And a military spec which also suggests that the coupling being ok where the area of the ss is small in comparison to the carbon steel.
The National Physical Laboratory also has a good reference in their "Guide to Good practice in corrosion control, Bimetallic Corrosion", but again I am looking for some more evidence or reference with specific reference to 316SS/carbon steel
The other issue would be crevice cracking? But from what I have seen that should be ok as well, esp if they use a denzo seal over the end of the threaded section - which they tend to do.
RE: 316SS fittinsg on Carbon steel, offshore environment - Hydraulic hose
Does anyone know if PTFE fastener coatings can be used for pipe threads?